Solving Fermi Paradox with logic not math.

[zerospeaks]

So, I was just thinking to myself and thought I would run this by you guys.

Using logic to solve "Where are they?"

1.If life exists here, it should exist elswhere.
2. If intelligent life exists it should exist elswhere.
3. Given the age of the universe some intelligent life should be billions of years old.
4. Those civilizations should have figured out ways around the vast distance limitations of the universe.
5. Intelligent civilizations explore and make maps.
6. Given a million years some intelligent civilizations should have mapped the entire universe.
7. They should know we are here.
8. So therefore, they choose NOT to make contact with us.

Was Roddenberry right all along? Would such an advanced species refrain from contacting us because we are still in the "stupid monkey" stage?
If they did land and say hey, we would most likely become a cargo cult. So I think they would know this and stay away.

So is my logic sound? They know we are here and leave us alone to develop.

This of course is not something we can know for fact, but I think it is the most likely scenario using deductive reasoning.

--edit--
Also, IF this is true... Would they have an incentive to help us out if we were headed towards doom?

[Mark6]

Your point 4 does not follow. For all we know, lightspeed barrier is insurmountable. An existence of well-defined problem does NOT guarantee the existence of a solution.

Your point 3 is also rather weak. For all we know, technological civilization requires conditions (such as abundance of metals) which have existed only recently in universe's history.

[zerospeaks]

About point 4.

If they have been around for a billion or billions of years. It would be safe to assume that at one point or another they would need to escape the death of their sun. If not then they did not survive and such could be the fate of all civilizations and in that case everything I said is worthless.

[edd]

I don't think any of those premises are completely sound. Some are probable, some are plausible, others are improbable and one or two might be worse than that.

Even the probable I would not use to argue thus, on the basis of the exceptionally large volume of Elsewhere

[edd]

Double please delete

[BenBurch]

I think its simpler than that;

Interstellar travel is nearly impossible.

Few civilizations try it.

Fewer succeed.

Those that do succeed seldom repeat the attempt.

And civilizations don't last that long.

[zerospeaks]

But guys... are you forgetting that splitting the atom was hard until we figured out how to do it.

Maybe we can not breach the light barrier, but theoretically we could bypass it all together.

Flying was impossible until two bicycle mechanics had an idea...

[Guybrush Threepwood]

Flying was impossible until two bicycle mechanics had an idea...

Umm... you might want to look up 'birds', 'bats' and 'hot air balloons' on Wikipedia

[zerospeaks]

I think you get my point guybrush.
Something that is not feasible today may be tomorrow.

Also last I checked there is no reason why we can not travel the universe except one thing. We don't have an energy source big enough.
When you start talking about bending space-time, then you need an almost infinite amount of energy.
So it seems to me, the only thing we need to do is solve the energy problem. Shouldn't be too hard on a scale of a billion year old civilization.

[BenBurch]

Well, I spent some time (several years) looking into the problems of interstellar flight.

And I won an engineering competition with my paper, too!

And the cost is such that the Earth could not now build a probably-successful starship if we devoted the whole planet to the project.

You need to be able to send off an entire small, functioning technological civilization.

You need hospitals and schools and nurseries and farms and...

And you are limited in the safe speed to travel by the presence of interstellar debris.

5% of the speed of light is about all you can hope for with any safety, and at that you are pushing a huge erosion shield ahead of your spacecraft.

Its 100 years (with time to accelerate and decelerate) to Alpha Centauri. Much longer to any place likely to have a planet we can live on.

All of your machinery will have to be totally rebuilt several times in flight because machinery just does not function for hundreds of years on its own.

Just not likely to be something first on the agenda for any race not doomed by some foreseeable but inevitable calamity.

[zerospeaks]

I was sort of talking about other ways of travel, like wormholes and such... but I completely agree with your assessment of "normal" means of travel.
The best we could hope for is probes right now.

[BenBurch]

Trouble with any probe is keeping it running that long without the ability to re-build it.

[zerospeaks]

Didn't ya hear? V-GER was rebuilt by the aliens! :D

[JoeTheJuggler]

About point 4.

If they have been around for a billion or billions of years. It would be safe to assume that at one point or another they would need to escape the death of their sun. If not then they did not survive and such could be the fate of all civilizations and in that case everything I said is worthless.

I also reject premise 3 and premise 4. (If you're making a logical argument, you should specify premises and conclusions. 3 and 4 do not follow from 1 and 2, so they must be premises.)

The entire argument is easy enough to refute since it could also be used to determine whether our civilization exists. We know we do exist, yet evidence of our existence isn't ubiquitous in the galaxy. Here's the simplified version of the argument.

P1. If intelligent life exists, evidence of it must be ubiquitous in the galaxy.
P2. Evidence of ET intelligent life is not ubiquitous in the galaxy.
C. Therefore ET intelligent life does not exist.

The problem is obviously in P1. If we applied the argument to intelligent life on Earth:
P1. If intelligent life exists, evidence of it must be ubiquitous in the galaxy.
P2. Evidence of intelligent life on Earth is not ubiquitous in the galaxy.
C. Therefore intelligent life on Earth does not exist.

it's plain the problem is with P1.

By the way, the way you formulate the argument, you could just use point number 2 as a premise. If you accept that premise, then you are done. You only need to prove the existence of intelligent life on Earth in order to prove the existence of intelligence elsewhere.

[JoeTheJuggler]

Well, I spent some time (several years) looking into the problems of interstellar flight.

And I won an engineering competition with my paper, too!

And the cost is such that the Earth could not now build a probably-successful starship if we devoted the whole planet to the project.

Even so, to attack this argument it's enough to prove that we have not sent out these probes (or otherwise made evidence of our existence ubiquitous). We needn't even worry whether or not it's possible.

The argument is basically saying that the absence of ubiquitous evidence proves the non-existence of the intelligent civilization. Again, if we think of ourselves, that same argument would disprove our existence, yet here we are.

[Vorticity]

Trouble with any probe is keeping it running that long without the ability to re-build it.

Maybe. But not... necessarily. Consider Pioneer 6 (http://en.wikipedia.org/wiki/Pioneer_6,_7,_8,_and_9#Pioneer_6). Launched in 1965, last successful telemetry contact in 2000. This thing operated on its own for at least 35 years. Possibly longer, since we don't know if it's still operational now. And that's 1965 technology.

If such a device can operate for 35 years within our solar system with it's relatively high debris density, and at a distance of 0.8 AU from the Sun, it seems entirely plausible that a more advanced technology might operate for centuries in interstellar space.

Of course, you'd be going much faster, and presumably encountering a much higher mass per unit area per unit time of debris...

[zerospeaks]

Side question....

Why don't we stay in constant contact with all of the "old" probes?
Such as pioneer and voyager.

[JoeTheJuggler]

It could be that FTL travel is impossible.

It could also be that FTL travel is possible, but it's never economically feasible.

It could be possible and economically feasible, but no intelligent civilization lasts long enough to develop it.

It could be possible and feasible, and one or more intelligent civilization has or will last long enough to develop it, but none has been motivated to do it.

It could be possible and feasible and one or more intelligent civilization has or will last long enough to develop it and at least one has been motivated to do it, but they still haven't had enough time to spread throughout the entire galaxy.

It could be [repeat everything above] and they've had enough time to spread throughout the galaxy, but we just missed detecting their prove or signal by a mere million (or thousand or hundred or 10) years.

The fact is, the argument is severely flawed.

Any one of the points I raised is enough to show why absence of evidence in this case is not evidence of absence.

ETA: BTW, I've seen formulations of an argument based on Fermi's Paradox to "prove" the non-existence of ET intelligence that do not depend on the assumption of FTL travel. Instead, they just substitute time and argue that self-replicating probes or other evidence should by now be ubiquitous. All the same problems exist for that severely flawed argument as well.

At best it proves that no ET intelligent civilization has existed long enough and been motived to discover possible and economically feasible technology that would allow it to spread evidence of its existence throughout the entire galaxy such that we would be guaranteed not to miss it. . . .yet.

In other words, the argument proves nothing at all.

[JoeTheJuggler]

By the way, the way you formulate the argument, you could just use point number 2 as a premise. If you accept that premise, then you are done. You only need to prove the existence of intelligent life on Earth in order to prove the existence of intelligence elsewhere.

In case you didn't follow this point. The following argument would make most of the long listing of premises unnecessary:

P1. If intelligent life exists in one place, it exists elsewhere.
P2. Intelligent life exists on Earth.
C. Therefore it exists elsewhere.

This is a valid, but not sound argument. It's valid in that the conclusion follows from the premises, but it is not sound because P1 is not true. Nevertheless, it shows that if you accept 2, then you can do away with all the other premises in the "argument" in the OP.

[zerospeaks]

Then let us start with the premise

1. There are other intelligent alien life capable of interstellar travel.

would they be aware of us? Have we made enough of an impression?

IF they ARE aware of us, would they have any reason to make contact?

If we were doomed and they knew it, would they have an incentive to save us?

[Mark6]

I was sort of talking about other ways of travel, like wormholes and such...
Which is basically wishful thinking.

Before 1903 heavier-than-air flying was unfeasible, but certainly did not break any laws of physics. Before 1947 flying faster than sound was also unfeasible, but did not break any laws of physics. Traveling faster than light DOES break laws of physics. Traveling through wormholes, to the best of current knowledge, requires matter with negative mass. For which there is absolutely no evidence it exists or could ever be created.

As I said, existence of a well-defined problem does not guarantee existence of a solution.

As for "they must have escaped from their dying Sun at some point", two obvious rebuttals:

1. Does not follow. For all we know, no civilization ever survived death of its sun.

2. Given millions of years of warning available, a civilization might escape its dying sun without resorting to wormholes, or even to relativistic travel. Ability to do so does not imply it can contact or affect in any way a civilization thousands of light-years away (us).

[JoeTheJuggler]

So is my logic sound?

No.

To be sound, the argument must be valid (the conclusion follows logically from the premises) and the premises must all be true.

What you have presented doesn't even take the form of an argument. It's more a long list of premises, most of which are not true. As I've shown, if your point 2 were true, then you could just use our existence as a second premise and jump to the conclusion without all the rest.

[ben m]

I was sort of talking about other ways of travel, like wormholes and such... but I completely agree with your assessment of "normal" means of travel.
The best we could hope for is probes right now.


We don't know if wormholes even exist. If they don't exist at all---i.e. if the laws of physics forbid them---then 1,000,000 years of technology can't make them, nor 1,000,000,000 years, nor a trillion. They may just not exist.

It's like saying "In the future, we may use isolated, stabilized top quarks for high-density data storage."

[Vorticity]

Side question....

Why don't we stay in constant contact with all of the "old" probes?
Such as pioneer and voyager.

This is actually an interesting question. The answer for most of them is "they're broken now". For others, I think they don't bother to commit the deep space network resources necessary to receive telemetry because the scientific instruments on board the still-operational probes are either broken or obsolete. Also, the strengths of the signals from some of these things are too low at this point to locate without considerable effort.

However, it's interesting to list the fates of the Explorer, Pioneer, and Voyager probes (info mostly from wikipedia):


Explorer program: (http://en.wikipedia.org/wiki/Explorer_program)

Some failed to achieve orbit. Most transmitted data for a few months or years, and then stopped. Presumably they're "broken". Some notable exceptions:

IMP-8 - Still operational after 36 years. They occasionally download data as part of a long-time-base magnetosphere experiment.

Various other Explorer missions are less than 15 years old, and are indeed largely operational and in contact.


Pioneer program (http://en.wikipedia.org/wiki/Pioneer_program)

Same story: Some lost on launch. Most (a very good record, actually) launched, transmitted data for months/years, and then "broke". Notable exceptions:

Pioneer 6, 7, and 8 (http://en.wikipedia.org/wiki/Pioneer_6,_7,_8,_and_9) may very well still be operational, with last telemetry contact with each 10-15 years ago. I think it's just not worth the resources to track such weak signals.

Pioneer 9 failed in 1983, after an operating life of 15 years.

Pioneer 10: Interstellar. Last signal aquisition: 2003. May still be operational, but the signal is too weak to detect.

Pioneer 11: Interstellar. Last signal 1995. Batteries now too weak.

Pioneer 12 & 13 burned up in Venus' atmosphere.


Voyager program: (http://en.wikipedia.org/wiki/Voyager_Program)

NASA maintains contact with both Voyager 1 and 2 as they search for the Sun's heliopause (http://en.wikipedia.org/wiki/Heliosphere#Heliopause).


So, to answer your question: They DO maintain contact, whenever possible, practical, and useful.

[JoeTheJuggler]

Then let us start with the premise

1. There are other intelligent alien life capable of interstellar travel.


You can't start an argument by asserting a conclusion as true (that is "Begging the Question").

No argument you make based on a premise that isn't true can be sound, though it might be valid. Which is really only useful for testing the form of an argument and not for giving you true conclusions.

For example, the following argument is valid but not sound:

P1. If fish could fly, the would be birds.
P2. Exocoetidae are fish that can fly.
C. Exocoetidae are birds.

The form of the argument is fine, but it can tell you nothing about whether these fish are actually birds because it starts with a false premise.

[Trakar]

So, I was just thinking to myself and thought I would run this by you guys.

Using logic to solve "Where are they?"

1.If life exists here, it should exist elswhere.

What precise conditions are necessary for the formation of life? Can we state with any certainty that these conditions are repeated elsewhere?

2. If intelligent life exists it should exist elswhere.

Again, what precise conditions are necessary to evolve intelligent life? Can we state with any certainty that these conditions are repeated elsewhere?

3. Given the age of the universe some intelligent life should be billions of years old.

Given that we can answer the first two sets of questions, how long does it take the universe to generate the conditions predicated by those answers?

4. Those civilizations should have figured out ways around the vast distance limitations of the universe.

This presumes that there are "ways around" such and that such civilizations persist long enough to figure out such out.

BTW there may well be several big steps potentially between "intelligent" and technological, and even intelligent and "civilization," at least as we think of it. Intelligence combined with more advanced physical tools, or less manipulative extensions, might never need or develop technologies. Intelligent species without a pack or herd socialization instinct might never develop a civilization.

5. Intelligent civilizations explore and make maps.

In the history of our species, what evidence do you have that this is typical or normal for an intelligent civilization? Are their other possibilities?

6. Given a million years some intelligent civilizations should have mapped the entire universe.

by what means and reasoning do you derive this as a given, or even plausible likelihood?

7. They should know we are here.

highly dependent upon all the unproven assertions above, and that they recognize us as anything worth any especial notice.

8. So therefore, they choose NOT to make contact with us.

Perhaps (presuming all of the above), they simply don't consider communication with us to be a priority, or we simply aren't clever enough or advanced enough to recognize their attempts at communication for what it is.


Also, IF this is true... Would they have an incentive to help us out if we were headed towards doom?

Think of the nature shows on Discovery channel and NatGeo, you don't see too many instances of the camera crew saving the baby elephant from the pack of hunting lions.

[Trakar]

And the cost is such that the Earth could not now build a probably-successful starship if we devoted the whole planet to the project.

You need to be able to send off an entire small, functioning technological civilization.

You need hospitals and schools and nurseries and farms and...

And you are limited in the safe speed to travel by the presence of interstellar debris.

5% of the speed of light is about all you can hope for with any safety, and at that you are pushing a huge erosion shield ahead of your spacecraft.

Its 100 years (with time to accelerate and decelerate) to Alpha Centauri. Much longer to any place likely to have a planet we can live on.

All of your machinery will have to be totally rebuilt several times in flight because machinery just does not function for hundreds of years on its own.

Just not likely to be something first on the agenda for any race not doomed by some foreseeable but inevitable calamity.

Certainly, however, when you look at a mature, system wide civilization that may have been existing predominantly in orbital colonies for tens+ millenia, leaping a few light years from the outer edge of our Oort cloud to the outer edge of a passing star's Oort cloud isn't that big of a leap. Probably more direct missions, but even at this slower "spread by contamination" rate, you should be able to cover most of the galaxy in a few billion years. While that doesn't address the universe as a whole it should set us an upper limit on the number and age of galactic technological civs (of course, until we fully explore our Oort, we can't say for sure they aren't there already!)

[Ziggurat]

Interstellar travel is nearly impossible.

Few civilizations try it.

Indeed. And why would they? There's a concept that economists are very familiar with, sometimes called a "future discount rate". Basically, a benefit in the future is worth less than a benefit now. The farther in the future that benefit is, the less worth it has. If interstellar colonization is sufficiently costly and takes sufficiently long to perform, then it will not get done. And I think it is both. So our race will eventually go extinct: so what? It's not worth it to me to make the sacrifices necessary to prevent that distant event. I won't live to see either the extinction of my species, or even the success of colonization efforts.

In fact, I know of only one motivating factor which is likely to overcome such reluctance to invest the necessary resources: religion.

[roger]

The form of the argument is fine, but it can tell you nothing about whether these fish are actually birds because it starts with a false premise.
He's no longer trying to figure out if the premise is true, he's trying to figure out what would follow if the premise is true.

[roger]

Then let us start with the premise

1. There are other intelligent alien life capable of interstellar travel.

would they be aware of us? Have we made enough of an impression?

Why would they be? I don't think you appreciate the size of our galaxy, let alone the universe. There are roughly 100 billion stars in this galaxy. interstellar dust and such makes many sight lines impossible. It's 100,000 light years edge to edge, 3000 light years thick. Our puny electromagnetic radiation hasn't begun to have the chance to travel the thickness of the disk, let alone the breadth.

You need to posit FTL travel, FTL communication, a network of vessels so incredibly numerous that they would be in regular contact with the earth, essentially unlimited energy and materials (how do you build all those ships? How do you move them all? How do you feed all the lifeforms on them?). And then you have to posit all of those billions of ships wasting enormous levels of resources just randomly sampling the EM spectrum looking for intelligence.

It just doesn't add up.

[JoeTheJuggler]

If such a device can operate for 35 years within our solar system with it's relatively high debris density, and at a distance of 0.8 AU from the Sun, it seems entirely plausible that a more advanced technology might operate for centuries in interstellar space.

This argues that it's possible. The logic in zerospeaks' argument(s) requires that it is necessary. In other words, it assumes that whatever is technologically possible will necessarily be done. In fact, it requires that it already has been done sufficiently long ago so that such evidence is ubiquitous in the galaxy by now.

That's why I say arguing that something is technologically impossible goes way beyond what is needed to refute the argument. The fact that it may be impossible (or merely that it might not have been done even if intelligent civilizations exists) is sufficient to refute the argument.

[BenBurch]

Certainly, however, when you look at a mature, system wide civilization that may have been existing predominantly in orbital colonies for tens+ millenia, leaping a few light years from the outer edge of our Oort cloud to the outer edge of a passing star's Oort cloud isn't that big of a leap. Probably more direct missions, but even at this slower "spread by contamination" rate, you should be able to cover most of the galaxy in a few billion years. While that doesn't address the universe as a whole it should set us an upper limit on the number and age of galactic technological civs (of course, until we fully explore our Oort, we can't say for sure they aren't there already!)

Don't assume that the problem of a generational starship and the problem of colonizing the Oort cloud are much different. I don't think that either ourselves or our machines are likely to be able to do it with anything other than great expense. Most civilizations will likely find that expense far too big.

In fact, I find the idea of a "system wide civilization" to be a REAL stretch.

[zerospeaks]

It just doesn't add up.

So what your saying is, they wouldn't even care about us until we stood up and said "hi". ?

[JoeTheJuggler]

He's no longer trying to figure out if the premise is true, he's trying to figure out what would follow if the premise is true.

I understand, but he's also asking if his logic is sound. (He specifically said he wants to make a logical argument--using deduction rather than evidence.)

If he's trying to prove or disprove whether ET intelligent civilizations exist (which is what seems to be his aim, especially based on the OP), then this premise simply begs the question.

If he's trying to make some other sound argument, it's enough to show that his first premise is false to show it is unsound.

[Bill Thompson]

Logically, according to Occom's Razor, the simplest answer is, despite the multitude of stars, there must be factors to do the Drake Equation that bring the occurrence of intelligent life in the galaxy to a very low probability. That is the answer to Fermi's Paradox, logically. All other answers are more improbable and complex and amount to being an apologist for ETI whose existance is based more on faith than logic.

[makaya325]

The most likely, and current explanation: Alien's do not exist, due to zero evidence.

[Dancing David]

About point 4.

If they have been around for a billion or billions of years. It would be safe to assume that at one point or another they would need to escape the death of their sun. If not then they did not survive and such could be the fate of all civilizations and in that case everything I said is worthless.

Well the speed of light limits travel, as does the distance.

[Skeptic]

But guys... are you forgetting that splitting the atom was hard until we figured out how to do it.

Maybe we can not breach the light barrier, but theoretically we could bypass it all together.

Not necessarily. Just because we really really want there to be a way around the lightspeed barried, doesn't mean there is going to be one.

[Dancing David]

Side question....

Why don't we stay in constant contact with all of the "old" probes?
Such as pioneer and voyager.


The life span of the power source and transmission distances.

[Dancing David]

Then let us start with the premise

1. There are other intelligent alien life capable of interstellar travel.

would they be aware of us? Have we made enough of an impression?

IF they ARE aware of us, would they have any reason to make contact?

If we were doomed and they knew it, would they have an incentive to save us?

Say there are five in the galaxy, they are really, really far apart on average and the cost of travel is prohibitive. Even communication to your own colonies is very, very slow.

[Perpetual Student]

Logically, according to Occom's Razor, the simplest answer is, despite the multitude of stars, there must be factors to do the Drake Equation that bring the occurrence of intelligent life in the galaxy to a very low probability. That is the answer to Fermi's Paradox, logically. All other answers are more improbable and complex and amount to being an apologist for ETI whose existance is based more on faith than logic.

It is equally easy to say:
Logically, according to Occam's Razor, the simplest answer is, because of the vast multitude of stars, there must be factors to do the Drake Equation that bring the occurrence of intelligent life in the galaxy to virtual certainty. The limiting reality of the speed of light is the answer to Fermi's Paradox, logically. All other answers are more improbable and complex and amount to being an apologist for the lack of direct evidence of ETI.

[JoeTheJuggler]

Logically, according to Occom's Razor, the simplest answer is, despite the multitude of stars, there must be factors to do the Drake Equation that bring the occurrence of intelligent life in the galaxy to a very low probability. That is the answer to Fermi's Paradox, logically. All other answers are more improbable and complex and amount to being an apologist for ETI whose existance is based more on faith than logic.

I understand your point, but assuming the unknown factors in the Drake Equation must necessarily bring the resulting probability to a low value is not a deductive argument. There is no logical reason that each unknown factor can't be 1. (And the known factors are mostly huge--even astronomic--numbers.)

Occam's Razor does not make any inductive logical argument against any hypothesis. In fact, the observation that the most elegant solution is preferred is largely an inductive matter. Occam's Razor does not tell us that the unknown values in the Drake Equation are likely or not to be small. (There is no unnecessary creation of entities required.)

The OP specifically said he wanted to make an argument with deductive logic.

ETA: In other words, I understand that it only takes any one factor in the Drake Equation to be near zero to make the final probability very near zero, but there is no logical argument that says any of those unknowns have to be near zero. The unknown values could be any number (except zero since we exist) without making the equation any more or less parsimonious (which is what Occam's Razor deals with).

[zerospeaks]

Logically, according to Occom's Razor, the simplest answer is, despite the multitude of stars, there must be factors to do the Drake Equation that bring the occurrence of intelligent life in the galaxy to a very low probability.

I disagree, I think the easiest explanation would be that abiogenesis is a chemical process like fire and it will happen wherever there is the materials and environment for it.

Given the size of the universe, that will be billions of places where life has begun on some level.

[Trakar]

Don't assume that the problem of a generational starship and the problem of colonizing the Oort cloud are much different. I don't think that either ourselves or our machines are likely to be able to do it with anything other than great expense. Most civilizations will likely find that expense far too big.

In fact, I find the idea of a "system wide civilization" to be a REAL stretch.

Quite possibly!

Though I see a mature, system wide civilization, as generally a first step toward anything larger. Our fiction and thus imaginations (or vice versa), however, seem to generally think that we will leap from planet-bound to galactic empire in a largely singular step.

[Dr. Trintignant]

And the cost is such that the Earth could not now build a probably-successful starship if we devoted the whole planet to the project.

I'm not convinced of that. GWP (gross world product) is over $50 trillion. Wars demonstrate that spending 25% of that is fairly sustainable. Over 40 years, that's $500 trillion (assuming no growth). I think that'll buy a pretty nice ship. If ship+launch costs are $100,000 a pound (quite high even by today's standards), $500T will buy a 2.5 million ton starship. That's close to the "super" Orion designs that Dyson and others speculated about in the 50's.

You need to be able to send off an entire small, functioning technological civilization.

Not necessarily. It depends on what kind of planet you land on. If you land on a Mars-like planet, then sure. But if you can find one with water and oxygen (perhaps someplace with microbial life), that's a pretty good start to avoiding high-tech structures.

You need hospitals and schools and nurseries and farms and...

Sure, but those can all exist in low-tech forms. The Amish survive pretty well, for instance, and have very low technological dependence. Again, though, this only works if you can find a reasonably hospitable planet.

5% of the speed of light is about all you can hope for with any safety, and at that you are pushing a huge erosion shield ahead of your spacecraft.

Yes, that's right. But note that if you have enough mass, you can just take along a few hundred years worth of food. You don't necessarily need a closed-cycle food system. That would eliminate a hugely complicating factor in ship design.

All of your machinery will have to be totally rebuilt several times in flight because machinery just does not function for hundreds of years on its own.

That's only because we don't normally build things to last 100 years. But that's largely a function of design. Ordinary light bulbs burn out after a few months of continuous use, but there are bulbs that have lasted >100 years, mainly because they sacrifice efficiency for life. Similar tradeoffs could be made for other machines.

You can also deign machines for ease of maintenance. Maybe you can't design a particular bearing to last 100 years. But perhaps you can design it to be replaceable with basic manual labor, and then supply the ship with lots of spares.

Of course, all of this reflects what's possible in principle. Perhaps alien civilizations never manage to direct sufficient resources in that direction. But if there are many of them, it would be surprising if none of them managed to do it.

- Dr. Trintignant

PS: I would be interested in reading your paper, if it's available online somewhere.

[BenBurch]

Think of a 10Gt ship and you are closer to the right size, doc.

Seriously.

[zerospeaks]

Hibernation anyone?

[BenBurch]

...

PS: I would be interested in reading your paper, if it's available online somewhere.

Sadly this was before the Internet as we know it. Mid-70s.

It was typewritten on an old Royal manual typewriter...

I wonder if I still have a copy any more or if it was lost in one of the myriad of things that ruined documents and books of mine over the years?

[BenBurch]

Hibernation anyone?

Cosmic ray damage.

And you still have the issue of keeping the machines alive while they keep you alive.

[zerospeaks]

Ummm, a shield from cosmic rays and an automated maintenance robot are not out of the realm of today's technology.
Not to mention future (or smarter species) technology.

[Toke]

Think of a 10Gt ship and you are closer to the right size, doc.

Seriously.
I read of some big cat or other that you need around 1000 individuals for a breeding population.
I am not sure how many is needed to maintain the knowledge of a high tech society.
Maintaining a ship require a lot of skills and spare parts, a generation ship would require some pretty fancy workshops.
How about landing, on a hopefully earth like planet with eatable plants and animals.
Interesting.

Is your paper available?

[zerospeaks]

Is the Titan possible? Given unlimited funds?

I mean the ship in Titan A.E. the movie.
It was a ship that contained all the genetic information for just about every life on earth and once it landed on a new planet (with the right conditions I am suspecting) it would create those life forms and let them go.

Is that possible?

[Toke]

Ummm, a shield from cosmic rays and an automated maintenance robot are not out of the realm of today's technology.
Not to mention future (or smarter species) technology.

I have considered the last weeks maintenance jobs I have done on board and decided that I would love to see the robot that could do any of it.

ETA: there were Molly and some Korean dogs, but that involved a live mother. I have not heard of the automated/artificial womb.

[Vorticity]

And you still have the issue of keeping the machines alive while they keep you alive.

Take turns sleeping.

At any rate, it seems to me to be much more probable that we'd "extend our presence" to the interstellar scale via automated probes rather than direct human travel. I remember reading that the Arecibo Observatory (http://en.wikipedia.org/wiki/Arecibo_Observatory) is large enough (305 m in diameter) to communicate with a similarly-sized radio telescope at the center of the galaxy, which is on the order of 30,000 light years away. Assuming that the required surface area scales as the square of the distance (and hence that the required radius scales linearly with the distance), two such dishes about 10 meters in diameter could communicate with each other even if 1000 light years apart. 10 meters is not really that big. So communication is not a problem.

Just how big is that? Not very. From the NASA Voyager FAQ (http://voyager.jpl.nasa.gov/faq.html):

The Voyager spacecraft weight, including hydrazine, at launch was 815 kg or about 1797 pounds. It was almost the weight and size of a sub-compact car. The current approximate weight of Voyager 1 is 733 kg and Voyager 2 is 735 kg. The difference is in the amount of hydrazine remaining. Hydrazine is being used to control the spacecrafts' attitude.

The spacecraft, without the various booms could fit inside a cube that is about 4 meters on each side. The approximate measurements of the different structures follow - please refer to the spacecraft picture at the above web site.

The high gain antenna is 3.7 meters across (diameter).

The magnetometer boom is 13 meters long

A 10-meter craft is on the same order of magnitude in size as the Voyager probes. Cost of launch would not really be a problem then, especially when compared with other activities, such as war.

The real problem is the time scale involved. From the same NASA web page:


Voyager 1 is escaping the solar system at a speed of about 3.5 AU per year.


That equates to about 18,000 years per light year. This would seem to be too slow for an impatient civilization. One possibility could be greater fuel and other resource expenditure (plus some not-entirely-beyond-reach technology) for the goal of increased initial speed, along with greater attention payed to gravitational slingshotting around the Sun and planets. This would perhaps increase the interstellar speed by an order of magnitude or two.

I can imagine a relatively long-sighted (e.g. 100-1000 years) civilization launching a large number (think hundreds) of such probes to nearby stars, with the promise of great scientific insights in the future when they arrive.

Naturally such probes would have to be "smart" and robust over the scale of centuries. The former seems plausible given current technology, and the latter seems possible, as I argued earlier.

So:

Interplanetary: Humans + Robots.
Interstellar: Robots.


ETA:

In a technological-civilization-rich universe, I would not expect the aliens themselves to be ubiquitous, but I could imagine their probes (many of which might be millions of years old) being ubiquitous. These wouldn't necessarily be easily detectable, however. They'd be too small to see unless they were in just the right spot and you knew what you were looking for and where to look. Also, the probes' signals would be highly directional toward their system of origin, and hence hard to pick up from a random vantage point such as ours.

[zerospeaks]

So where are the robots?

[ben m]

gravitational slingshotting around the Sun and planets. This would perhaps increase the interstellar speed by an order of magnitude or two.

a) You don't gain anything from a gravitational-slingshot around the Sun.
b) Gravitational slingshots can get you up to ~50 km/s; after that, basically, your trajectory doesn't bend that much skimming Jupiter's and Saturn's atmospheres. They're not massive enough to turn you around.

I can imagine a relatively long-sighted (e.g. 100-1000 years) civilization launching a large number (think hundreds) of such probes to nearby stars, with the promise of great scientific insights in the future when they arrive.


I agree. However, this doesn't rescue the Drake-style arguments. From this, at best, you can consider conclusions like "there isn't a hugely long-sighted, probe-launching civilization within 50 pc of the Sun". That is an entirely plausible statement. It is entirely unrelated to the Drake/Zerospeaks-style statements about colonizing civilizations or faster-than-light-exploring civilizations.

Where are the robots, Zerospeaks? Maybe one crash-landed in central Gondwandaland just after sending home a report about a cycad-covered planet with a unpleasant oxygen-choked atmosphere. (Or, for that matter: maybe one did a close flyby of Mars a billion years ago. Maybe there's one orbiting in the Solar System right now. Maybe there's one in the Oort Cloud due to fly by in 100,000 years. Don't assume that "aliens study Earth" has to look like "Alien ambassador lands on the UN Building between AD1955 and AD2009")

[Ziggurat]

Where are the robots, Zerospeaks?

On the moon, obviously. Waiting for us to find it. Haven't you seen 2001? ;)

[JoeTheJuggler]

Ummm, a shield from cosmic rays and an automated maintenance robot are not out of the realm of today's technology.
Not to mention future (or smarter species) technology.

Again, just because something is possible doesn't mean that an intelligent civilization will necessarily do it (as mentioned, it might be economically unfeasible, civilizations might not last long enough, or any civilization with that technology level might have not motivation to do that) , and your argument requires that is has to have done so long ago enough to fill the galaxy with evidence of its existence.

Or have you given up on the logical approach?

Arguing that the Earth could feasibly send out self-replicating probes (or might someday have the technology to colonize other planets by long voyages with people in some kind of suspended animation, or whatever), but that we have not done so yet actually refutes the argument based on Fermi's Paradox.

[zerospeaks]

Or have you given up on the logical approach?

I am enjoying the input I am getting. I am digesting it and formulating a different logical approach. So far, I am very sad. Logic may lead me to conclude we will never meet other life even if it exists.

I think we need to stay on the "where are the robots" for a second more without shrugging it off.

Should we not expect to be probed? I guess this would go back to calculating the number of probes likely and number of places they could go and then a statistical probability that we would be one of those places.

But that still brings us back to the question at hand no one has addressed.

If we have or will be probed. Would we know about it?
Would it make contact? Or would it be programmed to stay away from less advanced civilizations.
Would it provide assistance to us if we were in danger?

[Toke]

I wonder about the FLT-drive, but guess it is a long way off.
We don't even have blasters or light swords yet, and what self respecting pilot would set off in a starship without?:D


So far neither human nor machine have the lifespan for traveling to other stars.

[JoeTheJuggler]

I am enjoying the input I am getting. I am digesting it and formulating a different logical approach. So far, I am very sad. Logic may lead me to conclude we will never meet other life even if it exists.
Yup. There may be hundreds or thousands of intelligent civilizations (at a technological level comparable to our own), and we are likely never ever to see evidence of any of them. Space is really big, and things are spread far apart in space and time.


I think we need to stay on the "where are the robots" for a second more without shrugging it off.
Just so you realize that the lack of the robots is not evidence of the non-existence of other intelligences. (No more than our failure to already have filled the galaxy with evidence of our civilization is proof of our non-existence.)

Should we not expect to be probed? I guess this would go back to calculating the number of probes likely and number of places they could go and then a statistical probability that we would be one of those places.
No we should not expect to be probed--not in the sense that our not being probed says anything about the existence or non-existence of ETIs. In other words, absence of evidence can be significant where we expect that evidence. In this case, the absence of evidence is insignificant since we wouldn't expect any evidence of a civilization just like our own pretty much anywhere in the galaxy except right on top of us.

But that still brings us back to the question at hand no one has addressed.

If we have or will be probed. Would we know about it?
Would it make contact? Or would it be programmed to stay away from less advanced civilizations.
Would it provide assistance to us if we were in danger?
I suspect the reason no one has responded to these questions that invite utterly unfounded speculation is that they're completely off the topic you started.

[Dr. Trintignant]

Think of a 10Gt ship and you are closer to the right size, doc.

Seriously.

How many people are you assuming, and what propulsion technology? I am thinking of a couple thousand people (enough to maintain genetic diversity and form a decent size community) and Project Orion propulsion (so you don't need an extreme mass fraction).

Just as an example, 200 years of food for one person only weighs about 75 tons. For an average of 2000 people, the food only weighs 150 kt, which is a tiny fraction of both our estimates.

Cruise ships provide a decent approximation for the overall living quarters, and tend to run about 40 tons per person--80 kt for our 2000 people.

Obviously there's a lot more to it than this, but I don't see why gigatons are needed unless you have very inefficient propulsion (i.e., 99% mass fraction instead of <50%), need to go quite fast, need to go a very long ways (more than a few tens of light years, say), or have a huge population.

- Dr. Trintignant

[ben m]

I am digesting it and formulating a different logical approach.

I just want to add a flag to the word "logic". Y'know, unless you're talking about either formal philosophy or about digital electronics, I associate the word "logic" much more with bad reasoning than with good. Why is that? Well, to be honest, because of things like your first post. It's a line of 100% casual, conversational argument presented with a couple of formal-logic-like words attached (like "given" and "therefore"). That's fine, that's how people reason in general.

But when I see such reasoning with the words "I figured it out using LOGIC!" attached, it sounds like you assume that the results have some special force of truth. You see this all the time from anti-relativity crackpots, and I think it's part of why their positions are so unshakeable.

Anyway. I don't mean to accuse you of being a crackpot, I just want to disagree with your use of the word "logic".


I think we need to stay on the "where are the robots" for a second more without shrugging it off.

Should we not expect to be probed? I guess this would go back to calculating the number of probes likely and number of places they could go and then a statistical probability that we would be one of those places.


To my eye, that's two more utterly unknown, unknowable numbers that we'll multiply by one another.


If we have or will be probed. Would we know about it?
Would it make contact? Or would it be programmed to stay away from less advanced civilizations.
Would it provide assistance to us if we were in danger?

That depends; that depends; that depends; that depends. From the permutations of those four binary unknowns, you've got 2^4 = 16 possible plots for sixteen different science-fiction novels.

[BenBurch]

Recompute the mass fraction for an orion-type ship getting to 5% c.

Its not as good as you think.

I assumed a NERVA type nuclear rocket, which got us to 90% mass fraction as reaction mass.

And I assumed we would need 100K of humans to ensure a viable number of able scientists and engineers when you got there. Remember that really smart people are always a minority... Remember some people are just going to be artists...

[Roboramma]

I read of some big cat or other that you need around 1000 individuals for a breeding population. Or a few women and a lot of iced sperm.
Maybe fertilized eggs?

I am not sure how many is needed to maintain the knowledge of a high tech society. If we're talking about a few light year's trip, you don't need to. You just need to bring a big enough radio antenna . Of course, you'd want some experts, but new ones can be trained with info brought along and questioned asked of the home planet. Yes, that would take time, but once you're there, you've got time.

[Roboramma]

Recompute the mass fraction for an orion-type ship getting to 5% c.

Its not as good as you think.

I assumed a NERVA type nuclear rocket, which got us to 90% mass fraction as reaction mass.

And I assumed we would need 100K of humans to ensure a viable number of able scientists and engineers when you got there. Remember that really smart people are always a minority... Remember some people are just going to be artists...

Why do you need so many scientists and engineers when you get there? And even if there aren't very many good ones, are mediocre engineers not good enough to do the job?

[Hindmost]

I wonder why an alien species would come anywhere near planet earth. The aliens would have to as least reviewed some of our TV shows...scary stuff. They certainly would know we have nuclear weapons and have been war like for most of history. It would be like vacationing in Iraq. Even given, the travel time, I would pick a different location.

The nearest star is about 7000 times farther away than Pluto and that is about 4.3 light-years. It is taking ten years to get to Pluto--and we can't even get into its orbit. There really aren't many stars within 30 light-years and the energy requirements are just incredible to travel...and stop at a nearby star. Even considering fusion, it is doubtful that a journey is possible unless an armada of supplies went along for the ride.

The voyager probes are probably powered with pu-238 with an 85 year half-life. Their lifetime will be limited.

glenn

[BenBurch]

Why do you need so many scientists and engineers when you get there? And even if there aren't very many good ones, are mediocre engineers not good enough to do the job?

1. You will without a doubt have to re-engineer everything as you proceed. Trust me on this. Engineering is a process of continuous change as you find out what was wrong with what you did before.

2. You can't phone home for help.

3. You have a world to colonize, a civilization to contact, a thing to explore; You cannot do that with a handful of people at mostly 100 IQ (by definition.)

[Roboramma]

1. You will without a doubt have to re-engineer everything as you proceed. Trust me on this. Engineering is a process of continuous change as you find out what was wrong with what you did before. Assuming modern day technology, I can trust you on this, I suppose. Though multi-redundant systems should help to avoid those sorts of issues.

2. You can't phone home for help. Why not? It may take years to get an answer, but at least some problems should be such that they will be noticed years before they become catastrophic: ie. part X has failed. Yes, it has five levels of redundancy, so there's no rush to fix it, but we would like to, and we don't know how. Let's tell earth about our problem and tell them everything we know about it, and see if anyone back there can find a solution and present it in a form that we can implement.

3. You have a world to colonize, a civilization to contact, a thing to explore; You cannot do that with a handful of people at mostly 100 IQ (by definition.)
Once you get there you can breed.
Dumb people can have smart children.

[Roboramma]

My real issue though is that there's no reason to assume modern day technology. Computers and robots are improving. So is genetic engineering.

It may be very difficult and very expensive to send a human colony using modern technology to another star. It would be far less difficult and expensive to send some von neuman machines.

And if we really want a human presence? The machines can build a habitat and bring along some fertilized eggs to be grown into adult humans.

Hard? Definitely. Requires technology beyond what we currently possess? Definitely. But it also requires technology that is certainly possible. The AI will not need to do anything that human brains can't do, and there's no reason to think that the human brain is the ultimate in what is physically possible.

Faster than light travel, on the other hand, is very likely a pipe dream.

[Mark6]

You need to be able to send off an entire small, functioning technological civilization.

Not necessarily. It depends on what kind of planet you land on. If you land on a Mars-like planet, then sure. But if you can find one with water and oxygen (perhaps someplace with microbial life), that's a pretty good start to avoiding high-tech structures.
You think you could survive on circa-Cambrian Earth without high technology? With no soil bacteria and no soil to speak of?

Something very relevant I saw just a few minutes ago: How habitable is the Earth? (http://www.antipope.org/charlie/blog-static/2009/10/how_habitable_is_the_earth.html)


of the 4.6 Gy of Earth's known history, there's only been enough oxygen in the atmosphere for us to survive for about 0.5 Gy. For roughly 90% of the Earth's history we couldn't even breathe the air. And about 10-25% of the time, there have been ice ages so savagely fierce that the glaciers reached the tropics: odds are good that any meat probe landing on solid ground during these periods would rapidly die of exposure. So historically, Earth has only been inhabitable about 8% of the time — assuming you are lucky enough to find some solid ground. Once you factor in the random surface distribution, we're down to about 2% survivability.

[RecoveringYuppy]

Just as an example, 200 years of food for one person only weighs about 75 tons. For an average of 2000 people, the food only weighs 150 kt, which is a tiny fraction of both our estimates.

Actually the food itself will weigh a bit less than that, unless the biosphere aboard this ship has a cycle time of 200 years. Food can be recycled rather quickly.

[Hindmost]

My real issue though is that there's no reason to assume modern day technology. Computers and robots are improving. So is genetic engineering.

It may be very difficult and very expensive to send a human colony using modern technology to another star. It would be far less difficult and expensive to send some von neuman machines.

And if we really want a human presence? The machines can build a habitat and bring along some fertilized eggs to be grown into adult humans.

Hard? Definitely. Requires technology beyond what we currently possess? Definitely. But it also requires technology that is certainly possible. The AI will not need to do anything that human brains can't do, and there's no reason to think that the human brain is the ultimate in what is physically possible.

Faster than light travel, on the other hand, is very likely a pipe dream.

I am betting on Einstein when it come to FTL travel. And worm hole travel would be really energy prohibitive...if worm holes even exist.

I agree that robotic missions have the best possibility for application. But, I would think it would be difficult for machines to last the ~40000 years it would take to get to another planet--and survive all the radiation from cosmic rays. Most technology is very suseptible to radiation damage. Of course, we could send out an arc and never know if it worked.

Improvements can be very incremental. Propulsion hasn't changed much in the last 50 years. Computers, robotics and batteries are making small incremental steps. Until fusion power is available, which doesn't look promising right now, the energy we harness hasn't changed much either.

glenn

[RecoveringYuppy]

Personally, I think the colonization of the galaxy is going to be a lot like the original colonization of the surface of planet Earth. It will happen even though no one ever sets out to do it. It will likely happen at low speeds, probably about the same as solar orbital velocity. No one will ever consider themselves to be on a mission to another solar system, just like Australians don't consider themselves on a mission to India (or wherever continental drift winds up taking it).

[Trakar]

I am enjoying the input I am getting. I am digesting it and formulating a different logical approach. So far, I am very sad. Logic may lead me to conclude we will never meet other life even if it exists.

We may create other intelligent alien life forms. We're not far off from being able to directly and dramatically engineer ourselves and life in general. No telling how many different varients of "human" there will be in the next few thousand years.

[Michael Mozina]

Your point 4 does not follow. For all we know, lightspeed barrier is insurmountable. An existence of well-defined problem does NOT guarantee the existence of a solution.

Your point 3 is also rather weak. For all we know, technological civilization requires conditions (such as abundance of metals) which have existed only recently in universe's history.

FYI, while I tend to agree with your basic assessment of the argument, metals have existed in this universe for a very long time:

http://www.mpe.mpg.de/Highlights/pr20020708.html

[Michael Mozina]

So, I was just thinking to myself and thought I would run this by you guys.

Using logic to solve "Where are they?"

I guess my biggest "beef" with your argument was the use of the word "should". Yes, life *probably* exists somewhere out there in space besides just Earth, but did it develop "intelligent" life capable of building interstellar vehicles? We haven't even done that yet and our planet has been here for billions of years.

Even if a society develops to the point that they can build an interstellar vehicle, it too is bound by the same laws of physics that we are. Light speed seems to be the maximum speed limit of this physical universe, and humans have a limited lifespan, so something like intergalactic travel is out of the question. That would mean that intelligent life would need to develop inside *THIS* galaxy and to reach us in a human lifetime would require that such a civilization be located relatively close to us even by galactic standards.

http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/001205a.html

Is your logic sound? Well, maybe. :)

Looking around the planet we see that humans kill other humans for a wide variety of incredibly stupid reasons. Worse still, we kill other living beings just for sport. We exploit or own planet for profit regardless of the long term consequences for the environment. We abuse technology on a regular basis and we build instruments of war from every advanced technology that we can get our hand on. Why would any intelligent species risk the possibility of humans getting their hands on a transportation device or technology that might give us access to their planet? Even letting us know that they are "out there" would be dangerous. :)

Gene was probably right, but only *if* there is other intelligent life in our vicinity. That's a big "if" IMO. :)

[Dr. Trintignant]

Recompute the mass fraction for an orion-type ship getting to 5% c.

Its not as good as you think.

Probably not, though I was assuming a bit less than 5% of SoL. I've mostly gone with the various estimates I've read about. Maybe tonight I'll actually run the numbers.

I assumed a NERVA type nuclear rocket, which got us to 90% mass fraction as reaction mass.

According to Wikipedia, NERVA's specific impulse is 825 s in a vacuum. Estimates for Orion range from 10,000 to 1,000,000.

And I assumed we would need 100K of humans to ensure a viable number of able scientists and engineers when you got there. Remember that really smart people are always a minority... Remember some people are just going to be artists...

100k is a heck of a lot of people. I don't think you'd need that many. First off, intelligence is genetic to some extent, so if you were selective early on, you'd still end up with better than average people by the end. Second, they'll probably have a lot of free time, and so can educate the children well.

- Dr. Trintignant

[Trakar]

100k is a heck of a lot of people. I don't think you'd need that many. First off, intelligence is genetic to some extent, so if you were selective early on, you'd still end up with better than average people by the end. Second, they'll probably have a lot of free time, and so can educate the children well.

- Dr. Trintignant

The thing to remember is that you are talking about needing a full civ skillset, teachers, chefs, gardners, cops, bartenders, psychiatrists, vaccuum cleaner repairmen, etc., to support and supplement the physicists, pilots, engineers etc., who will attend to the colony (and what we are talking about is a colony in itself, not just a transport from point A to point B). You might be able to start out with a smaller crew, say between 10-20k and then allow the population to grow, this would allow for more freedom of choice with regards to careers for the next generations of crew.

[Corsair 115]

4. Those civilizations should have figured out ways around the vast distance limitations of the universe.


And what if the next nearest intelligent life form to us was in a galaxy five billion light years away? Even travelling at one million times faster than the speed of light, it'd still take five thousand years to get here from there.

The universe could be teeming with intelligent life and still be too far apart to visit each other or even know about each other's existence. The universe is just that damn big (and getting bigger all the time).

[Dr. Trintignant]

The thing to remember is that you are talking about needing a full civ skillset, teachers, chefs, gardners, cops, bartenders, psychiatrists, vaccuum cleaner repairmen, etc., to support and supplement the physicists, pilots, engineers etc., who will attend to the colony (and what we are talking about is a colony in itself, not just a transport from point A to point B). You might be able to start out with a smaller crew, say between 10-20k and then allow the population to grow, this would allow for more freedom of choice with regards to careers for the next generations of crew.

You've named a lot of occupations that I'm sure you don't need. Small farming communes hardly need chefs, bartenders, or vacuum repairmen; these are all optional things which you might have only once the colony grows. Further, multi-tasking is possible, so you may (for instance) not need a psychiatrist separate from the doctor.

Of course you wouldn't be able to immediately replicate modern life in a developed nation. Humans can get by and live happy lives on much less. And with the right head start, you can arrange things so that the colony can grow their technological base than if they had to do it from scratch.

- Dr. Trintignant

[Dr. Trintignant]

You think you could survive on circa-Cambrian Earth without high technology? With no soil bacteria and no soil to speak of?

Something very relevant I saw just a few minutes ago: How habitable is the Earth? (http://www.antipope.org/charlie/blog-static/2009/10/how_habitable_is_the_earth.html)

I've only read part of that link, and it is interesting, but I think the author makes some unfair assumptions. Our hypothetical colonists won't be landing in a random location and with no supplies. They will only go to systems with known Earth-like planets, will pick an optimal place on the surface, and have a fair amount of starting supplies--including a large sampling of Earth lifeforms (such as soil bacteria). They won't be planting food crops right away, but hydroponics is pretty low-tech, especially if the colonists have a few key supplies (plastic sheeting, fertilizer, etc.).

- Dr. Trintignant

[Dr. Trintignant]

Recompute the mass fraction for an orion-type ship getting to 5% c.

Its not as good as you think.

For the sake of argument, let's use some best case figures here.

The W87 warhead is thought to weigh 200 kg and produce a 475 kt blast. That's 2e15 joules. If we assume that all the energy goes into heating the casing, then by ke=mv^2/2 we should expect the particles to leave at 4.47e6 m/s.

The rocket equation is dv = ve*ln(m0/m1). If dv is twice (accelerate and decelerate) 2% of SoL, then we get: 6e6 m/s = 4.47e6 m/s * ln(m0/m1). Our mass fraction m1/m0 is then 0.26.

That's not too terrible, but of course I made some rather extreme assumptions about how much energy goes into the exhaust. Then again, the W87 warhead has all kinds of military features that you wouldn't need on an Orion vessel, so maybe some of that would balance out. The structure could be polyethylene, for instance, which would both lighten the warhead and allow more of the energy to be absorbed. Perhaps the explosive shell could be replaced with something more weight efficient. There's probably a lot you could do here.

- Dr. Trintignant

[BenBurch]

According to Wikipedia, NERVA's specific impulse is 825 s in a vacuum. Estimates for Orion range from 10,000 to 1,000,000.


COST.

Atom bombs are amazingly expensive fuel. (And we don't have enough material to make the triggers unless you can invent a pure fusion bomb.)

[Dr. Trintignant]

COST.

Atom bombs are amazingly expensive fuel. (And we don't have enough material to make the triggers unless you can invent a pure fusion bomb.)

I'll grant that the nuclear materials aren't cheap. But the rest of it is, all things considered--not much more complicated than a conventional explosive, really.

The ocean contains quite a lot of uranium. Seems like you could breed a huge amount of weapons-grade plutonium if so desired.

- Dr. Trintignant

[Roboramma]

The thing to remember is that you are talking about needing a full civ skillset, teachers, chefs, gardners, cops, bartenders, psychiatrists, vaccuum cleaner repairmen, etc., to support and supplement the physicists, pilots, engineers etc., who will attend to the colony (and what we are talking about is a colony in itself, not just a transport from point A to point B). You might be able to start out with a smaller crew, say between 10-20k and then allow the population to grow, this would allow for more freedom of choice with regards to careers for the next generations of crew.

There is absolutely no reason to bring "bartenders, vacuum cleaner repairmen, etc." as to the others, people can play double rolls.

Moreover, as I said before, there's really no reason to bring the whole civilization with you, just enough to survive until it can be recreated. A few or a dozen light years isn't out of contact, it's just difficult contact. We could, for instance, continuously beam them information about the earth, data, tutorials, etc. It may not be a conversation, but it would be enough to do the job.

[Roboramma]

I
I agree that robotic missions have the best possibility for application. But, I would think it would be difficult for machines to last the ~40000 years it would take to get to another planet--and survive all the radiation from cosmic rays. Most technology is very suseptible to radiation damage. Of course, we could send out an arc and never know if it worked.

1. Why should it take 40,000 years? There are ways to go much faster than Voyager is going. What's wrong with a light sail, for instance?
Or even project orion style propulsion, as another poster mentioned?
2. While I'm sure radiation damage is problematic, it's not insoluble. Just make the machines self-repairing, error-checking, and multi-redundant. This adds cost, but if you know what the level of radiation is, you will no how much added cost you need to make sure the machine is likely to survive intact and functional to it's destination.

Improvements can be very incremental. Propulsion hasn't changed much in the last 50 years. Computers, robotics and batteries are making small incremental steps. Until fusion power is available, which doesn't look promising right now, the energy we harness hasn't changed much either.
Computers are making small incremental steps? When I was a kid I played games my dad made on an apple 2e. When they went to the moon they made their calculations with slide rules. Hell, when they made the atom bomb they had teams of girls in a room doing calculations on an assembly line (until the computers, and the computer was no faster than the girls!*)

While fusion may take a long time, I find it likely that we'll be able to make it work eventually.

Of course some things will come slowly. And of course there are limits. I am only saying that I think, eventually, we will get to those limits.

*At least according to Feyman.

[Dancing David]

But that still brings us back to the question at hand no one has addressed.

If we have or will be probed. Would we know about it?
Would it make contact? Or would it be programmed to stay away from less advanced civilizations.
Would it provide assistance to us if we were in danger?


I think you need to divest yourself of the emotional side and just enjoy the universe. Try star gazing. The go here,

http://www.exploratorium.edu/ronh/solar_system/ and play around. It helps to understand the scale of the whole thing, if you make the Sun 1mm across then

Alpha Centauri is 18 mi. (19 km) away, just stop and think about that.
The galactic center is is 117,000 mi. (188,000 km.) now that is about half way to the moon on a grain of sand comparison.

Now this is just the scale of the galaxy, and it is very cool, we can see with our eye ~2,000 stars in the night sky, those are grains of san that are very far away. Very cool.


So back to your questions.

1. If we have or will be probed. Would we know about it?

Unlikely, the solar system is what about 5 billion years old and the humans have been part of it 80,000 years (gracile homo sap sap), so the existance of the solar system to the existance of humans is 62,500. Not very good odds that if the probe went through the system once that humans were here. 1/62,5000


2.Would it make contact? Or would it be programmed to stay away from less advanced civilizations.

Now that gets us to the 'Why the probe?" questions, what if they are just looking for certain systems and planets, will ours even be one they care about?
Will they even care about life?
Will they even have a prime directive or even care?

Rememebr, even if the probe communicates at the speed of light, the times are boggling, say it travels 10,000 light years at 1/10 the speed of light, that is 100,000 years and then the 10,000 to get the message. 110,000 years is a long time. You would probably not care about anything that far away except academicaly.

Would it provide assistance to us if we were in danger?

Unlikely given the distances and costs.

[Trakar]

You've named a lot of occupations that I'm sure you don't need. Small farming communes hardly need chefs, bartenders, or vacuum repairmen; these are all optional things which you might have only once the colony grows. Further, multi-tasking is possible, so you may (for instance) not need a psychiatrist separate from the doctor.

Of course you wouldn't be able to immediately replicate modern life in a developed nation. Humans can get by and live happy lives on much less. And with the right head start, you can arrange things so that the colony can grow their technological base than if they had to do it from scratch.

- Dr. Trintignant

We're talking about a generational ship to other star systems, not merely a small farming commune.

[Trakar]

There is absolutely no reason to bring "bartenders, vacuum cleaner repairmen, etc." as to the others, people can play double rolls.

Moreover, as I said before, there's really no reason to bring the whole civilization with you, just enough to survive until it can be recreated. A few or a dozen light years isn't out of contact, it's just difficult contact. We could, for instance, continuously beam them information about the earth, data, tutorials, etc. It may not be a conversation, but it would be enough to do the job.

Again, we are talking about the multigenerational ship to get to other star systems, not a colony on some far flung destination. This ship may well be in transit for centuries if not millenia, it will need sufficient crew size and skillsets to entirely rebuild the ship many times over during the journey, and an environment to support, maintain and replenish those who do that rebuilding.

[Trakar]

1. Why should it take 40,000 years? There are ways to go much faster than Voyager is going. What's wrong with a light sail, for instance?

I think most of us are talking about speeds much faster than Voyager, but considering the sizes of payloads needed, even using fusion power sources, you are going to use a small moon or good sized comet's worth of hydrogen to accelerate the payload up to 1/100th c.

[Dr. Trintignant]

We're talking about a generational ship to other star systems, not merely a small farming commune.

So? I don't see how that changes whether you need a bartender or not. The fact that small communes exist without bartenders proves that there is no inherent social need for them.

Yes, you'll need a fair amount of engineering talent to keep things running, although I'd think you'd want to design the ship to be as self-sustaining as possible.

Also, the needs change as time goes on. As the ship approaches the destination, the occupants can train the next generation in the direction they need--hydroponic farming instead of starship maintenance, for instance.

- Dr. Trintignant

[Ziggurat]

Hell, when they made the atom bomb they had teams of girls in a room doing calculations on an assembly line (until the computers, and the computer was no faster than the girls!*)

Originally, the computer was the girl (http://www.amazon.com/When-Computers-Human-David-Grier/dp/0691133824).

[Vorticity]

*At least according to Feyman.

Right, but if I remember correctly, he also noted that the computers were in practice faster, since they could work 24/7 and didn't need breaks.

An off-topic second hand anecdote:

I've published a number of papers with a relatively well-known scientist (who I'll not name) who worked with some of these early digital computers in the years after the war. I hear that many of these women - who worked during the war as "computers" in places like Los Alamos National Laboratory, where I work now - stayed on after the war as the primary operators of these early machines. In fact, many of them, who originally had little-to-no mathematical or computational knowledge, eventually became well-versed in early computer programming, becoming - in effect - some of the first computer scientists and algorithmists. This was really the beginning of computational physics as we know it today. And yet most of these women were in no way credited (via co-authorship) for their computational efforts, which in many cases lead to some of the most well-known early triumphs of computational physics.

Luckily, times have changed.

[Trakar]

So? I don't see how that changes whether you need a bartender or not. The fact that small communes exist without bartenders proves that there is no inherent social need for them.


Please demonstrate any independent human community of more than several thousand that does not consist of a fraction whose primary duties are food and beverage preparation and service.

what you choose to name them is variable, the service provided is basically the same regardless.


Yes, you'll need a fair amount of engineering talent to keep things running, although I'd think you'd want to design the ship to be as self-sustaining as possible.


I'd think so as well, but reducing the workload does not eliminate the need for a human component. the primary job of the support crew is to enable the primary crew to do their jobs for their entire lives without having to endure a completely mechanical existence. Additionally, they are the source of the replacement crew, and the means of raising and training that replacement crew.


Also, the needs change as time goes on. As the ship approaches the destination, the occupants can train the next generation in the direction they need--hydroponic farming instead of starship maintenance, for instance.

- Dr. Trintignant


Which is precisely why you need a full complement and diversity of skillsets. Of course, on a journey that lasts multiple centuries, you are going to need quite a few hydroponic farmers all along. And, while maintenance crews will certainly be necessary, I would imagine costant in-progress upgrading, redesign and rebuilding, and expanding, improving would be constantly ongoing. As for "destination," I imagine a good number of these people might opt for a continual journey. Perhaps sending excursions to explore star systems they pass near to, perhaps even harvesting some materials from these systems to restock their supplies and enable their nomadic interstellar colony to continue to grow. There may well be some who wish to pursue a different course (planetary colony if a suitable planet is encountered, or orbital colony life within a new star system, or even a new nomadic colony headed in a different direction). Its a gradual expansion system that I could envision as possible.

[Hindmost]

1. Why should it take 40,000 years? There are ways to go much faster than Voyager is going. What's wrong with a light sail, for instance?
Or even project orion style propulsion, as another poster mentioned?
2. While I'm sure radiation damage is problematic, it's not insoluble. Just make the machines self-repairing, error-checking, and multi-redundant. This adds cost, but if you know what the level of radiation is, you will no how much added cost you need to make sure the machine is likely to survive intact and functional to it's destination.


Computers are making small incremental steps? When I was a kid I played games my dad made on an apple 2e. When they went to the moon they made their calculations with slide rules. Hell, when they made the atom bomb they had teams of girls in a room doing calculations on an assembly line (until the computers, and the computer was no faster than the girls!*)

While fusion may take a long time, I find it likely that we'll be able to make it work eventually.

Of course some things will come slowly. And of course there are limits. I am only saying that I think, eventually, we will get to those limits.

*At least according to Feyman.

I shouldn't calculate stuff in my head anymore. My assumptions are that we are headed out to colonize an empty planet. The nearest viable star is about 100 to 200 light-years away. I assume fusion power and the ability to hit about 10 percent of the speed of light. So, the 40000 years is a bit high--order of magnitude or so. Thanks for finding the mistake. (note: I also believe that there should be a contigency to move on to a second system if the first one fails.)

Not much right around us...

http://www.atlasoftheuniverse.com/50lys.html

Comparing the first computers with modern stuff is not a good analogy. My laptop isn't much better than the one I had 10 years ago--there is increased functionality, but my word program from 2003 will suit me for a long time. The limits of silicon are starting to emerge. Quantum computing would be a shift of significant magnitude.

I really think propulsion needs a kick start. Solar sails are very limited and not really practical for space travel. Orion ships may have a method of pushing thru to the next star, but there isn't enough energy to run the ship unless fusion becomes a reality. Even fission would be very limiting.

Radiation levels in space are really big actually. To shield against cosmic rays, one would need about a fair thickness of water or equivalent to stop stuff. That would be enormous weight. We can't even make it to Mars right now. (there is a Scientific American article on this that give a reasonable overview) As far as self-repairing, that is science fiction if you ask me...we have difficulty keeping instrumentation systems running for 40 years. 4000 would really be tough as entropy is an evil electronic eating thing.

glenn

[Roboramma]

As far as self-repairing, that is science fiction if you ask me...we have difficulty keeping instrumentation systems running for 40 years. 4000 would really be tough as entropy is an evil electronic eating thing.

glenn

It may be science fiction in so much as we can't do it now, but our bodies are self-repairing, so there is clearly nothing that makes it impossible. I don't see what you think will stop us from making self-repairing machines.

(As to the rest of your post, I apologise, I'm in a bit of a rush now, but will try to respond later. I think you make good points, but they are points about what we can do now or in the near future, not what we will be able to do in the far long term. There are certainly limits to technology, but machines that can last for thousands of years or through hard radiation are not one that I see.)

[Toke]

I keep imagining colonist parachuting from a "lander" with backpacks.
Next step is to clear a runway, build cabins and clear farmland, so that they have food supplies and are ready for the next years batch of colonists.
(Assuming FLT ships and earth-like planet):)
Slight problem with doing the 10.000 years of domesticating of farm plants and animals in a timely manner)

[Dr. Trintignant]

Please demonstrate any independent human community of more than several thousand that does not consist of a fraction whose primary duties are food and beverage preparation and service.

First off, I am imagining a couple thousand, not several thousand. Second, demonstrating that is not necessary--it would only be necessary if people were incapable of cooking food for themselves, a statement we know to be false. As I and others have pointed out, people will have multiple roles. Cooking at a level sufficient for basic nutrition and enjoyment is something everyone can do.

Which is precisely why you need a full complement and diversity of skillsets. Of course, on a journey that lasts multiple centuries, you are going to need quite a few hydroponic farmers all along.

You don't need any in the beginning unless you grow food along the way. That's probably the right approach, but my starting position is one where only known technologies are used. We haven't built truly closed food systems yet, so my inclination is to simply bring the necessary food. This also simplifies things considerably--food recycling systems would be quite complicated, whereas stored food requires only a can opener.

As for "destination," I imagine a good number of these people might opt for a continual journey.

Can't work. The ship only has enough fuel to speed up and slow down once. Even turning the ship would be almost impossible. The best one could do, upon reaching a system that seemed suboptimal, is to look at systems almost directly past the one in question (one might use a gravitational slingshot to steer a tiny amount).

You basically need one ship per trip, unless some very exotic technologies are invented. If you want exponential colonization of the galaxy, each system needs to send out two generation ships. Do that and you can colonize the galaxy in a few million years using essentially current technology.

- Dr. Trintignant

PS: Bringing your food also forces the travelers to land instead of continuing on. So that's another advantage if the goal is colonization.

[makaya325]

If there were advanced civilizations in our Galaxy, it would be appropiate to assume that they would have visited us already, and colonized the rest of the galaxy by now

[BenBurch]

If there were advanced civilizations in our Galaxy, it would be appropiate to assume that they would have visited us already, and colonized the rest of the galaxy by now

Assuming that it is even feasible to do it. That's the rub.

[makaya325]

Assuming that it is even feasible to do it. That's the rub.

There is no reason to doubt that a civilization far more advanced than man can perform, well, inhuman things, such as maniupalting gravity, creating portals (Wormholes)

[Roboramma]

There is no reason to doubt that a civilization far more advanced than man can perform, well, inhuman things, such as maniupalting gravity, creating portals (Wormholes)

There is certainly reason to doubt that any civilization, no matter how advanced, is able to do things that are impossible.

And there is very good reason to believe that getting information from point A to point B faster than light is impossible.

[BenBurch]

There is certainly reason to doubt that any civilization, no matter how advanced, is able to do things that are impossible.

And there is very good reason to believe that getting information from point A to point B faster than light is impossible.

Problem is we can *imagine* those things. This does not make them possible.

[Trakar]

First off, I am imagining a couple thousand, not several thousand. Second, demonstrating that is not necessary--it would only be necessary if people were incapable of cooking food for themselves, a statement we know to be false. As I and others have pointed out, people will have multiple roles. Cooking at a level sufficient for basic nutrition and enjoyment is something everyone can do.

So you are going to duplicate the food preparation equipment multiple times creating more mass to ship and making ship design more complicated? Yes, when we are talking about crews up to a few tens of individuals, fend-for-yourself is workable, but in most situations (ie., ship crews, military units, etc.,) even at small group numbers, yet alone thousands, or as will most likely be desired for any generational venture, tens of thousands, dedicated specialists are needed for a lot of these tasks. I'm sure everyone on such a voyage would have several roles, and will serve rotations in their secondary and tertiary tasks, but this does not eliminate the need for these skillsets, nor does it really reduce the number of people required. A primary aspect that you seem to be overlooking is that this is not a short duration event we aren't talking about dealing with cramped WWII submarine conditions for a couple of months while the crew travels from point A to point B (and even WWII submarines had cooks), we are talking about a breeding population of (at a minimum) thousands of people, many of whom will be born and die on this vessel between when it is launched and when it reaches its destination. You cannot realistically design schedules where people eat, work, and sleep in a tight unending cycle for generations and expect the system to work. The crew will need regular work shifts, a majority of their time each day away from that work shift, rest and recreation days off, educational and play periods for the children, retirement facilities for the aging, etc.,. All of these are a intrinsic part of creating a functional multigenerational ship.



You don't need any in the beginning unless you grow food along the way. That's probably the right approach, but my starting position is one where only known technologies are used. We haven't built truly closed food systems yet, so my inclination is to simply bring the necessary food. This also simplifies things considerably--food recycling systems would be quite complicated, whereas stored food requires only a can opener.


Farming is an established, well understood and accepted means of food recycling. Stored food for thousands of people for hundreds+ years is a tricky calculation and dead payload. Growing food also helps with atmosphere and water recycling, waste processing and adds psychological benefits.


Can't work. The ship only has enough fuel to speed up and slow down once. Even turning the ship would be almost impossible. The best one could do, upon reaching a system that seemed suboptimal, is to look at systems almost directly past the one in question (one might use a gravitational slingshot to steer a tiny amount).


Actually you only use fuel to accelerate the ship. Harvesting en passant would be a tricky process but considering the relatively low passing speeds the nomad colony would be within a half a light year of the passing system for around a century. This gives some time to work with. Harvesting crews and those who wish to off-ship to the passing star system would disembark at a bit beyond the target system's Oort radius and accelerate toward the target system. Deceleration is accomplished primarily with EM magsails functioning as drag chutes. Harvest crew is looking for an appropriate cometary body to accelerate back to rendevous with the colony. Of course the vast majority of the cometary mass will be used up accelerating the body to rendevous, but with appropriate selection the cost/benefit ratios can be both positive and of benefit allowing the colony to continue modest growth as it continues its journey. The only "sub-optimal" system these colonies might pass, would be those without any formation debris (planetary/cometary clouds/belts). The off-shippers would be looking for materials to build new orbital colonies, if there are habitable or near-habitable planets those options would exist, though I doubt that option would be particularly attractive to a race that had long since (even prior to embarking on the nomadic colony) moved to the point where the majority of its species was born, lived and died in orbital colonies.


You basically need one ship per trip, unless some very exotic technologies are invented. If you want exponential colonization of the galaxy, each system needs to send out two generation ships. Do that and you can colonize the galaxy in a few million years using essentially current technology.

- Dr. Trintignant


Nothing I've suggested requires any revolutionary technological leaps, incremental advances and refinements of current technologies will suffice (with the possible exception of fusion power - which is pretty much a requisite).


PS: Bringing your food also forces the travelers to land instead of continuing on. So that's another advantage if the goal is colonization.

You have an artificially limited definition of colonization

[JoeTheJuggler]

I just want to add a flag to the word "logic". Y'know, unless you're talking about either formal philosophy or about digital electronics, I associate the word "logic" much more with bad reasoning than with good. Why is that? Well, to be honest, because of things like your first post. It's a line of 100% casual, conversational argument presented with a couple of formal-logic-like words attached (like "given" and "therefore"). That's fine, that's how people reason in general.

But when I see such reasoning with the words "I figured it out using LOGIC!" attached, it sounds like you assume that the results have some special force of truth. You see this all the time from anti-relativity crackpots, and I think it's part of why their positions are so unshakeable.

Anyway. I don't mean to accuse you of being a crackpot, I just want to disagree with your use of the word "logic".

Thank you! And well-said.

I think that's what I've been trying to say, but at the same time trying to treat his arguments as if they were meant to be actual logical arguments.

ETA: And no one's commented on the strange dichotomy "logic not math". A mathematical proof is a type of formal logic. But I take "math" in the OP to mean inductive reasoning based on real world measurements.

[JoeTheJuggler]

If there were advanced civilizations in our Galaxy, it would be appropiate to assume that they would have visited us already, and colonized the rest of the galaxy by now

Not at all. Even if civilizations more advanced than us existed, there are any number of reasons why it's wrong to posit that they must necessarily have colonized the entire galaxy (or, more accurately, that they must necessarily have spread evidence of their existence everywhere in the galaxy).

I made a list earlier (http://forums.randi.org/showthread.php?postid=5255998#post5255998). Any one of them is sufficient to show why the argument based on Fermi's Paradox fails.

Please note, that we don't have to prove, for example, that FTL travel is impossible. It's enough to know for sure that it MIGHT be impossible*--that is sufficient to show that it's wrong to posit that this spread throughout the galaxy is necessary. (And if it's not necessary, then the absence of evidence doesn't mean anything in this context.)

It's also enough that any one of the other reasons I gave in the list (http://forums.randi.org/showthread.php?postid=5255998#post5255998)for the absence of evidence might be true to refute the logic of this argument.

For this argument to work, every one of those items in the list (http://forums.randi.org/showthread.php?postid=5255998#post5255998) MUST necessarily be false. We can't rule any of them out at this point, so the argument is not sound.

[RecoveringYuppy]

@JoeTheJuggler,

But FTL travel isn't necessary to colonize the galaxy.

[Dr. Trintignant]

So you are going to duplicate the food preparation equipment multiple times creating more mass to ship and making ship design more complicated?

Much of it could be shared. But yes, basic items like teapots and such would be duplicated. People will want private food preparation equipment anyway.

A primary aspect that you seem to be overlooking is that this is not a short duration event we aren't talking about dealing with cramped WWII submarine conditions for a couple of months while the crew travels from point A to point B

Not at all. In fact, the way I envision it, most people will have nothing to do most of the time. The ship will be automated and require almost no maintenance. Food, as I said, will be supplied. The only real roles are for things like doctors. The rest of the time will be spent doing basic human tasks such as cooking or cleaning, or simply relaxing or working on a hobby.

If someone wants to be a bartender in their evenings, they're more than welcome, but there's no need to dedicate someone to the task.

The greatest challenge, I think, is preparing the colony generation. You can't depend on people retaining skills that aren't required on the ship, so some of them will have to be learned anew. There will be libraries and such, but nothing beats hands-on experience. They may just have to learn as they go along.

Farming is an established, well understood and accepted means of food recycling.

Farming on a ship is not. BioSphere 2 didn't work, and that had a huge number of advantages in comparison.

Of course, people can have gardens and such if the lighting capability is high enough, so that fresh vegetables and such are available. But the crew shouldn't have to depend on that, because there are so many things that can go wrong along the way.

Deceleration is accomplished primarily with EM magsails functioning as drag chutes.

Unknown technology. Has anyone even done the math for a multi-million-ton ship using drag chutes? This isn't the same as a space probe--cube-square scaling laws probably apply here.

Nothing I've suggested requires any revolutionary technological leaps, incremental advances and refinements of current technologies will suffice.

That's not enough for me. Much of what you named is still speculative, even if there's no obvious technological reason they can't happen. Further, I want technologies which are not just available, but extremely well established, so that their properties can be predicted over multiple centuries.

(with the possible exception of fusion power - which is pretty much a requisite)

My concept doesn't require fusion, except in the thermonuclear warheads it uses.

You have an artificially limited definition of colonization

Yes, indeed I have, because my goal is to demonstrate that with currently available technologies, we could plausibly launch an interstellar ship. The main things that are lacking are political will and return on investment. It's the kind of thing that we could start building today if we found out the sun will go nova in a century, and we had to colonize elsewhere to avoid it.

Yes, I think that in practice, if interstellar travel ever happens, it will be much more complicated than just basic colonization. But I wanted to answer the original question of why we don't see any aliens, and wanted to eliminate the argument that unknown technologies won't work for some reason. So I focus on known technologies.

- Dr. Trintignant

[kevinquinnyo]

Somewhat veering off topic, but:

(preface: I am a layman, this is just out of curiosity, so I apologize in advance if this sounds just ridiculous)

Does anyone think this is even remotely feasible?:

Could computing power become so great in the future, that the question of whether or not intelligent life develops elsewhere on the galaxy could be answered with a reasonably high probability of accuracy by using some sort of advanced universe modeling software?

And also, what sort of computing power would be necessary to make even a rough calculation as such?


I guess the real question is, is there proof that a computer could not possibly make an accurate model of the universe to answer these types of questions.

EDIT: And I guess to further that question, is the technological leap for this type of insane computing power likely as difficult to achieve as light speed travel?

[Trakar]

Yes, indeed I have, because my goal is to demonstrate that with currently available technologies, we could plausibly launch an interstellar ship.

And I am talking about a potential future where the majority of humanity has lived in orbital colonies for millenia, undertaking a migration into the rest of the galaxy. We are working from different premises to start with, and arguing against propositions that don't apply to the other's premise. Neither of our positions are directly related to the OP, therefore we aren't discussing so much as arguing across each other. Even as stated, I don't think your proposal is workable, but if you'd care to start a seperate thread and lay out the basic principles of your premise, I would be happy to join a discussion of the proposal. If not, we've gone too far afield of the OP and aren't likely to find much common ground between our disparate premises or proposals so it is probably best to end this interaction.

[Toke]

Could computing power become so great in the future, that the question of whether or not intelligent life develops elsewhere on the galaxy could be answered with a reasonably high probability of accuracy by using some sort of advanced universe modeling software?
I don't think that processor power or software can compensate for lack of information.

[Trakar]

I don't think that processor power or software can compensate for lack of information.

That is the issue!

it isn't so much an issue of computational power, but rather some basic understandings and raw data that we currently lack.

[McHrozni]

1.If life exists here, it should exist elswhere.

Plausible, but unproven.

2. If intelligent life exists it should exist elswhere.

Possible, but less likely than 1, and equally unproven.

3. Given the age of the universe some intelligent life should be billions of years old.

Possible, but currently unprovable.

4. Those civilizations should have figured out ways around the vast distance limitations of the universe.

Completely untrue. It is possible that such distance limitations are indeed impossible to bridge in a reasonable time period, and it is possible this point is completely wrong.

5. Intelligent civilizations explore and make maps.

Plausible, but unproven. We only have 1 such civilization to work with.

6. Given a million years some intelligent civilizations should have mapped the entire universe.

Possible, but given point 4., completely unreasonable to presume to be true. The time could be too short, the limitations of the universe too severe. It is possible they aren't, but we can't say it is.

7. They should know we are here.

Possible, but again, unreasonable to presume to be true, same as 6.

8. So therefore, they choose NOT to make contact with us.

This is completely unreasonable, the limitations physics show could be too severe, or maybe they mapped Earth a million years ago and ignored it since ... there are doubts at each stage of the process. I could go on and on.

McHrozni

[JoeTheJuggler]

Somewhat veering off topic, but:

(preface: I am a layman, this is just out of curiosity, so I apologize in advance if this sounds just ridiculous)

Does anyone think this is even remotely feasible?:

Could computing power become so great in the future, that the question of whether or not intelligent life develops elsewhere on the galaxy could be answered with a reasonably high probability of accuracy by using some sort of advanced universe modeling software?

And also, what sort of computing power would be necessary to make even a rough calculation as such?

Computing power can only operate on known data. If the known observations and measurements do not include the information that could lead one to conclude a probability for intelligent life, all the computer power in the world will not give you that information.

In fact, that's the thing about logic: the conclusion really is there inherent in the premises. If you use valid arguments, the conclusion must follow from the premises. If the premises are correct, then such an argument is sound.

Logic (and computation is just another word for doing logic in the subset of logic which is one or another formal mathematical system) cannot give you brand new information that is not logically inherent in the premises.

Now, something computers are really good at is crunching a lot of numbers in a short time, so they can be used to make very complicated models of the real world. These models though are not like straight logic. They only tell us that if the rules of the model are accurate descriptions of the real world, then we can calculate an outcome based on a certain set of initial conditions. Unfortunately, in the real world, chaos seems to be the rule rather than the exception, so very very tiny errors in the initial conditions can throw off the outcome by a lot. (Think of our weather models. They're pretty accurate within 24 hours, but 4 weeks or 6 months out, they're not much better than random guesses, or the Farmer's Almanac!) At any rate, models don't give you conclusions that have to be true. If you want to compare them to logic, they're equivalent to starting with a conditional premise, like this:

Iff p then q.

Trouble is, we don't know which of the following arguments is sound:

Iff p then q.
p
Therefore q.

Iff p then q.
Not p.
Therefore not q.

[Toke]

I wonder if anybody have tried breeding mice in zero-G, and what that indicate for the people born and growing up on a generation ship.

[Dancing David]

@JoeTheJuggler,

But FTL travel isn't necessary to colonize the galaxy.

Then how long would it take?

At .1 c it would take forty years to get to Alpha Centauri, say the nearest habitable planet with resources is close, 50 light years. So it takes 500 years to get there.

How long does it take a colony to get to the point where it can send off colonists, lets be generous and say 100 years. So that is 600 years from one planet to the next, at a distance of 50 light years, our galaxy is roughtly 100,000 light years across.

So 100,000/50=2,000, which is also pretending we are in the middle of the galaxy.
2,000 x 600= 1,200,000 years.

So 1,200,000 years is very long time to colonise the galaxy, with geneous extimates, if we say that usable panets with resources are 50 light years apart and that it takes a colony 100 years to be able to launch. (Traveling at .1 c)

If it takes 500 years to launch then the math becomes 2,000 x 1,000 = 2,000,000 years.

Now say that the nearest usuable planet is 200 light years and that launch is 100 years:
Then we have 2,000 years per trip at .1 c but only 500 hops. So that is 2,100 x 500= 1,050,000 years for colonization of the galaxy.

But .1 c is a really high value, what if it is .01 c?
Then a fifty light year trip takes 5,000 years, and so hop time becomes 5,100 years.

That is 10,000,000 years to colonise the galaxy.

Now this is not even counting the time it takes to send out probes and find usable systems as well.

[RecoveringYuppy]

@DancingDavid,

I think your numbers are in the right ballpark for accuracy. I think you've probably overestimated the speed it would likely happen at and, consequently, underestimated the time.

I think colonization will happen at roughly the speeds we find things moving around naturally in orbit around a star and I arrive at 300 million years to colonize the galaxy. That's only 3% of the time the galaxy has been around, so the "Fermi question" becomes how come no one else is only 3% ahead of us?

With your numbers the question becomes how come no one is only .1% or .2% ahead of us?

[Trakar]

I wonder if anybody have tried breeding mice in zero-G, and what that indicate for the people born and growing up on a generation ship.

Why would you expect zero g condtions on a generation ship?

[Trakar]

Then how long would it take?

At .1 c it would take forty years to get to Alpha Centauri, say the nearest habitable planet with resources is close, 50 light years. So it takes 500 years to get there.

How long does it take a colony to get to the point where it can send off colonists, lets be generous and say 100 years. So that is 600 years from one planet to the next, at a distance of 50 light years, our galaxy is roughtly 100,000 light years across.

So 100,000/50=2,000, which is also pretending we are in the middle of the galaxy.
2,000 x 600= 1,200,000 years.

So 1,200,000 years is very long time to colonise the galaxy, with geneous extimates, if we say that usable panets with resources are 50 light years apart and that it takes a colony 100 years to be able to launch. (Traveling at .1 c)

If it takes 500 years to launch then the math becomes 2,000 x 1,000 = 2,000,000 years.

Now say that the nearest usuable planet is 200 light years and that launch is 100 years:
Then we have 2,000 years per trip at .1 c but only 500 hops. So that is 2,100 x 500= 1,050,000 years for colonization of the galaxy.

But .1 c is a really high value, what if it is .01 c?
Then a fifty light year trip takes 5,000 years, and so hop time becomes 5,100 years.

That is 10,000,000 years to colonise the galaxy.

Now this is not even counting the time it takes to send out probes and find usable systems as well.

You're just looking at distances, but even here 10,000,000 years is a cosmic blink of the eye, only a bit longer than our homo-pan clade originated. It shouldn't be necessary for a species to completely colonize the galaxy before we'd be aware of them. Any big chunk of the galaxy that was technologically colonized and well travelled should be noticeable, unless they are incredibly efficient and intentionally quiet,...which for all we currently know may be requisite to galactic colonization!

All of this presumes that the parent population and all subsequent colonies only make one effort each colonization, and a straight line jump of colonies stretching across the galaxy doesn't really equate to galactic colonization. Run your figures at 0.01c and figure that the initial population launches ten colony efforts to start with and another ten each century after that (remember "colonies" aren't dependent upon habitable Earth-like planets, just starlight and the materials to build colonies). Assume the same for each star system colonized.

[McHrozni]

@DancingDavid,

I think your numbers are in the right ballpark for accuracy. I think you've probably overestimated the speed it would likely happen at and, consequently, underestimated the time.

I think colonization will happen at roughly the speeds we find things moving around naturally in orbit around a star and I arrive at 300 million years to colonize the galaxy. That's only 3% of the time the galaxy has been around, so the "Fermi question" becomes how come no one else is only 3% ahead of us?

With your numbers the question becomes how come no one is only .1% or .2% ahead of us?

There are quite a few variables ignored.
First, there may not be an available bridge of habitable planets between "us" and "them". Secondly, we also assume that a species will continue such expansion uninterrupted for millions of years. That too is very hard to support, 300 million years ago was before the age of dinosaurs. A lot can change in that time in a species.
Moreover, we're assuming "they" would also want to contact us. Perhaps they're shy and don't want any contact with another intelligent species.

I can think of more reasons, but I think you get the picture.

McHrozni

[Trakar]

@DancingDavid,

I think your numbers are in the right ballpark for accuracy. I think you've probably overestimated the speed it would likely happen at and, consequently, underestimated the time.

I think colonization will happen at roughly the speeds we find things moving around naturally in orbit around a star and I arrive at 300 million years to colonize the galaxy. That's only 3% of the time the galaxy has been around, so the "Fermi question" becomes how come no one else is only 3% ahead of us?

With your numbers the question becomes how come no one is only .1% or .2% ahead of us?

We know that the Galaxy was a very different place 5 billion years ago, its quite possible that the conditions to give rise to stars and planetary systems sufficiently like ours to produce a similar history were rare enough that we are indeed one of the anomalously early representatives to reach the point we have without being "reset" by external or internal factors. And we still haven't proven that we can and will reach the point of galactic colonization without being reset. If the universe were infinitely old, or even if conditions had been largely the same as they are now through out the course of the last 12-14 Billion years of the Universe's existence, then Fermi's paradox would be more paradoxical. But the universe has changed as it has aged and conditions have evolved. The further back in time we go, the more energetic and hostile our galaxy becomes and the rarer the conditions and elements we recognize as essential in our formative history become. It may not be that we are alone, but merely that we are among the first, to reach this point.

[Toke]

Why would you expect zero g condtions on a generation ship?

The ship would not have enough mass to give any practical gravity, particularly not on the inside, acceleration is just at the start and end of the journey.

Spinning it to get one G was something I did not consider.
It would add some serious demand for hull strength and quite likely some bearings to maintain.

[RecoveringYuppy]

First, there may not be an available bridge of habitable planets between "us" and "them".
We're talking about millions of years in space. They (or we) are going to be adapted to space over that time. Planets, with their high gravity making their resources inaccessible, may be obstacles.

Secondly, we also assume that a species will continue such expansion uninterrupted for millions of years. That too is very hard to support, 300 million years ago was before the age of dinosaurs. A lot can change in that time in a species.
Sure, what's wrong with changing species a few million times during this process? I'd expect that the timeframe and distribution of resources thoughout the galaxy will inevitably lead to millions of new descendant species from us, not to mention all the lifeforms we take with us.

[RecoveringYuppy]

It may not be that we are alone, but merely that we are among the first, to reach this point.
That would be my guess too.


And we still haven't proven that we can and will reach the point of galactic colonization without being reset.
Yes, our "Permanent occupation of space" is nine years old tomorrow IIRC. Not too far along towards 300 million.

[McHrozni]

We're talking about millions of years in space. They (or we) are going to be adapted to space over that time. Planets, with their high gravity making their resources inaccessible, may be obstacles.

What about stars with no planets, or with no planets with useful resources? In this planet-hopping scenario, they would be significant obstacles indeed. What if Earth is the only planet (or Sol the only system) in the wider area that has useful resources, and the entire region is useless for colonization anyway?

Sure, what's wrong with changing species a few million times during this process? I'd expect that the timeframe and distribution of resources thoughout the galaxy will inevitably lead to millions of new descendant species from us, not to mention all the lifeforms we take with us.

In that case, how do we know we aren't, in fact, descendants of one such space fearing species in the first place? Maybe a hybrid with the local stock? I wouldn't consider this a particularly outrageous proposal, comparing all the other leaps of faith we already had to make in this thread.

McHrozni

[RecoveringYuppy]

What about stars with no planets, or with no planets with useful resources? In this planet-hopping scenario, they would be significant obstacles indeed. What if Earth is the only planet (or Sol the only system) in the wider area that has useful resources, and the entire region is useless for colonization anyway?

Seems unlikely but, OK, what about it? Would be interesting to wonder if we'd go directly across the galaxy, or would it be more likely we'd follow the spiral arms due to their greater density?


In that case, how do we know we aren't, in fact, descendants of one such space fearing species in the first place? Maybe a hybrid with the local stock? I wouldn't consider this a particularly outrageous proposal, comparing all the other leaps of faith we already had to make in this thread.
Do you mean the original instance of life on Earth? I suppose at the moment there is no way to rule that out. If you mean humans in particular that's ruled out by DNA comparison with other animals. Not much reason to think that separate instances of life are going to be able to hybridize. Hybridization only works on Earth between very closely related species. And we all share the same genetic code.

[JoeTheJuggler]

@JoeTheJuggler,

But FTL travel isn't necessary to colonize the galaxy.
I know, and I said as much in the post where I made the list of ways (http://forums.randi.org/showthread.php?postid=5255998#post5255998) to refute the argument based on Fermi's Paradox (see the ETA bit).

It's not necessary to prove that FTL is impossible in order to refute the argument based on Fermi's Paradox.

The argument requires that a civilization make evidence of their existence ubiquitous in the galaxy. The fact that we don't have that evidence does not prove that intelligent civilizations don't exist. (Again, we are an intelligent, technology-using civilization, and we haven't come close to making evidence of our existence ubiquitous in the galaxy.)

As I mentioned when I made my list (http://forums.randi.org/showthread.php?postid=5255998#post5255998), I have heard formulations of Fermi's Paradox that don't require FTL travel. Instead they require self-replicating probes and/or that the civilization is old enough to have spread throughout the galaxy. In that case, just substitute that stuff instead of FTL travel for the first couple of points in my list. The other points are the same and any one is sufficient to refute the argument that absence of evidence in this case is evidence of the absence of ETIs.

[Trakar]

The ship would not have enough mass to give any practical gravity, particularly not on the inside, acceleration is just at the start and end of the journey.

Spinning it to get one G was something I did not consider.
It would add some serious demand for hull strength and quite likely some bearings to maintain.

Actually the loads are generally within the normal tolerances of what's required for pressure and any energetic manuevering considerations, a bit more, but not terribly so, and more than pays for itself in the other benefits it confers, especially in a multigenerational mission profile. In anything multigenerational you are talking decent sized think Stanford Torus (at the least) with fuel storage and engines. No real need for bearings, rotate the entire structure.

[JoeTheJuggler]

I think colonization will happen at roughly the speeds we find things moving around naturally in orbit around a star and I arrive at 300 million years to colonize the galaxy. That's only 3% of the time the galaxy has been around, so the "Fermi question" becomes how come no one else is only 3% ahead of us?

With your numbers the question becomes how come no one is only .1% or .2% ahead of us?
There's no logical reason to assume that any civilization has to be ahead of us. (To do so requires making one or more assumptions.)

There could also be a tendency of civilizations to self-destruct before they set off colonizing the galaxy.

It could also always turn out to be economically feasible, or there could always turn out to be a lack of motivation.

Again, there are a number of ways to refute the logical argument based on Fermi's Paradox.

If we're speaking of other than deductive logic, about all we can say at this point is that we don't know.

I would cite the tendency of humans to think of themselves as special and unique that has led us to wrong premature conclusions very often, and the observation that our presence is fully explicable by the laws of physics, chemistry and biology (esp. evolution), and there's no reason to assume those things operate differently elsewhere (or that there's a dearth of necessary materials or insufficient time elsewhere), so I would be surprised if it turns out we are unique in the galaxy. However, at this point, we simply don't know.

In these discussions, I always cite what Carl Sagan had to say when pressed on this issue:
Originally Posted by Sagan
I'm often asked the question, "Do you think there is extraterrestrial intelligence?" I give the standard arguments--there are a lot of places out there, and use the word billions, and so on. And then I say it would be astonishing to me if there weren't extraterrestrial intelligence, but of course as yet there is no compelling evidence for it. And then I'm asked, "Yeah, but what do you really think?" I say, "I just told you what I really think." "Yeah, but what's your gut feeling?" But I try not to think with my gut. Really, it's okay to reserve judgement until the evidence is in.
I got this quote from Sagan's introduction to The Outer Edge: Classic Investigations of the Paranormal edited by Joe Nickell.

[Toke]

I was thinking about the disadvantage of rotating the telescopes and other navigational gear.
On second thought that is light stuff and can be put on it's own little rotating dome in front. (With plenty of spare bearings in stock.)

[JoeTheJuggler]

I think colonization will happen at roughly the speeds we find things moving around naturally in orbit around a star and I arrive at 300 million years to colonize the galaxy. That's only 3% of the time the galaxy has been around, so the "Fermi question" becomes how come no one else is only 3% ahead of us?

With your numbers the question becomes how come no one is only .1% or .2% ahead of us?
There's no logical reason to assume that any civilization has to be ahead of us. (To do so requires making one or many assumptions.)

There could also be a tendency of civilizations to self-destruct before they set off colonizing the galaxy.

It could also always turn out to be economically feasible, or there could always turn out to be a lack of motivation.

Again, there are a number of ways to refute the logical argument based on Fermi's Paradox.

If we're speaking of other than deductive logic, about all we can say at this point is that we don't know.

I would cite the tendency of humans to think of themselves as special and unique that has led us to wrong premature conclusions very often, and the observation that our presence is fully explicable by the laws of physics, chemistry and biology (esp. evolution), and there's no reason to assume those things operate differently elsewhere (or that there's a dearth of necessary materials or insufficient time elsewhere), so I would be surprised if it turns out we are unique in the galaxy. However, at this point, we simply don't know.

In these discussions, I always cite what Carl Sagan had to say when pressed on this issue:
Originally Posted by Sagan
I'm often asked the question, "Do you think there is extraterrestrial intelligence?" I give the standard arguments--there are a lot of places out there, and use the word billions, and so on. And then I say it would be astonishing to me if there weren't extraterrestrial intelligence, but of course as yet there is no compelling evidence for it. And then I'm asked, "Yeah, but what do you really think?" I say, "I just told you what I really think." "Yeah, but what's your gut feeling?" But I try not to think with my gut. Really, it's okay to reserve judgement until the evidence is in.
I got this quote from Sagan's introduction to The Outer Edge: Classic Investigations of the Paranormal edited by Joe Nickell.

[RecoveringYuppy]

There could also be a tendency of civilizations to self-destruct before they set off colonizing the galaxy.


I appreciate most of what you're posting but have this nagging feeling you're arguing against some form or implication of the paradox that I'm not familiar with.

To my way of thinking about this, civilizations destroying themselves early (and becoming non-existent in the process) would be one of the more obvious implications or explanations of the apparent paradox, not a refutation of it.

Fermi's paradox is an argument to contradiction. The conclusion of the argument is that one of the premises must be wrong. Assuming that civilizations live long is one of the premises that can be wrong and resolve the paradox.

[Trakar]

I was thinking about the disadvantage of rotating the telescopes and other navigational gear.
On second thought that is light stuff and can be put on it's own little rotating dome in front. (With plenty of spare bearings in stock.)

Mag-lev or just free floating alongside the vessel, once initial acceleration is complete, there's no reason that instruments and equipment can't be parked away from the primary vessel where it won't be impacted by ship process and crew vibrations and influences.

[Dancing David]

Mag-lev or just free floating alongside the vessel, once initial acceleration is complete, there's no reason that instruments and equipment can't be parked away from the primary vessel where it won't be impacted by ship process and crew vibrations and influences.

Or posted at the axis of rotation and then decoupled.

[Corsair 115]

It may not be that we are alone, but merely that we are among the first, to reach this point.


Perhaps. Or perhaps it's just that intelligent life does not occur that frequently within each galaxy. Even if there was only, on average, one intelligent race per galaxy, given that there are over 100 billion galaxies in the universe, that'd mean there are some 100 billion intelligent races in the universe. But because the distance between galaxies is so vast, without a way to bridge that vast distance those intelligences are effectively cut off from each other.

[zerospeaks]

So here is two questions...

1. Assuming what I said was true and intelligent life knows we are here. Have we done anything as a species to justify contact?

2. Generation ships that could be in space for a thousand years or more.... fascinating. Just the thought of such a thing leads me to a wonderful little question.... Could the artificial environment on such a ship be programed to slowly (over hundreds maybe thousands of generations) shift to conditions of outer space? Could we guide ourselves to evolve to have bodies that can survive in outer space? Evolution seems to come up with some pretty nifty answers to survive in almost any condition. Could it be possible then that we could "force" evolution (even if it is millions of generations) to adapt us to live in outer space? Could you imagine?
It get's my imagination center going tingly in a good way just to think about it!!!!

[zerospeaks]

Double post, please delete.

[RecoveringYuppy]

@zerospeaks,

There is no telling how long or how many attempts it would take, but, yes, I think the human race could adapt to space if given the time. Or we could adapt space to us.

[zerospeaks]

There is no telling how long or how many attempts it would take, but, yes, I think the human race could adapt to space if given the time. Or we could adapt space to us.

I think I have just found my mission in life!!!

I know science has ethical laws. However....
Fruit flies are ok right?

So I take some fruit flies.... and I breed them.... and I change their environment to be more like space slowly......

I am totally drooling at the mouth right now!!

P.S. I drool a little when I think I have a really good idea.

[zerospeaks]

So now I believe I have solved the problem.

So.... we need to calculate a rough estimate of how long an intelligent species (such as us) would have advanced notice of impending doom.

Would that amount of time be enough to breed themselves into a caste system to adapt a portion of themselves to survive without their home planet?

Remember if time is short, they could use a generation ship to accomplish this.

So this is not only likely but completely feasible.

Once again maybe Roddenberry was right. Maybe the ultimate evolution of a species is to transcend the need for a planet or artificial planetary environment.

Dang, that guy really must have sat around just thinking of this all the time.

-Edit-
HOLY CRAP!!!
That would explain why we have never made contact with aliens.
They would no longer be able to survive on a planet, and would have no interest in life that does so.

-Edit again-
And the reason we have not been contacted by other life could also be explained by a Dyson Sphere. Don't make me start another thread people! I think ALL of these ideas pertain to my original line of reasoning.

[roger]

You're just looking at distances, but even here 10,000,000 years is a cosmic blink of the eye, only a bit longer than our homo-pan clade originated. It shouldn't be necessary for a species to completely colonize the galaxy before we'd be aware of them. Any big chunk of the galaxy that was technologically colonized and well travelled should be noticeable, unless they are incredibly efficient and intentionally quiet,...which for all we currently know may be requisite to galactic colonization!

My bolding.

Okay, so you are basically assuming that for 10MM years homo sapiens will suddenly
1) stop evolving
2) remain focused on a single cause despite being separated into entirely different cultures
3) that separated cultures will not evolve into different creatures than those they left behind

I recognize those aren't 3 fully independent points, but any thought of generational starships purposefully trying to populate the galaxy (to what end, I wonder) seems rather naive. After only a handful of jumps you are going to be dealing with a different species.

In comparison, our longest existing Governments run just over 200 years, and cultures how many years? We've only been Homo Sapiens for 200K years. Neanderthals have been gone for a mere 30,000 years. A true blink in time compared to this project.

Blithely sitting and calculating optimal strategies for expansion rather misses these points. And of course, the biggest point of all - why????

[makaya325]

Not at all. Even if civilizations more advanced than us existed, there are any number of reasons why it's wrong to posit that they must necessarily have colonized the entire galaxy (or, more accurately, that they must necessarily have spread evidence of their existence everywhere in the galaxy).

Aliens did not have to visit during Human's evolutionary history. It may be reasonable to assume that, Given how many 100 million years life has existed, that Alien life, in some form, should have presented itself by now.

[Roboramma]

My bolding.

Okay, so you are basically assuming that for 10MM years homo sapiens will suddenly
1) stop evolving
2) remain focused on a single cause despite being separated into entirely different cultures
3) that separated cultures will not evolve into different creatures than those they left behind

I recognize those aren't 3 fully independent points, but any thought of generational starships purposefully trying to populate the galaxy (to what end, I wonder) seems rather naive. After only a handful of jumps you are going to be dealing with a different species.

In comparison, our longest existing Governments run just over 200 years, and cultures how many years? We've only been Homo Sapiens for 200K years. Neanderthals have been gone for a mere 30,000 years. A true blink in time compared to this project.

Blithely sitting and calculating optimal strategies for expansion rather misses these points. And of course, the biggest point of all - why????


I don't think the idea is that the colonizing is some grand mission: just that colonies will tend to send out new colonies.

I mean, that's basically the same way that humans expanded over the globe: it didn't require some extremely long lived homogenous culture spanning thousands of years: just that over time people moved on.

If there is a reason for us to form a colony, then the same reason will likely apply to the colony. And of course the math changes if it takes longer, and if, for instance, some colonies fail, but while that changes the length of time it takes, it does change the inevitability of the thing.

Of course, you may suggest that most colonies will fail to send out new colonies. I, personally, find that unlikely, but it's not something that we can know very well now, which leaves me much like the Juggler upthread, rather uncertain.

[makaya325]

It is quite rude to assume that Alien life likely has Technology. What if we are wrong, and they are instead like Animals, intelligent but without the use of technology?

[Roboramma]

It is quite rude to assume that Alien life likely has Technology. What if we are wrong, and they are instead like Animals, intelligent but without the use of technology?

I would imagine that most intelligent life is of that sort, but the question is, is there some that is of our sort? That is, are there technological civilizations out there?

[Trakar]

Perhaps. Or perhaps it's just that intelligent life does not occur that frequently within each galaxy. Even if there was only, on average, one intelligent race per galaxy, given that there are over 100 billion galaxies in the universe, that'd mean there are some 100 billion intelligent races in the universe. But because the distance between galaxies is so vast, without a way to bridge that vast distance those intelligences are effectively cut off from each other.

Galaxies come in all sizes, but yeah, I get what you're shooting at and largely agree. Intelligent, technological life can be very, very rare, and well dispersed, and yet in an infinite universe, still be, infinite, in representation.

[Trakar]

So here is two questions...

1. Assuming what I said was true and intelligent life knows we are here. Have we done anything as a species to justify contact?

2. Generation ships that could be in space for a thousand years or more.... fascinating. Just the thought of such a thing leads me to a wonderful little question.... Could the artificial environment on such a ship be programed to slowly (over hundreds maybe thousands of generations) shift to conditions of outer space? Could we guide ourselves to evolve to have bodies that can survive in outer space? Evolution seems to come up with some pretty nifty answers to survive in almost any condition. Could it be possible then that we could "force" evolution (even if it is millions of generations) to adapt us to live in outer space? Could you imagine?
It get's my imagination center going tingly in a good way just to think about it!!!!

If that was the goal, engineering the result would probably be much quicker than trying to force adaptation and evolution.

[Trakar]

My bolding.

Okay, so you are basically assuming that for 10MM years homo sapiens will suddenly
1) stop evolving
2) remain focused on a single cause despite being separated into entirely different cultures
3) that separated cultures will not evolve into different creatures than those they left behind

How did you derive this from what I said:
[QUOTE]You're just looking at distances, but even here 10,000,000 years is a cosmic blink of the eye, only a bit longer than our homo-pan clade originated. It shouldn't be necessary for a species to completely colonize the galaxy before we'd be aware of them. Any big chunk of the galaxy that was technologically colonized and well travelled should be noticeable, unless they are incredibly efficient and intentionally quiet,...which for all we currently know may be requisite to galactic colonization!

much less that I was such assumptions as the basis for the types of conclusions you are drawing?


I recognize those aren't 3 fully independent points, but any thought of generational starships purposefully trying to populate the galaxy (to what end, I wonder) seems rather naive.

In my senario, colonization is more a side product than the primary goal. The primary goal is the support and growth of the original colony (which is the generation "ship"). Colonization occurs as segments of the original colony decide that they wish to start a new colony either not subject to the conditions and pressures of spending so much of their existence in the barrens of interstellar space, or because they feel the need to follow a different path.


After only a handful of jumps you are going to be dealing with a different species.

a handful of jumps? no, most jumps are a few hundred years in duration, our species is essentially unchanged over the last 100,000 years or so and with only minor changes for twice that long. Under the provinces of nature, evolution is the product of changing environments, for the most part, these colonies provide a stable environment. Of course, we are on the verge of be able to recreate ourselves, so it is entirely possible that the species which undertakes such a venture to begin with, while originally derived from humanity, is not strictly homo sapiens sapiens.


In comparison, our longest existing Governments run just over 200 years, and cultures how many years?

Makes little difference what form of civil governance the people choose, change to or decide to do without. Once the journey begins, the passengers are simply payload. If they kill themselves off, they kill themselves off, and that effort won't yield many colonial offshoots. If most of the passengers decide to head back to the Solar system at the first star encounter, then they leave the nomad colony decelerate into the system, build a new colony and head back the way they came. Those that choose to continue would have a lot more space and resources at their disposal due to the decision of most to abandon the colony.


We've only been Homo Sapiens for 200K years. Neanderthals have been gone for a mere 30,000 years. A true blink in time compared to this project.

Blithely sitting and calculating optimal strategies for expansion rather misses these points. And of course, the biggest point of all - why????

Again, I'm not talking about a band of people launching such a venture in the next few years. I'm talking about a situation a few thousand years down the road, where the vast bulk of humanity already lives in free-floating colonies throughout the solar system. For this set of humanity, the idea moving beyond the horizons of our solar system, to neighboring stars and regions of space really won't seem that revolutionary of a concept.

[JoeTheJuggler]

Aliens did not have to visit during Human's evolutionary history. It may be reasonable to assume that, Given how many 100 million years life has existed, that Alien life, in some form, should have presented itself by now.

They had to have visited us during a time when we would have recognized their visit as evidence of alien intelligent life for the argument that the absence of evidence proves the non-existence of alien intelligent life.

The point you raise is one I think I made somewhere on this thread. The absence of evidence could also be explained by a near miss (in astronomical terms)--that is we missed a spacecraft or self-replicating probe (or whatever other evidence of their existence is being posited as necessarily being ubiquitous) that passed through our neck o' the woods a mere million years (or 100,000 years, 10,000 years or--depending on what type of evidence--100 years) ago.

ETA: I'm not sure what you mean by "it may be reasonable to assume" but I can say that it definitely is unreasonable to make an argument based on the assumption that if ETIs exist they MUST have made themselves known to us by now.

[Trakar]

Aliens did not have to visit during Human's evolutionary history. It may be reasonable to assume that, Given how many 100 million years life has existed, that Alien life, in some form, should have presented itself by now.

It took 5 billion years for our Star to yield us. Roughly a third of the age of the Universe. The early epochs of the universe were extremely hostile to life as we know it. Its a precarious balance between enough catastrophism to drive evolution and spur development, and a gentle enough environment to allow technological species and civilizations to grow and thrive.

[JoeTheJuggler]

It is quite rude to assume that Alien life likely has Technology. What if we are wrong, and they are instead like Animals, intelligent but without the use of technology?
Humans are not the only species on Earth to use tools and have culture. (Even specifying "technology" doesn't make intelligence an all-or-nothing thing.) We differ in degree, not kind, from animals with regard to intelligence.

I for one would be keenly interested in finding a planet with something analogous to non-human primates or intelligent cetaceans or even something with the intelligence level of birds. I would consider such aliens to be examples of alien intelligence.

[makaya325]

I would imagine that most intelligent life is of that sort, but the question is, is there some that is of our sort? That is, are there technological civilizations out there?

Well, look at Homo sapiens. We are the only species to develop technology out of millions of other species on earth. Who is to say that we should even expect the same circumstances to arise again?

[JoeTheJuggler]

Well, look at Homo sapiens. We are the only species to develop technology out of millions of other species on earth.
Again, not a true statement.

There've been as many as a dozen or more now-extinct hominid species that made and used stone tools (and fire). There are other species alive now that use tools, and several species that pass along identifiable cultures (for example, the technology of opening walnuts with stones by some groups of chimpanzees).


Who is to say that we should even expect the same circumstances to arise again?
Who is claiming that we should expect that?

The search for extra terrestrial intelligence is not the search for extraterrestrial homo sapiens.

There are many traits, even in our small sample of the Earth's biota, that have shown to be very adaptive and arise again and again. (This is the idea of convergent evolution.) The same solutions to similar problems are apt to evolve over and over. Intelligence may well be one of these. That is not to say intelligence like ours is at all inevitable, but it might not require the exact same conditions and the exact same history.

[makaya325]

Joe, Aliens would still have to have some kind of appendages to create technology, unless they can move things with their mind! :eek:

[Dancing David]

yes and no, is a pseudo pod an appendage?

[JoeTheJuggler]

I appreciate most of what you're posting but have this nagging feeling you're arguing against some form or implication of the paradox that I'm not familiar with.

To my way of thinking about this, civilizations destroying themselves early (and becoming non-existent in the process) would be one of the more obvious implications or explanations of the apparent paradox, not a refutation of it.

Fermi's paradox is an argument to contradiction. The conclusion of the argument is that one of the premises must be wrong. Assuming that civilizations live long is one of the premises that can be wrong and resolve the paradox.

You're right, maybe I'm not replying to an argument anyone on this thread has been making. (I'm not sure, though. It sounds like that is what Makaya is arguing--and it sounds like what he did argue in one of his bigfoot threads before his conversion.) At any rate, I have seen Fermi's Paradox used as the basis for an argument that the absence of evidence proves that ETIs don't exist. For example, in this thread (http://forums.randi.org/showthread.php?postid=4411678#post4411678), amb insists that Fermi's Paradox is proof that we are unique in the galaxy.

As an argument to contradiction, I find Fermi's Paradox useless. If the question is which premise is wrong, I think there's a chance that they're all wrong (and most of the premises are just implied rather than clearly expressed). The overall premise is that if intelligent life existed, evidence of its existence must necessarily be ubiquitous in the galaxy already. That assumption doesn't even fit the one datapoint we know of for sure--the one intelligent civilization we know of, ourselves.

It sounds rather like saying that if gravity existed we would expect the toss of an honest coin to result in it landing on edge. Since it doesn't, what's wrong with the premises?

[JoeTheJuggler]

Joe, Aliens would still have to have some kind of appendages to create technology, unless they can move things with their mind! :eek:
Yes? So? (And how exactly do you define "appendage" when you're talking about alien anatomy?)

Your line of reasoning was basically to say look at all the conditions and historical accidents that it took to result in the evolution of homo sapiens and then to ask, "Who is to say that we should even expect the same circumstances to arise again?" I pointed out that the search for extra terrestrial intelligence is not the search for extra terrestrial homo sapiens. We are neither looking for nor expecting an exact duplication of conditions and history of the Earth somewhere else.

It may well be that intelligence is one of those things that evolution converges on. It also may not be. We just don't know.

ETA: As far as your very strange statement about appendages, it sounds like you're arguing simultaneously for and against convergence. You say that the odds are against something like a human evolving, but then you seem to accept that "appendages" would probably evolve under a wide variety of conditions (as they have on Earth).

[roger]

I don't think the idea is that the colonizing is some grand mission: just that colonies will tend to send out new colonies.

I mean, that's basically the same way that humans expanded over the globe: it didn't require some extremely long lived homogenous culture spanning thousands of years: just that over time people moved on.

If there is a reason for us to form a colony, then the same reason will likely apply to the colony. And of course the math changes if it takes longer, and if, for instance, some colonies fail, but while that changes the length of time it takes, it does change the inevitability of the thing.

Of course, you may suggest that most colonies will fail to send out new colonies. I, personally, find that unlikely, but it's not something that we can know very well now, which leaves me much like the Juggler upthread, rather uncertain.
Well, no 'colony' is going to have, or develop, or maintain the ability for inter/intra-galactic travel. We were talking about sending a few thousand to hundred thousand people, all of whom are going to be focused on survival and infrastructure on the new planet.

Once again it comes to cost. What does it take for a civilization to mount an expedition of this size. We are theorizing that the world right now just about has the capacity to do so in terms of economics and technology.

The new colony will obviously have a huge leg up on this, having just accomplished it successfully, and they'll hopefully have some kind of working ship, but it'll be a long, long time before they have the resources in place to mount a new expedition with what is essentially no pay off for them or their immediate descendents.

None of that argument says it can't happen or won't happen. All it says is that any assumption of the time period that assume that once it starts it just continues in an exponential manner is rather mistaken.

It's easy to 'just move on' in a single world where all you need is an ox and a cart with a very high payoff to do so. It's entirely different to travel many light years in a generational ship with 0 payoff to the people paying for it.

With all our money and skill, we haven't sent people back to the moon yet. We've never had an underwater society. It kind of makes sense to establish a moon outpost or underwater outpost because of resources. The outpost generates either intellectual or material goods, and the taxpayer benefits. Likewise, solar system-scale outposts make some kind of economic sense too. Gases from Jupiter, iron from the asteroids, energy collection from the sun, etc. But venture beyond the solar system and the costs skyrocket (economic and personal - you sign up for you and your future generations to live and die in a tin can), and the return on investment plummets. Once you've done it once, you've collected about all the IP you can from it. No reason for you or the resulting colony to do it again from an economics standpoint.

It'll go slow. There's just not much of a reason to go (compared to the cost), besides your star blowing up. The people leaving are essentially lost to the senders, except in the rare case where you are going just a few light years, in which case you can have status updates, but not to much in the way of 'conversation'. Once your round trip distance exceeds a generation, forget about it.


And now, if we agree it will be very slow, tell me, given that we have all of these essentially independent cultures and species, how long will all of these cultures last? So colony A sends people on a trip, then colony A has a MAD event. Our oldest Government is not much more than 2 centuries. We have no data, but is it reasonable to assume that the rate of sending a generational starship is significantly higher than the death rate of a culture? Remember, we have no data on that - we could be teetering on the brink of failure (someone invents a germ warefare technique that gets out of control, nuclear holocaust, etc), or just at the beginnings of becoming a global civilization with a million year longevity. Who knows?

There's just nothing I can see that will sustain a migration in any way that would actually lead to exponential growth.

[makaya325]

ETA: As far as your very strange statement about appendages, it sounds like you're arguing simultaneously for and against convergence. You say that the odds are against something like a human evolving, but then you seem to accept that "appendages" would probably evolve under a wide variety of conditions (as they have on Earth).

Well, how would they be able to construct starships without any kind of appendages? They do not have to be hands, they could be tentacles, claws, etc. How else can aliens construct things without moving anything physically?

[zerospeaks]

Can someone remind me again why we are just pushing aside the possibility of FTL travel?

[Toke]

Can someone remind me again why we are just pushing aside the possibility of FTL travel?

Current physics does not allow it, and there is no change in sight.
(not that I know of, but I am not a physicist)

[Dancing David]

Can someone remind me again why we are just pushing aside the possibility of FTL travel?

Because there is no way around c at this time. It would require a whole, new whole new set of theories and experiments.

Beyond even imagination at this time.

[roger]

Can someone remind me again why we are just pushing aside the possibility of FTL travel?For exactly the same reason you aren't considering "possibilities" like a species being able to teleport anywhere instantly just with their minds, or the existance of perpetual motion machines (free endless energy),, etc.

[zerospeaks]

For exactly the same reason you aren't considering "possibilities" like a species being able to teleport anywhere instantly just with their minds, or the existance of perpetual motion machines

I cannot and will not look at a speed barrier the same as perpetual motion.
There was a time when it was believed a human going faster than 35 mph would make his blood boil.

Perhaps we have not observed something in nature going faster than light because it is going too fast to see it?

I just don't want to dismiss it without any thought.
If I understand what I read about the Alcubierre drive, then it does not violate the laws of physics and would work if we just had enough energy.
Energy is something that is solvable. We could easily find a new source of energy that could gives our physics equations whole new meanings.

[Toke]

As far as I know the Alcubierre drive require energy on the order of solar masses or more. If it is possible to build it.

[ben m]

I cannot and will not look at a speed barrier the same as perpetual motion.

But you should. The grounds for rejecting FTL travel are exactly the same as the grounds for rejecting "free energy": they're forbidden by very basic laws of physics (conservation of energy in one case, causality in the other), and there is no evidence whatsoever that these laws are wrong. There's not even a hint that these laws are "only approximately right" as there is for General Relativity and quantum field theory; they seem to be absolutely true. There's not even a particular good way to write a coherent hypothesis under which they're wrong.

The "we used to think the sound barrier was inviolable too" statement is misguided. Revolutionary War soldiers were already firing supersonic bullets; Galileo already knew that light moved faster than sound. No well-informed person ever thought that supersonic motion was forbidden by physics; some people may have disagreed on the level of engineering difficulty. Ditto for the 100mph "barrier" or any other such thing.

[makaya325]

Because there is no way around c at this time. It would require a whole, new whole new set of theories and experiments.

Beyond even imagination at this time.

Yet why is it still discussed in the scientific community as being "Hypothetical" and not "Impossible"? There are Scientists, not the kook's, who believe it is possible to at least approach the speed of light, which is 186,282 miles per second. :D

[ben m]

Yet why is it still discussed in the scientific community as being "Hypothetical" and not "Impossible"? There are Scientists, not the kook's, who believe it is possible to at least approach the speed of light, which is 186,282 miles per second. :D

You can hypothesize that Special Relativity is not true. If that hypothesis is true, then perhaps FTL travel is just an engineering problem.

That is different than saying that FTL is *already* just an engineering problem, and hypothesizing that advanced technology will eventually get there. Nope, if SR is true, then it's true everywhere, and it constrains the engineering of today's spaceships in exactly the same way that it constrains the engineering of hyper-advanced civilizations living on a Dyson sphere around Tau Bootis.

"Approach" is fine. We approach the speed of light all the time. We've got electrons "approaching" the speed of light in the accelerator down the hall. Those electrons obey SR and it takes an absurd amount of energy (per unit mass) to accelerate them.

[zerospeaks]

You can hypothesize that Special Relativity is not true. If that hypothesis is true, then perhaps FTL travel is just an engineering problem.

The expansion of the universe itself moments after the big bang violated SR. The expansions was for a period faster than the speed of light.

So we don't need to wonder about "is the expansion or contraction of space-time faster than light possible" because obviously it is.

[Toke]

The expansion of the universe itself moments after the big bang violated SR. The expansions was for a period faster than the speed of light.

So we don't need to wonder about "is the expansion or contraction of space-time faster than light possible" because obviously it is.

The Alcubierre drive is a combination of engineering, and getting more energy that the universe contains, problem.

[zerospeaks]

The Alcubierre drive is a combination of engineering, and getting more energy that the universe contains, problem.

I missed the infinite energy requirement.
Oh that's right! There isn't one.
It is a finite energy drive.

But even if it isn't, it is possible our concept of energy will change in the future, and energy we see now as infinite or unobtainable will be very obtainable.

[Roboramma]

Well, no 'colony' is going to have, or develop, or maintain the ability for inter/intra-galactic travel. Why not? In the beginning? Likely not, it will take time to develop infrastructure.
But after a few thousand years? What would stop the colony from developing exactly as much industry as the "motherland"?

We were talking about sending a few thousand to hundred thousand people, all of whom are going to be focused on survival and infrastructure on the new planet.
In the beginning, of course. And as that infrastructure develops, and approaches what it was back home, what then?

Moreover, while some are talking about going with today's technology, I find that unlikely: not because it couldn't be done, but because technology is advancing. As I said before, von neuman style machines could work at developing the infrastructure of the colony even before any humans arrive: if any humans go at all.

Once again it comes to cost. What does it take for a civilization to mount an expedition of this size. We are theorizing that the world right now just about has the capacity to do so in terms of economics and technology. And a thousand years from now? While sending megatons of material might be increadibly expensive, sending a few small, but self-reproducing robots capable of making use of the materials there will be orders of magnitude cheaper.

On the other hand, if we did find that we wanted to send live humans out there, if we begin to make use of the resources available to us off the earth, the cost becomes a much smaller percentage of what we have.

The new colony will obviously have a huge leg up on this, having just accomplished it successfully, and they'll hopefully have some kind of working ship, but it'll be a long, long time before they have the resources in place to mount a new expedition with what is essentially no pay off for them or their immediate descendents. What's a long time?
And why no pay off? There's plenty of pay off that I can see. Beyond just exploration, there are plenty of resources. Maybe it's not worth it to ship things back to the parent star, but information can be shipped pretty cheap. Science can be done with the resources found out there.


With all our money and skill, we haven't sent people back to the moon yet. Fourty years is a blink of an eye on the timescales we're talking about.
Nasa is talking about going back to the moon.
The chinese want to do so as well.

We've never had an underwater society. It kind of makes sense to establish a moon outpost or underwater outpost because of resources. The outpost generates either intellectual or material goods, and the taxpayer benefits. Likewise, solar system-scale outposts make some kind of economic sense too. Gases from Jupiter, iron from the asteroids, energy collection from the sun, etc. And once we've established that sort of infrastructure and industry, suddenly the costs to go beyond our own star look less daunting in comparison to what we have available.

But venture beyond the solar system and the costs skyrocket (economic and personal - you sign up for you and your future generations to live and die in a tin can), and the return on investment plummets.
Assuming that our lifespans will stay about the same for the next millions of years. Something I find very unlikely.

Once you've done it once, you've collected about all the IP you can from it. No reason for you or the resulting colony to do it again from an economics standpoint. How's that? I mean, why is the second one less valuable than the first?

It'll go slow. There's just not much of a reason to go (compared to the cost), besides your star blowing up. The people leaving are essentially lost to the senders, except in the rare case where you are going just a few light years, in which case you can have status updates, but not to much in the way of 'conversation'. Once your round trip distance exceeds a generation, forget about it. How long is a generation?
Reasons for going:
- Curiousity and exploration
- Science
- To exploit the resources of other stars:
a) Because those going find that there is not enough for them around this one.
b) because people here want things sent back
i) energy (in the form of a laser aimed at our solar system, for instance)
ii) the products of computation (which requires energy, and if we are using up what we've got here, we may want more from there)
iii) Other resources which have become so rare as to actually be worth shipping from elsewhere.
iv) family photos from the new colony.
- Others that I haven't thought of.


And now, if we agree it will be very slow, tell me, given that we have all of these essentially independent cultures and species, how long will all of these cultures last? So colony A sends people on a trip, then colony A has a MAD event.
First: I don't expect colonies to be build on planets. Asteroids and comets are much better for spacefaring civilizations.
Given that, it's pretty difficult for them to destroy themselves.

Our oldest Government is not much more than 2 centuries. We have no data, but is it reasonable to assume that the rate of sending a generational starship is significantly higher than the death rate of a culture? There is a big difference between a government colapsing, being overthrown, etc. and all the people dying.
Rome may have fallen, but the romans didn't go extinct.

Remember, we have no data on that - we could be teetering on the brink of failure (someone invents a germ warefare technique that gets out of control, nuclear holocaust, etc), or just at the beginnings of becoming a global civilization with a million year longevity. Who knows?

There's just nothing I can see that will sustain a migration in any way that would actually lead to exponential growth.

Right. If civilizations tend to destroy themselves before making colonies, then of course you won't see colonies. If they don't then I think you will see colonies.
And each colony can be treated as a new civilization, which happens to have the jump start of having already aquired a high level of science and technology, and probably have a communications line with it's home system from which it can access new science and technology. But that aside, it is not much different from a new civilization emerging, and as such, as I said, if they tend to form colonies, so will the colony itself.

[Roboramma]

I missed the infinite energy requirement.
Oh that's right! There isn't one.
It is a finite energy drive.

But even if it isn't, it is possible our concept of energy will change in the future, and energy we see now as infinite or unobtainable will be very obtainable.Energy produces gravity.
If it's there, you can see its effects through the effects of gravity.

[theprestige]

Umm... you might want to look up 'birds', 'bats' and 'hot air balloons' on Wikipedia

I think you get my point guybrush.
Something that is not feasible today may be tomorrow.
I know I'm late to the party, and I agree it's a good point, but perhaps the work of the Wright Brothers isn't the best support for that point...

Rather than birds and bats and hot air balloons, you might want to look up Octave Chanute. Just prior to the Wright Brother's breakthroughs, he compiled a history of humanity's work on heavier than air flight up until that point. It included a careful analysis of over a hundred years of documented experimentation, and studies of several different airship designs and discussions of their merits and flaws. It also included calculations of thrust-to-weight ratios and the lifting properties of a wide range of airfoil designs. Finally, it included a complete review of the state of the art at that time, the problems that still needed to be solved, and the most likely way forward.

At the urging of mutual friends, he forwarded a copy of his book to the Wright Brothers, and subsequently consulted with them on their work.

The Wright Brothers' success was not sudden breakthrough in a previously unknown field. It was the final step in a long, incremental process where each little advance was widely known and well-understood.

[Hindmost]

There is more to this than just propulsion. For a ship to move through space, it has to have energy for life support. Deep space doesn't have a lot of heat hanging about. Add the shielding requirements for cosmic rays and the weight of the ship becomes enormous. How do you carry that much energy around and manage to move quite a few light-years...which could take a 1000 years. Nuclear fission could not provide enough energy for that duration even with breeder techology carried along the way. That leaves fusion--which is not very compact.

FTL...I am betting on Einstein. But even if there is a possibility, the energy requirements will most likely be substantial.

I am not an expert, but I am fairly sure that cosmic inflation does not violate GR--it was assumed that gravity didn't "exist" yet. And it is all math and not verified. It was very brief too.

glenn

[RecoveringYuppy]

I cannot and will not look at a speed barrier the same as perpetual motion.
There was a time when it was believed a human going faster than 35 mph would make his blood boil.

Others have already pointed out that all laws of physics indicate exceeding c is not possible. I'd add that we've done experiment accelarating atoms to very high speeds and verified those laws of physics. Unless you've got a reason to think that things made out of those atoms will somehow break the laws of physics that their parts can't, we're kind of stuck. Yeah, we may find out what we know is wrong, but right now, what we know is consistent with every bit of evidence.

[roger]

Why not? In the beginning? Likely not, it will take time to develop infrastructure.
But after a few thousand years? What would stop the colony from developing exactly as much industry as the "motherland"? I was using 'colony' in the sense it is ordinarily used - a small outpost. So far we have talked about a generation ship requiring the economy of a planet. That's not a 'colony' in my dictionary :) And you don't get from a few thousand people to a planet economy in a short period of time. 5-10 thousand years? Sure.

As for the rest, I'm not interested in going back and forth in point by point rebuttal.I'm not disputing such a thing is possible, just that it'll go a lot slower than some have posited. It won't go at a speed where a colony lands, and quickly mount a new mission for the reasons I listed. There's no reason to, it's enormously expensive, and once you've done it once, you already have gained that intellectual knowledge. Furthermore, once you are separated, you are different species and different cultures. Talking about what humans 'have' and how that will make expansion easier seems misguided. That's the sort of idea you get in space opera science fiction - it doesn't seem particularly realistic.


Oh, and if we can send nanobots to create an entire world's infrastructure without human supervision, why exactly would we send humans anyway? The nanobots can gather and transmit any interesting information if they have that level of sophistication.

As for your reasons for going, I find it hard to agree. Of course it is all hand waving on both our parts, but turn it around for a second - imagine the earth is a colony right now of some older civilization that sent us out 50,000 years ago. Okay, cool. We've finally built the capacity and world economy to think about going past the edges of the solar system. Are we going to start raping earth and shipping it off to Zeta Pau, our ancestors and now different species, and 7 governments past the one that originally sent us? There's barely enough resources on Earth to support us. No way we are going to direct all our efforts and all our money to send stuff back to people we've never seen, never talked to, and have no way to control us. Remember the American Revolution? A mere ocean separated us. Our next goal would be to do something useful to us - like colonize the moon.

But let's say we are selfless, and decide to serve our galatic overlords that have absolutely no control over us. What do we send them? How do we know what they want? If we are separated by 50,000 light years, they and we will be different species in the time between an 'order' and receiving the goods on the other end. The scales just don't work.

Maybe one day in a spirit of adventure and generosity we'll send some people off to another world, but what a laugh to think that in 10,000+ years we'd suddenly start receiving care packages from them of stuff we need. 'ha ha they are sending us petrochemicals - how quaint - we solved that problem 20,000 years ago when we found planet Oily'.

You can alter that equation by making it just a few humans, and a lot of robots, but again it's barely efficient for us to extract and transport goods just here on Earth. Now we are postulating boosting it into orbit, sending it on a several thousand year journey, in the hopes (cause you won't know) that the original species still wants the unobtanium you are sending them, and will be waiting and watching for it. And you are talking about 1 shipment every 5,000 years unless you are positing say 10,000 ships, which will require a huge amount of infrastructure and materials to build and maintain. We sure aren't going to be spending the earth's economy to launch what amounts to a few container ships worth of 'stuff', so we are talking huge ships, requiring huge resources to build. I just don't see how it adds up. Rather more sensible to just limit your population so you can adequately use the resources of your own planet.

In any case you are no longer talking about a colony but mining. Who'd volunteer for that? Just send the nanobots. In any case, it's just hand waving. There's all kinds of things that are vastly uneconomic to do. Given the vast distances (space and time) that habitable words are separated, it takes a lot more than saying "we'll ship resources back to earth" to make a convincing argument.

I just find the whole concept of 'humans' occupying the galaxy very dubious. I wouldn't be surprised at all to find that some of the life forms in the galaxy were the result of a colonization. Nor would I be surprised that whatever life form resulted from that colonization eventually went ahead and colonized another world. But to think that they maintained their same species, allegience to a Government that no long exists to them, etc? Nah. That the expansion will be cumulative, and that the species that launched it 10 coloniess back still exists in some intelligent form? Nah again.

[zerospeaks]

The Wright Brothers' success was not sudden breakthrough in a previously unknown field. It was the final step in a long, incremental process where each little advance was widely known and well-understood.


Oh my. That sounds a lot like physics today.
Just 60 years ago techyon particles were impossible.

Now we think they probably do exist, we just do not have the means to detect them.

This is a MAJOR point to be discussed. If special relativity is true then it would explain why we do not see anything passing c.
It would be invisible to us.
Not a violation of physics, just an untestable at this point.

If you are saying surpassing c is impossible then I would once again mention the expansion of the universe after the big bang.
And what of a singularity?
After the event horizon c becomes meaningless.

[Hindmost]

Oh my. That sounds a lot like physics today.
Just 60 years ago techyon particles were impossible.

Now we think they probably do exist, we just do not have the means to detect them.

This is a MAJOR point to be discussed. If special relativity is true then it would explain why we do not see anything passing c.
It would be invisible to us.
Not a violation of physics, just an untestable at this point.

If you are saying surpassing c is impossible then I would once again mention the expansion of the universe after the big bang.
And what of a singularity?
After the event horizon c becomes meaningless.


The evidence for SR and GR are extensive. There is also a difference between the expansion of the universe and an object propagating through space. Points in space can be receding from each other faster than the speed of light...however, an object still cannot travel faster than c when traveling through space. This does not violate SR or GR.

An object traveling faster than light would be traveling backwards in time. This is believed to yield causality problems and not possible.

There is no evidence for tachyons....just some math.

Even traveling close to or faster than light doesn't solve the energy issues.

glenn

[zerospeaks]

Hindmost,

I am no longer talking about traveling through space.
Every other person on this thread is.

If we are traveling through space point A to point B, then sure. You are correct.

I am talking about either
A) Warping, expanding or contracting space.
B) Tunneling through it...
C) Folding it.


All of these things are possible in mathematics.
For all we know these things could occur in nature right now.

We would have no way of detecting it, if it did.

Which brings me back to the point I was trying to make when I started this thread which everyone seems to be ignoring.

If such things are possible, and we are so primitive that we can not even detect them. Then why would an alien race spend even one second on us? Would we stop in africa to try and explain algebra to a colony of ants on our way to australia?

[ben m]

Just 60 years ago techyon particles were impossible.

Now we think they probably do exist, we just do not have the means to detect them.

This is not true.


If you are saying surpassing c is impossible then I would once again mention the expansion of the universe after the big bang.


The expansion of the Universe did not violate causality, did not violate SR, and did not do anything remotely relevant to the question of whether hyperadvanced civilizations could explore/colonize/contact the galaxy.


And what of a singularity?
After the event horizon c becomes meaningless.

Again, this is simply not true.

[ben m]

I am talking about either
A) Warping, expanding or contracting space.
B) Tunneling through it...
C) Folding it.

All of these things are possible in mathematics.

These things sometimes appear to be possible in rather difficult and error-prone mathematics. The Alcubierre drive, for example, may not work even in math---read the Wikipedia article about it, for example, and note Krasnikov's and Coule's objections---and certainly does not work unless Nature allows the existence of "exotic matter" which it simply may not do. Alcubierre's exotic matter may be as utterly nonexistent as (say) a cubic black hole or a stable muonium atom or a charged photon.

Ditto for white holes, wormholes, etc. Just because you can find a science paper saying "Here is some math describing X" does not mean "X can exist under our laws of physics", much less "X could in principle be used for acausal travel of the sort you need for colonization"

[zerospeaks]

Ditto for white holes, wormholes, etc. Just because you can find a science paper saying "Here is some math describing X" does not mean "X can exist under our laws of physics", much less "X could in principle be used for acausal travel of the sort you need for colonization"

But if I understand math correctly,

Sometimes in math you end up with a variable that seems impossible.
Like time reversal was seen in math used by engineers in th late 1800's and they scoffed at it saying "this is impossible, the math must be wrong"

Then along came einstein, and he showed how time reversal's were possible.

Then the mathematician's said "oh yeah... now it makes sense."

I admit my ignorance on this matter. I am not a physicist. However the ones that I have talked to speak of such things (wormholes, warp-drive) not as impossible but currently unobtainable.

I have also have numerous conversations with one of my best friends who has far greater credentials in math than I. He has agreed that the math shows such things as (tachyons) to not only be possible but a certainty. However he has confessed that even if such things exist we may NEVER be able to control or interact with them.

I am asking you the reader to suspend our current laws of physics for just a moment. Let us at least start with the premise that FTL is possible. Now......

Where are the aliens?

I see nothing wrong with theoretical physics. Let us use some now.

[Trakar]

If we are traveling through space point A to point B, then sure. You are correct.

I am talking about either
A) Warping, expanding or contracting space.
B) Tunneling through it...
C) Folding it.



In the manner which you seem to be proposing, this requires the ability to produce and manipulate negative energy, something we have no compelling evidence for, yet alone an understanding of sufficient to allow its manipulation.

[zerospeaks]

In the manner which you seem to be proposing, this requires the ability to produce and manipulate negative energy, something we have no compelling evidence for, yet alone an understanding of sufficient to allow its manipulation.

SEE!!

Will you guys please stop with the debunking?
I get it. No known laws....blah...blah...

Fine, my solving fermi's paradox logic is completely bunk so far.

Can we please go with the assumption that FTL travel is possible and some (even if only 1) race has discovered it.

What then? Should we expect contact?

[Trakar]

SEE!!

Will you guys please stop with the debunking?
I get it. No known laws....blah...blah...

Fine, my solving fermi's paradox logic is completely bunk so far.

Can we please go with the assumption that FTL travel is possible and some (even if only 1) race has discovered it.

What then? Should we expect contact?

If you could travel infinitely fast, how long would it take you to explore infinite space?

Basically if you are waving a magic wand, then just about anything is possible, but if you are sticking to the universe we observe about us and as we currently understand it, FTL isn't possible.

If you want a logical assessment based upon the universe we see and understand (however, imperfectly) then we have laid out the likelihoods, probabilities and qualifications. Pixie dust won't really change these factors.

[zerospeaks]

If you could travel infinitely fast, how long would it take you to explore infinite space?

I thought the universe was finite in size.

[Trakar]

I thought the universe was finite in size.

This is uncertain, we know it is much bigger than what we can see, some calculations give size to this, but it is possible that it is infinite.

Is the Universe finite or infinite? An interview with Joseph Silk (http://www.esa.int/esaSC/SEMR53T1VED_people_0_iv.html)

[zerospeaks]

Wait a minute.

Every neuron in my brain is firing.

Infinite is logically and philosophically impossible.

[GlennB]

Wait a minute.

Every neuron in my brain is firing.

Infinite is logically and philosophically impossible.

You were happy to suspend known science a little while ago with "let's suppose FTL travel is possible".
Science doesn't know everything therefore anything is possible is not a useful approach. I think homeopaths use it :D

[zerospeaks]

Dang it GlennB,

I am talking about suspending disbelief to allow something that is THEORETICALLY possible.

Not something that is completely impossible on all counts.
Well.... at least to the human brain infinity is impossible.
But fine.... *sigh*
The street goes both ways.

If you are allowing infinity to be a possibility in this discussion then it would only be fair to allow FTL travel as a possibility in this discussion.

Something that no one has done yet.

And isn't that where the fun is? To dream of possibilities?

[zerospeaks]

Oh... and... last I checked FTL travel does not violate physics, it violates energy constraints and complicates things.

If you wish to remain in this current line of reasoning, then the very least that I ask is to start with the assumption that a civilization somewhere has achieved what we would consider insurmountable energy.

[Trakar]

Oh... and... last I checked FTL travel does not violate physics, it violates energy constraints and complicates things.

If you wish to remain in this current line of reasoning, then the very least that I ask is to start with the assumption that a civilization somewhere has achieved what we would consider insurmountable energy.

Weren't you the one saying that infinities were inconcievable? Travelling at C requires an infinite amount of energy for any object with mass. FTL requires greater than infinite energies and would seem to result in temporal paradoxes.

[zerospeaks]

Weren't you the one saying that infinities were inconcievable? Travelling at C requires an infinite amount of energy for any object with mass. FTL requires greater than infinite energies and would seem to result in temporal paradoxes.

Yes, in point A to point B travel, yes.

I am talking about warping or expanding space-time.

Ya know, the theoretical stuff.

Let's assume that our current physics is equivalent to bronze age.
And a race somewhere has reached the space age.

You understand my metaphor, ...... I hope.

[Trakar]

Yes, in point A to point B travel, yes.

I am talking about warping or expanding space-time.

Ya know, the theoretical stuff.

Let's assume that our current physics is equivalent to bronze age.
And a race somewhere has reached the space age.

You understand my metaphor, ...... I hope.

That isn't FTL, and it requires something even more unimaginable that infinities, negative energy (think about the inherent contradiction in that term) and exotic matter (matter that isn't matter and doesn't display the properties of matter as we know and understand it). and a means to manipulate these things.

It seems that the only reason you think these terms are more comfortable than infinities, is because you don't understand what they are, or what is necessary for them exist.

Personally, I hope FTL in some form does exist, but there is no evidence at the current time, that makes such likely, or even probable, proposing such as a given premise upon which to base further supposition, is akin to wondering if a functional wishing well could cure terminal cancer. If you are trying to use logic to resolve the Fermi paradox, adding in ftl muddies the water and confuses the question more than it resolves anything.

[zerospeaks]

If you are trying to use logic to resolve the Fermi paradox, adding in ftl muddies the water and confuses the question more than it resolves anything.

Sadly, I believe I have solved Fermi's paradox using logic after listening to the excellent input on this thread.
The conclusion I have determined seems to be rational and logical.
However, it is depressing and saddens me to a great deal.

The probability is high that other life exists.
The probability that other life has achieved what we would consider intelligence is also high.
The probability that some (if not all) intelligence has learned to use tools and by extension technology is also high. For what is technology if not a tool?
The probability that intelligent life has reached out across the galaxy contacting others is incredibly low. Almost zero.
The probability that we will contact other intelligent life in our (entire species) lifetime is even lower.

The only hope for our species to contact another advanced species is if we are in close range of another. When I say close, I mean within 10,000 years of LY or so. The only message that may ever happen is : we are here.

The reply... may never make it.

This is depressing to say the least.

[makaya325]

"Approach" is fine. We approach the speed of light all the time. We've got electrons "approaching" the speed of light in the accelerator down the hall. Those electrons obey SR and it takes an absurd amount of energy (per unit mass) to accelerate them.

The laws of Physics do not restrict any Civilization from bending time and space, AKA creating a wormhole, does it?

[makaya325]

At least FTL travel is not considered "woo" in the Scientific community, only Problematic. Just because we can't do it, does not mean a civilization millions of years more advanced can't

[Roboramma]

Oh, and if we can send nanobots to create an entire world's infrastructure without human supervision, why exactly would we send humans anyway? The nanobots can gather and transmit any interesting information if they have that level of sophistication. I agree with that. Actually, my points about sending things back here (be it energy, science, or materials), was meant to suggest sending robots to collect it, rather than humans.

I can imagine humans wanting to go for their own sake, and I can even imagine us wanting to send humans for some of the same reasons that we put astronauts on the moon, but I agree that in general its not a very worthwhile endevor, particularly when anything a human can do, a robot will, in the future, be able to do better and cheaper.
The only real reason for humans to go is simply that there isn't enough space here for all of us, and they want more of their own. (Or for their decedents).

[Skeptic]

I cannot and will not look at a speed barrier the same as perpetual motion.
There was a time when it was believed a human going faster than 35 mph would make his blood boil.

There was also a time they said the earth was round, revolved around the sun, and had water in its oceans. Just because something was believed in the past doesn't mean it's wrong.

[Skeptic]

The expansion of the universe itself moments after the big bang violated SR. The expansions was for a period faster than the speed of light.

I am quite sure you're misunderstanding cosmology here.

[makaya325]

There was also a time they said the earth was round, revolved around the sun, and had water in its oceans. Just because something was believed in the past doesn't mean it's wrong.

True, but most of our assumptions turned out to be false, based on lack of replication and lack of imagination.

[roger]

I agree with that. Actually, my points about sending things back here (be it energy, science, or materials), was meant to suggest sending robots to collect it, rather than humans.

I can imagine humans wanting to go for their own sake, and I can even imagine us wanting to send humans for some of the same reasons that we put astronauts on the moon, but I agree that in general its not a very worthwhile endevor, particularly when anything a human can do, a robot will, in the future, be able to do better and cheaper.
The only real reason for humans to go is simply that there isn't enough space here for all of us, and they want more of their own. (Or for their decedents).And on that note, I consider all of this thinking fun, but entirely pointless. I recall reading Asimov (or somebody) stories with the voyagers using slide rules. We are just terrible at predicting future technologies and how we use them.

Who is to say we don't upload our consciousness just as soon as it is possible? That could well be easier to achieve than intergalactic travel. Or we mess up our environment so many times that evolution takes us on a path to lesser intelligence? Etc. It's fun to speculate how one history line might turn out, if everything was goldilocks just so, but I don't think it tells us much that is predictable.

On the face of it, I don't see a species similar to homo sapiens colonizing the galaxy. We could do it with nanobots, but again, the question becomes why?

Everyone talks about just building a ship and sending it out. But how many centuries of research would it be to figure out the problems, even for a nano-embryonic ship? At what cost? Sure, in that case there would be tons of practical spin offs from all the technology, but we really don't have the need for a computer that lasts 50K years, let alone an galactic scale drive.

And in the case of a generation ship? Our space shuttle budget is measured in the billions per year. You can't just build a generation ship and launch it, you need to study the environment for decades, experiment, etc. So, what, a quadtrillion? DOD budget for a year is $500B, and for that we get some tanks, air planes, boats, and a bit of research into things like autonomous robots (my current career, btw). Maybe my meter is uncalibrated, but all that seems like play toys compared to what we are proposing.

But we have to use my own argument against me here. Who knows what the next 'computer' level breakthrough will be, and what effects it will have? Control of our biology would vastly change the equations for the ship, albeit not the reason for going. A technology dump from a million year old alien civilization? Yet still the galaxy's scale, and relative utter emptiness mocks us. As we are today, any mission is a throw away - our current civilizations will never see the result. Even with an infinite lifespan, distances makes meaningful communication impossible. 20K years is still 20K years, and we can pack a lot into them. What an unimaginably dull and static world it would be to have no major changes in that time. OTOH, what an unimaginably exciting place if people are actually making 50K year plans. I don't know which way to fall on that one.

In the meantime, back to reality, we can't decide whether to put a traffic circle in place of the light on main street. :) I jest, but that is rather closer to the scale of our planning abilities. Things like our moon shots, the atom bomb, and a few other things stand out for their determination and 'long term' planning.

We do have longer term planning - the space mission being the obvious example. But we are sort of trundling along, trying the next logical thing (oh, too expensive to send people to mars, let's send 10 robots. Oh, no political will to send 10 robots, and we found this neat atmosphric issue, so let's send 2 robots to study the atmosphere.) I don't see the 'trundle' points that take us to galactic travel.

Something trivial in comparison, and pretty vital to our survival - watching and preventing large earth impacts - gets nothing much more than a laugh and some token funds.

No, I just don't see it happening, with this species, with this African plains grown brain.

[roger]

zerospeaks, I apologize if it seems that I am going off on a tangent on your thread, but I think it pretty well answers your questions. Even with FTL drive, the question still remains why? The scale is vast, far beyond what our brains can understand, and the economics of it doesn't make sense.

Sure, if you want to posit any old physics - FTL travel, basically free energy, instantaneous communication across vast distances, then you can argue for a colonized galaxy. But what's the point - if you stipulate anything is possible, then yes, anything is possible. It's a tautological point. Where's the fun/interest in that discussion? Read some space opera (I love space opera, that is not a put down), enjoy it, but don't think it is telling you about the galaxy. It's playing tennis without a net.

So, if you stipulate FTL travel, I ask you, what are the energy budgets? Why would a race spend that budget for FTL travel? How would they decide where to go (we understand the behavior of the electromagnetic spectrum very well - you aren't ever going to use optical telescopes to see little beings running around on another planet)?

You can't get any traction on it. An unknown species, evolved under unknown pressures, to solve unknown problems, with unknown brain capacities, with an unknown civilization, with unknown goals, using unknown technologies with unknown limitations and unknown energy budgets, utilizing other unknown technologies and physics, with unknown needs and desires, would do what?

It's unknown and unknowable. You can't tell me what is in my pocket, and you have far less unknowns in that equation.

[Dancing David]

The expansion of the universe itself moments after the big bang violated SR. The expansions was for a period faster than the speed of light.

Nope, the framework was expanding. C itself would have remained the same after inflation


So we don't need to wonder about "is the expansion or contraction of space-time faster than light possible" because obviously it is.

Now that is an issue for Sol I. or Ziggy to answer.

[Dancing David]

Oh my. That sounds a lot like physics today.
Just 60 years ago techyon particles were impossible.

Maybe you want to study a little more of the history of physics, tachyons ("http://en.wikipedia.org/wiki/Tachyon) are hypothesized particles. And if theye xist then that does not mean you could convert yourself into tachyons and thereby travel faster than c.

Now we think they probably do exist, we just do not have the means to detect them.

And that does not mean you could use them to go FTL.


This is a MAJOR point to be discussed. If special relativity is true then it would explain why we do not see anything passing c.
It would be invisible to us.
Not a violation of physics, just an untestable at this point.

And not useful as propulsion.


If you are saying surpassing c is impossible then I would once again mention the expansion of the universe after the big bang.

And you would still be wrong.

And what of a singularity?
After the event horizon c becomes meaningless.
No it doesn't, c is exactly the same, the path of the light is altered. The speed is teh same, the path is curved extremely.

[Dancing David]

Hindmost,

I am no longer talking about traveling through space.
Every other person on this thread is.

If we are traveling through space point A to point B, then sure. You are correct.

I am talking about either
A) Warping, expanding or contracting space.
B) Tunneling through it...
C) Folding it.


All of these things are possible in mathematics.

then show me teh math and the theory and the data to support it.

Unless you mean speculation.
:)

For all we know these things could occur in nature right now.

We would have no way of detecting it, if it did.

Which brings me back to the point I was trying to make when I started this thread which everyone seems to be ignoring.

If such things are possible, and we are so primitive that we can not even detect them. Then why would an alien race spend even one second on us? Would we stop in africa to try and explain algebra to a colony of ants on our way to australia?

Why would a bear be catholic?

[Dancing David]

SEE!!

Will you guys please stop with the debunking?
I get it. No known laws....blah...blah...

Fine, my solving fermi's paradox logic is completely bunk so far.

Can we please go with the assumption that FTL travel is possible and some (even if only 1) race has discovered it.

What then? Should we expect contact?

Why don't we just assume that we can ride the backs of Invisible Pink Unicorn's and then ask the same question?

You want the Religion and Philosophy forum!

:)

[Toke]

Why don't we just assume that we can ride the backs of Invisible Pink Unicorn's and then ask the same question?

You want the Religion and Philosophy forum!

:)

Well, if you find the blueprints for the Millennium Falcon and it can be build for a few hundred grand, there will, shortly after, be humans everywhere inhabitable.:)

[Jack by the hedge]

Well, if you find the blueprints for the Millennium Falcon and it can be build for a few hundred grand, there will, shortly after, be humans everywhere inhabitable.:)

Lookin' forward to that! Last one to make the Kessel run in less than twelve parsecs is a... Oh. Wait a minute.:boggled:

[zerospeaks]

Why would a race spend that budget for FTL travel? How would they decide where to go (we understand the behavior of the electromagnetic spectrum very well - you aren't ever going to use optical telescopes to see little beings running around on another planet)?


I could easily see another space race in our future, if we discover a relatively close earth like planet. We may race against each other once again to put a flag in it.
Economies are built on such things.

[roger]

I could easily see another space race in our future, if we discover a relatively close earth like planet. We may race against each other once again to put a flag in it.
Economies are built on such things.
Multiple competing generation ship designs and implementations?!?!?!

It's a real question if the world's economy could support one ship.

[BenBurch]

The one unanswerable question; If we build a generation ship, can we regulate its society such that it does not collapse en-route?

Robert A. Heinlein's story Universe was the first to raise that issue, and I have not seen a solution to the problem since.

Then there is the ethics issue; We are dooming generations to perform a task we set for them. Why should they want to?

[Elf Grinder 3000]

On the face of it, I don't see a species similar to homo sapiens colonizing the galaxy. We could do it with nanobots, but again, the question becomes why?

Everyone talks about just building a ship and sending it out. But how many centuries of research would it be to figure out the problems, even for a nano-embryonic ship? At what cost? Sure, in that case there would be tons of practical spin offs from all the technology, but we really don't have the need for a computer that lasts 50K years, let alone an galactic scale drive.

And in the case of a generation ship? Our space shuttle budget is measured in the billions per year. You can't just build a generation ship and launch it, you need to study the environment for decades, experiment, etc. So, what, a quadtrillion? DOD budget for a year is $500B, and for that we get some tanks, air planes, boats, and a bit of research into things like autonomous robots (my current career, btw). Maybe my meter is uncalibrated, but all that seems like play toys compared to what we are proposing.


I think if our species can do it they will, no matter what the cost. Maybe we could send out a probe with robots piloting it. Even if it took 20K years to reach its destination if you are wondering why I would point to the space program as it stands now....

A lot of it like the international space station and human launches into space are not really for research, but because people are interested. THis has probably been brought up in other threads.

[Hindmost]

I think if our species can do it they will, no matter what the cost. Maybe we could send out a probe with robots piloting it. Even if it took 20K years to reach its destination if you are wondering why I would point to the space program as it stands now....

A lot of it like the international space station and human launches into space are not really for research, but because people are interested. THis has probably been brought up in other threads.

20k...that's about three times longer than recorded history. Unless survival was in jeopardy, people don't have the attention span or the forward thinking for the type of planning that would be required.

glenn

[roger]

I think if our species can do it they will, no matter what the cost. Maybe we could send out a probe with robots piloting it. Even if it took 20K years to reach its destination if you are wondering why I would point to the space program as it stands now.....We are talking about conquering the galaxy, not sending out a lone ship to some nearby star. It (the former) just doesn't make any sense.

[Corsair 115]

I could easily see another space race in our future, if we discover a relatively close earth like planet.


Who needs another planet multiples of light years away? We've got an entire solar system of our own to play around in, and it provides a huge amount of resources and living space. Granted, we'd have to construct that living space, but the resources are there to do it.

[Corsair 115]

The one unanswerable question; If we build a generation ship, can we regulate its society such that it does not collapse en-route?

Robert A. Heinlein's story Universe was the first to raise that issue, and I have not seen a solution to the problem since.


If one wanted to engage in unlikely hypotheticals, there's also the chance of something like A.E. van Vogt's story Far Centaurus when the astronauts were dispatched on a five hundred year journey to a nearby star system (using suspended animation rather than a generation ship) only to discover that, during their voyage, humanity had indeed cracked the faster-than-light problem and beaten them to the star system by a couple of hundred years.

[ben m]

If one wanted to engage in unlikely hypotheticals, there's also the chance of something like A.E. van Vogt's story Far Centaurus when the astronauts were dispathed on a five hundred year journey to a nearby star system (using suspended animination rather than a generation ship) only to discover that, during their voyage, humanity had indeed cracked the faster-than-light problem and beaten them to the star system by a couple of hundred years.

IIRC something similar happens in "Songs of Distant Earth" by Clarke.

[ben m]

Who needs another planet multiples of light years away? We've got an entire solar system of our own to play around in, and it provides a huge amount of resources and living space. Granted, we'd have to construct that living space, but the resources are there to do it.

Imagine that in the future we're so good at living in closed systems, recycling 100% of our waste, and stabilizing populations, that a 20,000 year closed spaceship colony/ecosystem/society can be constructed, sealed off, and sent away without being a suicide mission. That's pretty good engineering right there.

Doesn't that tell you that we've basically solved the supposed problems---living space and lack of resources on Earth---that supposedly makes us need colonies to begin with? If we've got the ecosystem awareness and population-stabilization solutions that make the starship possible, then presumably we've gotten pretty good at living sustainably on Earth and don't need to leave.

[Dancing David]

Then there is Pohl's "The Gold at the Starbow's End" total fantasy and uses a warp drive. Superhumans come back and take over the earth.

[Trakar]

Multiple competing generation ship designs and implementations?!?!?!

It's a real question if the world's economy could support one ship.

Well, and for the time and cost or one such mission, we could build an awful lot of colonies much closer to home. A new Earth-like planet would spark the imagination, but I seriously don't see it lighting off any rush to get there, particularly as it isn't likely around any of the relatively nearer stars.

[Trakar]

The one unanswerable question; If we build a generation ship, can we regulate its society such that it does not collapse en-route?

Robert A. Heinlein's story Universe was the first to raise that issue, and I have not seen a solution to the problem since.

Then there is the ethics issue; We are dooming generations to perform a task we set for them. Why should they want to?

I think the framing of the question is off, but that is the reason that I propose that such might be better off designed as colonies in their own right, rather than as transports from point A to B. Of course, the way some of the people here are envisioning such it seems a prison-like existence and the question is not merely logical, but if their path were followed, I don't see how any generation ship could work. Failure is always a possibility, the trick is in minimizing its potential for realization.

[Trakar]

Imagine that in the future we're so good at living in closed systems, recycling 100% of our waste, and stabilizing populations, that a 20,000 year closed spaceship colony/ecosystem/society can be constructed, sealed off, and sent away without being a suicide mission. That's pretty good engineering right there.

Doesn't that tell you that we've basically solved the supposed problems---living space and lack of resources on Earth---that supposedly makes us need colonies to begin with? If we've got the ecosystem awareness and population-stabilization solutions that make the starship possible, then presumably we've gotten pretty good at living sustainably on Earth and don't need to leave.

This presumes that the only means of making generation ships is through this method, and that the only reason for travelling the universe is to escape our own excrement. Neither are solid proposals, in my opinion.

[makaya325]

What is it called when, just because one can not concieve of something, that it is impossible?

[RecoveringYuppy]

Argument from incredulity.

[Dancing David]

But it is not an argument from incredulity when one gives the basis for the negation.

[makaya325]

I thought it was the arguement from "Lack of Imagination"

http://en.wikipedia.org/wiki/Argument_from_ignorance

[Elf Grinder 3000]

20k...that's about three times longer than recorded history. Unless survival was in jeopardy, people don't have the attention span or the forward thinking for the type of planning that would be required.

glenn

Its similiar to a time capsule.

[Hindmost]

Its similiar to a time capsule.

Well, not really. A time capsule is fairly inert. One does not expect to emerge alive from the time capsule. The energy requirements for keeping people alive for about one to two thousand years are significant--even if there is hibernation. Keeping electronics viable for 50 years is difficult. Traveling through interstellar space with constant bombardment from cosmic rays which will damage anything, the probability for crossing the cosmos is really slim...but I am still hopeful someone is out there.

Any alien species has the same limitations as we all have the same basic elements to use and of course the laws of physics related to momentum, thermo..etc.

glenn

[Trakar]

Well, not really. A time capsule is fairly inert. One does not expect to emerge alive from the time capsule. The energy requirements for keeping people alive for about one to two thousand years are significant--even if there is hibernation. Keeping electronics viable for 50 years is difficult. Traveling through interstellar space with constant bombardment from cosmic rays which will damage anything, the probability for crossing the cosmos is really slim...but I am still hopeful someone is out there.

Any alien species has the same limitations as we all have the same basic elements to use and of course the laws of physics related to momentum, thermo..etc.

glenn


Well in a nomadic colony/generation starship there is little reason to think that the denizens wouldn't continue to develop, grow and change in their opinions and perspectives (not to mention their scientific and technological developments). You are right, time capsule is inappropriate.

[tsig]

Well in a nomadic colony/generation starship there is little reason to think that the denizens wouldn't continue to develop, grow and change in their opinions and perspectives (not to mention their scientific and technological developments). You are right, time capsule is inappropriate.

I think you've hit upon a real problem with generational ships. Even if we had the technology to do it you still have the same human at the wheel.

Maybe a religious cult would develop that refused to believe that they were on a ship and decided to go outside or political factions wiped each other out or a Heaven's gate type cult gained supremacy and they all commit suicide.

Easter Island seems a good example of what could happen.

[Trakar]

I think you've hit upon a real problem with generational ships. Even if we had the technology to do it you still have the same human at the wheel.

Maybe a religious cult would develop that refused to believe that they were on a ship and decided to go outside or political factions wiped each other out or a Heaven's gate type cult gained supremacy and they all commit suicide.

Easter Island seems a good example of what could happen.

That is a problem, as equally likely as in any other isolated colony that depended heavily upon the scientific education, training and skills of its population. Not impossible, but a concern to be sure. The bigger problem isn't in the entire crew going Jonestown, but rather the lone whacko deciding he must preserve the universe from human contamination. Part of the reaso you need broad-spectrum communities and lots of diversionary social activities, and regular medicaland mental health evaluations.

[makaya325]

Would it be concievable for a civilization, lets say 1 million years more advanced than us, to manipulate the Laws of Physics?

[RecoveringYuppy]

Would it be concievable for a civilization, lets say 1 million years more advanced than us, to manipulate the Laws of Physics?

Wouldn't that be definitionally impossible? Whatever you're allowed to do in regard to manipulation would simply be accounted for in the laws.