have they found anything?

[amb]

Good post Bill, and sensible beyond reason.

[JoeTheJuggler]

Believing in ETI is a faith not a science.
I'm not a "believer". I've stated my position clearly many times on this thread. That position is, "We don't know." I've been arguing against the position that the absence of evidence in this case is the evidence of absence.



Let me ask you this. Are YOU a scientist? What is your profession?
Irrelevant. The logic stands on its own.


The logic to explain away Fermi's Paradox could just as easily be applied to the existance [sic] of Santa Claus.
Wrong.

One could say "The North Pole is a huge area. It is absurd to think there is no Santa Claus there." just as logically as saying "There are billions of stars. It is absurd to think there is no other ETI near by".
Straw man. (Generally when you have to make up quotes attributed to your opponent, you're engaging in an argument against a straw man position and not a real opponent.) I even numbered my points. Not one of them is this quote you just invented that no one said.

If you study logic you will see that it is not possible to prove a negative.
Wrong.
The following argument:
P1. If P then not-Q.
P2. P.
C. Not-Q.
is valid. If the two premises are valid it is sound. For example:
If it is raining out, I will not go to the game.
It is raining out.
I will not go to the game.

I understand the statement, "You can't prove a negative (http://skepticwiki.org/index.php/%22You_Can%27t_Prove_a_Negative%22)" usually means something other than what you clearly claim it means.


Fermi did not have probes in mind. He had colonization. When he asked "where are they" he knew in his mathicaly genius mind that if life was common in the Universe, the galaxy should be colonized by now. That is it. That is the end of story. No probes, dude. Someone taught you a buchet of hog wash.
I used probes because that's how many people today formulate it. The points I have to refute the argument work just as well with colonization. There is a false assumption (actually a false dichotomy) in saying either the entire galaxy should be colonized, or intelligent civilizations do not exist. And it's simple to demonstrate. We exist, and yet evidence of our existence is not ubiquitous in the galaxy.

We are late comers.
How do you know that? At any rate, at best then you're simply arguing that long-lived intelligent civilizations substantially older than ours don't exist. (And even at that, it's a weak argument. It still relies on several assumptions any one of which might be false.)
If life like ours comes about frequently, the galaxy should be colonized by now.
That doesn't follow. We are a "life like ours" and we haven't colonized the galaxy (and may never do so, for all we know).



It does not matter why they are not here and why we seem to be alone. THe point is that it seems we are.
The point is that the fact that they are not here doesn't mean they don't exist. I can look into my back yard and see no sign of the existence of a dog. Does it follow that there are no dogs?


If life like ours statistically came about often in the universe, our galaxy should be colonized by now.
You have no evidence to support this assumption. And yet your argument requires this assumption to be true.



Absence of evidence is evidence of absence in a court of law, in science, and in the scientific method.
And that's why I specifically said "in this case". Absence of evidence where we have no good reason to expect that evidence is not evidence of absence. (See my no evidence of a dog in my backyard example.)

[Bill Thompson]

I'm not a "believer". I've stated my position clearly many times on this thread. That position is, "We don't know."
You could just as logicaly insist that we do not know if Santa exists.

We know enough.

We know that we are here because of a series of very unlikely fortunate events.

We know that the universe is hostile to life.

[Bill Thompson]

The following argument:
P1. If P then not-Q.
P2. P.
C. Not-Q.
is valid. If the two premises are valid it is sound. For example:
If it is raining out, I will not go to the game.
It is raining out.
I will not go to the game.


This only proves that you do not get it.
"I will not go to the game" is not a negative just because the word "not" is in it.
It is not an example of a logical construct or proof.
"If I do not eat I will not trow up" can also be one of your examples. It is series of events, not a proof. You don't get it.


The logic to explain away Fermi's Paradox could just as easily be applied to the existance of Santa Claus.

Wrong.


Explain yourself. Explain how your logic is any different. You say "absence of evidence is not evidence of absense". The same can be applied to Santa Claus.

You say that a negative can be proven. Take the challenge then. Prove that Santa does not exist.

[Bill Thompson]

Good post Bill, and sensible beyond reason.
Infinitely sensible? :boggled:

[Bill Thompson]

Good post Bill, and sensible beyond reason.
if amb makes a post, a non-post will not be made.

See, Joe? A conditional statement is not a proof!

[amb]

Infinitely sensible? :boggled:

Er......no, only as far as this discussion carries it. :)

[amb]

It is a fact though that lovers of S/F as I am also but not the far fetched stuff like Star Wars, do think that the universe is teeming with intelligent ETs.
But when it's considered the many almost miraculous events that led to intelligent life to form on this planet, it's doubtful that that is the case. There's no denying that given the almost infinite number of stars in the cosmos there's bound to be other Earths out there somewhere, but not anywhere near the number some people like Joe like think.

[Roboramma]

Believing in ETI is a faith not a science.

"Refuting" it would be like refuting Mormonism to a Mormon. Which is very easy. The fact that the mormon doesn't accept the refutation doesn't mean it's not easy to refute.
If you can refute what Joe presented, do so. If you can't, perhaps that shows something...

As technology advances and we learn more we find that the Universe is Life Hostile and we are just very lucky to have had Earth form the way it did. Fermi had a point. There is no paradox. People call it a paradox because they refuse to believe it. What do you mean when you say that universe is life hostile? Please be specific.

I remember you had some sort of elaborate and incorrect interpretation on what Fermi meant. So I am going to pass on reading your apologist postings supporting your faith. Did you read my post above? The fermi paradox is simply noting two aparently contradictory things to both be true.
The solution to the paradox is to realize that they either are not contradictory, or not both true.
You've chosen one of them and decided that it is not true, but there are many other ways to reconcile it with reality.

Why not start a discussion threat supporting the existance of Santa Claus. I am completely serious. The logic to explain away Fermi's Paradox could just as easily be applied to the existance of Santa Claus. One could say "The North Pole is a huge area. It is absurd to think there is no Santa Claus there." just as logically as saying "There are billions of stars. It is absurd to think there is no other ETI near by". The two are not in any way analogous.

There is absolutely no reason to believe that an impossible being would exist at the north pole, no matter how big it is.
On the other hand, intelligent life is possible. It is possible for it to come into existence without any outside interference. How frequently that happens is up for debate, but we know it does happen, because we have an example of it having happened once.
Whatever the likihood that life will evolve on any particular planet, the more planets there are, the more chance that it evolved on at least one of them, and the same is true of intelligent life.
All that is necessarily true. It doesn't mean that intelligent life is common, of course. If we want to look at how likely it is, we need to look closer, but there is certainly some probability greater than zero.

[JoeTheJuggler]

This only proves that you do not get it.
ETA: revised response: That was a well reasoned and thoughtful reply to the points I made. Oh wait--no it wasn't.




"I will not go to the game" is not a negative just because the word "not" is in it.
It is not an example of a logical construct or proof.
"If I do not eat I will not trow up" can also be one of your examples. It is series of events, not a proof. You don't get it.
ETA: Yes--the presence of the word "not" before a proposition is exactly what makes it a negative.
How about an even more trivial example:
P1. If a team loses a game, they do not win it.
P2. My team lost today.
C. My team did not win the game today.


You specifically made the claim that one cannot logically prove a negative. I pointed out that you're wrong, and you are.

I also pointed out that I understand that that's not what most people mean when they say "you can't prove a negative". (They actually mean it's difficult to prove the non-existence of something.)

As you pointed out wrt Santa Claus, in terms of science, we can indeed provide reasonable proof of the non-existence of something. (The example I like to use is the non-existence of phlogiston. By measuring the result of a combustion reaction with hydrogen, we get a result that is inconsistent with the theory of phlogiston, so we have effectively proven the non-existence of phlogiston.)


Explain yourself. Explain how your logic is any different. You say "absence of evidence is not evidence of absense". The same can be applied to Santa Claus.

You say that a negative can be proven. Take the challenge then. Prove that Santa does not exist.
Predictions made by the Santa Claus theory repeatedly fail to come true.

At any rate, I'm not asking you or anyone to prove the non-existence of ETIs. I'm merely pointing out that the evidence or lack of evidence available to us does not support that conclusion--not even tentatively. The fact is, we don't know.

Again, the best analogy is if I glance in my backyard and look for evidence of the existence of dogs. I see none. Is it reasonable to conclude that dogs do not exist? Or even that they're scarce? About all you can conclude is that evidence of the existence of dogs is not ubiquitous. It's wrong to assume that either evidence of the existence of dogs ought be ubiquitous or dogs either don't exist or are scarce. The fact is, based solely on a glance in the backyard, I don't know whether dogs exist and if they do how frequent they are.

Oh--to make the analogy more correct, I should specify that there is a dog inside my house sitting by my feet. So I know that at least one dog exists. (Unlike anything similar to the Santa Claus analogy.)

ETA: And wrt to the existence of ETIs, they are really just Intelligent Civilizations that are not ours. We already know ours exists, so we know that at least one intelligent civilization exists. So your idea of not proving a negative is moot. We've already disproven the negative. (While it might be difficult to prove that no black swans exist, it is easy to prove that they exist by providing one example.)

[JoeTheJuggler]

Of interest to this thread: a "super-earth" where liquid water is possible:

http://www.time.com/time/health/article/0,8599,1947868,00.html

[Bill Thompson]

Which is very easy. The fact that the mormon doesn't accept the refutation doesn't mean it's not easy to refute.
If you can refute what Joe presented, do so. If you can't, perhaps that shows something...

What do you mean when you say that universe is life hostile? Please be specific.

G.D.!! Just google, "Refuges for Live in A Hostile Universe"
I will put a copy online and send you a book list.

http://www.google.com/search?hl=en&q=Refuges+for+Live+in+A+Hostile+Universe&ei=63ApS86FKoi4swPC2L26BA&sa=X&oi=revisions_inline&ct=unquoted-query-link&ved=0CAYQgwM

Of interest to this thread: a "super-earth" where liquid water is possible:



Even our Earth ought not have life apart from microbial. Pointing to other earths and claiming that intelligent life must be abundant shows you do not know Earth's history.



ETA: Yes--the presence of the word "not" before a proposition is exactly what makes it a negative.
How about an even more trivial example:
P1. If a team loses a game, they do not win it.
P2. My team lost today.
C. My team did not win the game today.



That is a case statment, not a proof.

Now, take up my challenge and prove that Santa does not exist.

[shadron]

Even our Earth ought not have life apart from microbial. Pointing to other earths and claiming that intelligent life must be abundant shows you do not know Earth's history.

Do tell, Bill. I'd certainly like to know what in Earth's history necessarily rules out the the fact that we shouldn't have multicellular life here. I'm all ears.

[JoeTheJuggler]

Even our Earth ought not have life apart from microbial.
Science doesn't deal with "ought" for issues like these.

ETA: And it's statements like these that make me think rare Earthers are arguing a Creationist/ID agenda.

[JoeTheJuggler]

That is a case statment, not a proof.
http://www.thefreedictionary.com/logical+proof

I dunno, but I think maybe you're confusing computer programming with logical proof.

Another example:

If phlogiston existed, a sample that is burned would always weigh less after burning than it does before.
When you burn a sample of hydrogen gas, you get a sample of water that weighs more than the hydrogen gas did.
Phlogiston doesn't exist.

It's the same thing. Also the same with Santa Claus. If Santa Claus were true, predictions made by the Santa Claus theory would come true consistently, but they don't. For example, if Santa Claus were real, we predict sleigh tracks on the roof and gifts appearing under the tree that no normal human put there.

So far, no prediction that would come true only if ETIs didn't exist has come true. There is no reason to rule out the possibility of the existence of ETIs.

Again, the analogy you keep ignoring about the existence of extra-my-house dogs based on a quick glance at my backyard is appropriate.

[Bill Thompson]

Joe, do you spend a lot of time here because you are knowledgeable about this subject and you want to inform us, or is there some other reason?

Assuming that you are knowledgeable, can you answer these 10 questions and tell me if you have seen the three articles I have listed below?


Why is the moon essential for our existence?
What is what Dana Mackenzie calls "The Big Splat" and why is it important to understanding how our Earth-Moon set up is uncommon in the Universe?
Why is Jupiter essential for our existence?
Why is a system of plate tectonics vital for the development of life forms?
How did early microbial life shape the world and set the stage for later life forms and what is that uncommon in the universe?
How did early plant life shape the world and set the stage for later life forms and what is that uncommon in the universe?
What effects did mass extinctions have on evolution?
What effect did the "Snow Ball Earth" have on the evolution of life on Earth?
What does the fact that "Snow Ball Earth" existed have on the liklihood life being common in the universe?
What does human psychology have to do with the fact that so many people believe in extra-terrestrial life?
Galactic Chemical Evolution: Implications for the Existence of Habitable Planets.
Virginia Trimble in Extraterrestrials: Where Are They?
Edited by M. H. Hart and B. Zuckerman. Cambridge University Press, 1995.
http://astro.wsu.edu/hclee/pasa_review_GCE.pdf

An Estimate of the Age Distribution of Terrestrial Planets in the
Universe: Quantifying Metallicity as a Selection Effect.
Charles H. Lineweaver in Icarus, Vol. 151, No. 2, pages 307–313; June 1,
2001. Preprint available at astro-ph/0012399
http://arxiv.org/abs/astro-ph/0012399
http://arxiv.org/PS_cache/astro-ph/pdf/0012/0012399v2.pdf

The Galactic Habitable Zone: Galactic Chemical Evolution. Guillermo
Gonzalez, Donald Brownlee and Peter D. Ward in Icarus, Vol. 152, No. 1,
pages 185–200; July 1, 2001. Preprint available at astro-ph/0103165
http://arxiv.org/abs/astro-ph/0103165
http://arxiv.org/PS_cache/astro-ph/pdf/0103/0103165v1.pdf

[Bill Thompson]

http://www.thefreedictionary.com/logical+proof

I dunno, but I think maybe you're confusing computer programming with logical proof.


Cut to the chase. Show me. Prove that Santa does not exist.

Stop beating around the bush.

[Bill Thompson]

Science doesn't deal with "ought" for issues like these.

ETA: And it's statements like these that make me think rare Earthers are arguing a Creationist/ID agenda.

It is all a matter of simple statistics. If something happens rarely, the odds are low that it happens commonly.

[Bill Thompson]

Do tell, Bill. I'd certainly like to know what in Earth's history necessarily rules out the the fact that we shouldn't have multicellular life here. I'm all ears.

Ice reflects light. The sea does not as much. Each one hundred thousand years we have an ice age and each one is a roll of the dice. If the ice sheet advances past where St. Louis is, we have crossed the point of no return.

The idea of "snow ball earth" was discovered by a Russian scientist and Carl Segan when they crunched the numbers of what an all out nuclear war would do to the earth. If the sun was blocked out and if temperatures went down far enough for long enough we would hit a tipping point.

The idea of snow ball earth was made before it was discovered that it had once really happened.

Also, it should be like that right now if not for a stroke of luck.

It was dumb luck that volcanic activity broke us from the "snow ball earth" according the discovery channel episode. If we did not win that proverbial lottery, we would be locked in ice.

Like I said, ice reflects light. The sea does not as much. Each one hundred thousand years we have an ice age and each one is a roll of the dice. Glacier evidence on the equator now proves that during one of those ice ages, the ice sheet advanced past the point of no return and the advancing ice sheet form the north and the south met at the equator.

Luckily we have tectonic plates. Luckily they just happened to make enough volcanoes all at the same time (after about 30 million years of being an ice planet, as I recall) and broke the snowball earth.

The Earth was young then. Somehow microbial life existed and survived but more complex life would be impossible to evolve.

[Bill Thompson]

It's the same thing. Also the same with Santa Claus. If Santa Claus were true, predictions made by the Santa Claus theory would come true consistently, but they don't. For example, if Santa Claus were real, we predict sleigh tracks on the roof and gifts appearing under the tree that no normal human put there.


The same holds true for Fermi's observation. If the rise of intelligent life was common in the universe, they should be EVERYWHERE and proof of their existance would be unavoidable.

[Bill Thompson]

It's the same thing. Also the same with Santa Claus. If Santa Claus were true, predictions made by the Santa Claus theory would come true consistently, but they don't. For example, if Santa Claus were real, we predict sleigh tracks on the roof and gifts appearing under the tree that no normal human put there.


Finally we are getting somewhere. Santa made the tracks disappear.
Predictions? Santa does not follow your schedule, he has his own schedule. The ways of Santa are mysterious.

You say that if you make a prediction about Santa and it does not come true, then he does not exist? Dude, EVERY prediction of if and when we would get a signal from SETI@HOME has been wrong!!

[JoeTheJuggler]

Bill, everything you're raising has been answered in this thread already.

You're entirely too hostile for conversation.

[Bill Thompson]

Joe, I ask you to provide proof that Santa does not exist. I am still waiting.

You say that there is no Santa because there is no evidence.

But that contradicts what you said earlier when you said that absence of evidence is not evidence of absence.

Is this a topic you do not take seriously? Did you answer those 10 questions?
http://forums.randi.org/showpost.php?p=5421767&postcount=1016

[LarianLeQuella]

Joe, I ask you to provide proof that Santa does not exist. I am still waiting.



Not to step on Joe's toes here, but the entire fable of Santa is well know in its origins and can be traced through all the numerous permutations that finally arrived at the current fable. Also, specific statements regarding Santa are patently false. We have explored the surface and underside of the North Pole quite extensivelly, and found no workshop. The stories indicate that one should be there, but it's not, so the story itself is false.

After that, people invoking magic or whatnot to desperately try to keep the story alive are grasping at straws.

Kind of reminds me of other stories that people cling to.

So far, no prediction or statement about ETI having any measurable effect on us has been made, thus the jury is still out.

[Bill Thompson]

Not to step on Joe's toes here, but the entire fable of Santa is well know in its origins and can be traced through all the numerous permutations that finally arrived at the current fable. Also, specific statements regarding Santa are patently false. We have explored the surface and underside of the North Pole quite extensivelly, and found no workshop. The stories indicate that one should be there, but it's not, so the story itself is false.


That is not a proof. Prove that he does not exist. Saying that there are fables that can be traced back regarding Santa does not prove that he does not exist.

ET and ETI and ETL all have fables too that date back longer than the fables regarding Santa.

By the way, people thought Mountain Gorillas were fables too once. Saying that something is based on fables does not prove that it does not exist.

Also saying that "Santa is not there" is not proof that he does not exist!! You could fly over the North Pole and say "see, he is not there" to someone and they could easily just say that Santa knew you were coming and he is hiding.

[arthwollipot]

Wait - is Bill actually asking someone to prove the nonexistence of something?

[Roboramma]

Hey Bill:
http://forums.randi.org/showthread.php?p=5425042#post5425042

Just for fun. :D

[Roboramma]

Wait - is Bill actually asking someone to prove the nonexistence of something?

No, he's suggesting that those who think that the probability of extraterrestrial intelligence elsewhere in our galaxy is high are doing so.

Basically he says, "I can't prove that ETIs don't exist just like you can't prove that there's no Santa Claus, but the lack of evidence for them suggests that they don't exist, just like the lack of evidence for Santa Claus suggests that he doesn't exist."

Of course, there's a problem with that. The problem with Santa Claus is that we are lacking evidence for his existence that we would expect to have if he existed. That's not the case with ETIs.

[Roboramma]

G.D.!! Just google, "Refuges for Live in A Hostile Universe"
I will put a copy online and send you a book list.

I'm not looking for a book list, I'm looking for you to make your case.

[Roboramma]

Joe, I ask you to provide proof that Santa does not exist. I am still waiting.

You say that there is no Santa because there is no evidence. We know there is no Santa because there is no evidence where we would expect to find it.

I remember when I was about 5 years old, I wondered if Santa was real. I knew it was possible that my parents were simply putting the presents there for me, so I decided that I'd have to wait until I was older and had moved out on my own to see if Santa brought presents for me.
Of course, long before that I had other evidence of Santa's non-existence, but even as a five year old I could think of a test for the existence of not of Santa.

Regarding ETI, what particular test are you suggesting has been done and found that the evidence showed that ETI doesn't exist?

[arthwollipot]

No, he's suggesting that those who think that the probability of extraterrestrial intelligence elsewhere in our galaxy is high are doing so.

Basically he says, "I can't prove that ETIs don't exist just like you can't prove that there's no Santa Claus, but the lack of evidence for them suggests that they don't exist, just like the lack of evidence for Santa Claus suggests that he doesn't exist."

Of course, there's a problem with that. The problem with Santa Claus is that we are lacking evidence for his existence that we would expect to have if he existed. That's not the case with ETIs.Thanks for summarising. I've only been skim-reading this thread for some time now.

[shadron]

Ice reflects light. The sea does not as much. Each one hundred thousand years we have an ice age and each one is a roll of the dice. If the ice sheet advances past where St. Louis is, we have crossed the point of no return.

The idea of "snow ball earth" was discovered by a Russian scientist and Carl Segan when they crunched the numbers of what an all out nuclear war would do to the earth. If the sun was blocked out and if temperatures went down far enough for long enough we would hit a tipping point.

The idea of snow ball earth was made before it was discovered that it had once really happened.

Also, it should be like that right now if not for a stroke of luck.

It was dumb luck that volcanic activity broke us from the "snow ball earth" according the discovery channel episode. If we did not win that proverbial lottery, we would be locked in ice.

Like I said, ice reflects light. The sea does not as much. Each one hundred thousand years we have an ice age and each one is a roll of the dice. Glacier evidence on the equator now proves that during one of those ice ages, the ice sheet advanced past the point of no return and the advancing ice sheet form the north and the south met at the equator.

Luckily we have tectonic plates. Luckily they just happened to make enough volcanoes all at the same time (after about 30 million years of being an ice planet, as I recall) and broke the snowball earth.

The Earth was young then. Somehow microbial life existed and survived but more complex life would be impossible to evolve.

OK, fine. Without plate tectonics we would not have multi-cellular life. Then, what do you suppose is the probability that a planet of our size will be sufficiently tectonically active to escape a snowball event?

That would be a function of our internal temperature, I presume. Our internal temperature depends on several things:

- The raw size of the planet, providing sufficient materials described in the next three points and a sufficiently insulative mantle blanket to promote an active interior.
- The initial kinetic/potential energy available to convert to heat, which, if our size is constant would be roughly the same.
- The proportion of iron available, which, while falling towards the core in the "iron catastrophe", also gives up its potential energy into heat.
- The amount of uranium, thorium and other radioactive species/isotopes available to decay and this give up heat.

I don't see how tectonics would be a low probability occurrence for any given rocky planet of our general size placed within a liquid water domain. Both the freezing and the melting appear to be limited run-away thermal processes, and therefore inevitable if the triggering conditions are available, therefore I don't see why the snowball earth would be an ultimate peril for multi-cellular life. Indeed, it would have to be held in abeyance for perhaps 50 million years, that could well be enough to start multicellular creatures. It was only about 40 million years from the end of the Marinoan snowball to the first appearance of multicellular creatures (sponges, jellyfish, nidarians) in the Ediacarian period.

[amb]

The arguments put forward of why ET is not yet here is weak in a galaxy that is up to 13 billion years old. Every possibility is possible in such a vast galaxy with possibly up to 400 billion stars. At least some of these stars would have sprouted a life bearing planet perhaps billions of years ago. And at least some of a nearby advanced planet perhaps a million years more advanced than us should by now have discovered us. They haven't which could mean we are alone in this part of the galaxy at least, or we are one of the first.

[Roboramma]

The arguments put forward of why ET is not yet here is weak in a galaxy that is up to 13 billion years old. Every possibility is possible in such a vast galaxy with possibly up to 400 billion stars.
Every possibility is possible? Well, yeah.

But impossible things aren't. And things which are improbable enough remain improbable even after many billions of years.

It really is possible that interstellar travel simply doesn't happen. It might be technically impossible (there was a thread recently in which quite a few people argued just that).

At least some of these stars would have sprouted a life bearing planet perhaps billions of years ago. And at least some of a nearby advanced planet perhaps a million years more advanced than us should by now have discovered us.
That's the part that you need to justify. What makes you think that they would necessarily have the means and the motivation do to so?

[RecoveringYuppy]

It really is possible that interstellar travel simply doesn't happen. It might be technically impossible (there was a thread recently in which quite a few people argued just that).

How could it be technically impossible when it happens naturally? Over the time frames involved the natural velocities of comets and the stars themselves are sufficient for a lot of migration.

[JoeTheJuggler]

No, he's suggesting that those who think that the probability of extraterrestrial intelligence elsewhere in our galaxy is high are doing so.

Basically he says, "I can't prove that ETIs don't exist just like you can't prove that there's no Santa Claus, but the lack of evidence for them suggests that they don't exist, just like the lack of evidence for Santa Claus suggests that he doesn't exist."
Kind of. I pointed out that in this case (existence of ETIs) the absence of evidence is not evidence of absence, to which Bill said that you can't logically prove a negative. I pointed out that as the statement was worded, it's wrong and gave several examples of logical proofs of negatives. I even indicated that I was aware that what he probably meant was that it's difficult to prove the non-existence of something. (The "there are no black swans" issue--it's easy enough to disprove, but how do you prove it?)


Of course, there's a problem with that. The problem with Santa Claus is that we are lacking evidence for his existence that we would expect to have if he existed. That's not the case with ETIs.
Exactly. The argument for the non-existence of ETIs based on lack of evidence assumes that existence of an ETI must be ubiquitous in the galaxy. There are any number of reasons why they might not be.

It's not that we have to prove which if any of these (the numbered points I've made on this thread for nearly a year now) is true. It's enough that any one of them is possible to show that the evidence of ETIs (if they exist) need not be ubiquitous. Thus, the absence of evidence in this case is not evidence of absence.

The analogy I've been making is this situation: I've got a dog here in the house next to me, but when I glance out the window to my back yard, I don't see any evidence of extra-in-my-house dogs. It's absurd to claim therefore that there are no dogs anywhere else in the world other than the one here in my house.

Proving the non-existence of Santa Claus or phlogiston (surely we have!) is beside the point anyway. No one is claiming you've got to have proof of the non-existence of ETIs.

I'm just pointing out that the argument for the non-existence of ETIs based on the lack of evidence is not valid. Again, we are an intelligent civilization, and evidence of our existence (whether self-replicating probes, galaxy-wide colonization or whatever) is not ubiquitous. Another civilization contemplating our existence and using your reasoning would incorrectly conclude that we do not exist. Yet here we are.

Also the Rare Earth arguments have been thoroughly debunked, and the connection of these arguments to Creationist/ID proponents has been shown. That's why the backward thinking that every aspect of conditions here MUST be prerequisite to complex or intelligent life is so similar to Creationist/ID and Fine Tuning arguments.

[JoeTheJuggler]

It really is possible that interstellar travel simply doesn't happen. It might be technically impossible (there was a thread recently in which quite a few people argued just that).
Also, one of my numbered points, it might be technically possible but for other reasons something no civilization ever ends up making use of. (Or technically possible but something no civilization ever discovers.)

Again, the argument amb and Bill have been pushing rests on the assumption that it's not only technically possible but absolutely inevitable that an intelligent civilization would discover it and be motivated to exploit the technology and make evidence of their existence ubiquitous throughout the galaxy.

There are all sorts of possible explanations why this assumption doesn't have to be true. (And for the argument to work, the assumption must be true.)

It could be technologically impossible (and rather than address FTL, interstellar travel, self-replicating probes or ANY specific formulation of Fermi's Paradox, I'm referring to the very general proposition that an ETI would make evidence of its existence ubiquitous in the galaxy).

It could be possible, but no civilization lasts long enough to discover it.

It could be possible and civilizations could last long enough, but it could be that civilizations at that level always (or even usually) lack the motivation to do it.

It could be possible and civilizations could last long enough and have the motivation, but the technology could be economically impractical.

It could be that all those things are in place, but evidence doesn't last long enough to remain ubiquitous throughout the galaxy for any length of time. (In my dog analogy, what if a dog had just walked through my back yard a few minutes before I looked out? What if a civilization had colonized all of the universe, but then abandoned some bits of it a mere 100 million years ago, so that our corner of it shows no sign of their presence? What if a probe had passed near or even through our solar system a mere 1000 years ago?)

[Bill Thompson]

OK, fine. Without plate tectonics we would not have multi-cellular life. Then, what do you suppose is the probability that a planet of our size will be sufficiently tectonically active to escape a snowball event?


Almost nill.

Seems like a pretty unlikely balancing act to me.

A reoccurring inferno like Venus or a dead dirt ball like Mars I think would be more common. Earth has threaded a proverbial needle by astronomically absurd good luck.

It is not just plate tectonics. It is plate tectonics and them all making big enough volcanoes all at the same time to break the freeze. Otherwise, we would be a snowball planet today. That was winning the lottery in a big way. And I do not think such a thing has happened since. So it is perfect timing as well.

We owe our existance to the fact that there are so many stars. Otherwise, the odds would not be in favor for us to exist.

[Bill Thompson]

We know there is no Santa because there is no evidence where we would expect to find it.



That does not make any sense. We are talking about Santa.

But If you are drawing a parallel with ETI, then we are alone for all practical purposes. Because there are less and less places we find that are life-friendly the more we learn about the Universe.

[Bill Thompson]

Joe, come out of your fantasy comfort world and answer these questions:

http://forums.randi.org/showpost.php?p=5421767&postcount=1016

I think they are too upsetting to you and you would prefer to think we are not alone. It is only human nature to be this way. Human beings are social creatures and the idea of being alone or isolated is too much to handle.

[Roboramma]

How could it be technically impossible when it happens naturally? Over the time frames involved the natural velocities of comets and the stars themselves are sufficient for a lot of migration.
This is what happens when I make other people's arguments: I tend to screw them up. :P

Personally, I think that interstellar travel is quite possible and something that we are likely to partake in at some point in the future.

I guess what I'm suggesting though is that it may be impossible for intelligent lifeforms to send themselves to other stars. But to be honest, when you put it like that I can't really agree with that. So, I will modify my statement:

Interstellar travel may be so difficult to engage in that no technological civilization has engaged in it, regardless of how many there have been to this point in the history of the galaxy.

It may be so difficult that while some civilizations do engage in it, they don't get very far: they travel to one or two other nearby stars, perhaps, and don't go further because they find the rewards aren't worth the effort.

Or it may be that civilizations, once they reach the stage that interstellar travel is possible, simply tend not to be interested in interstellar travel.

Personally the Fermi Paradox does modify my guess as to the probability of ETIs in our galaxy, in such a way that I think it's less likely than I did before I'd heard of the Fermi Paradox. But it certainly doesn't modify it all that much, because there are so many possibilities other than "life is rare" that explain it.

[JoeTheJuggler]

Joe, come out of your fantasy comfort world and answer these questions:

http://forums.randi.org/showpost.php?p=5421767&postcount=1016


Asked and answered months ago on this thread. These are basically the Rare Earth arguments.

And your constant insults don't advance the conversation in any way.

ETA: I derive no comfort from acknowledging that we don't know whether or not there are ETIs throughout our galaxy. My position has consistently been just that: we don't know.

[JoeTheJuggler]

Interstellar travel may be so difficult to engage in that no technological civilization has engaged in it, regardless of how many there have been to this point in the history of the galaxy.

It may be so difficult that while some civilizations do engage in it, they don't get very far: they travel to one or two other nearby stars, perhaps, and don't go further because they find the rewards aren't worth the effort.

Or it may be that civilizations, once they reach the stage that interstellar travel is possible, simply tend not to be interested in interstellar travel.
Exactly. Or civilizations don't last long enough to discover everything that is technologically possible. Or they lose interest. Or technologically possible doesn't ever equate with feasible.


Personally the Fermi Paradox does modify my guess as to the probability of ETIs in our galaxy, in such a way that I think it's less likely than I did before I'd heard of the Fermi Paradox. But it certainly doesn't modify it all that much, because there are so many possibilities other than "life is rare" that explain it.
Given the size of the galaxy, and how spread apart things are, it doesn't alter my view (which is simply we don't know) any more than a glance into my backyard supports the idea that dogs that live beyond my house are rare or don't exist.

Even if there were relatively many ETIs in the galaxy, we wouldn't expect anything we've observed (receiving a radio message, for example) to be different than it is (no more than I have any reason to expect to see evidence of a dog when I glance out the back window).

Absence of evidence where you don't expect there to be evidence is not evidence of absence.

[Bill Thompson]

Jeezus H Christ. This thread is still alive? Has anything changed?

People will not let go of a faith. Ever.

Science and statistics say that intelligent life is uncommon in the universe and the places where they can exist is getting smaller and smaller the more we learn about the universe. So the SETI apologists are motivated by faith and wishful thinking alone.

Joe will be making posts here for years. He will do this as if doing so will change the facts.

[Bill Thompson]

Asked and answered months ago on this thread. These are basically the Rare Earth arguments.

And your constant insults don't advance the conversation in any way.

ETA: I derive no comfort from acknowledging that we don't know whether or not there are ETIs throughout our galaxy. My position has consistently been just that: we don't know.

What insults?!

And have you read Rare Earth? It is a title for a book. Or you just find the concept on its face value absurd and refuse to dig any deeper?

No, you have not answered the questions.

What I think is you take it at face value and, of course, by name "Rare Earth" is a silly idea. So you use the straw man argument to draw a simple character of the idea so you can dismiss it.

There are other stars. There are other planets. Too many to count (and yet not infinate). So on the face of it, it is silly to think we are alone. And those who do are arrogant. Right? Am I getting your thought pattern down pretty accurately here?

You have yet to write a simple proof that Santa does not exist.

You have yet to write a proof for a negative. Case statements are not logical proofs. Proove that something does not exist.

you have yet to answer the 10 questions. Taking a brush stroke and labeling them as rare earth nonsense is not answering the questions.

Answer the questions. They do not have the term "rare earth" in them at all. They have just as much to do with frozen yogurt as rare earth. It is simple science, math, and guess what else. STATISTICS!! Everything, as it turns out, really is a numbers game.

Accusing me of insulting you is a cheap trick to avoid answering my questions.

Also, you contradict yourself! You insist that Santa does not exist because there is a lack of evidence that he exists. And then you insist that there is ETI because "absence of evidence is not evidence of absence".

[shadron]

Almost nill.

Seems like a pretty unlikely balancing act to me.

A reoccurring inferno like Venus or a dead dirt ball like Mars I think would be more common. Earth has threaded a proverbial needle by astronomically absurd good luck.

It is not just plate tectonics. It is plate tectonics and them all making big enough volcanoes all at the same time to break the freeze. Otherwise, we would be a snowball planet today. That was winning the lottery in a big way. And I do not think such a thing has happened since. So it is perfect timing as well.

We owe our existance to the fact that there are so many stars. Otherwise, the odds would not be in favor for us to exist.

What can you show to back up your hunch? Perhaps all that was needed was a few very ashy, Plinian volcanoes that spread ash all over the place.

[JoeTheJuggler]

What insults?!
Your repeated questions of my credentials when I'm not holding myself out as an authority (my arguments stand on their own and don't rely on my credentials), and your questioning my motivation for participating in this thread.

These things are irrelevant to the discussion.


And have you read Rare Earth? It is a title for a book.

Yes, and read the thread. We have discussed the book at some length.

[JoeTheJuggler]

And then you insist that there is ETI because "absence of evidence is not evidence of absence".
This is a complete misrepresentation of my position which I have consistently and frequently stated. My position is that we don't know whether ETIs exist.

And I repeat that in this case, absence of evidence is not evidence of absence.

The assumption that if ETIs exist, then evidence of their existence must be ubiquitous in the galaxy is flawed.

The arguments that every detail about conditions here on Earth are prerequisite to the evolution of complex life is flawed (and typical of the backward thinking of the Fine Tuning argument promoted by Creationists).

[amb]

We have had radio/television/ astronomy signals for around 60 years now, that's a radius of 60 light years in which there are dozens of sun like stars to receive these signals, even in their weakened state a highly evolved civilization would be able to pick them up as would we with the giant radio radar discs that exist around the world that are capable of picking up a signal from a pulsar 100 light years away, yet all there is is silence both ways. Could it be that there's no one there to receive or send back any signals? Perhaps, and this is an old argument, there is only microbial life on most of these if any, life bearing rocky planets?

[Roboramma]

Amb, this is from page 6, and has been reposted at least once already.

Can you not see how it shows your last post to have very little significance to the thread topic? Did you not already see that before you posted it (given that you were involved in this discussion when it came up again on page 17 or 18?
If you really disagree and think that this post doesn't clear up this issue, can you please explain why?

It is very unlikely that alien civilizations are going to pick up television transmissions according to the table from this site:
http://www.faqs.org/faqs/astronomy/faq/part6/section-12.html

see copy of table in this post:
http://forums.randi.org/showpost.php?p=3557598&postcount=82

Note the range for UHF television (2.5 AU) and the range for the UHF carrier (0.3 LY). Neither estimate is enough to make it out to the nearest star. They don't list a range for VHF television but FM radio is in the middle of the VHF television band and the estimated range for that is 5.4 AU. Again no where near enough to make it to the first star.

The optimistic ranges for detecting a nearby planet are based on either massively powerful transmitters or highly focused outputs from large transmitters.

The calculations that I made in a previous post suggested that one would need an Arecibo sized antennae with a 250,000 watt transmitter to be able to send a detectable signal to a planet as far away as 150 light years.

This is easily with the capability of earth's technology. The Arecibo antennae has only limited steering capability. I think it is mostly constrained by the direction it is pointing as it rotates with the earth so there are lots of potential targets it couldn't be aimed at. The 250,000 watts could be pulsed so that no where near 250,000 watt of continuous power would be required. But will the powers that be that control enough of earth's resources ever feel like funding a major effort to transmit to unknown alien civilizations?

Post where the calculation was discussed:
http://forums.randi.org/showpost.php?p=3565450&postcount=94

I think the most likely intentionally produced electro magnetic radiation produced on the earth today that could be detected by an alien civilization would be from radars. These are focused and some of them are very powerful. I notice that the table lists the range of a particular weather radar as .01 light years. That doesn't validate my guess because it lists the range of a UHF carrier as .3 light years but I suspect that other radars would do better. Military radars might do much better.

But even if the ranges of military radars are much greater than what is listed for the weather radar in the table, the ranges are still probably much too small to get much beyond the nearest stars.

In another post I linked to an article discussing the feasibility of a laser transmitter to reach stars. If the powers that be wanted to dedicate some resources to this idea the authors suggest that we might hit a 1000 light years with a currently feasible optical laser. I think that bumps the stars for which a signal might be detected from about a 1000 that lie within 100 light years to about a 100,000 that lie within a 1000 light years.

The article on the possibility of optical SETI:
http://seti.harvard.edu/oseti/tech.pdf

[JoeTheJuggler]

We have had radio/television/ astronomy signals for around 60 years now, that's a radius of 60 light years in which there are dozens of sun like stars to receive these signals, even in their weakened state a highly evolved civilization would be able to pick them up

No they couldn't, and this was covered long ago.

ETA: I also recall that I asked if you're going to assume that magic technology MUST exist if any ETIs exist (and since it doesn't, they don't), why not extend your argument and claim that there are no other ETIs in the entire universe? After all, if you presume magic technology MUST happen, then why not some serious magic technology, like instantaneous teleportation or a panopticon (capable of seeing and playing back all events throughout all of space and time)?

There's also no technology that would let an intelligent civilization thousands of light years away detect the first time humans used fire.

[JoeTheJuggler]

By the way, another explanation for the lack of evidence of ETIs is the possibility that they don't want us to see evidence of their existence. Again, if you're going to assume every technology that is possible must have been developed and used millions of years ago, then why not allow for something like the ability to keep a relatively primitive civilization in the dark?

[amb]

Read the update of this especially.

http://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Miscellaneous/2009_March_1

[amb]

No they couldn't, and this was covered long ago.

ETA: I also recall that I asked if you're going to assume that magic technology MUST exist if any ETIs exist (and since it doesn't, they don't), why not extend your argument and claim that there are no other ETIs in the entire universe? After all, if you presume magic technology MUST happen, then why not some serious magic technology, like instantaneous teleportation or a panopticon (capable of seeing and playing back all events throughout all of space and time)?

There's also no technology that would let an intelligent civilization thousands of light years away detect the first time humans used fire.

That's nonsense. A civilization only one thousand years ahead of us would seem as magic to us. Who knows what future discoveries will bring, what new form of power using the sun itself, what powerful transmitters and receivers, like you keep saying, we at this stage do not know.

That article in Wiki says we may have to revise our estimates of alien lifeforms in the cosmos because of the negative results which are not likely to improve in the foreseeable future.

[Roboramma]

That's nonsense. A civilization only one thousand years ahead of us would seem as magic to us. Who knows what future discoveries will bring, what new form of power using the sun itself, what powerful transmitters and receivers, like you keep saying, we at this stage do not know.

That article in Wiki says we may have to revise our estimates of alien lifeforms in the cosmos because of the negative results which are not likely to improve in the foreseeable future.

There is a big difference between their technology seeming like magic and their technology being capable of any magical thing you can imagine.

If, for instance, you encountered some technologically primitive people and found that one of them was suffering from a disease treatable through modern medicine, and treated them, they might then expect that you could bring their dead friends back to life, but regardless of your technology seeming like magic, it still has limits, and you wouldn't be able to help them there.

Similarly, whatever technological advances are possible, and I'm sure there are many that we haven't even conceived of yet, there are also some which simply are not. You seem to be suggesting that you know which is which when you say that they will necessarily be able to detect our (very faint) signals.

As to your previous post, I haven't finished reading the link, but I'll try to get to it. :)

[JoeTheJuggler]

That's nonsense. A civilization only one thousand years ahead of us would seem as magic to us.
How do you know that?

I don't believe that for a minute.

like you keep saying, we at this stage do not know.
Yes, and you keep making assertions as if you do know.

[JoeTheJuggler]

There is a big difference between their technology seeming like magic and their technology being capable of any magical thing you can imagine.


Well said.

And on top of that, amb's argument not only depends on any magical thing one can imagine being technologically possible, it depends on the assumption that whatever is possible absolutely will happen.

The argument depends on the assumption that such things as interstellar travel, colonization/exploration of the galaxy are so inevitable that the lack of ubiquitous evidence of this sort of thing leads to the conclusion that ETIs don't exist.

[Bill Thompson]

This is a complete misrepresentation of my position which I have consistently and frequently stated. My position is that we don't know whether ETIs exist.


And how is that any different from saying we do not know if Santa exists?

And, besides, aren't you saying YOU don't know if ETI exists? Shouldn't you speak for yourself here?

[Roboramma]

And how is that any different from saying we do not know if Santa exists?

And, besides, aren't you saying YOU don't know if ETI exists? Shouldn't you speak for yourself here?

Well, in the general sense of it's saying we don't know something exists, it's the same.

In the specific sense of why he's saying it, it's very different.

Why is it different? Because there is a great deal of evidence that there is no Santa, whereas there is very little evidence that there are no ETIs.

To put that slightly differently: of the two possibilities:
a) there is no santa
b) there is a santa
"a" is the far more parsimonious conclusion.

Of the two possibilities:
a) there are no ETIs
b) there are ETIs
there is some evidence that leads us toward "a", and some that leads toward "b", but neither has any particularly compelling evidence, so the best we can do is to say, "we don't know".

Now, personally, when I examine the evidence, I think that there being some ETIs in the universe, even in our galaxy, is more likely than not, but I don't find that conclusion to be all that solid, and would not be all that surprised if there were none. That is, I think the evidence leans toward "b", but not particularly strongly.
Joe may be more in the middle than me, which I think is an entirely reasonable position. Others look at the evidence and think it leans more toward "a", which I again consider to be quite reasonable. Those, however, who say that "a" is assured are, in my opinion, fooling themselves, and so far have failed to make a strong case.

As to amb, I'm still not sure where he sits, as sometimes he seems to say that "a" is almost certain, whereas other times he says that "b" is true, but the number of ETIs is certainly very small. I have none of that certainty, I wouldn't be surprised if there were a great many ETIs, nor if there were very very few of them.

[LarianLeQuella]

We have had radio/television/ astronomy signals for around 60 years now, that's a radius of 60 light years in which there are dozens of sun like stars to receive these signals, even in their weakened state a highly evolved civilization would be able to pick them up as would we with the giant radio radar discs that exist around the world that are capable of picking up a signal from a pulsar 100 light years away, yet all there is is silence both ways.

OH FOR ****'S SAKE, are you deliberately being daft? This has been addressed NUMEROUS times, and Robo just quoted the specific post. Even with an Aericibo array on A. Centaruri, our civilization is UNDETECTABLE. That's only a measly 4 light years away! Pulsars and stars are totally different... *sigh* It's like arguing wiht a creationist, same old tired canards repeated over and over again. I can see why Joe would accuse you of that mentality.

By the way, I used to think that anyone wihtin 60 light years could detect us, but then that nasty inverse square law showed me the folly of that train of thought and I had to re-evaluate it. Why have you not done so in the faceof physics?

[LarianLeQuella]

Of the two possibilities:
a) there are no ETIs
b) there are ETIs
there is some evidence that leads us toward "a", and some that leads toward "b", but neither has any particularly compelling evidence, so the best we can do is to say, "we don't know".


Thank you! Exactly what I've been driving at. The thing that is particlarly frustrating is that in order to support position a, a myriad of unfounded assertions are made ("Rare Earth", "evolution only works as observed on earth with earthlike results", and a "60 light year buble" in particular). By making those tyeps of assertions, proposition a is weakened. The don't necessarially strengthen proposition b, but are just plain unfounded.

[JoeTheJuggler]

Well, in the general sense of it's saying we don't know something exists, it's the same.

In the specific sense of why he's saying it, it's very different.

Why is it different? Because there is a great deal of evidence that there is no Santa, whereas there is very little evidence that there are no ETIs.

To put that slightly differently: of the two possibilities:
a) there is no santa
b) there is a santa
"a" is the far more parsimonious conclusion.

Of the two possibilities:
a) there are no ETIs
b) there are ETIs
there is some evidence that leads us toward "a", and some that leads toward "b", but neither has any particularly compelling evidence, so the best we can do is to say, "we don't know".

Yup. We know Santa doesn't exist the same way we know phlogiston doesn't exist--through science.
ETA: Actually we can go farther with the Santa hypothesis. If you include the definition of Santa Claus to be the stuff about him visiting all the homes of children who receive Christmas presents and delivering said presents, we can show that that's impossible.

There is no scientific evidence to support the proposition that we know ETIs do not exist. Again, the best analogy is the one I've been making about the existence of dogs outside my house when a quick glance out the window reveals a complete absence of evidence of such dogs.

ETA: It's not that the absence of evidence is never evidence of absence. It's that the absence of evidence where there's no reason to assume it must exist is not absence of evidence, and that is the case here.

[Bill Thompson]

Well, in the general sense of it's saying we don't know something exists, it's the same.

In the specific sense of why he's saying it, it's very different.

Why is it different? Because there is a great deal of evidence that there is no Santa, whereas there is very little evidence that there are no ETIs.

To put that slightly differently: of the two possibilities:
a) there is no santa
b) there is a santa
"a" is the far more parsimonious conclusion.

Of the two possibilities:
a) there are no ETIs
b) there are ETIs
there is some evidence that leads us toward "a", and some that leads toward "b", but neither has any particularly compelling evidence, so the best we can do is to say, "we don't know".


Internet forums are where the uninformed get a chance to preach. You have ignored lots of fundamentals. For example, one fundamental you ignore is that no one cares if there is another planet with ETI with life all over it in another galaxy. In fact, Star Wars could be 100% factual. No one cares. No one cares because the distances between galaxies are too far to care.

No one cares if a creature called Santa exists in some place where we have no hope of every seeing or knowing of.

And ALL of the evidence talken completely leads us to think we are alone in the galaxy and the more we learn the more alone we seem and the fewer places for ETL AND ETI to hide get smaller and smaller.

I am discussing on another web forum the fact that the Book of Abraham has been debunked with a Mormon. I show him the facts and he simply cannot see it. It is as if his brain simply cannot see simple logic. His faith blinds him. It is also our faith in ETI that is the reason why Fermi's Observation is called Fermi's Paradox. We simply cannot see it eventhough it is very simple to understand.

Then again, maybe for some people it is not simple to understand. Maybe most people cannot fathom billions of years. I9 billion years is a hell of a long time. If ETI came about commonly in nature, the Milky Way would be 100% colonized. That is all. We came about late in the game. Our sun and planets came from an older exploded stars. There were lots and lots of star systems before then. I have explained this lots of times. Why is it, in person, I can get people to see this but on the interent I am just wasting my time?

Science works like this. If you belive something exists, you have to prove it. It does not work the other way. You do not prove that something does NOT exist. That is impossible.

Let me put it this way. It is highly improbable that there is anyone in the Milky Way like us. In fact, it is a huge waste of money.

A multi-millionare friend of mine, Paul Allen, has build a huge telescope array in California to find a signal form ETI. Paul is not a scientist. He is basically a rich guy with a lot of faith and dreams. I think that he should have thrown that money towards cancer research. Ironically enough, he has gotten cancer.

Before Seti@Home was launched people would spend their retirement money and kids college funds on radio equipment listening for signals. It seems to me that they did this because our culture raises us to believe that is it impossible for us to be alone.

The irony of ironies is that if they was ETI, they would not be interested in us at all because we are so stupid.

[Roboramma]

Internet forums are where the uninformed get a chance to preach.
No argument here...

You have ignored lots of fundamentals. For example, one fundamental you ignore is that no one cares if there is another planet with ETI with life all over it in another galaxy. In fact, Star Wars could be 100% factual. No one cares. No one cares because the distances between galaxies are too far to care. I care. So clearly your assertion that no one cares is false.

There are even ways to look for such civilizations. If you are right and ETI tends to colonize its galaxy we can look for the evidence of their technology in those galaxies. Dyson spheres, etc.

And ALL of the evidence talken completely leads us to think we are alone in the galaxy and the more we learn the more alone we seem and the fewer places for ETL AND ETI to hide get smaller and smaller. So make this case. So far all you've said is, "you can't talk about ETI because you haven't proven that it exists, and it's not my job to show that it doesn't." If you have evidence that there are no ETIs, present it.
It is also our faith in ETI that is the reason why Fermi's Observation is called Fermi's Paradox. We simply cannot see it eventhough it is very simple to understand. Wrong. As I said before, it's called Fermi's Paradox because it is the observations of two apparently contradictory things.

Then again, maybe for some people it is not simple to understand. Maybe most people cannot fathom billions of years. I9 billion years is a hell of a long time. I would go so far as to say that no one understands billions of years.
If ETI came about commonly in nature, the Milky Way would be 100% colonized. That is all. That is not all, and you have completely ignored all the arguments to the contrary. Rather than simply continue to make this assertion, why don't you address those arguments?

We came about late in the game. Our sun and planets came from an older exploded stars. There were lots and lots of star systems before then. I have explained this lots of times. Why is it, in person, I can get people to see this but on the interent I am just wasting my time? Because while that's all well and good, none of it shows that ETIs tend to colonize their entire galaxy.

Nor does it show that, for instance, we're not one of three technological civilizations. The choice isn't between "very very many" and, "only one." There could be thousands, but if you think that an argument that shows there aren't thousands shows that there are no others, I think you've failed to examine your own argument.

Science works like this. If you belive something exists, you have to prove it. It does not work the other way. You do not prove that something does NOT exist. That is impossible. So, if I say that there is at least one animal species that is not yet known to science, I am necessarily wrong, correct?

:confused:

Let me put it this way. It is highly improbable that there is anyone in the Milky Way like us. How do you calculate that particular probability?

[amb]

How do you calculate that particular probabilty

Because of the many almost miraculous events that lead to the first life forms on Earth.

[Roboramma]

Because of the many almost miraculous events that lead to the first life forms on Earth.

Can you show me that math?

[JoeTheJuggler]

For example, one fundamental you ignore is that no one cares if there is another planet with ETI with life all over it in another galaxy. In fact, Star Wars could be 100% factual. No one cares. No one cares because the distances between galaxies are too far to care.

I care. I'm very curious about this universe we live in. I want to know more about it.

At any rate, if you're going to redefine ETIs to mean only ETIs we can interact with, I probably agree with your position. (Rhetorically, though, I don't think that redefinition is honest.) See my first post in this thread (http://forums.randi.org/showthread.php?postid=4279474#post4279474) (from about a year ago) where I said,
It could be that everything is just so freakin' spread out in space and time, and life forms with whom we'd be able to communicate are so (relatively) rare that it's extremely unlikely that two will ever be in near enough proximity in time and space.

And from my second:
And again, "extremely rare" is a relative idea.

Stuff is really spread out. Higher life forms could occur pretty regularly but still be rare enough that no two such planets would be in proximity in space and the life forms at the appropriate levels to communicate close enough in time for there ever to be communication.

I've been arguing against amb's idea that complex life other than our own probably doesn't exist in the galaxy (and at one point he said there are probably no more than a dozen in the entire universe). As I've been saying all along, the evidence we have doesn't warrant such a conclusion. About all we can say is that we don't know.

Further, we have no reason to suspect there's something actually unique about us. The laws of physics, the availability of various elements, the duration of time--all are the same in many other points in the galaxy.

The Carl Sagan quote I provided several times best expresses my position. Here it is again:

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.

[JoeTheJuggler]

Because of the many almost miraculous events that lead to the first life forms on Earth.

Can you show me that math?

It doesn't matter anyway, because that's a backward way of looking at things. Life evolved to fit conditions, not the other way around. Calculating the odds of everything that had to happen for humans to evolve and then asking (even as a rhetorical question) "Whoa! What are the odds against that?!" is a form of the Texas Sharpshooter fallacy.

And I think it's no accident that when he tries to argue this way, amb ends up using religious words like "miraculous". This backward approach is the same one the Fine Tuning argument uses. (ETA: And I think Fine Tuner is the next in the series of repackaging a theist idea as something sciency: Creationism, Creation Science, Intelligent Design, and now Fine Tuner. Whatever the label, they're talking about a supernatural/religious non-explanation for natural phenomena.)

[Bill Thompson]

It is a faith.
Science looks for things before deciding if they are there.
Faith assumes something is there and ignores all science that says it is not there.

[Roboramma]

It is a faith.
Science looks for things before deciding if they are there.
Faith assumes something is there and ignores all science that says it is not there.

Your view of science is somewhat naive, but anyway, no one here has "decided they are there". You have decided they are not, the rest of us are uncertain.

[amb]

Can you show me that math?

Not to specification but around billions to one. Remembering that science has yet to solve the riddle of life's beginnings.

[Roboramma]

Not to specification but around billions to one. Remembering that science has yet to solve the riddle of life's beginnings.

What I'm getting at is that you are giving a rather specific result, but not giving us the details of how you get that result.

Saying, "Well, it's hard for life to come about, because X, Y, Z" doesn't do it: that could lead to billions to one or tens to one, and you haven't distinguished between those two, so how do you expect to convince us to do so?

Basically, so far all the arguments here have been very vague, which isn't surprising given that, once again, the real conclusion is we don't know.

[Bill Thompson]

Joe, in this issue, your only barrier to knowledge is the perception that you already have it.

[Bill Thompson]

Your view of science is somewhat naive, but anyway, no one here has "decided they are there". You have decided they are not, the rest of us are uncertain.

But to go with what we know so far, it is unlikely and as time goes on it become less likely as we learn more. Experience shows that once something points one way it does not reverse itself.

It is not just a game or a matter of opinion. It is a gamble. Do we gamble our time and resources towards looking or do we spend our money on more immediate and pressing issues -- issues that can save lives?

[JoeTheJuggler]

Joe, in this issue, your only barrier to knowledge is the perception that you already have it.

Gee that's quite an insightful and well-reasoned response to the content of the arguments I've made.

Oh wait--no it's not.

ETA: And to repeat for about the umpteenth time: my position is that we don't know. So how is that the perception that I already have knowledge? In fact, your ad hominem remark seems to apply to your position better than it does the one most of us hold--i.e. that we don't know whether or not ETIs exist or if they do how rare or common they are.

[JoeTheJuggler]

But to go with what we know so far, it is unlikely and as time goes on it become less likely as we learn more. Experience shows that once something points one way it does not reverse itself.
What?! That's not in the least bit true. It was once thought that the Earth was the center of the universe. It was once thought that humans were separate from the rest of the animal kingdom. The trend, if any, has been the repeated lesson that there is nothing special or unique about humans or that the Earth has any special central location in the cosmos.

It is not just a game or a matter of opinion. It is a gamble. Do we gamble our time and resources towards looking or do we spend our money on more immediate and pressing issues -- issues that can save lives?
We discussed this aspect very early in the thread. SETI is privately funded. It doesn't take money away from anything else.

Also, pretty much any scientific endeavor produces side effects that might benefit us in unrelated areas. (One example I gave is that the SETI@home project probably taught us a lot about distributed information processing. Also, I'm sure the algorithms used to analyze the data from Arecibo have probably improved.)

However, these considerations only apply if you are certain that no ETIs exist, and as has been shown, we have no such certainty. (Again, we've only just barely glanced out the window to get a peek at our own backyard, to use my dog analogy again.)

The Kepler mission, for example, is not a waste of money. There is great value in learning about our universe. If for no other reason but that we humans have curious minds. We ask questions, and remain curious while those questions remain unanswered. And when our questions are answered (provisionally at least), those answers lead us to new questions.

[amb]

University of California physicist and astronomer Ben Zuckerman is on record as having said that if the Milky Way were home to technologically advanced civilisations, we would know.

Prof. Zuckerman is no idiot.

[JoeTheJuggler]

University of California physicist and astronomer Ben Zuckerman is on record as having said that if the Milky Way were home to technologically advanced civilisations, we would know.

Prof. Zuckerman is no idiot.

You've presented a false dichotomy here. You're suggesting that either Zuckerman is an idiot or his statement is correct. It could be that he is not an idiot and his statement is false.

Also, you're arguing by improper use of authority. The position Zuckerman expressed is by no means the consensus view in the field (see point 4 in the Exposition section here (http://www.fallacyfiles.org/authorit.html)), and it's not based on sound reasoning. (I've argued all the assumptions you'd need to make to think that evidence of ETIs would necessarily be ubiquitous in the galaxy.)

Or maybe you're lifting something out of context and he's talking about a super-advanced technology in a super-long-lived civilization that has motive to spread throughout the galaxy. (And in that case, why not postulate super-advanced technology capable of hiding evidence of their existence from us?)

Zuckerman is involved in the search for extra-solar rocky planets. He's also concerned about environmental issues such as wildlife conservation, deforestation, sprawl, wilderness preservation, overpopulation, energy alternatives, and climate change. (He's also very involved with the Sierra Club.)

He certainly doesn't share the opinion that looking for potential extra solar Earth-like planets that might sustain life is a waste of money.

Did you get that quote from this book (http://www.amazon.com/Extraterrestrials-Where-They-Ben-Zuckerman/dp/0521448034)?

[amb]

No but thanks for that title. I have ordered it. I read that reference from a local newspaper article on SETI. Paul Davies also does not think it's a waste of money, but thinks the odds of finding anything are astronomical. The man who did more for SETI than almost anyone Carl Sagan if he was alive today would be surprised at the results so far, but I'm certain he would lobby the US government to increase the effort.
My only hope is that I'm still alive if ever we get any results. For me, nothing else is as important as finding intelligent life on another world. Alas, I have been born in the wrong era. In around fifty or so years I feel we will know one way or the other whether we are alone in the galaxy or not.

[Roboramma]

In around fifty or so years I feel we will know one way or the other whether we are alone in the galaxy or not.

What particular data do you think we'll have in fifty years that will tell us one way or the other?

Personally I think it's possible but extremely unlikely that we'll find out that, yes, there are other civilizations out there in the next fifty years.

We will have some evidence that impacts on the question and can alter our predictions slightly one way or the other: the search for earth like planets will have some interesting data by then, for instance.

But I'm curious what particular data you think we'll find that can give us a definite conclusion.

[amb]

The discovery of a duplicate planet to Earth with all the right ingredients for probable life.
A rocky planet with water has been discovered already, but it's almost Jupiter sized. Imagine the pressure of it's atmosphere, any life there would be like nothing we can even begin to imagine, or it's just microbial. I think questions like that will be answered in around 50-100 years if not a lot sooner.

[JoeTheJuggler]

Paul Davies also does not think it's a waste of money, but thinks the odds of finding anything are astronomical.
And how does that differ from my position? It differs from your position because you have said that it's impossible for another intelligent civilization to evolve.

The man who did more for SETI than almost anyone Carl Sagan if he was alive today would be surprised at the results so far, but I'm certain he would lobby the US government to increase the effort.
Why do you think he would be surprised? I have shown you his position--we don't know.


In around fifty or so years I feel we will know one way or the other whether we are alone in the galaxy or not.
So you do admit that the evidence points only to the conclusion, "We don't know"? You're finally putting aside all this Rare Earth stuff and your argument based on Fermi's Paradox that says we do know something based on the fact that evidence of ETIs isn't ubiquitous?

[JoeTheJuggler]

The discovery of a duplicate planet to Earth with all the right ingredients for probable life.
The problem is, with the Rare Earth approach, everything about the Earth is considered "the right ingredients". So you really are looking for an exact duplicate of the Earth, which isn't going to happen.


A rocky planet with water has been discovered already, but it's almost Jupiter sized.
I don't think you have your facts right.

Imagine the pressure of it's [sic] atmosphere, any life there would be like nothing we can even begin to imagine, or it's just microbial. I think questions like that will be answered in around 50-100 years if not a lot sooner.
You can't seem to make up your mind whether life that's nothing like we can even imagine is possible or whether we know that it must be microbial.

I think you're wrong on what we will know about extra-solar planets. We still don't know for sure whether microbial life currently exists or existed in the past on Mars, and it's quite a bit closer than any of these extrasolar planets!

At great distance, I think the best we can hope for in the near future is more information about planets that might have liquid water, and maybe a planet whose atmosphere is severely out of homeostasis (like an oxygen rich atmosphere). Darling explains that even this condition is possible through abiotic means (one stage of runaway green-house conditions might be an increase in oxygen, IIRC).

There was a time when the methane plumes we've found on Mars would have been considered slam-dunk evidence for the existence of at least ancient life there, but now we can conceive of abiotic origins. (The isotope ratio of the hydrogen in the water vapor associated with some of these plumes is now what we're considering that slam-dunk evidence.)

[amb]

The existence of rocky planets in the Goldilocks zone and evidence of liquid water would be a start. We at this moment in time do not have the means to detect such conditions.
You should really read our Presidents excellent book, Death From The Skies for a better idea of what I'm talking about. The universe is a very hostile place for the start of life as we know it.

[JoeTheJuggler]

The existence of rocky planets in the Goldilocks zone and evidence of liquid water would be a start. We at this moment in time do not have the means to detect such conditions.
But that lack of evidence doesn't support the contention that ETIs are non-existent (or rare or common or anything).

We don't have evidence for such things because we haven't yet looked. (Or rather, with Kepler, we are just now looking.)

BTW, we do have evidence of a rocky planet (a "super-Earth") where liquid water is possible (http://forums.randi.org/showthread.php?t=162407).

[amb]

The rest of the article also says ''it's highly unlikely this planet can harbor life as we know it'' because it's likely to be too hot and too close to it's star, meaning a locked orbit similar to Mercury. Who knows, it may be teeming with microbes though.

Microbes will be here on Earth billions of years after most other life will become extinct because of an expanding sun will fry everything else.

[JoeTheJuggler]

The rest of the article also says ''it's highly unlikely this planet can harbor life as we know it'' because it's likely to be too hot and too close to it's [sic] star, meaning a locked orbit similar to Mercury. Who knows, it may be teeming with microbes though.
Um. . if it's "too hot and too close" to harbor life as we know it, it wouldn't be teeming with microbes. So again, the point is we don't know.

Also, as noted earlier in the thread, one of the places Drake says we ought consider are planets tidally locked around red dwarfs. There will be a twilight zone region on such planets where interesting things might happen. But we don't know.

And we're not likely to find out for a long long time. (Again, we're still not even sure if Mars harbors life or even once did.)

[Bill Thompson]

What?! That's not in the least bit true.

If you read my links you would see that it is true. You haven't. So you don't.

It has nothing to do with a flat earth or any of the other poo you want to throw in the pot.

[amb]

Um. . if it's "too hot and too close" to harbor life as we know it, it wouldn't be teeming with microbes.
Wrong. Microbes have been found to live in live volcanoes, under the seabed where there is tremendous pressure and heat from volcanic vents and not a single ray of sunshine right here on Earth.

[LarianLeQuella]

amb, Joe's point is that it's either life as we know it (everything on earth), or not life as we know it (the things we have no frikkin clue about).

You are stating that you are both for and against the position at the same time. Shroedinger would be proud. :p

[JoeTheJuggler]

If you read my links you would see that it is true. You haven't. So you don't.


No. It's not true that "Experience shows that once something points one way it does not reverse itself." Experience tells us that anytime we think there is something unique or special about humans or the Earth, we were wrong.

At any rate, the claim that "it's unlikely" based on current evidence is not supported. We simply don't know. So there is nothing pointing any particular way to begin with.

ETA: It has nothing to do with a flat earth or any of the other poo you want to throw in the pot.
And why did you bring up "flat earth" as if it were an argument I made? I said no such thing. I guess you'd rather debate a strawman position than mine.

[JoeTheJuggler]

Wrong. Microbes have been found to live in live volcanoes, under the seabed where there is tremendous pressure and heat from volcanic vents and not a single ray of sunshine right here on Earth.

What Larian said. Microbes are indeed "life as we know it".

You contradicted yourself by saying it's not likely to harbor life as we know it and that it is likely to be teeming with microbes.

[amb]

Yes I realise that. But what type of microbes? If microbes are found on Mars and they are similar to Earth's, it will mean that there has been cross migration by meteors or such, for otherworldly microbes will be nothing like Earth's.

[Roboramma]

Yes I realise that. But what type of microbes? If microbes are found on Mars and they are similar to Earth's, it will mean that there has been cross migration by meteors or such, for otherworldly microbes will be nothing like Earth's.

That's actually one of the big questions. Will they be like earth's? If there is life that independently arose elsewhere, will it be carbon based? Will it use proteins? DNA?
We still don't know the answers to those questions, of course. But otherworldly microbes will likely have some things in common with Earth's - for example, they'll be capable of reproduction. In fact, its the likelihood that there are only so many ways to go about living that makes up most of your argument, really. Otherwise, life would arise everywhere.

Does life require liquid water? Does it require carbon? These are the questions we need to answer before we determine that only planets in the "goldilocks zone" are capable of harbouring life.

[JoeTheJuggler]

Yes I realise that. But what type of microbes? If microbes are found on Mars and they are similar to Earth's, it will mean that there has been cross migration by meteors or such, for otherworldly microbes will be nothing like Earth's.
But you were talking about an extrasolar planet, not Mars.

And when we pointed out your contradiction (that the planet cannot be both inhospitable to "life as we know it" and teeming with microbes), you said, "Wrong."

[amb]

Carbon and water are essential. Perhaps silicone can be substituted but water is essential, most astrobiologists agree on that point. If not so, then we would have found some kind of microbes on the moon. Carbon, hydrogen, oxygen and nitrogen are the prime elements of life. Why is that so? Why those elements and not others? Simple really: because they are four of the five most abundant elements on Earth. The fifth is helium, but it's an inert gas and takes absolutely no part in any known chemical reactions.
Water is the miracle substance that makes life and our world possible, but without carbon even that would not suffice to make life possible. So, what my point is that the first generation of stars, possibly the second as well was necessary to produce this carbon in the cores of exploding stars. Even planets would not have been possible without the elements spewed out of a supernova to create the dust to form them. All this took billions of years, hence some astronomers theories that we may be one of the first rational animals to evolve in this almost infinite universe. If the first and second generation of stars took say, 10 billion years from birth to death to create the third generation of stars which our sun seems to be if the age of the universe is correct, I see that perhaps they are correct in their estimations.

[Bill Thompson]

Carbon and water are essential.
Liquid water, that is. And that is very rare in the universe. Water "boils" at room temperature in a vaccume (I have seen this myself in high school physics class). It takes just the right touch of air pressure and temperature to contain liquid water. They are looking for ice on the moon, not liquid water. And the water on Mars goes from vapor to ice and is only liquid water for a brief time.

[amb]

Of course. Accept my apology. I meant to state liquid water, not Ice.

[JoeTheJuggler]

Carbon, hydrogen, oxygen and nitrogen are the prime elements of life. Why is that so? Why those elements and not others? Simple really: because they are four of the five most abundant elements on Earth.
Your logic here is severely flawed. You're making the same mistake as you have for some time now--that whatever happens on Earth is the absolute ideal for life. The fact is, you don't know that.

Also, you have your facts wrong (again). The 5 most most abundant elements in the Earth's crust are oxygen, silicon, aluminum, iron and calcium. [Linky (http://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust).] Carbon is the 15th most abundant.

If you're talking about the atmosphere, it's primarily nitrogen (nowadays, anyway--and I'm sure you know the oxygen wasn't there before biological processes put it there).

And if abundance on Earth is what makes these the "prime elements of life", then why aren't these other elements "prime elements of life"?

So, what my point is that the first generation of stars, possibly the second as well was necessary to produce this carbon in the cores of exploding stars. Even planets would not have been possible without the elements spewed out of a supernova to create the dust to form them. All this took billions of years, hence some astronomers theories that we may be one of the first rational animals to evolve in this almost infinite universe. If the first and second generation of stars took say, 10 billion years from birth to death to create the third generation of stars which our sun seems to be if the age of the universe is correct, I see that perhaps they are correct in their estimations.

You might be interested in a Hubble story that hit the news today. The first generation of galaxies formed even earlier than previously thought. Hubble has seen the primordial population of galaxies that formed just 500-600 million years after the Big Bang.

http://www.cnn.com/2010/TECH/space/01/05/hubble.new.galaxies/index.html

Also, I've addressed your argument that there hasn't been enough time for intelligent civilizations to arise before. It's easy enough to refute. There has been enough time, because we're here. No more time has passed here since the Big Bang than anywhere else in the universe.

[amb]

Also, you have your facts wrong (again). The 5 most most abundant elements in the Earth's crust are oxygen, silicon, aluminum, iron and calcium. [Linky.] Carbon is the 15th most abundant
The elements I mentioned are essential for life, not the most abundant.

[davefoc]

Carbon and water are essential. Perhaps silicone can be substituted but water is essential, most astrobiologists agree on that point. If not so, then we would have found some kind of microbes on the moon. Carbon, hydrogen, oxygen and nitrogen are the prime elements of life. Why is that so? Why those elements and not others? Simple really: because they are four of the five most abundant elements on Earth. The fifth is helium, but it's an inert gas and takes absolutely no part in any known chemical reactions.
Water is the miracle substance that makes life and our world possible, but without carbon even that would not suffice to make life possible. So, what my point is that the first generation of stars, possibly the second as well was necessary to produce this carbon in the cores of exploding stars. Even planets would not have been possible without the elements spewed out of a supernova to create the dust to form them. All this took billions of years, hence some astronomers theories that we may be one of the first rational animals to evolve in this almost infinite universe. If the first and second generation of stars took say, 10 billion years from birth to death to create the third generation of stars which our sun seems to be if the age of the universe is correct, I see that perhaps they are correct in their estimations.

A somewhat off topic question occurred to me as a result of amb's post: What is the minimum number of elements contained in a living organism? Does every known living organism have at least oxygen, hydrogen, nitrogen and carbon? What other elements, if any, are in the living organism with the least number of elements?

[Lukraak_Sisser]

You'd need at least phosphorus and all known organisms also at least need sulphur, magnesium, sodium, potassium and iron off the top of my head.
The list is probably a lot longer though

[JoeTheJuggler]

The elements I mentioned are essential for life, not the most abundant.

So how should I know when you don't mean what you say?

Carbon, hydrogen, oxygen and nitrogen are the prime elements of life. Why is that so? Why those elements and not others? Simple really: because they are four of the five most abundant elements on Earth. The fifth is helium, but it's an inert gas and takes absolutely no part in any known chemical reactions.

[JoeTheJuggler]

A somewhat off topic question occurred to me as a result of amb's post: What is the minimum number of elements contained in a living organism? Does every known living organism have at least oxygen, hydrogen, nitrogen and carbon? What other elements, if any, are in the living organism with the least number of elements?

Good question.

IMO, the line between just chemistry and life is not so sharp. A virus has some genetic material (DNA or RNA) and a protein coat. (ETA: And a prion is just a protein.)

In the best theories of abiogenesis, you had some sort of self-replicating polymer. (I think that's where you could argue life began. You would already have a form of selection because there are bound to be more of a self-replicating polymer in any sample of water than other molecules.) Once it's enclosed in a simple membrane vessicle, you have something resembling a proto-cell. It "reproduces" when the vessicle grows into a microtubule and then breaks into two by purely chemical/mechanical means. Again, a self-replicating molecule is more likely to be present in greater abundance in the two daughter proto-cells than other molecules.

ETA: But I don't think this is a useful approach, because these elements have been abundant in the universe for billions of years. And, as mentioned above, more time has not elapsed here on Earth than anywhere else in the universe, so I can't see how this argues something special or different or unusual about the Earth.

[A. Zaitsev]

www(dot)youtube(dot)com/watch?v=-YLHMpcVbuw

Faces From Earth

"message in bottle" for probable ETI

[JoeTheJuggler]

www(dot)youtube(dot)com/watch?v=-YLHMpcVbuw

Faces From Earth

"message in bottle" for probable ETI


For convenience:

http://www.youtube.com/watch?v=-YLHMpcVbuw

(Unfortunately, the video has embedding disabled.)

[A. Zaitsev]

(Unfortunately, the video has embedding disabled.) I have informed about this new

Message to probable ETI

in order to note that such activity also gain ground...

[amb]

So how should I know when you don't mean what you say?

You been a man of science should know that. :)

[amb]

I have informed about this new

Message to probable ETI

in order to note that such activity also gain ground...

Think of a civilization just one thousand years ahead of us, with the same curiosity as man who also has sent probes into the infinite universe, or just our galaxy. My argument is that we should have received a clue of their existence by now. We haven't, that seems to prove that at best we are one of the few civilizations in existence, or at worsts, one of the few in the whole universe.

[shadron]

The elements I mentioned are essential for life, not the most abundant.

Yes, that's right. According to joe your quote is:

Carbon, hydrogen, oxygen and nitrogen are the prime elements of life. Why is that so? Why those elements and not others? Simple really: because they are four of the five most abundant elements on Earth.

They are essential to life, not because they're particularly abundant, but because they are fantastically, chemically flexible. They are capable of all sorts of neat things: carrying energy, linking into long chains, which can be folded into complex shapes whose surfaces are conducive to catalyzing reactions, creating useful structures (like membranes, cells with vacuoles, structural elements), and so on.

Dr. Peter Ward says that the growing consensus among biologists and chemists is that there probably are not any other chemistries upon which life can be built besides ours; other life may incorporate other elements, but they probably won't be life if they aren't centered around those four elements.

[JoeTheJuggler]

Think of a civilization just one thousand years ahead of us, with the same curiosity as man who also has sent probes into the infinite universe, or just our galaxy. My argument is that we should have received a clue of their existence by now. We haven't, that seems to prove that at best we are one of the few civilizations in existence, or at worsts, one of the few in the whole universe.

A big hole in your logic is the two parts I highlighted. We are an intelligent civilization that has NOT sent out probes that are now ubiquitous in the galaxy.

This flaw was part of the numbered rejection of your argument for the non-existence of ETIs based on Fermi's Paradox. There are many ways to explain Fermi's Paradox other than the conclusion that they don't exist.

I wish you'd quit repeating this mistake.

[JoeTheJuggler]

You been a man of science should know that. :)

Been?

I think you're confusing science with some sort of paranormal ability. Frankly, neither can resolve sloppy thinking and sloppy writing.

[JoeTheJuggler]

Yes, that's right. According to joe your quote is:


Don't take my word for it. That's actually what he wrote:

http://forums.randi.org/showthread.php?postid=5473744#post5473744

[RecoveringYuppy]

A big hole in your logic is the two parts I highlighted. We are an intelligent civilization that has NOT sent out probes that are now ubiquitous in the galaxy.

There might be holes in his logic, but our civilization don't serve as a counter example to what you qoted him saying because we aren't a thousand years more advanced than we are. And a thousand years isn't a big amount of time in regard to the Fermi Paradox.

[JoeTheJuggler]

There might be holes in his logic, but our civilization don't serve as a counter example to what you qoted him saying because we aren't a thousand years more advanced than we are. And a thousand years isn't a big amount of time in regard to the Fermi Paradox.

No. He meant that this civilization a thousand years ahead of us sent out probes a thousand years ago. We've been going over and over this for about year on this thread.

He's arguing that the only explanation for Fermi's Paradox is that ETIs do not exist. I've pointed out several times there are a number of other explanations. (I even numbered them.) That any one of them is possible refutes the argument amb has been making, and at this point all of them are possible.

Just off the top of my head, the points I made are that the technology to make evidence of a civilization ubiquitous in the galaxy might not be possible.

If possible, it might be that no civilization lasts long enough to discover it.

If discovered, it might be that the technology isn't feasible (economically, perhaps).

If feasible, it might be that such civilizations have no motivation to fill the galaxy with evidence of their existence (that is, they might choose not to use the technology).

It could also be that evidence of their existence is *almost* ubiquitous in the galaxy, and just missed us by a mere light year's distance or a mere thousand years' (or million years') time.

It could also be that such advanced ETIs are so advanced they could make themselves undetectable to us by intention.

Finally, it could be that no ETIs exist.

The lack of evidence does not point to this last explanation as the only possibility.

So my position is, we don't know whether or not ETIs exist.

[amb]

We don't know yes, but my point been is that the universe is not a friendly place for life as we know it. I have put up the fact that more than 70% of the stars in our galaxy are not like our sun. A few a are twenty times bigger than good old sol. The majority though are much smaller than sol and that most of these are binary, therefore not suitable for any animal life. Radiation in space will kill any life form within minutes without protective life support systems as it would on all planets without a protective atmosphere which is only possible on rocky planets around the the same size and distance from their mother star as Earth is. And the most important thing that life needs to flourish, liquid water. I don't believe any kind of animal life is possible without this essential ingredient. It may be in abundance in space as hydrogen, but liquid water? It may prove to be rare.

[A. Zaitsev]

www(dot)youtube(dot)com/watch?v=-YLHMpcVbuw

Faces From Earth

"message in bottle" for probable ETI

this url is correct now:

www()youtube()com/watch?v=6p6KwSe9E7E

[JoeTheJuggler]

We don't know yes, but my point been is that the universe is not a friendly place for life as we know it.

And it's been pointed out to you that thinking in terms of whether certain conditions are "friendly" to life is a backward approach, and also that evolution seems to be driven by trauma rather than friendliness in the environment.

But, in fact, you don't know that there aren't a great many places in the galaxy as "friendly" as the Earth. You also don't know that the Earth is the most "friendly" place for life in the galaxy, but you reason as if it were.

In fact, everything you raise here has already been raised and refuted months ago:

I have put up the fact that more than 70% of the stars in our galaxy are not like our sun. A few a are twenty times bigger than good old sol. The majority though are much smaller than sol and that most of these are binary, therefore not suitable for any animal life.
First, you don't know that life is impossible around larger stars (in the twilight zones on a tidally locked planet orbiting a red giant, for example). Second, even if it is, how many stars does that leave that are prime candidates? It's still a huge number. And we still don't know how common Earth-like planets are, but the trend seems to be that whenever we have employed a method to detect planets of given characteristics, we have found them in abundance.

Radiation in space will kill any life form within minutes without protective life support systems as it would on all planets without a protective atmosphere which is only possible on rocky planets around the the same size and distance from their mother star as Earth is.
Also asked and answered. We're not talking about life in space, but on planets or large moons. There are plenty of ways the environment can protect life from damaging radiation. There are also ways that life could evolve its own protection. It may also be that more radiation would be a less friendly environment and spur more rapid evolution giving the odds for complex and intelligent life an advantage rather than a disadvantage.

And the most important thing that life needs to flourish, liquid water. I don't believe any kind of animal life is possible without this essential ingredient. It may be in abundance in space as hydrogen, but liquid water? It may prove to be rare.
But it may not prove to be rare. Since you have no evidence that liquid water is rare, you can't assume it is.

[amb]

When we look up at the night sky under ideal conditions away from the city glare, with the naked eye we see around 3000 stars out of the myriads that are out there, the common gut feeling is that surely out there are millions of civilizations in the vastness of space. It is difficult to believe we may well be alone. But appearances can be deceptive. Out of that roughly 3000 stars we can see with the naked eye, how many of those observed stars do you think would be hospitable to our form of life. Very few is my guess.
The gut reaction we perhaps all feel when we look at the night sky-there must be intelligent life somewhere in the vastness of space is not a good guide. We have to be guided by reason, not gut reaction, when discussing this matter.
The Drake equation is a product of several terms. If one of those terms is zero, then the product of the Drake equation will be zero; if several of the terms are small, then the product of the D equation will be very small. We will be alone.
If one factor in the D equation is close to zero, then we can reasonably identify that factor as being the solution to Fermi's paradox.
There are still many scientists who argue that the emergence of life was almost miraculous fluke, a one time event a 1 in 10 with 100 zeros event, a number that dwarfs the number of planets in the universe, and when expressed as a probability becomes, for practical purposes, indistinguishable from zero.
The improbability of the prokaryote-eukaryote transition could be another reason for Fermi's paradox.
There may be a number of reasons or one single reason/solution to the paradox. but it all boils down to that we are one of a few, or we could very well be alone. We could be unique. Excuse me if I wondered around a little on this post, I'm on my fourth stubby of beer. :p

[JoeTheJuggler]

When we look up at the night sky under ideal conditions away from the city glare, with the naked eye we see around 3000 stars out of the myriads that are out there, the common gut feeling is that surely out there are millions of civilizations in the vastness of space. It is difficult to believe we may well be alone. But appearances can be deceptive. Out of that roughly 3000 stars we can see with the naked eye, how many of those observed stars do you think would be hospitable to our form of life. Very few is my guess.
The gut reaction we perhaps all feel when we look at the night sky-there must be intelligent life somewhere in the vastness of space is not a good guide. We have to be guided by reason, not gut reaction, when discussing this matter.
See the Sagan quote I offered. Many of us don't like to think with our gut.



There may be a number of reasons or one single reason/solution to the paradox. but it all boils down to that we are one of a few, or we could very well be alone. We could be unique. Excuse me if I wondered [sic] around a little on this post, I'm on my fourth stubby of beer. :p
No. You're wrong. There is also the possibility that there could be hundreds or even thousands of ETIs similar to us in the galaxy.

All your speculation on the probabilities with insufficient information to calculate them doesn't eliminate this possibility.

[LarianLeQuella]

Out of that roughly 3000 stars we can see with the naked eye, how many of those observed stars do you think would be hospitable to our form of life. Very few is my guess.

You would be guessing wrong! Every single one of them will have a "zone" that a planet could orbit in that would provide all the things that we see here as far as the chemistry goes. And again, while our type of chemistry (carbon based) may seem the most likely type, discovering life forms on a body like Europa would surely throw a lot of monkey wrenches into any speculation.

Look, I don't disagree that we don't know.

heck, I don't even disagree that advanced ETI is quite unlikely/rare.

What I do dissagree with, and have a lot of disrespect for are your assertions as fact that it has to be on a planet like earth, and life forms that are earthlike, with humanlike psychology. Those assertions are totally unfounded, if not downright delusional.

Excuse me if I wondered around a little on this post, I'm on my fourth stubby of beer. :p

Lightweight! :p

[amb]

Europa should prove very interesting as scientists/astrobiologist think there may be a liquid water world there under the mantle of ice, possibly heated by the moons own core. I think more effort should be made to that moon than to Mars which seems to be a dead world like our moon. Imagine the repercussions if some kind of life is found there under all that ice.

[JoeTheJuggler]

Europa should prove very interesting as scientists/astrobiologist think there may be a liquid water world there under the mantle of ice, possibly heated by the moons own core. I think more effort should be made to that moon than to Mars which seems to be a dead world like our moon. Imagine the repercussions if some kind of life is found there under all that ice.

We don't know that Mars is a dead world. The methane plumes seem to indicate otherwise. (Or at least that there was once life.)

But this is an important point: we don't know. And both Mars and Europa are closer by lightyears than even the nearest extrasolar planet.

And yet you're making pronouncements about the existence of ETIs throughout the entire galaxy (and beyond)!

[Bill Thompson]

The bottom line is that a couple billion years is too long.

It will take less that 10 million for human beings to colonize the whole galaxy.

The Milky Way existed for billions of years before our sun was even born. So, logically, if life like us is common, they should be everywhere now.

The bottom line is that a couple billion years is too long.

I deal with religious people who refuse to see evidence or turn away for logical constructs in these chat forums. Mormons, Muslims, Scientologist and the SETI faithful all have the same mind set to me.

Snake Oil is Snake Oil. Putting money into SETI when it can help us in other ways hurts us all.

[Roboramma]

It will take less that 10 million for human beings to colonize the whole galaxy. Do you have any support for that statement?
Because that seems more like a statement of faith than anything that the "SETI faithful" have said in this thread.

[JoeTheJuggler]

The bottom line is that a couple billion years is too long.

It will take less that 10 million for human beings to colonize the whole galaxy.
There are at least two things wrong with this statement. One is that the search for ETIs is not the search for human beings. The other is the point Roboramma made. That point is the same basic idea I've been listing as a refutation for the argument that ETIs do not exists based on Fermi's Paradox. There are a number of other possible explanations for the lack of evidence of ETIs at this point.

The Milky Way existed for billions of years before our sun was even born. So, logically, if life like us is common, they should be everywhere now.
That's not logical. There could be other civilizations more or less equal to our own, and we would not expect them to have filled the galaxy with evidence of their existence since we have not done so.

Putting money into SETI when it can help us in other ways hurts us all.
This point too has been covered. It's a relatively small amount of money. None of it is taxpayer money. There are potential payoffs for this kind of project--even aside from the long-shot payoff of finding a signal from an ETI.

[amb]

That's not logical. There could be other civilizations more or less equal to our own, and we would not expect them to have filled the galaxy with evidence of their existence since we have not done so.
But we have been here less than 50.000 years as a civilization. If we manage to survive the next 100.000 years, the galaxy will be at our mercy. I'm certain we will have colonies on at least half the solar system, and probably robotic probes searching for signs of life in other nearby galaxies.

[RecoveringYuppy]

That's not logical. There could be other civilizations more or less equal to our own, and we would not expect them to have filled the galaxy with evidence of their existence since we have not done so.

In that numbered list of reasons you have posted before, could you run down the minimum that you think need to be true for this to be the case?

The scenario where the galaxy is populated by civilizations rougly equivalent to our own and no others more advanced who've gone on to colonize seems to require a lot of conditions to have been true for all civilizations that ever existed. Or it seems to require that civilization is destined to appear simultaneously and this is the time.

[JoeTheJuggler]

In that numbered list of reasons you have posted before, could you run down the minimum that you think need to be true for this to be the case?

Logically, for the lack of evidence to point to the conclusion that ETIs don't exist, absolutely none of the other explanations can be possible. I've stated this elsewhere. You'd have to refute all the other possibilities.

[JoeTheJuggler]

But we have been here less than 50.000 years as a civilization.

Exactly. So the only example we have of an intelligent civilization doesn't support any conclusions you want to make about longevity of civilizations and what must inevitably happen.

I have ceded the fact that the lack of evidence proves that no super-advanced civilization exists that has made evidence of their existence ubiquitous in the galaxy. (And even in that scenario, it doesn't prove that a long-lived advanced civilization doesn't exist. If you're going to assume super-advanced technology, why not also assume the ability to hide evidence of their existence from us? I don't think such a thing is very likely, but I'm just pointing out the logical flaw in your argument.)

[JoeTheJuggler]

The scenario where the galaxy is populated by civilizations rougly equivalent to our own and no others more advanced who've gone on to colonize seems to require a lot of conditions to have been true for all civilizations that ever existed. Or it seems to require that civilization is destined to appear simultaneously and this is the time.
I don't follow. The scenario where the galaxy is populated by civilizations roughly equivalent to our own is consistent with the lack of evidence. (And it doesn't require there to be no others more advanced, but merely no others more advanced that have made evidence of their existence ubiquitous in the galaxy. What if that advanced civilization has colonized say 1/4 of the galaxy but not our immediate area?)

[RecoveringYuppy]

@JoetTheJuggler,

Nice sidestepping, please explain what it would it take to make your list of numbered "reasons" consistent with either the scenario you mentioned before or the scenario you're positing now.

[JoeTheJuggler]

@JoetTheJuggler,

Nice sidestepping, please explain what it would it take to make your list of numbered "reasons" consistent with either the scenario you mentioned before or the scenario you're positing now.

I sidestepped nothing. My list of is not a list of "reasons"--it's a list of alternative possible explanations for the Fermi Paradox (that is, for the lack of evidence of the existence of ETIs). In order for the explanation, "no ETIs exist" to be proven, you would have to eliminate all these other possibilities. If even one of them remains a possibility, then the lack of evidence fails to prove that ETIs do not exist.

I suggest you read through the thread. All of this has been covered. (And I did answer your question about my numbered list. And in at least several versions of my numbered list--I've repeated it several times over the one year plus life of this thread--I made this very clear by saying that if any one of these explanations remains, it refutes the argument amb has been making: that the lack of evidence of ETIs proves their non-existence.)

Basically this argument depends on a great number of assumptions to be true, and we have no reason to claim that all these assumptions are true.

For the record (and about the twentieth time), my position on the question of the existence of ETIs is simply that we don't know. I am in no way claiming proof of the existence of ETIs.

[amb]

Agnosticism is a fair view to take in this regard. But it's not all that different to been agnostic in religious matters. The center position is for people who will not commit to one way or the other, fence sitters if you prefer.
If on the other hand, one looks at the age of this universe, the unlikely odds of life starting from the raw elements that were made in the original B/B, and having to be processed in giant stars that had to explode to spew material that was produced in the stars core in order for planets to form into the vast reaches of space, a cycle that is ongoing, death of one leads to life of another, the energy never dying, but recycled over and over. Perhaps in some little corner of the universe, the first elements came together to produce more elements that finally over who knows how much time produced the first microbes and or cell.
I have argued before, that if this planet was completely destroyed, and every hint of life came to an end. What are the chances life will once again start here like it did 4 billion years ago? Let alone a homo sapien like creature.

[Roboramma]

I don't follow. The scenario where the galaxy is populated by civilizations roughly equivalent to our own is consistent with the lack of evidence. (And it doesn't require there to be no others more advanced, but merely no others more advanced that have made evidence of their existence ubiquitous in the galaxy. What if that advanced civilization has colonized say 1/4 of the galaxy but not our immediate area?)

I don't really think you can make that argument: if there are other civilizations we don't expect them to have preferentially arisen at a point in time close to us. But the time in which they could have arisen is large enough that not arising at exactly the same time means they'd likely be very much older.

Of course, if there are only a few civilizations, its possible (though unlikely) that just by chance they may have arisen at a time close to ours. But if there are very many, that they all did is pretty damn unlikely.

Which suggests that if there are other civilizations they either have a very different sort of development from us (for instance, they may have mastered chemisty, but not other forms of technology), or they are very much more advanced than us.

Note, however, that more advanced than us does not imply capable of interstellar travel, as we simply don't know what is required for that.

[JoeTheJuggler]

I don't really think you can make that argument: if there are other civilizations we don't expect them to have preferentially arisen at a point in time close to us. But the time in which they could have arisen is large enough that not arising at exactly the same time means they'd likely be very much older.

Of course, if there are only a few civilizations, its possible (though unlikely) that just by chance they may have arisen at a time close to ours. But if there are very many, that they all did is pretty damn unlikely.

Which suggests that if there are other civilizations they either have a very different sort of development from us (for instance, they may have mastered chemisty, but not other forms of technology), or they are very much more advanced than us.

Note, however, that more advanced than us does not imply capable of interstellar travel, as we simply don't know what is required for that.

ETA: I never said anything that claims that the civilizations would have had to arise preferentially close to us in time. (See below.) However, that is in fact one of the Rare Earth arguments--that there hasn't been enough time since the formation of our galaxy, since heavier metals require at least a couple of generations of stars to have preceded the present. (I linked to something recently though that counters this--the first galaxies formed earlier than was previously thought.) And it fits with the point I've been making again and again: no more time has passed here than elsewhere in the galaxy, and yet here we are.

Yes. I agree. [ETA: with you final sentence, that is.]

My point is that it is possible for there to be plenty of civilizations at more or less our level. But I've also said, as you do, that it's also possible that there are any number of other explanations for why we haven't seen evidence of ETIs yet.

I've listed them several times. One is, as you say, there could be older and more advanced civilizations that aren't capable of interstellar travel (either because it's not practical, it's not feasible, or for some reason they all lack the motivation to use it).

It could be that no technological civilization lasts that long (and that position is quite credible given how close we've come to ending our own civilization, and the fact that we've yet to deal with several very daunting problems, like population). That would result in the scenario described above--where the only civilizations extant in the galaxy are more or less on par with our own, and we lack the ability to detect them (or them us, or any one to detect any other) unless we get extremely lucky.

Or it's possible we are unique.

As I said, we just don't know.

[JoeTheJuggler]

Agnosticism is a fair view to take in this regard. But it's not all that different to been [sic] agnostic in religious matters. The center position is for people who will not commit to one way or the other, fence sitters if you prefer.
That's absurd. When we are ignorant, scientifically the only reasonable position is to say we don't know.

Agnosticism as the term originated referred to the belief that God is unknowable (sort of like deism). As it's used today, it is the belief or doctrine that we don't (or can't) know whether or not God exists. (And seen that way, it's the only reasonable position, and is not a substitute for being an atheist--in fact all atheists are also agnostics.)

Atheism is either the lack of belief in the existence of a god or gods (weak atheism, or what I think of as a[theism]; or the belief in the non-existence of a god or gods (strong atheism, or what I think of as [athe]ism). From a scientific or skeptical point of view, I see atheism as the provisional acceptance (or rejection) of a proposition based on what the evidence points to. (Either the acceptance of the proposition, "No god exists" or the rejection of the proposition, "A god or god exists.")

So, while we are all "agnostics" wrt the existence of ETIs (that is we don't know), we lack the evidence to provisionally come to the conclusion that ETIs do not exist. That is, there's no reason at this point to believe that ETIs don't exist.

Again, see the Carl Sagan quote--it's OK to postpone reaching a conclusion in the absence of evidence.


My bolding:
If on the other hand, one looks at the age of this universe, the unlikely odds of life starting from the raw elements that were made in the original B/B, and having to be processed in giant stars that had to explode to spew material that was produced in the stars core in order for planets to form into the vast reaches of space, a cycle that is ongoing, death of one leads to life of another, the energy never dying, but recycled over and over.
Again, your reasoning here is more similar to that of Creationists/ID proponents.

How did you calculate "the unlikely odds"?

Perhaps in some little corner of the universe, the first elements came together to produce more elements that finally over who knows how much time produced the first microbes and or cell.
I suggest you watch this video on abiogenesis again (or for the first time if you haven't yet). Please watch the entire thing--the meat of it doesn't start right away. The process is no great mystery and doesn't strain probability as you suggest.
U6QYDdgP9



I have argued before, that if this planet was completely destroyed, and every hint of life came to an end. What are the chances life will once again start here like it did 4 billion years ago?
Indeed. What are the odds?

I don't claim to know, but I'm sure your claim of certain knowledge that it's astronomically improbable is unfounded.

We know how chemistry works, and the process of abiogenesis doesn't seem as unlikely as you think.

[amb]

Joe, video doesn't work.

Note, however, that more advanced than us does not imply capable of interstellar travel, as we simply don't know what is required for that.
We know what's required. We at this point in time, and for the foreseeable future don't look like developing it. We need to be able to travel at least at 20% of light speed in order for us to get anywhere, and then it will probably be robots not perishable delicate humans who will do the traveling. Unless we make a superman with experimentation with the genetic code by then, maybe in 10.000 years.

[LarianLeQuella]

If we manage to survive the next 100.000 years, the galaxy will be at our mercy. I'm certain we will have colonies on at least half the solar system, and probably robotic probes searching for signs of life in other nearby galaxies.

Really? On what grounds are you making that statement? For all we know humanity may decide that we're too big a harm to the rest of the galaxy, and be content with staying here and dying with our sun (hihgly unlikely given our evolutionary track record, but just saying that it's not an innevitability).

While this assertion isn't nearly as outlandish as your many other assertions, please try to take out the way we currently think and behave.

[JoeTheJuggler]

Joe, video doesn't work.
Sorry. Truncated the yt code. But I have posted this on this thread before.

Here it is again:

U6QYDdgP9eg

ETA: You made an assertion on "the odds," and I asked how you calculated those odds. You're just going to ignore that?

[RecoveringYuppy]

Joe, video doesn't work.

We know what's required. We at this point in time, and for the foreseeable future don't look like developing it. We need to be able to travel at least at 20% of light speed in order for us to get anywhere, and then it will probably be robots not perishable delicate humans who will do the traveling. Unless we make a superman with experimentation with the genetic code by then, maybe in 10.000 years.

Not sure why you think 20% is necessary. Over the immense time frames available even speeds we've already achieved or that exist in nature could support an interstellar migration. Over immense periods of times you've got the opton of simply waiting for some other star to come to you. The stars are in motion. Over the course of the next 10 to 20 thousands our nearest stellar neighbor will have changed. Not too much closer, but then we're just one example. We don't know if planets exist at Rigil Kentaurus, but if we were there instead of orbiting Sol our existing probes would already be reaching interstellar distances, simply because it's a binary (or more) star system and the nearest star is just that close.

[JoeTheJuggler]

Not sure why you think 20% is necessary. Over the immense time frames available even speeds we've already achieved or that exist in nature could support an interstellar migration.

And yet, we haven't even come near attempting any sort of interstellar travel--even unmanned.

One of my numbered points was that even if it's technologically possible it might be economically not feasible or such a civilization might lack sufficient motivation to undertake such a project.

Or, these kinds of civilizations might not endure and thus these "immense time frames" may not be "available".

ETA: So at best it's premature to conclude the non-existence of ETIs based on the lack of evidence. Again, there are several plausible explanations for Fermi's Paradox, so no single one of them is proven.

[LarianLeQuella]

Yeah, the numbers may not take into account the failure rate of each mission. Maybe some civilizations did try, but they lost so many ships and people that they finally said, "Sod it, this sucks!" Colonization of space can only be incredibly more dangerous than the efforts the Europeans had on their first steps to the America's. The Vikings pretty much said "Sod it." and I don't think they lost a vast number of ships, just that it didn't pay off. Now imagine spending trillions of dollars per ship, loading it up, only to have them fail time and time again due to whatever... Yeah, might as well start in on a dyson sphere instead and see what you can manage from there...

[JoeTheJuggler]

Yeah, the numbers may not take into account the failure rate of each mission. Maybe some civilizations did try, but they lost so many ships and people that they finally said, "Sod it, this sucks!" Colonization of space can only be incredibly more dangerous than the efforts the Europeans had on their first steps to the America's. The Vikings pretty much said "Sod it." and I don't think they lost a vast number of ships, just that it didn't pay off. Now imagine spending trillions of dollars per ship, loading it up, only to have them fail time and time again due to whatever... Yeah, might as well start in on a dyson sphere instead and see what you can manage from there...

And even if they're successful, these long-term intergenerational migration ships would be one-way affairs.

They would be all cost and no return for the people staying on the home planet. So again, it could be economically unfeasible or such civilizations could simply lack the motivation to undertake the colonization of the galaxy.

[RecoveringYuppy]

And yet, we haven't even come near attempting any sort of interstellar travel--even unmanned.
That seems like you didn't read what you were responding to. Of couse the human race hasn't waited for tens of thousands of years during the half century we've had minimal space flight. ???
ETA: So at best it's premature to conclude the non-existence of ETIs based on the lack of evidence. Again, there are several plausible explanations for Fermi's Paradox, so no single one of them is proven.
Thanks, I saw that the first hundred times you posted it. But I've yet to see you (maybe I missed it) put some actually numbers on your explanations and come up with a plausible scenario that has us not alone in the galaxy.

[RecoveringYuppy]

They would be all cost and no return for the people staying on the home planet.

They wouldn't necessarily cost the home planet anything at all.

[RecoveringYuppy]

Yeah, the numbers may not take into account the failure rate of each mission. Maybe some civilizations did try, but they lost so many ships and people that they finally said, "Sod it, this sucks!" Colonization of space can only be incredibly more dangerous than the efforts the Europeans had on their first steps to the America's. The Vikings pretty much said "Sod it." and I don't think they lost a vast number of ships, just that it didn't pay off. Now imagine spending trillions of dollars per ship, loading it up, only to have them fail time and time again due to whatever... Yeah, might as well start in on a dyson sphere instead and see what you can manage from there...

Very very ironic post you've constructed there. The Vikings failed with their ships but at the very time they were failing humans had already walked to the "new world". The highly ambitious direct from Earth to the next star system isn't the only model available.

And so what if colonizing the galaxy has to wait until we've built a Dyson sphere first? Even low rates of population growth could have the solar system populated with a hundred trillion people in only five centuries.

[JoeTheJuggler]

They wouldn't necessarily cost the home planet anything at all.

There's no such thing as a free lunch spacecraft.

[JoeTheJuggler]

Very very ironic post you've constructed there. The Vikings failed with their ships but at the very time they were failing humans had already walked to the "new world". The highly ambitious direct from Earth to the next star system isn't the only model available.
Irrelevant. No one is going to walk to another planet.



And so what if colonizing the galaxy has to wait until we've built a Dyson sphere first? Even low rates of population growth could have the solar system populated with a hundred trillion people in only five centuries.
No one is denying that colonizing the galaxy isn't in the realm of the possible. The point is that it's not inevitable that is must have happened long before now if there are any ETIs. The fact that no one has colonized every cubic inch of the galaxy doesn't prove that no ETIs exist.

There are several other possible explanations for the lack of evidence of ETIS (that is, other explanations for Fermi's Paradox). Since there are more than one possible explanations for the lack of evidence, the lack of evidence doesn't prove any one possible explanation.

So, to the question of the existence of ETIs, the only answer we have is that we don't know.

[JoeTheJuggler]

That seems like you didn't read what you were responding to. Of couse the human race hasn't waited for tens of thousands of years during the half century we've had minimal space flight. ???

ETA: To review--I was pointing out that the fact the the technology exists for humans to have sent out interstellar crafts before now doesn't mean that we necessarily have done so. And in fact, we haven't. That supports the argument I've been making. The fact that a technology is possible or even available doesn't create the logical necessity that it must be used.

I suggest you read the entire thread then. The lack of evidence of ETIs has been offered as proof that we are alone. I've been pointing out that there may be civilizations just like our own in the galaxy and we wouldn't have any evidence of their existence.

Thanks, I saw that the first hundred times you posted it. But I've yet to see you (maybe I missed it) put some actually numbers on your explanations and come up with a plausible scenario that has us not alone in the galaxy.
I don't have to. My position is that we don't know. I'm not arguing that I have evidence of the existence of ETIs. I'm pointing out that the lack of evidence at this point doesn't prove their non-existence.

Every one of the alternative explanations I have given for Fermi's Paradox is plausible.

[RecoveringYuppy]

There's no such thing as a free lunch spacecraft.
That may not be true. If at some time in the future someone colonizes an object that is on an interstellar trajectory anyway, and it is a a space based society that is colonizing off world objects anyway, there may be no incremental cost.

But even if that isn't true there is no reason why colonizing other solar systems has to cost the home world anything. The cost could be entirely born by the people who do it.

Irrelevant. No one is going to walk to another planet.
You could try reading for understanidng, I think the point I was making is clear.
I suggest you read the entire thread then.
I'd already read the thread in it's entirety the first time you suggested that. I'm not really interested in addressing the rest of your post point by point because it's already been addressed and you don't seem interested in framing your argument in a way that would be persuasive to me.

[RecoveringYuppy]

For all we know humanity may decide that we're too big a harm to the rest of the galaxy, and be content with staying here and dying with our sun (hihgly unlikely given our evolutionary track record, but just saying that it's not an innevitability).

Humanity has never made a collective decision. Even if 99.9% of humanity decides this, if .1% of humanity goes off and colonizes the galaxy anyway it still gets done. So, yes it's highly unlikely. And to explain away the absence of ETIs we have to presume they all reach this decision and maintain it.

It would be a bass-ackward conclusion to reach too. How exactly could we harm inanimate asteroids?

Can anyone cite a lifeform that has refrained from moving in to an environment it can occupy? Some may have instinctive population control instincts that limit them when they fully occupy a niche, but I'm not familiar with any that refuse to move in to a new niche. We seem to be moving in to every niche we can. Some, such as Antartica or the Sea floor, are not exactly natural for us.

[RecoveringYuppy]

And again, while our type of chemistry (carbon based) may seem the most likely type, discovering life forms on a body like Europa would surely throw a lot of monkey wrenches into any speculation.
Europan life wouldn't necessarily have to have a different chemistry. All the same elements are available there.

[JoeTheJuggler]

That may not be true. If at some time in the future someone colonizes an object that is on an interstellar trajectory anyway, and it is a a space based society that is colonizing off world objects anyway, there may be no incremental cost.
Who said anything about "incremental cost"? I'm saying since a one-way trip would be all cost to the home world (the first one), it could be that no civilization is ever motivated to do it.

But even if that isn't true there is no reason why colonizing other solar systems has to cost the home world anything. The cost could be entirely born by the people who do it.
Who are these people? They have no home world? If they leave forever, it is a net cost to the home world with no hope of a return in any reasonable time period (without assuming FTL travel or some such).


You could try reading for understanidng, I think the point I was making is clear.
Why the hostility?
I do understand. You were criticizing the analogy of the lack of motivation for the Vikings to continue sending trips to the New World. But walking to a new planet is obviously not analogous. If interstellar spacecraft prove to be too expensive for any civilization ever to pursue, there will be nothing analogous to walking there.

I'd already read the thread in it's [sic] entirety the first time you suggested that. I'm not really interested in addressing the rest of your post point by point because it's already been addressed and you don't seem interested in framing your argument in a way that would be persuasive to me.
No--I'm interested in framing my argument in a logical manner. Apparently logical arguments aren't "persuasive" to you. (I think you mean "convincing" rather than persuasive.)

Look the only thing I've been doing with the numbered points is showing that there are several possible explanations for the lack of evidence of ETIs (or Fermi's Paradox). Therefore, the lack of evidence doesn't prove any one of them is correct.

This was to refute amb's argument that the lack of evidence proves that we are unique and alone in the galaxy--that ETIs do not exist.

My position on the question of the existence of ETIs is that we don't know. The only way to refute that position is to bring evidence or logical argument that we do in fact know.

[JoeTheJuggler]

Humanity has never made a collective decision.
I think you are mistaken. I think maybe you mean humanity has never made a world-wide unanimous decision, but every large project has been a collective project.

Even if 99.9% of humanity decides this, if .1% of humanity goes off and colonizes the galaxy anyway it still gets done. So, yes it's highly unlikely. And to explain away the absence of ETIs we have to presume they all reach this decision and maintain it.
This is logically wrong. No one is "explaining away" the absence of evidence of ETIs. We're merely pointing out that since there are several possible explanations for the absence of evidence, the absence of evidence is not proof of the non-existence of ETIs. To argue that the absence of evidence is conclusive requires you to assume that a number of things must have inevitably happened long ago such that evidence of ETIs must necessarily be ubiquitous in the galaxy.

Those assumptions are unfounded. We simply don't know.


Can anyone cite a lifeform that has refrained from moving in to an environment it can occupy?
Yes. Humans have not colonized the galaxy.

Some may have instinctive population control instincts that limit them when they fully occupy a niche, but I'm not familiar with any that refuse to move in to a new niche. We seem to be moving in to every niche we can. Some, such as Antartica or the Sea floor, are not exactly natural for us.
You're simply ignoring the points I've raised.

No one said there has to be any "refusal" to move to a new environment (a niche is an ecological role, that's not what you mean surely).

Have humans refused to colonize the galaxy?

I know, you'll reply that we haven't had time to, but what if no other civilization has had time to? No more and no less time has elapsed here than any other place in the galaxy.

[RecoveringYuppy]

Who said anything about "incremental cost"?
??? I did. You're quoting me.

I'm saying since a one-way trip would be all cost to the home world (the first one), it could be that no civilization is ever motivated to do it.
And I'm saying that there are colonization models that require no incremental cost. Some colonization models happen as a side effect of simply moving around.

Who are these people? They have no home world? If they leave forever, it is a net cost to the home world with no hope of a return in any reasonable time period (without assuming FTL travel or some such).
They could be living in their homeworld as they make the migration. In many scenarios the cost, assuming there is one, could be born by the people making the journey.

Why the hostility?

It's annoyance that this could be an interesting conversation but you seem to be flooding it. And intentionally not understanding.

I do understand. You were criticizing the analogy of the lack of motivation for the Vikings to continue sending trips to the New World. But walking to a new planet is obviously not analogous. If interstellar spacecraft prove to be too expensive for any civilization ever to pursue, there will be nothing analogous to walking there.
There is no if about it. He cited a way that is more expensive than other scenarios.

No--I'm interested in framing my argument in a logical manner. Apparently logical arguments aren't "persuasive" to you. (I think you mean "convincing" rather than persuasive.)
Whatever. It's not like my life hinges on this interesting conversation in a way that really makes a difference between those words.

I think you are mistaken. I think maybe you mean humanity has never made a world-wide unanimous decision, but every large project has been a collective project.
This is why I'm annoyed. It's perfectly obvious that I meant a unanimous decision from the context immediately surrounding that sentence. Read the very next sentence to see that my point is that if even a small portion of the human race ignores the decision not to explore the galaxy then it doesn't matter what the rest of the race decided.

Yes. Humans have not colonized the galaxy.
That doesn't refute my point. We have gone there and stayed there haven't we? We haven't refused to occupy that niche.

You're simply ignoring the points I've raised.
No, I've read them. I don't find them convincing and I don't see you wanting to make them convincing to me.

No one said there has to be any "refusal" to move to a new environment (a niche is an ecological role, that's not what you mean surely).
Niche can be used casually to mean either, but since we'll make it an ecological niche for ourselves and any other lifeforms we take as we go there it hardly makes a difference.

[amb]

Originally Posted by JoeTheJuggler View Post
Yes. Humans have not colonized the galaxy
Yet. We shouldn't be expected to colonise the galaxy seeing that the first rocket wasn't invented until very recently by Werner Von Braurn. [spel] Since then we have landed a man on the moon. Imagine what the next couple of centuries will bring travel wise.

[RecoveringYuppy]

Yet. We shouldn't be expected to colonise the galaxy seeing that the first rocket wasn't invented until very recently by Werner Von Braurn. [spel] Since then we have landed a man on the moon. Imagine what the next couple of centuries will bring travel wise.
Good point about our near future. There is no hint of us collectively deciding not to expand in to space now. There are now more countries sponsoring space programs. Private corporations are making plans. Private citizens have bought their way in to space. There are even private individuals sponsoring their own pet space projects.

[JoeTheJuggler]

??? I did. You're quoting me.
And you were replying to my statement that there is no such thing as a free spacecraft.

And I'm saying that there are colonization models that require no incremental cost. Some colonization models happen as a side effect of simply moving around.
Again, there is no model where an interstellar spacecraft is free. My point is that this cost could make the launch of such craft not feasible. This is a plausible possible explanation for Fermi's Paradox. Therefore Fermi's Paradox does not point to the conclusion that there are no ETIs.

They could be living in their homeworld as they make the migration. In many scenarios the cost, assuming there is one, could be born by the people making the journey.
Exactly, and it might be that that cost is prohibitive.

It's annoyance that this could be an interesting conversation but you seem to be flooding it. And intentionally not understanding.
This sort of thing doesn't advance the conversation at all. I've made a clear argument that refutes the argument that the lack of evidence of ETIs proves that ETIs don't exist.




This is why I'm annoyed. It's perfectly obvious that I meant a unanimous decision from the context immediately surrounding that sentence. Read the very next sentence to see that my point is that if even a small portion of the human race ignores the decision not to explore the galaxy then it doesn't matter what the rest of the race decided.
Yes, and I indicated that I understood your intent, even though what you said wasn't that. (You said humans have never made a collective decision, which isn't true. And, in the context, that's really what we're talking about. A large investment would require a collective decision, but not necessarily a unanimous one.)

With amb, I have learned that he sometimes wants me to take very strange statements at face value, and other times not. So I was doing the only reasonable thing and checking that I was understand you correctly.

Niche can be used casually to mean either, but since we'll make it an ecological niche for ourselves and any other lifeforms we take as we go there it hardly makes a difference.
By "casually" you mean "incorrectly"? You're talking about a change in location not niche. The niche we occupy on any other planet would likely be very similar to the one we occupy here.

[RecoveringYuppy]

By "casually" you mean "incorrectly"? You're talking about a change in location not niche. The niche we occupy on any other planet would likely be very similar to the one we occupy here.

Sheez. Every dictionary I've consulted says that a niche can be a position or place. So location would be covered. Also, the definitions involving "market niche" and "ecological niche" would be appropriate since we are talking about a future where space has been developed.

I don't think any of your other points need to be addressed for a fiftieth time.

[JoeTheJuggler]

Yet. We shouldn't be expected to colonise the galaxy seeing that the first rocket wasn't invented until very recently by Werner Von Braurn. [spel] Since then we have landed a man on the moon. Imagine what the next couple of centuries will bring travel wise.

Yes, I can imagine such things. However, you can't make a logical argument based on the assumption that you know what will inevitably happen, because you don't know they will happen.

Again, the argument that Fermi's Paradox proves we are alone is logically flawed because it makes assumptions like this.

We may never achieve interstellar travel at all. We may go extinct or our civilization collapse before that is possible. Or we may continue on but find that interstellar travel never becomes economically feasible. Or it could be feasible, for whatever reason we may not be motivated to do it. (These are all points I've made before, which is why your post about how recently we started experimenting with rockets--it's Werner Von Braun--does nothing to bolster your argument. It still relies on assumptions we don't know to be true.)

ETA: Please note: I recognize and accept that it is also possible that it could be economically feasible to colonize the galaxy or otherwise make evidence of a civilization's existence ubiquitous in the galaxy. I'm not contesting that point. I'm pointing out, simply, that there are other plausible explanations for Fermi's Paradox other than that ETIs do not exist.


There is no hint of us collectively deciding not to expand in to space now.
This is all backwards. It's as if you assume if we don't make some sort of decision not to, we will naturally or automatically inevitably colonize the galaxy without making a decision to do so.

We don't know that we, or any possible ETI civilization, must inevitably achieve interstellar travel and make evidence of our existence ubiquitous in the galaxy. The argument that says the only explanation for Fermi's Paradox is that ETIs do not exist rests on that assumption, which is why it is logically flawed.
_______

Recovering Yuppy, I suggest you take a deep breath and calm down.

You have accused me of sidestepping a question I clearly answered. You have accused me of not understanding your posts, when in fact I have understood clearly, despite your sloppy use of language.

You've accused me of "flooding" the thread and refusing to understand your arguments. In fact, I understand the argument that the lack of evidence proves the non-existence of ETIs. I've just been pointing out that it's logically flawed. It depends on several assumptions that we don't know to be true.

I'm not arguing that I know ETIs exist or that I know we are not unique in the galaxy. My position is and has been that we don't know the answer to these questions. I'm in favor of continuing to explore the universe and in particular to gather information that might help us answer these questions. (For example, the Kepler mission is very exciting.)

[JoeTheJuggler]

I don't think any of your other points need to be addressed for a fiftieth time.

What are you talking about?

In order to refute the argument I've made, it would be necessary to prove that the only possible explanation for Fermi's Paradox is that ETIs don't exist. To do that, you would have to show that each of my numbered points is impossible.

No one has done that, much less addressed those points 49 times!

If what you say is true, it should be no problem for you to address each of those points once anyway, and show how each of them is impossible.

See my ETA in the previous post. I'm not saying, nor have ever disagreed with, the proposition that interstellar travel might be feasible. I'm only pointing out that it's not inevitable. There are other possible explanations.

So the fact is we simply don't know whether ETIs exist (or even questions about how rare or common they might be if they do exist).

[Roboramma]

And you were replying to my statement that there is no such thing as a free spacecraft. And he pointed out that in a way there is. At least, there's a way for a space colony to become an interstellar craft for free. To be more precise, it's possible to choose a body to build a colony on such that, at no more cost than building a colony on any other body, the colony will drift to another star.

I think it's a good point, actually. Some comets and other bodies that come close to earth may have interstellar trajectories that intersect other stars.

I would like to say, though, that there is an opportunity cost, in the sunlight that will be denied during the journey, and if the journey is tens of thousands of years long, that's not meaningless. But it can certainly be made up for by not having to compete for resources at the new star.


Again, there is no model where an interstellar spacecraft is free. My point is that this cost could make the launch of such craft not feasible. This is a plausible possible explanation for Fermi's Paradox. Therefore Fermi's Paradox does not point to the conclusion that there are no ETIs. I think you missed the part where he explained what he means by free interstellar craft. Again, he's suggesting choosing an appropriate body for doing something that we'd already be doing anyway (living in space) such that it happened to intersect another star. As we don't have to do any of the acceleration/deceleration, the interstellar travel part of the cost is free. The other costs are costs that would have been born by any space colony anyway, which is what he means by saying that there are no incremental costs.

I again agree that this is a meaningful point, but as I said, I do think that the opportunity costs are meaningful and it's conceivable that people simply won't choose to do interstellar travel if it means being away from your main power source for tens of thousands of years. It's also likely that any such advanced civilization will be very interdependent, the costs of being separated from that civilization and it's products will also be prohibitive.
The degree to which either of those objections are meaningful, though... well, I'm not confident that it's enough to argue that we won't go interstellar, but personally I think we very likely will. :P

Yes, and I indicated that I understood your intent, even though what you said wasn't that. (You said humans have never made a collective decision, which isn't true. And, in the context, that's really what we're talking about. A large investment would require a collective decision, but not necessarily a unanimous one.) Look back at the context, he said that in response to the suggestion that humans would make a conscious choice not to go interstellar for moral reasons. All it takes is a few people disagreeing to change that.
He's not saying that interstellar travel requires a unanimous decision, he's saying that purposely not doing interstellar travel for a cultural or moral reason requires a unanimous decision, and that such unanimous decisions are not things humans do.

[Roboramma]

We may never achieve interstellar travel at all. We may go extinct or our civilization collapse before that is possible.
While I agree with this, I don't think it works here because if this is the general case, it means that technological civilizations last a very short time, and thus at any particular point in time (like now) there are unlikely to be more than one.

Or we may continue on but find that interstellar travel never becomes economically feasible.
This I agree with in principle. Though personally I think it likely that it will become economically feasible, anyone who thinks that's certain is fooling themselves.

Or it could be feasible, for whatever reason we may not be motivated to do it. (These are all points I've made before, which is why your post about how recently we started experimenting with rockets--it's Werner Von Braun--does nothing to bolster your argument. It still relies on assumptions we don't know to be true.) I'd like to point out that this is a rather meaningful point as well. In particular as our advancing technology effects us culturally the drive to procreate, the need for ever more resources, etc. may simply no longer be there, and thus the drive to move to other stars may disappear as well. Again I think anyone who suggests that they know what humans 1000 years from now will want is fooling themselves.

[Roboramma]

In reference to the Fermi Paradox I also think we need to consider what we mean by technological civilization. Our technology is advancing exponentially, but that doesn't have to be the case. Homo Erectus had technology at the hand ax level that didn't advance for millions of years. (I think it's homo erectus, anyway, one of our ancestors. After the technology had advanced, very slowly, for a long time, its was steady for a long time, then modern humans came along and started making different hand axes, and soon after, even better ones, etc.)

Could the same sort of very slow technological advance lead to an agricultural or even industrial civilization? Could a species be extremely good at figuring out how to use other organisms as tools (ie. through artificial selection using the biological products of other organisms as tools), but not be good at doing physics, for instance?
I don't know that that sort of technological civilization is likely to be more rare than our own, but it would fit my definition of ETI.

For this and many more reasons I still agree with Joe that the evidence simply isn't strong enough one way or the other and the only conclusion at this point is that we don't know.

I do think, though, that in the future we will have more and more evidence and at some point, whether we make contact or not, we may be able to say one way or the other. Not yet, though.

[JoeTheJuggler]

I think you missed the part where he explained what he means by free interstellar craft.
I didn't miss it. He said that the incremental costs (as you say, the cost beyond the humongous cost of building a colony) might be zero. See below:

I again agree that this is a meaningful point, but as I said, I do think that the opportunity costs are meaningful and it's conceivable that people simply won't choose to do interstellar travel if it means being away from your main power source for tens of thousands of years.
Which is exactly why I said there's no such thing as a free lunch spacecraft.

That saying is invoked to address opportunity costs. (Even if someone pays for your lunch, it's still not really free to you.) (ETA: We don't know what economic considerations there might be. It is possible that such a project never becomes economically feasible.)

The degree to which either of those objections are meaningful, though... well, I'm not confident that it's enough to argue that we won't go interstellar, but personally I think we very likely will. :P
All I'm arguing is that it's not inevitable that we will achieve interstellar travel or that any other ETIs that may or may not exist will necessarily have achieved whatever it takes to make evidence of their existence ubiquitous in the galaxy before we came along to notice that evidence wasn't there.


Look back at the context, he said that in response to the suggestion that humans would make a conscious choice not to go interstellar for moral reasons. All it takes is a few people disagreeing to change that.
He's not saying that interstellar travel requires a unanimous decision, he's saying that purposely not doing interstellar travel for a cultural or moral reason requires a unanimous decision, and that such unanimous decisions are not things humans do.
And I pointed out that the argument he is defending requires a lot more than not making a unanimous decision not to travel. He clearly implied that if we do not make such a decision, we will certainly achieve interstellar travel. That simply doesn't follow.

Again, I'm not arguing that we will not achieve interstellar travel. I'm also not arguing that it's impossible for an intelligent civilization to make colonize the galaxy (or otherwise make evidence of their existence ubiquitous throughout the galaxy). I'm just arguing that it's not inevitable, and the lack of evidence that it has happened does not argue for the non-existence of ETIs.

[JoeTheJuggler]

While I agree with this, I don't think it works here because if this is the general case, it means that technological civilizations last a very short time, and thus at any particular point in time (like now) there are unlikely to be more than one.
No--it's just saying it may be possible that no civilization lasts long enough to achieve interstellar travel (or whatever it takes to make evidence of their existence ubiquitous in the universe). There may be quite many civilizations.




This I agree with in principle. Though personally I think it likely that it will become economically feasible, anyone who thinks that's certain is fooling themselves.
And that's exactly the point I've been making. The argument that amb put forth is that Fermi's Paradox can only be explained by the non-existence of ETIs. I've been pointing out that that conclusion depends on a great many assumptions that may be summarized as the assumption that if any ETIs exists that they must certainly have made evidence of themselves ubiquitous in the galaxy.


I'd like to point out that this is a rather meaningful point as well. In particular as our advancing technology effects us culturally the drive to procreate, the need for ever more resources, etc. may simply no longer be there, and thus the drive to move to other stars may disappear as well. Again I think anyone who suggests that they know what humans 1000 years from now will want is fooling themselves.
Thanks. And it's one of the points on my numbered list that none of my detractors have yet addressed--not even once.

Exactly. Even if the technology is possible, and a civilization lasts long enough to develop that technology, and it's economically feasible to use, it could be that a civilization lacks the motivation to use it. We simply don't know.

And the argument that the lack of evidence at this point means that ETIs don't exist is based on the assumption that we know with certainty.

[RecoveringYuppy]

I think it's a good point, actually. Some comets and other bodies that come close to earth may have interstellar trajectories that intersect other stars.

And the stars themselves are in motion. Over immense time periods there are going to be close approaches.

I would like to say, though, that there is an opportunity cost, in the sunlight that will be denied during the journey, and if the journey is tens of thousands of years long, that's not meaningless.

But even that doesn't have to be a cost to interstellar migration. If some colonies have artificial sources of light and power because they are mining the Oort cloud then that won't be an incremental cost caused by them embarking on an interstellar journey. Migration may come as a side effect of other activities without ever even being an explicit intent to migrate.


This I agree with in principle. Though personally I think it likely that it will become economically feasible, anyone who thinks that's certain is fooling themselves.
Firstly, I'm not so sure about that. We're doing more and more of it now. It's becoming cheaper as we do it. And there's a very strong case that simply getting up 90 miles is the most expensive part. What does it cost to get up to orbit 90 miles above the planet? How much more do you spend to go the next billion miles to the outer planets?

We've already developed plausible plans for building a self sufficient colony in space. If we do that we are going to be living in a solar system where some people find it cheaper to go almost anywhere in the solar system except for the surface of planets, including returning to Earth. That's going to change things.

Secondly, even if it's economically prohibitive for some races to explore the galaxy is it going to be so for all of them? All races will be born in circumstances that make it expensive? Not one of them ever arises on a planet with lower escape velocities? None of them ever have a satellite that's more amenable to colonization? None of them are ever closer to a neighboring star?


And I pointed out that the argument he is defending requires a lot more than not making a unanimous decision not to travel. He clearly implied that if we do not make such a decision, we will certainly achieve interstellar travel. That simply doesn't follow.
I didn't imply that. I meant it exactly the way Roborama just explained it to you.

Look back at the context, he said that in response to the suggestion that humans would make a conscious choice not to go interstellar for moral reasons. All it takes is a few people disagreeing to change that.
He's not saying that interstellar travel requires a unanimous decision, he's saying that purposely not doing interstellar travel for a cultural or moral reason requires a unanimous decision, and that such unanimous decisions are not things humans do.

[JoeTheJuggler]

But even that doesn't have to be a cost to interstellar migration. If some colonies have artificial sources of light and power because they are mining the Oort cloud then that won't be an incremental cost caused by them embarking on an interstellar journey. Migration may come as a side effect of other activities without ever even being an explicit intent to migrate.
How are those things not costs?

At any rate, the argument depends on more than "may" or "might be".

It is still possible that interstellar spacecraft never become economically feasible. In other words, there are explanations for Fermi's Paradox other than that ETIs don't exist.


What does it cost to get up to orbit 90 miles above the planet?
Quite a lot.
How much more do you spend to go the next billion miles to the outer planets?
More than it costs to get up to orbit 90 miles and not go the next billion miles. The former is a subset of the latter.

We've already developed plausible plans for building a self sufficient colony in space. If we do that we are going to be living in a solar system where some people find it cheaper to go almost anywhere in the solar system except for the surface of planets, including returning to Earth. That's going to change things.
Yes, that's the one thing about the future we do know--things will change. But we don't know how.

Secondly, even if it's economically prohibitive for some races to explore the galaxy is it going to be so for all of them?
I am not claiming proof that it is, merely that it's a possibility. Yes, it is possible that civilizations don't last long enough to achieve interstellar travel. It's possible that they last long enough but that it's never economically feasible. It's possible that it's at least sometimes economically feasible, but that no ETI is ever motivated to do it (or to do it to the extent that evidence of their existence is ubiquitous in the galaxy).

All races will be born in circumstances that make it expensive? Not one of them ever arises on a planet with lower escape velocities? None of them ever have a satellite that's more amenable to colonization? None of them are ever closer to a neighboring star?
Most of these questions aren't relevant, but yes, all those things are possible.

Living on a planet with lower escape velocity, having a satellite that's amenable to colonization, being nearer to the next star would still not make the ubiquitous evidence of such a civilization


I didn't imply that. I meant it exactly the way Roborama just explained it to you.
In that case, it's irrelevant. You certainly made it sound like you were countering my argument. (I'm not sure who raised the moral objection idea, but yes, it is possible that a civilization has a unanimous moral objection to colonizing the galaxy. My point was the more general idea that it could be, for reasons we don't know or can't conceive of at this point, that while such advanced civilizations might be able to do whatever it takes to make evidence of their existence ubiquitous in the galaxy, they will lack the motivation to do so.)

[A. Zaitsev]

NewScientist Magazine, No 2744 (23 Jan 2010)

Cover
www()newscientist()com/currentcover()jpg

and three articles are about Interstellar Radio Messages to ETIs:

Exolanguage: do you speak alien?
www()newscientist()com/article/mg20527441.300-exolanguage-do-you-speak-alien.html

Earth calling: A short history of radio messages to ET
www()newscientist()com/article/dn18417-earth-calling-a-short-history-of-radio-messages-to-et.html

Hello ET, we come in peace
www()newscientist()com/article/mg20527442.600-hello-et-we-come-in-peace.html

[JoeTheJuggler]

For convenience (active links):

NewScientist Magazine, No 2744 (23 Jan 2010)

Cover
www.newscientist.com/currentcover.jpg

and three articles are about Interstellar Radio Messages to ETIs:

Exolanguage: do you speak alien?
www.newscientist.com/article/mg20527441.300-exolanguage-do-you-speak-alien.html

Earth calling: A short history of radio messages to ET
www.newscientist.com/article/dn18417-earth-calling-a-short-history-of-radio-messages-to-et.html

Hello ET, we come in peace
www.newscientist.com/article/mg20527442.600-hello-et-we-come-in-peace.html

[amb]

We have been sending messages into space for around fifty years now. What it means is that if there are beings of some kind out there remotely like us, they are at least further away than 25 light years. We really have a long way to go before we know for sure whether ''are we alone?''

[A. Zaitsev]

We have been sending messages into space for around fifty years now. What it means is that if there are beings of some kind out there remotely like us, they are at least further away than 25 light years. We really have a long way to go before we know for sure whether ''are we alone?'' First IRM = Interstellar Radio Message was sent in 1974, that is 2010-1974=36 yeasrs ago, only...

Also, please read: Calculations show that, at an interplanetary distance,
we can discover an intelligence with a
level of development that is similar to that of
Earth’s civilization. We can make this discovery
without transmission of special radio signals by
extraterrestrial intelligence, by only the radio
emission of various radio devices. However, we
cannot discover such intelligence at distances
starting from the nearest star.

Thus, in order to discover intelligence situated
near a certain star via measurements in a radiofrequency
band, this intelligence should use
radio transmitters that are significantly more
powerful than those used on the Earth (while it is
not clear for which needs this increased power
could be required) or this intelligence should
radiate special signals that are intended to make
its presence known.

Quote from:

docs()google()com/fileview?id=0B3dfv8xNOu48OTZmNTdlODAtODFiNi00MmQ2L WJjOTAtZDE1OTBkNjMzOGE0&hl=en

[LarianLeQuella]

We have been sending messages into space for around fifty years now. What it means is that if there are beings of some kind out there remotely like us, they are at least further away than 25 light years. We really have a long way to go before we know for sure whether ''are we alone?''

For some reason, maybe AMB thinks the inverse square law doesn't apply to omnidirectional signals? Our own civilization is virtually undetectable with our best technology beyond the orbit of Pluto. Of course, this has been pointed out ad nauseum...

The signals Dr. Zaitsev points out are focused signals, and as best as I can tell, none of them have even brushed by any solar systems that may be in their way. So for all intents and purposes, our civilization has sent out exactly zero signals that are receivable by anyone at this moment.

And Dr. Z's link: http://docs.google.com/fileview?id=0B3dfv8xNOu48OTZmNTdlODAtODFiNi00MmQ2L %20WJjOTAtZDE1OTBkNjMzOGE0&hl=en

[JoeTheJuggler]

We have been sending messages into space for around fifty years now. What it means is that if there are beings of some kind out there remotely like us, they are at least further away than 25 light years.
Not really. Our broadcast signals (like TV) would be undetectable beyond our solar system, and these other signals are narrow beams directed at specific targets. Also, even if a signal were received, you need to allow time for a reply. And that's making the assumption that an ETI that receives a signal will necessarily reply. (There's a movement here on Earth that says we shouldn't reply if we receive a signal.)

Even so, the volume of space of a radius 25 l.y. is a teeny-tiny part of the volume of the galaxy.

We really have a long way to go before we know for sure whether ''are we alone?''
Yes. That's pretty much what I've been saying all along. At best it's premature to claim that we are alone.

At worst, as with your argument based on Fermi's Paradox, it's illogical.

[amb]

I found this video very interesting and thought provoking. If you have a half hour to kill, watch it.
http://www.veoh.com/collection/SpaceTV/watch/v455817CbpAAc78