Expanding Universe and the Red Shift

[ynot]

The expanding universe concept is usually presented as the main evidence to support the validity of The Big Bang Theory. Or at least it gives great weight to the Theory. Personally, I don’t support in the Big Bang Theory regardless of whether or not the universe is expanding (but would be more likely to if it indeed is).

That an expanding universe would cause a “red shift” in distant stars makes perfect sense to me so there is no problem there. I guess the main concern I have is that that an observable effect of an expanding universe should be that distant stars would be fading out and disappearing (maybe this is happening and I’m simply ignorant of the fact). The Hubble telescope was aimed at a “blank“ area of space and set with a long exposure. Surprise, surprise, it was found that the “blank” space in fact contained a wealth of galaxies etc. So it is possible for things to move beyond our current view.

I believe that there are possible alternatives to the concept that an expanding universe causes the “red shift and offer a few below“. Will try to keep things brief.

Cosmic Sunset - I don’t believe this one is very likely, but throw it in anyway. When there are a lot of dust or smoke particles in the atmosphere you get a lovely orange/red sunset. Perhaps space contains a type of “space dust” that causes an observable reddening effect of distant stars. The greater the distance, the greater the effect.

Degrading Light - Perhaps light degrades as it travels over great distances and the infrared end of the spectrum simply survives the longest.

Multi-Speed Light - This is my favoured concept. Perhaps different parts of the light spectrum travel at different speeds, and the infrared end of the spectrum travels faster than the ultraviolet. If this were so, it would cause a “red shift” effect. The greater the distance, the greater the effect.

I’m not an academic so hope my half-baked ideas aren’t too simplistically naïve. If you’re not rolling around the floor with laughter, I would appreciate any feedback anyone cares to offer.

[KingMerv00]

The expanding universe concept is usually presented as the main evidence to support the validity of The Big Bang Theory. Or at least it gives great weight to the Theory. Personally, I don’t support in the Big Bang Theory regardless of whether or not the universe is expanding (but would be more likely to if it indeed is).

That an expanding universe would cause a “red shift” in distant stars makes perfect sense to me so there is no problem there. I guess the main concern I have is that that an observable effect of an expanding universe should be that distant stars would be fading out and disappearing (maybe this is happening and I’m simply ignorant of the fact). The Hubble telescope was aimed at a “blank“ area of space and set with a long exposure. Surprise, surprise, it was found that the “blank” space in fact contained a wealth of galaxies etc. So it is possible for things to move beyond our current view.

I believe that there are possible alternatives to the concept that an expanding universe causes the “red shift and offer a few below“. Will try to keep things brief.

Cosmic Sunset - I don’t believe this one is very likely, but throw it in anyway. When there are a lot of dust or smoke particles in the atmosphere you get a lovely orange/red sunset. Perhaps space contains a type of “space dust” that causes an observable reddening effect of distant stars. The greater the distance, the greater the effect.

Degrading Light - Perhaps light degrades as it travels over great distances and the infrared end of the spectrum simply survives the longest.

Multi-Speed Light - This is my favoured concept. Perhaps different parts of the light spectrum travel at different speeds, and the infrared end of the spectrum travels faster than the ultraviolet. If this were so, it would cause a “red shift” effect. The greater the distance, the greater the effect.

I’m not an academic so hope my half-baked ideas aren’t too simplistically naïve. If you’re not rolling around the floor with laughter, I would appreciate any feedback anyone cares to offer.


Actually my answer is the same to all three:

Not all stars/galaxies are red shifting, only the majority. Some are blue shifting towards us. This is to be expected because some stars/galaxies may be under the influence of other forces like gravity. All three hypothesis above fail to explain the existance of any blue shift.


I now have a question for the forum in general:

Has anyone measured rotating galaxies for the red shift? The portions of a galaxy rotating away from us should be more red shifted than the portions rotating towards us. Can we measure the red shift this precisely? If so, it would pretty much prove that the shifts are caused by movement.

[Dragon]

ynot,

Have a look at this wikipedia article (http://en.wikipedia.org/wiki/Redshift) on the redshift. It should make you understand why all three of your ideas are non-starters. For instance the diagram on the right shows how the whole spectrum of a distant star is redshifted, red bits, blue bits, blank bits, the lot.

[KingMerv00]

I now have a question for the forum in general:

Has anyone measured rotating galaxies for the red shift? The portions of a galaxy rotating away from us should be more red shifted than the portions rotating towards us. Can we measure the red shift this precisely? If so, it would pretty much prove that the shifts are caused by movement.

I looked it up, so I guess I'll answer my own question.

From our good friends at wikipedia (http://en.wikipedia.org/wiki/Redshift):

Redshifts have also been used to measure the velocity of gas of interstellar clouds (http://en.wikipedia.org/wiki/Interstellar_clouds), the rotation of galaxies (http://en.wikipedia.org/wiki/Galaxy_rotation_problem), and the dynamics (http://en.wikipedia.org/wiki/Dynamics) of accretion (http://en.wikipedia.org/wiki/Accretion_theory) onto neutron stars (http://en.wikipedia.org/wiki/Neutron_star) and black holes (http://en.wikipedia.org/wiki/Black_hole) which exhibit both Doppler and gravitational redshifts.

Emphasis mine.

Check out the link. It helps alot.

[KingMerv00]

ynot,

Have a look at this wikipedia article (http://en.wikipedia.org/wiki/Redshift) on the redshift. It should make you understand why all three of your ideas are non-starters. For instance the diagram on the right shows how the whole spectrum of a distant star is redshifted, red bits, blue bits, blank bits, the lot.

NO! It was MY link! Mine!

[KingMerv00]

ynot,

Just thought I say that all of your questions were reasonable. You don't have to label yourself "naive" or call your ideas "half-baked" just because they aren't in the majority. Doubt is very healthy.

Heck, I just learned that astronomers have this red shift measurement down more accurately than I had thought before. Yay for me.

[CurtC]

[FONT=Verdana][SIZE=2]...regardless of whether or not the universe is expanding...The universe is undoubtedly expanding.
I guess the main concern I have is that that an observable effect of an expanding universe should be that distant stars would be fading out and disappearing (maybe this is happening and I’m simply ignorant of the fact).I don't understand your reasoning here. Fading out and disappearing? You mean getting more and more dim because they are now farther away? If that's what you're saying, then I guess if you lived for a few hundred million years and compared how bright the stars are now versus when you were younger (if you have a good memory), then just maybe you might notice a difference. But in time spans less than that, such as our <80 years of making extra-galactic observations, the remote galaxies will be hardly at all further than they were 80 years ago. This reminds me of the janitor at a museum telling a visitor that a particular fossil is 15 million and 20 years old: "When I first started working here 20 years ago, they told me it was 15 million years old then."
The Hubble telescope was aimed at a “blank“ area of space and set with a long exposure. Surprise, surprise, it was found that the “blank” space in fact contained a wealth of galaxies etc. So it is possible for things to move beyond our current view.I don't see how your last sentence follows from the first two. Yes, there are galaxies every which way we look. What was that about moving beyond our current view?
Cosmic Sunset - I don’t believe this one is very likely, but throw it in anyway. When there are a lot of dust or smoke particles in the atmosphere you get a lovely orange/red sunset. Perhaps space contains a type of “space dust” that causes an observable reddening effect of distant stars. The greater the distance, the greater the effect.With the sunset, we start with a full spectrum of white light, and remove some of the blue light, so the remaining light tends to have more red photons. But with receding galaxies, the individual photons have been shifted down in frequency. There are speficic frequencies of light that stars emit, which can be measured extremely accurately, and are due to the nature of the sub-atomic processes that created a photon. Those specific frequencies are shifted down in frequency with distant galaxies, not just that the higher-frequency ones have been weeded out.
Degrading Light - Perhaps light degrades as it travels over great distances and the infrared end of the spectrum simply survives the longest.Again, this wouldn't explain the red shift I duscuss above.
Multi-Speed Light - This is my favoured concept. Perhaps different parts of the light spectrum travel at different speeds, and the infrared end of the spectrum travels faster than the ultraviolet. If this were so, it would cause a “red shift” effect. The greater the distance, the greater the effect.Well, we have a pretty good handle on the speed of light, plus even if infrared travels faster, we'd also by now be seeing the bluer colors, which even though they're younger, would still be getting to us in the right proportion. Plus, it doesn't explain the red shift as discussed above.

Sorry to burst your bubble, but the facts falsify your different hypotheses. If you can come up with others that fit the observed facts, that would be great. So far, no one has come up with anything other than the Big Bang/Inflation model that works.

[cbish]

Cosmic Sunset - I don’t believe this one is very likely, but throw it in anyway. When there are a lot of dust or smoke particles in the atmosphere you get a lovely orange/red sunset. Perhaps space contains a type of “space dust” that causes an observable reddening effect of distant stars. The greater the distance, the greater the effect.

Degrading Light - Perhaps light degrades as it travels over great distances and the infrared end of the spectrum simply survives the longest.

Multi-Speed Light - This is my favoured concept. Perhaps different parts of the light spectrum travel at different speeds, and the infrared end of the spectrum travels faster than the ultraviolet. If this were so, it would cause a “red shift” effect. The greater the distance, the greater the effect.


I'll simplify

1) And this cosmic dust would be what?
2) Degrading light. Any study or demonstration of this phenomena?
3) Multi-speed. See #2

[chipmunk stew]

ynot,

Just thought I say that all of your questions were reasonable. You don't have to label yourself "naive" or call your ideas "half-baked" just because they aren't in the majority. Doubt is very healthy.

Heck, I just learned that astronomers have this red shift measurement down more accurately than I had thought before. Yay for me.Also, a fine brainstorm of possible alternative explanations. Sometimes, the good ideas that don't bear out in reality are the most interesting ones to explore. You're doing what scientists do.

I had a lousy science program in high school. We studied almost exclusively correct hypotheses. We rarely formulated our own. This was the cram your head with facts philosophy of teaching. It would have been much more engaging and enlightening had we brainstormed possible alternative explanations and then explored their viability. Science is actually better at eliminating ideas than confirming them. You can often disprove a hypothesis absolutely, but you can never prove one absolutely.

[Dr. Fendetestas]

Has anyone measured rotating galaxies for the red shift? The portions of a galaxy rotating away from us should be more red shifted than the portions rotating towards us. Can we measure the red shift this precisely? If so, it would pretty much prove that the shifts are caused by movement.

Yes, it has been done. Actually, one of the secondary distance indicators is the Tully Fischer relation:

Light from galaxies has spectra formed by narrow lines. But, as you pointed out, if a galaxy rotates, part of it is coming towards us and part is getting away. This causes part of the light to be blue-shifted and part to be red-shifted. The net result is a broadening of the initially narrow lines. By measuring the spectra of these galaxies, we can infer their rotation speed from the width of the lines. The faster a galaxy spins, the bigger its luminosity is and from this we can estimate the distance (by comparing its luminosity to the brightness we perceive).

[bjb]

Wow, you guys didn't miss anything, even the redshift of a spinning galaxy! I would like to add further evidence for the Big Bang theory, the presence cosmic microwave background. The observation that the universe is expanding was made first and the Big Bang theory was developed to explain the expansion. Soon afterwards , some sort of cosmic background radiation was predicted to exist as an 'echo' of the big bang, but it was not measured until the 60's.

It's fine to come up with alternatives to accpeted theories, however, redshift and cosmic background radiation are real and measurable phenomenon, not theoretical abstractions, so your theory had better have a good explanation for them.

[Grounded]

<...snip...> Soon afterwards , some sort of cosmic background radiation was predicted to exist as an 'echo' of the big bang, but it was not measured until the 60's.
<snip>

What is this 'echo', and what did it reflect from. If the answer is other objects floating in space, it seems the 'signal' would be very small. Any references would be great!

[Art Vandelay]

[FONT=Verdana][SIZE=2] Cosmic Sunset - I don’t believe this one is very likely, but throw it in anyway. When there are a lot of dust or smoke particles in the atmosphere you get a lovely orange/red sunset. Perhaps space contains a type of “space dust” that causes an observable reddening effect of distant stars. The greater the distance, the greater the effect.The sun looks yellow because the blue part of the spectrum is scattered. Note that the blue doesn't disappear, it's just scattered. That's why the rest of the sky looks blue. If there were space dust scattering blue light, we should see a blue sky, even at night.

Multi-Speed Light - This is my favoured concept. Perhaps different parts of the light spectrum travel at different speeds, and the infrared end of the spectrum travels faster than the ultraviolet. If this were so, it would cause a “red shift” effect. The greater the distance, the greater the effect.If this were the case, the different parts of the spectrum wouldn't synch up. If we see a star get eclipsed by a planet, we should see the red part of the spectrum eclipsed at a different time from when the blue part gets eclipsed.

Good brainstorming, though.

[KingMerv00]

What is this 'echo', and what did it reflect from. If the answer is other objects floating in space, it seems the 'signal' would be very small. Any references would be great!

"Echo" probably wasn't the right analogy. "Afterglow" is more appropriate. The CMBR is energy left over from the Big Bang and it is found everywhere with astonishing uniformity. I'll just give you the link since it will undoubtedly explain it better than I could.

http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation

[Melendwyr]

The universe undoubtedly has a redshift. It's not clear that it's actually expanding.

The Big Bang is the best explanation yet for the sum of evidence. That doesn't mean it's a good explanation...

[KingMerv00]

The universe undoubtedly has a redshift. It's not clear that it's actually expanding.

The Big Bang is the best explanation yet for the sum of evidence. That doesn't mean it's a good explanation...

I'd say it is a very reasonable one. I think you are being kind of harsh. Eh, who knows, maybe the red shift is a glitch in the matrix.

[Melendwyr]

Don't get me wrong, the expansion hypothesis explains Olbers' Paradox, the Cosmic Microwave Backround, the redshifting... it's just that it also requires some very, very odd assertions, among which is the idea that matter-energy is independent of the space it moves through.

If our meager exploration of space as taught us anything, it's that our ideas about the universe rarely survive close examination of the things we're speculating about. Our ability to draw conclusions about the structure of the universe as a whole is questionable.

[Grounded]

"Echo" probably wasn't the right analogy. "Afterglow" is more appropriate. The CMBR is energy left over from the Big Bang and it is found everywhere with astonishing uniformity. I'll just give you the link since it will undoubtedly explain it better than I could.

h_t_t_p://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation

Sorry if this is out of scope for this discussion.

It is curious to me that this microwave background is described as having density (only "5x10-5 of the total density of the universe"). Doesn't density imply mass? Can the expansion of the universe be quantified in real terms that even I could understand? Maybe this should be a separate thread - I don't want to hold anyone up.

Thanks for the link KingMerv00. I've got more homework to do.

[Grounded]

The universe undoubtedly has a redshift. It's not clear that it's actually expanding.

The Big Bang is the best explanation yet for the sum of evidence. That doesn't mean it's a good explanation...

Is there proof that the universe is cooling? If so, expansion is required - where/how else would the energy be dissipated.... (wait, fusion and intense gravity - that's it. The universe will become a huge black hole:eek: )

I'm serious about the cooling/expansion - I admit I got carried away in the parenthesis. It's hard to demonstrate emotion/joking on the keyboard.

[cbish]

The universe undoubtedly has a redshift. It's not clear that it's actually expanding.

The Big Bang is the best explanation yet for the sum of evidence. That doesn't mean it's a good explanation...

Go on! What would be?

[CurtC]

What is this 'echo', and what did it reflect from. If the answer is other objects floating in space, it seems the 'signal' would be very small.I'll take a stab at an understandable explanation. It takes light some amount of time to travel to us, right? So if we look at a galaxy that's 50 million light years away, we're seeing it as it was 50 million years ago. So looking out very far is looking back in time. If we see a really distant galaxy 10 billion light years away, we're seeing it as it was 10 billion years ago. Look past those, and you'll see whatever was there at the beginning of time. Those photons have been travelling 13.7 billion years, since the universe first cooled enough to allow photons to pass through, and are just now arriving at our instrument.

[PixyMisa]

The reason none of those explanations works is because of a misunderstanding of the term "red shift". Red shift doesn't mean the light becomes more red; it may do so, or it may become less red.

Red shift is the same thing as the Doppler Effect. You know how with train whistles and police sirens, they are higher pitched when they are approaching you and lower when they are moving away? Of course, the whistle doesn't change pitch just as it passes you.

Let's say the train's whistle is at 1000 cycles per second, and the train is moving towards you at 10 metres per second. It sounds its whistle when it is 100 metres away, and keeps sounding until it is 100 metres past. That takes 20 seconds in all.

But the speed of sound is about 330 metres per second. So the very first sound from the whistle takes about a third of a second to reach you. The first 10 seconds worth of whistle is squashed into 9.7 seconds - when the train is right beside you, the time taken for the sound to reach you is negligible.

And similarly, as the train moves away from you, it takes 10.3 seconds for all the sound to reach you until the whistle cuts off when the train is 100 metres away.

So in the as the train moves towards you, all the sound is shifted upwards in pitch by about 3%, to about 1031 cycles per second, and as it moves away the pitch drops by about 3%, to 971 cycles per second.

Now, here's the thing: If the train played a tune on its whistle rather than a constant tone, the same effect would apply to all the notes, and to the durations of the notes.

How does this apply to the Cosmological Red Shift? I'm glad you asked! :D

Light emitted by stars is neither a single pure frequency nor a perfect continuous spectrum. Every chemical element has a number of characteristic frequencies at which it can emit or absorb light - these frequencies depend on the number of electrons in the atoms. Here is a picture of part of the spectrum of our Sun (http://csep10.phys.utk.edu/astr162/lect/sun/spectrum.html).

These spectral lines are very useful because they let us detect what elements are present in a given star. They also provide a marker as to what frequency the light was originally emitted at, and allow us to tell if it has been shifted by the Doppler Effect.

So if we know of a set of lines that look like this:

RED || ||| | | || || || | | | ||| BLUE

And when we look at the visible light of a particular star, we see:

RED ||| | | || || || | | | ||| | | | BLUE

We can see that by sliding the spectrum of the star to the right, suddenly all the lines match up. That means that the light has been shifted redwards, what we call a "red shift".

The Cosmic Sunset won't do this; it just decreases the amount of blue light and increases the amount of red light.

Degrading Light won't do this either. We'd simply stop seeing the spectral lines at the blue end; the ones at the red end would remain in place.

Multi-Speed Light wouldn't do it. I don't see how multi-speed light would have any effect at all (in this situation).

One thing that works is the Doppler Effect.

Another is the "Tired Light" conjecture, which suggests that over very very long distances, light gradually loses energy. Unfortunately, that contradicts Relativity, Quantum Mechanics, and the First Law of Thermodynamics, so it's not taken very seriously.

[PixyMisa]

I'd say it is a very reasonable one. I think you are being kind of harsh. Eh, who knows, maybe the red shift is a glitch in the matrix.

It's fixed in 3.1.

[PixyMisa]

Which just struck me as a really good argument against the "the Universe is a simulation" idea. If the Universe was a simulation, we'd see all these glitches and discontinuities as patches were rolled out. Like Mercury would suddenly start following Newtonian mechanics instead of Relativity, and then would jump in its orbit when they fixed it.

[AnotherSillyAlias]

Which just struck me as a really good argument against the "the Universe is a simulation" idea. If the Universe was a simulation, we'd see all these glitches and discontinuities as patches were rolled out. Like Mercury would suddenly start following Newtonian mechanics instead of Relativity, and then would jump in its orbit when they fixed it.


Hmmm... this could explain the biblical flood story.

Way back in the simulation something went wrong and the Earth got covered in water. Obviously this was not supposed to happen so the programers had to do some hasty fiddling with the code and restart the whole thing. The Ark and it's inhabitants were simply templates for getting stuff going again.

I think the code needs a lot more fiddling!

[SpaceFluffer]

If our meager exploration of space as taught us anything, it's that our ideas about the universe rarely survive close examination of the things we're speculating about. Our ability to draw conclusions about the structure of the universe as a whole is questionable.Nahh, I think it's just your ability to draw conclusions that's questionable.

[ynot]

[quote=KingMerv00;1368692]Actually my answer is the same to all three:

Not all stars/galaxies are red shifting, only the majority. Some are blue shifting towards us. This is to be expected because some stars/galaxies may be under the influence of other forces like gravity. All three hypothesis above fail to explain the existance of any blue shift.
quote]
Obviously the universe is never totally static. I would have thought that a blue shift would be more difficult to explain in an expanding universe than a relatively static one. Especially given that an expanding universe creates the opposite of a blue shift (red shift). Surely whatever causes a blue shift in an expanding universe could also apply to relatively static one. If not, please why not.

[ynot]

ynot,

Just thought I say that all of your questions were reasonable. You don't have to label yourself "naive" or call your ideas "half-baked" just because they aren't in the majority. Doubt is very healthy.

Heck, I just learned that astronomers have this red shift measurement down more accurately than I had thought before. Yay for me.

Thanks - I think it is more my own opinion that the ideas I have submitted may be naïve and half-baked as they come more from a collection of random thoughts over many year rather than any form of researched scientific study.

[PixyMisa]

Obviously the universe is never totally static. I would have thought that a blue shift would be more difficult to explain in an expanding universe than a relatively static one. Especially given that an expanding universe creates the opposite of a blue shift (red shift). Surely whatever causes a blue shift in an expanding universe could also apply to relatively static one. If not, please why not.

We explain red shift by motion. If the object is moving away from us - as all really distant objects are, because the expansion of the Universe overwhelms their individual motion - then the light is red shifted. If the object is moving towards us, like some of the galaxies in our local group, then the light is blue shifted.

None of your three explanations allow for blue shift at all.

[ynot]

The universe is undoubtedly expanding.
I don't understand your reasoning here. Fading out and disappearing? You mean getting more and more dim because they are now farther away? If that's what you're saying, then I guess if you lived for a few hundred million years and compared how bright the stars are now versus when you were younger (if you have a good memory), then just maybe you might notice a difference. But in time spans less than that, such as our <80 years of making extra-galactic observations, the remote galaxies will be hardly at all further than they were 80 years ago. This reminds me of the janitor at a museum telling a visitor that a particular fossil is 15 million and 20 years old: "When I first started working here 20 years ago, they told me it was 15 million years old then."
I don't see how your last sentence follows from the first two. Yes, there are galaxies every which way we look. What was that about moving beyond our current view?

If something is constantly travelling away for me, I expect that it will end up being so far away that it will end up being out of my field of vision. Likewise, if the universe is constantly expanding and constantly travelling away, I would expect distant parts of it to travel out of my field of vision (not naked eye vision of course). Surely if the expansion is uniform and constant, very distant objects would be travelling away from my relative position at an ever accelerating and extremely rapid rate.

With the sunset, we start with a full spectrum of white light, and remove some of the blue light, so the remaining light tends to have more red photons. But with receding galaxies, the individual photons have been shifted down in frequency. There are speficic frequencies of light that stars emit, which can be measured extremely accurately, and are due to the nature of the sub-atomic processes that created a photon. Those specific frequencies are shifted down in frequency with distant galaxies, not just that the higher-frequency ones have been weeded out.
Again, this wouldn't explain the red shift I duscuss above.

I didn’t particularly like this one either.

Well, we have a pretty good handle on the speed of light, plus even if infrared travels faster, we'd also by now be seeing the bluer colors, which even though they're younger, would still be getting to us in the right proportion. Plus, it doesn't explain the red shift as discussed above.

It is not a matter of one eventually catching up with the other, it is the quantity delivered. I am suggesting that if the infrared was travelling faster than the ultraviolet and a greater quantity of infrared was reaching the retina, that the object emitting the light would appear more red in colour. If two conveyor belts that shared the same start and finish points were delivering a substance, wouldn’t one that was travelling twice the speed of the other deliver twice the amount of substance?

[ynot]

I'll simplify

1) And this cosmic dust would be what?
2) Degrading light. Any study or demonstration of this phenomena?
3) Multi-speed. See #2

1) Don't know. I was not trying to prove it, just suggest it.
2) After much internet searching I found http://www.talkorigins.org/indexcc/CE/CE425.html Tired light is new to me.
3) No. Do you know of any study or demonstration that disproves this suggestion?

[ynot]

Sorry to burst your bubble, but the facts falsify your different hypotheses. If you can come up with others that fit the observed facts, that would be great. So far, no one has come up with anything other than the Big Bang/Inflation model that works.
Sorry - Forgot to say - I didn't have a bubble - just some ideas

[ynot]

Also, a fine brainstorm of possible alternative explanations. Sometimes, the good ideas that don't bear out in reality are the most interesting ones to explore. You're doing what scientists do.

I had a lousy science program in high school. We studied almost exclusively correct hypotheses. We rarely formulated our own. This was the cram your head with facts philosophy of teaching. It would have been much more engaging and enlightening had we brainstormed possible alternative explanations and then explored their viability. Science is actually better at eliminating ideas than confirming them. You can often disprove a hypothesis absolutely, but you can never prove one absolutely.
Thanks for your kind words - You think you had it bad? You only had a lousy program. I had a lousy School. (is that a Monty Python skit I here?). It was so bad I left the education system at age 14. And have been trying to educate myself ever since.

[ynot]

Thanks

The sun looks yellow because the blue part of the spectrum is scattered. Note that the blue doesn't disappear, it's just scattered. That's why the rest of the sky looks blue. If there were space dust scattering blue light, we should see a blue sky, even at night.
I didn't mean to say the process was the same (or even similar) as it is in a sunset. I was simply suggesting that there might be something (anything) in space that effects light so that when the light is observed after having travelled a great distance, it appears red.

If this were the case, the different parts of the spectrum wouldn't synch up. If we see a star get eclipsed by a planet, we should see the red part of the spectrum eclipsed at a different time from when the blue part gets eclipsed.
I am only suggesting a relatively small difference in speed so the effect would only be apparent over immense distances.

[ynot]

The universe undoubtedly has a redshift. It's not clear that it's actually expanding.

The Big Bang is the best explanation yet for the sum of evidence. That doesn't mean it's a good explanation...
The light at the end of the tunnel may not be a train after all!

[PixyMisa]

It is not a matter of one eventually catching up with the other, it is the quantity delivered. I am suggesting that if the infrared was travelling faster than the ultraviolet and a greater quantity of infrared was reaching the retina that the object emitting the light would appear more red in colour.

1. That's not what would happen.
2. That's not what we see.
3. That's not what "red shift" means.

If two conveyor belts that shared the same start and finish points were delivering a substance, wouldn’t one that was travelling twice the speed of the other deliver twice the amount of substance?

No.

[PixyMisa]

I didn't mean to say the process was the same (or even similar) as it is in a sunset. I was simply suggesting that there might be something (anything) in space that effects light so that when the light is observed after having travelled a great distance, it appears red.

Well, the light doesn't appear red, so this is kind of pointless. The spectrum as a whole is shifted towards lower frequencies, which is entirely different.

[ynot]

Thought I would thank everyone for the contributions. I really get a buzz from this stuff but unfortunately I’m not able to spend much time on the forum (too busy - self employed and the boss is a slave driver).

I don't mean to be confrontational in saying this but sometimes I wonder if some of you respond to threads from an almost dogmatic belief position. “I know this, and this doesn’t agree with that, so that is wrong”. It’s always easier to accept a new idea if it supports a currently held idea. This applies equally to myself as well of course and is in no way mean to relate to replies to my post. In fact I have been impressed with the quality of response and will learn heaps from it - Thanks again.

[PixyMisa]

I don't mean to be confrontational in saying this but sometimes I wonder if some of you respond to threads from an almost dogmatic belief position. “I know this, and this doesn’t agree with that, so that is wrong”.

It's not a question of dogma, it's a question of your conjectures not matching observed facts - including the fact of red shift, which is the whole reason you proposed them in the first place.

None of the three mechanisms you suggested would produce red shift. That is the problem.

[ynot]

It's not a question of dogma, it's a question of your conjectures not matching observed facts - including the fact of red shift, which is the whole reason you proposed them in the first place.

None of the three mechanisms you suggested would produce red shift. That is the problem.
Thanks to the replies, I now have a better understanding of the expanding universe/red shift (but not by any means complete of course) and agree with your comment above. I havn't given up on chalenging the validity of the issue however - I would like to revisit the point I was trying to make with conveyor belt question so will phrase it differently in the hope of getting a yes answer . . .

There are two machine guns. One fires 100 rounds per second and the other fires 200 rounds per second. If both are fired at a target for one second, would one gun fire twice as many bullets in to the target than the other?.

[Roboramma]

There are two machine guns. One fires 100 rounds per second and the other fires 200 rounds per second. If both are fired at a target for one second, would one gun fire twice as many bullets in to the target than the other?.

The analogy doesn't line up to light, though.

A machine gun firing twice as many rounds per second would be like a star giving off twice as many photons/second. Which isn't what you're suggesting. You're suggesting that one wavelength would travel faster than another.

You could phrase the question, "If there were two machine guns, both firing at the same rate, but one which fired bullets that traveled at speed X, and the other fired bullets at speed 2X, would the targets have the same number of impacts, or more?"
The answer is that while the first impact would come from the gun whose bullets travelled faster, after that the rate of impact would match up perfectly. So basically, no. The second guns bullets would be more spread out (in space, not time) on the way to the target, but you would have the same number of impacts/second. That number would be dependant not upon the speed of the bullets, but on the rate of fire.

Don't take my word for this, though, I think I'm right, but I just thought about this in my head, and could have made an error. Work through it yourself.

But as PixyMisa points out, I don't see what this has to do with redshift.

[Mojo]

There are two machine guns. One fires 100 rounds per second and the other fires 200 rounds per second. If both are fired at a target for one second, would one gun fire twice as many bullets in to the target than the other?.Well, yes, because you've stated in the question that one fires twice as many bullets in a given time than the other does.

But how is this at all relevant to red-shifted light?

ETA: Beaten to it...

[Roboramma]

Here's the thing, ynot. From what I know (which isn't much) redshift is perfectly explained by the Doppler affect.
No one has suggested any other mechanism that would shift the entire spectrum of light emitted from a distant body. But this is exactly what we would expect to see happening if that body is moving away from us.

You can't explain it by some of the light being left behind along the way, because we're not receiving less light than we would expect to(well, unless I misunderstand), it's just different wavelengths. But the weird thing is that those wavelengths all have a similar pattern to what we'd expect from that body- just slightly shifted toward red.

Of course there could be another explanation other than movement. But considering how well expansion explains the observations, it would have to be a very good one. Preferably one which made new predictions.

[KingMerv00]

Obviously the universe is never totally static. I would have thought that a blue shift would be more difficult to explain in an expanding universe than a relatively static one. Especially given that an expanding universe creates the opposite of a blue shift (red shift). Surely whatever causes a blue shift in an expanding universe could also apply to relatively static one. If not, please why not.


Well take a rotating galaxy for example. The part moving away from us would be red shifted,, the part moving towards us is blue shifted and the parts moving laterally to us wouldn't have either. This has been observed and shows that the spectrum shifts are caused by movement.

Just because a galaxy as a whole is moving away from us does not mean that every portion of it is.

[KingMerv00]

If something is constantly travelling away for me, I expect that it will end up being so far away that it will end up being out of my field of vision. Likewise, if the universe is constantly expanding and constantly travelling away, I would expect distant parts of it to travel out of my field of vision (not naked eye vision of course). Surely if the expansion is uniform and constant, very distant objects would be travelling away from my relative position at an ever accelerating and extremely rapid rate.



I didn’t particularly like this one either.



It is not a matter of one eventually catching up with the other, it is the quantity delivered. I am suggesting that if the infrared was travelling faster than the ultraviolet and a greater quantity of infrared was reaching the retina, that the object emitting the light would appear more red in colour. If two conveyor belts that shared the same start and finish points were delivering a substance, wouldn’t one that was travelling twice the speed of the other deliver twice the amount of substance?


Your conveyor belt analogy isn't right. In order to see more lower spectrum (red) light, the star would have to emit more of it. Also, if the lower spectrum light traveled faster, it would appear disproportionately dimmer compared to the higher spectrum.

Why dimmer? Hmm...how do I explain this.

Ok you have two belts. One moving at rate X and the other moving at 2X. At the start of each, you have a guy who places a red photon on it at the rate of one per second. Now imagine you are at the end of each belt, what do you see?

The X belt's photons are coming of more densely packed than the 2X belt. Densely packed photons means more energy is striking your eye at any given moment, and therefore appears brighter. In order to appear just as bright as the X belt, the 2X belt guy would have to double his rate.

WARNING: NOT a cosmologist. I am but a mere chemist. I really don't know anything useful. I am willing to be corrected.

-----------------------------------------------------------------
Another thing to think about:

I plan on beating the rotating galaxy example to death, so bear with me.

Say we have two identical stars (sample spectum emitted, same size, etc) in the same galaxy that are both the same distance away from us. The only difference ... one rotate towards us and one rotates away. What would we expect to see?

In your theory, they would appear identical because they are both the same distance away.

In the Big Bang Theory, we would observe one red shifted and the other blue shifted.

We see the latter.

[KingMerv00]

I don't mean to be confrontational in saying this but sometimes I wonder if some of you respond to threads from an almost dogmatic belief position. “I know this, and this doesn’t agree with that, so that is wrong”. It’s always easier to accept a new idea if it supports a currently held idea. This applies equally to myself as well of course and is in no way mean to relate to replies to my post. In fact I have been impressed with the quality of response and will learn heaps from it - Thanks again.


I can see that some of the terse responses you have received may have seemed dogmatic to you. That really doesn't matter. All that matters is the evidence. Are they right or not?

Not to be confrontational (:D), but you seem overly worried that because the Big Bang seems to agree with one particular interpretation of the Bible. If it makes you feel any better, Genesis doesn't really fit with the BB all that well. The universe is too old, and the order of Creation is all screwed up.

[wollery]

Just as a point of order;

The vast, vast majority of stars that we can observe are within our own Milky Way Galaxy, and their positions and velocities relative to us are unaffected by the Universal expansion. Their redshifts or blueshifts are due to their orbits around the Galactic centre.

The few individual stars we can see outside the Milky way are almost all either Cepheid variables, in Local Group galaxies (such as Andromeda) and nearby galaxies, or novae or supernovae in other galaxies. These objects are all gravitationally bound to their parent galaxies and are therefore subject to the same redshift as their parent galaxy.

Talking about the redshift/blueshift of stars as regards Universal expansion is thus redundant.

Doppler shift (ie velocity) is the only workable explanation for galactic redshifts that I know of (see PixyMisa's excellent first post for an elegant description of why that is), and having spent several years working in an astrophysics research institute staffed largely by cosmologists and extragalactic astronomers I feel fairly certain that I would have heard of any viable alternatives.

The remarkably well constrained relationship between the redshifts and distances of galaxies leads to the almost inescapable conclusion that the Universe is expanding, and that this expansion is slowing down.

[KingMerv00]

...., and that this expansion is slowing down.

Really? I've heard numerous times that the expansion is accelerating.

[Melendwyr]

I hate to point this out, but the "Tired Light" hypothesis is actually a subset of the "Expanding Space" hypothesis. What, you thought the light started out red-shifted? What, you thought those distant objects were actually moving?

Guess again.

[KingMerv00]

I hate to point this out, but the "Tired Light" hypothesis is actually a subset of the "Expanding Space" hypothesis. What, you thought the light started out red-shifted? What, you thought those distant objects were actually moving?

Guess again.

Well "moving" is just the easiest way to picture an increase in distance over a period of time.

[SpaceFluffer]

Really? I've heard numerous times that the expansion is accelerating.It is - we have pretty strong evidence for a positive cosmological constant.

[Diamond]

A couple of things:

1. The speed of light is predicted as a constant regardless of relative motion or wavelength by Maxwell's equations of Electromagnetism.

2. The expansion of the Universe is predicted by Einstein's General Relativity theory (although strictly speaking it predicts that the Universe is either contracting or expanding but cannot be static). Einstein then added a cosmological constant to keep the Universe static (which is what was generally believed at the time). Georges LeMaitre proved that Einstein's Cosmological constant leads to a highly unstable equilibrium, which in turn would produce either a quick contraction or runaway expansion.

So we interpret the red shift of most galaxies as a Universal expansion. The Cosmic Microwave Background Radiation is the extremely red-shifted afterglow of the hot early Universe when it was ~300,000 years old (whatever that means).

[wollery]

Really? I've heard numerous times that the expansion is accelerating.Yeah, it's complicated by several factors, but for the vast majority of the Universe's history the expansion has been decelerating, hence the Hubble constant being pretty, well, constant at ~70km/s/Mpc (ie the further away something is the faster it's going and the further back in time it's light was emitted).

There is evidence to suggest that the rate of deceleration has dropped and that the expansion may actually be beginning to accelerate, but it's far from conclusive.

[wollery]

It is - we have pretty strong evidence for a positive cosmological constant.Ooh, nice plot, where's that from?

I have to admit, being a nearby stellar observer, I've not been keeping fully up to date on this stuff. I stand corrected.

Of course, evolution of type 1A supernova properties could throw a spanner in those works!

edited to correct speeling

[SpaceFluffer]

Understandable! The evidence for a positive cosmological constant comes from Type-1a Supernova in the range z=0.2-1.2 or thereabouts, which didn't come into it's own as a technique until the past 5-8 years.

However, the CMB provides an important cross-check on this, and there's enough evidence to support a positive cosmological constant without the SNe 1a evidence, since we know the matter density and total density to good precision on the basis of WMAP data alone.

The plot is from a paper by Saul Perlmutter, but doesn't show experimental data. It just shows the different histories that result when one changes the cosmological constant from negative to positive.

[CurtC]

The plot is from a paper by Saul Perlmutter, but doesn't show experimental data. It just shows the different histories that result when one changes the cosmological constant from negative to positive.I thought those little black dots, with error bars, were the experimental data. No?

[SpaceFluffer]

I'm sorry, you're quite right.

[I less than three logic]

Just to beat a dead horse. :D

Your explanations are interesting; however, they are built on a flawed interpretation of what red shift is. Any explanations geared toward explaining a false representation of the red shift will be easily and quickly explained away.

Red shift doesn’t mean we are getting more red light, or that even the stars look redder. In fact, if you follow what red shift means we get (at least see) less red light, the light that started as red light has been stretched to a slightly longer wavelength and is now infrared and beyond our visible spectrum. Orange light has been stretched to red, yellow to orange, blue to green, and so on. Also, the ultraviolet, which was slightly too small to be seen before, has now been stretched a bit and fills the violet light spectrum we’re used to seeing and completes the full spectrum white light we see the stars as.

The next logical question is; if the light is still white, how do we tell there has been a red shift. For this we have to use spectroscopy. Every element (such as hydrogen, oxygen, iron, gold, etc) gives specific bands of light when heated to the glowing point, or in the case of stars, absorb specific bands of light when pure white light is shown thru it. This is very consistent, and we are very good at lining up the lines to identify the element. The red shift was kind of discovered by accident. When they went to identify the elements of different stars the lines didn’t line up, but if they moved the expected lines towards the red side of the spectrum they lined up again. This combined with the idea of the Doppler Effect, suggests that the distance between the source of the light and us is increasing.

Few links:
http://en.wikipedia.org/wiki/Redshift
http://en.wikipedia.org/wiki/Spectroscopy
http://www.astro.ucla.edu/~wright/doppler.htm
http://coolcosmos.ipac.caltech.edu/cosmic_classroom/cosmic_reference/redshift.html

[ynot]

I simply don’t have time to respond to all the replies but thanks for them all (very helpful). The “penny has dropped” (like it when that happens) regarding exactly what the red shift is so can now better understand the error of my ways. The dead horse can now be buried.

I still have some Big Bang itches to scratch though - If the universe is constantly expanding what area is it expanding in to? Is it occupying a space that was formally nothing? If so, what is nothing. It would have to be absolute nothing, not relative nothing. It is difficult for me to accept the concept that the universe has an outer edge let alone that it is expanding in to a space that was formerly absolute nothing. How can absolute nothing exists?

[KingMerv00]

I simply don’t have time to respond to all the replies but thanks for them all (very helpful). The “penny has dropped” (like it when that happens) regarding exactly what the red shift is so can now better understand the error of my ways. The dead horse can now be buried.

:dig:

I still have some Big Bang itches to scratch though - If the universe is constantly expanding what area is it expanding in to? Is it occupying a space that was formally nothing? If so, what is nothing. It would have to be absolute nothing, not relative nothing. It is difficult for me to accept the concept that the universe has an outer edge let alone that it is expanding in to a space that was formerly absolute nothing. How can absolute nothing exists?


Well, I'll try my best to answer some of these later.

Here is a question for you though: Why would it be so hard to imagine an edge to the universe? Why is an infinite universe any easier?

(The universe doesn't have an edge as far as we know. I'm only asking because it is important to remember that unbelievable does not mean untrue.)

[PixyMisa]

I hate to point this out, but the "Tired Light" hypothesis is actually a subset of the "Expanding Space" hypothesis.

I hate to point this out, but no it isn't.

Tired light is an explanation for cosmological red shift in a static Universe. (Clearly it's not needed in an expanding Universe.) It claims that red shift is produced by distance rather than relative motion. This is both impossible and wrong. (http://www.astro.ucla.edu/~wright/tiredlit.htm)

[ynot]

[/size][/font]

[font=Verdana][size=2]:dig:



Well, I'll try my best to answer some of these later.

Here is a question for you though: Why would it be so hard to imagine an edge to the universe? Why is an infinite universe any easier?

(The universe doesn't have an edge as far as we know. I'm only asking because it is important to remember that unbelievable does not mean untrue.)

Oh Dear - No my head really hurts! -

A thing is expanding but it doesn't have any edge to define its size? You seem to be able to consturct clear explainations so I await with interest.

It is easier for me to accept the concept of infinity rather than an edge that has something that is nothing beyond it (hope that makes some form of sense).

[Melendwyr]

I hate to point this out, but no it isn't. Wrong.

Tired light is an explanation for cosmological red shift in a static Universe. (Clearly it's not needed in an expanding Universe.) It claims that red shift is produced by distance rather than relative motion. This is both impossible and wrong. (http://www.astro.ucla.edu/~wright/tiredlit.htm) There is no "relative motion" in the expanding universe hypothesis. However, as light travels, extra space keeps popping up in between one crest and another. The net result is that the longer light travels, the greater its wavelength and the less energy it contains.

Whether you claim that light vibrates more slowly in itself, or that the expansion of space stretches out the vibration, the effect is the same.

[Art Vandelay]

Which just struck me as a really good argument against the "the Universe is a simulation" idea. If the Universe was a simulation, we'd see all these glitches and discontinuities as patches were rolled out. Like Mercury would suddenly start following Newtonian mechanics instead of Relativity, and then would jump in its orbit when they fixed it.Don't be silly. Every time there's an upgrade, all memories of events before the upgrade are also modified.

Yeah, it's complicated by several factors, but for the vast majority of the Universe's history the expansion has been decelerating, hence the Hubble constant being pretty, well, constant at ~70km/s/Mpc (ie the further away something is the faster it's going and the further back in time it's light was emitted). Seems to me that the dimension of the Hubble Constant is frequency. 70 km/s/Mpc works out to be about 2*10^-18 hertz, right? For light, that corresponds to a wavelength of about 6*10^26 meters. So galaxies further than that would be traveling faster than light?

How constant is the Hubble Constant across time? Across space?

I think that that the popular presentation of Hubble Expansion is a bit misleading, since it has to be more complicated than just stuff moving away from each other like in the balloon analogy. Because of relativity, each point must see a different "balloon".

KingMerv00Here is a question for you though: Why would it be so hard to imagine an edge to the universe? Why is an infinite universe any easier?
How would it have an edge? What would the edge be made out of? What happens if you hit it?

[Melendwyr]

No, no galaxies ever travel faster than light. Extra space is popping up between them and us faster than their light can reach us... so we never see it.

[PixyMisa]

Wrong.

Wrong.

There is no "relative motion" in the expanding universe hypothesis.

Sure there is. Distant galaxies really are moving away from us. The source of that movement is the expansion of the Universe, but the movement is real.

The problem with "tired light" is that it (a) it contravenes the First Law of Thermodynamics (it is impossible) and Quantum Mechanics (it is impossible) and it makes predictions which are not borne out by evidence (it is wrong). See the link I provided you for a fuller explanation.

It's not a restatement of the Doppler Effect, it's just plain wrong.

[PixyMisa]

Anyway, my point was not the fine distinction between relative motion and an expanding universe.

My point was that the tired light conjecture does not produce the same predictions as expansion-induced red shift.

[PixyMisa]

What's more, distant objects act in other ways as though they were moving relative to us. For example, supernova explosions in distant galaxies exhibit time dilation exactly as you would expect if the red shift were due to relative motion.

Mathematically, yes, they are moving relative to us. If they are far enough away, they are moving, relative to us, faster than the speed of light. But it's only possible for them to be moving away faster than the speed of light, so no signal can ever reach us, so they are causally disconnected from us - not part of the observable Universe.

Just as a note, I've seen estimates of the size of the actual, as opposed to observable Universe as 156 billion light years across. Here, for example. (http://www.space.com/scienceastronomy/mystery_monday_040524.html) But I don't fully understand how they get this number.

[LordoftheLeftHand]

I simply don’t have time to respond to all the replies but thanks for them all (very helpful). The “penny has dropped” (like it when that happens) regarding exactly what the red shift is so can now better understand the error of my ways. The dead horse can now be buried.

I still have some Big Bang itches to scratch though - If the universe is constantly expanding what area is it expanding in to? Is it occupying a space that was formally nothing? If so, what is nothing. It would have to be absolute nothing, not relative nothing. It is difficult for me to accept the concept that the universe has an outer edge let alone that it is expanding in to a space that was formerly absolute nothing. How can absolute nothing exists?


I'll take a stab at... People forgive me if I make any mistakes...

The red shift is an integral part of the Big Bang theory. Hubble noticed that the distance of remote objects was related to their red shift (the velocity they are receding from us). Objects that are farther away are moving away faster than objects that are closer. Furthermore there seemed to be a direct relationship between these two number. If you divide the distance of object 1 by the speed (red shift) of object 1 you get a result called Hubble's Constant. If you divide the distance of object 2 with the speed of object 2 you get the same result! (Hubble's Constant). This can be explained by two different scenario that I can think of:


1: The universe started with its matter clumped into small location. The rest of the universe was just infinite empty space. Some type of rapid expansion took place (explosion) and pushed the matter out into the empty space.

Imagine a car bomb. The car explodes and throws pieces in every direction. Some pieces fly far away and some not so far. Let’s say it throws tire #1 15 feet and tire #2 30 feet. Imagine we took a picture during the explosion. The tires would be flying through the air towards their final destinations. If you measured the distance (during the explosion)from the drivers seat to the tires you would find that tire #2 would be farther away from the car than tire #1, in fact it would likely have traveled twice the distance (because it would likely be moving twice as fast). If you divide the distance between tire #1 and the drivers seat by the speed it was flying you would get a number we will call the Tire Constant. If you did the same with tire #2 you would get the same answer. If you repeat these measurements from a different location (say across the street instead of the drivers seat) you would get a different answer for each tire (there would be no Tire Constant). So in this model the only location where the Tire Constant would hold true would be from the drivers seat. This means that for this scenario to be true the Earth would have to be in the “center” of the universe (drivers seat). In this model empty space is infinite and there is no edge of the universe.


2: The universe started with its matter clumped into small location. This small location is the entire universe. There is no empty space “outside” of it. Somehow “empty space” was “injected” into this small location.

Imagine 3 ants standing on an collapsed balloon. Ant #1 and #2 are standing right next to each other and ant #3 is standing a little farther away. Then someone starts to pump air into the balloon, inflating it. The skin of the balloon stretches and the distance between all of the ants starts to increase. Ant #1 notices that ant #2 is still closer than ant #3 but that both of them appear to be running away from him! He measures the distance to ant #2 and divides it by the speed that ant #2 is moving away. He calls this number the Ant Constant. Then he measures the distance to ant #3 and divides it by the speed that ant #3 is moving away and gets the same answer! In fact all the ants perform this calculation and they all come to the conclusion that everyone is running away from them at a ratio described by the Ant Constant! Each ant thinks he is at the center of his universe and everyone else is running away. In a way each ant would be correct, he is at the “center” of his universe. In this model the universe would have a finite area (the surface area of the balloon) that is increasing. There is no simple edge of the universe (as the balloon has no real edge).

LLH

[Rockin' Rick]

All of the tools used, radio astronomy, visible light telescopes, and background microwave radiation all suggest that the universe expanding. What's more is it's rate of expansion is increasing. The rate measurements were made by monitoring specific types of super novi. These short-lived cosmic events (short on a cosmic scale) have been monitored to try to predict the rate at which objects in the universe are moving apart. The red-shift, which is akin to the Doppler effect has been in practice for a long time. A huge number of objects have examined over this time.

I highly recommend a PBS Nova miniseries titled "Origins". Last I noticed it was available at Netflix.

[Art Vandelay]

Mathematically, yes, they are moving relative to us. If they are far enough away, they are moving, relative to us, faster than the speed of light. But it's only possible for them to be moving away faster than the speed of light, so no signal can ever reach us, so they are causally disconnected from us - not part of the observable Universe.There's two problems that I have with that. First of all, the "out of sight, out of mind" idea doesn't satisfy me. Secondly, if a galaxy is moving faster than c in one frame of reference, then it must be moving faster than c in every frame of reference. Which means that its will be moving faster than c with respect even to galaxies right next to it.

If you repeat these measurements from a different location (say across the street instead of the drivers seat) you would get a different answer for each tire (there would be no Tire Constant). Only if you assume that this different location is in the same frame of reference as the driver's seat.

He measures the distance to ant #2 and divides it by the speed that ant #2 is moving away. He calls this number the Ant Constant. Then he measures the distance to ant #3 and divides it by the speed that ant #3 is moving away and gets the same answer! In fact all the ants perform this calculation and they all come to the conclusion that everyone is running away from them at a ratio described by the Ant Constant! Except that that doesn't work with relativity, because velocities are not additive. Suppose that ant one is halfway between ants two and three. All three ants agree that the distance from one to two is the same as the distance from one to three. Ant one should see that the velocities of two and three are of equal magnitude, but opposite direction. And two is going to see that the distance to ant three is twice the distance to ant one. If the velocity of ant one, according to ant two, is v, then the velocity of of ant three, according to ant two, is not 2v, but 2v/(1+v^2).

Rockin' Rick: the plural of "nova" is "novae".

[PixyMisa]

There's two problems that I have with that. First of all, the "out of sight, out of mind" idea doesn't satisfy me. Secondly, if a galaxy is moving faster than c in one frame of reference, then it must be moving faster than c in every frame of reference. Which means that its will be moving faster than c with respect even to galaxies right next to it.
Yeahbut - There is no frame of reference in which any two galaxies are moving faster than the speed of light relative to one another. That such a state exists is a straightforward inference from the expansion of the universe, but you can't use it to construct a frame of reference. Anything moving away from you faster than the speed of light is not in your frame of reference, pretty much by definition.

If we take this definition from Wikipedia:

A frame of reference is the perspective from which a system is observed. In physics (http://en.wikipedia.org/wiki/Physics), it provides a set of axes (http://en.wikipedia.org/wiki/Coordinate_axis) relative to which an observer can measure the position and motion of all points in a system, as well as the orientation of objects in it.
Then logically, since you cannot observe or measure anything moving away from you faster than the speed of light, even if you can infer the existence of such things they do not form part of your frame of reference.

Look, I'm not married to this particular way of describing cosmological red shift. If you argue that it is unclear, then I might well agree, but I don't think it is actually wrong. If you take the motion as real, all the calculations work just fine, causality is preserved.

[ynot]

I'll take a stab at... People forgive me if I make any mistakes...

The red shift is an integral part of the Big Bang theory. Hubble noticed that the distance of remote objects was related to their red shift (the velocity they are receding from us). Objects that are farther away are moving away faster than objects that are closer. Furthermore there seemed to be a direct relationship between these two number. If you divide the distance of object 1 by the speed (red shift) of object 1 you get a result called Hubble's Constant. If you divide the distance of object 2 with the speed of object 2 you get the same result! (Hubble's Constant). This can be explained by two different scenario that I can think of:


1: The universe started with its matter clumped into small location. The rest of the universe was just infinite empty space. Some type of rapid expansion took place (explosion) and pushed the matter out into the empty space.

Imagine a car bomb. The car explodes and throws pieces in every direction. Some pieces fly far away and some not so far. Let’s say it throws tire #1 15 feet and tire #2 30 feet. Imagine we took a picture during the explosion. The tires would be flying through the air towards their final destinations. If you measured the distance (during the explosion)from the drivers seat to the tires you would find that tire #2 would be farther away from the car than tire #1, in fact it would likely have traveled twice the distance (because it would likely be moving twice as fast). If you divide the distance between tire #1 and the drivers seat by the speed it was flying you would get a number we will call the Tire Constant. If you did the same with tire #2 you would get the same answer. If you repeat these measurements from a different location (say across the street instead of the drivers seat) you would get a different answer for each tire (there would be no Tire Constant). So in this model the only location where the Tire Constant would hold true would be from the drivers seat. This means that for this scenario to be true the Earth would have to be in the “center” of the universe (drivers seat). In this model empty space is infinite and there is no edge of the universe.


2: The universe started with its matter clumped into small location. This small location is the entire universe. There is no empty space “outside” of it. Somehow “empty space” was “injected” into this small location.

Imagine 3 ants standing on an collapsed balloon. Ant #1 and #2 are standing right next to each other and ant #3 is standing a little farther away. Then someone starts to pump air into the balloon, inflating it. The skin of the balloon stretches and the distance between all of the ants starts to increase. Ant #1 notices that ant #2 is still closer than ant #3 but that both of them appear to be running away from him! He measures the distance to ant #2 and divides it by the speed that ant #2 is moving away. He calls this number the Ant Constant. Then he measures the distance to ant #3 and divides it by the speed that ant #3 is moving away and gets the same answer! In fact all the ants perform this calculation and they all come to the conclusion that everyone is running away from them at a ratio described by the Ant Constant! Each ant thinks he is at the center of his universe and everyone else is running away. In a way each ant would be correct, he is at the “center” of his universe. In this model the universe would have a finite area (the surface area of the balloon) that is increasing. There is no simple edge of the universe (as the balloon has no real edge).

LLH

Thanks LeftHand - Do you know what the right hand is doing? (sorry, that must have been asked 100 times)

Thanks for the reply. Think I understand the mechanics/physics of a constant, uniform 3D expansion. I appreciate that it’s often hard to express ideas in words, so I hope I’m not being too pedantic here. The singularity (clump) is often described as being infinitely small and infinitely dense but surely it would defy description as being all of existence there would nothing else to draw a comparison with. Perhaps one could say that the matter component of the universe was more compact than it is now. Unless of course it is infinitely small compared to the little finger of God. Perhaps we are all trapped in the lungs of God and at present things are expanding because he is breathing in. The collapse will be when he breaths out. Hope the bugger doesn’t sneeze. Can you give an example of “empty space” (absolute nothing)? What we call space within the universe is not empty. As the theists say “well how do you explain the unexplainable”.

The balloon analogy works for me if you use it to explain the expansion but not the lack of an edge. The natural direction of motion is linea. The circumference of a balloon is circular. A line has ends (edges) a circle doesn’t. Also the balloon has an edge in that it has a surface. The universe does not have a surface. The idea (that some people have) that, if you travel through the universe in a straight line you will eventually end up where you began, is the stuff of theists as far as I’m concerned.

Just had an idea from something I said above (probably been done before and discarded as tripe). Maybe all the matter of the universe was the singularity and everything else of existence that is not matter (maybe even anti-matter) was external to the singularity. Matter is now expanding in to the infinite space that this other “non-matter stuff” occupies. Maybe as the matter is expanding, the “non-matter stuff” is contraction at the same rate to preserve a balance.

[PixyMisa]

The singularity (clump) is often described as being infinitely small and infinitely dense but surely it would defy description as being all of existence there would nothing else to draw a comparison with.

Right. That's why we call it a "singularity"; it's the point at which the laws of physics break down. We have no way to describe what it was like. But it's a pretty straightforward prediction: If the Universe is expanding, just track that expansion backwards, and at the point that time began, all the matter was in one place. Infinitely small and dense.

Perhaps one could say that the matter component of the universe was more compact than it is now.

No, not just the matter component; space itself was compressed to a point.

As the theists say “well how do you explain the unexplainable”.

We don't. In science, we say "At at time zero, the universe was infinitely dense and infinitely small, and we cannot say anything else about it."

The balloon analogy works for me if you use it to explain the expansion but not the lack of an edge. The natural direction of motion is linea. The circumference of a balloon is circular.

Start drawing a line along the balloon. Soon enough, you'll go right round the balloon and back to the starting point. On the surface of a balloon, straight lines are curved in the third dimension.

A line has ends (edges) a circle doesn’t.

A line only has ends if it's finite in length.

Also the balloon has an edge in that it has a surface. The universe does not have a surface.

A balloon is a two-dimensional sheet that is curved closed in the third dimension. The Universe is (we think) similarly curved closed in a higher dimension.

The idea (that some people have) that, if you travel through the universe in a straight line you will eventually end up where you began, is the stuff of theists as far as I’m concerned.

Well, that's exactly what would happen for an ant circumnavigating the balloon, and it's what would happen to you if the Universe were finite, closed, and static. But since the Universe is expanding outwards, you can't ever do this.

Just had an idea from something I said above (probably been done before and discarded as tripe). Maybe all the matter of the universe was the singularity and everything else of existence that is not matter (maybe even anti-matter)

Anti-matter is just matter. Really.

was external to the singularity. Matter is now expanding in to the infinite space that this other “non-matter stuff” occupies.

Nope. If that was true we wouldn't see the Cosmic Microwave Background, and we do.

[69dodge]

Secondly, if a galaxy is moving faster than c in one frame of reference, then it must be moving faster than c in every frame of reference. Which means that its will be moving faster than c with respect even to galaxies right next to it.I think you're thinking about special relativity.

What's a "frame of reference" in general relativity? No such thing, really, except locally.

[LordoftheLeftHand]

Unless of course it is infinitely small compared to the little finger of God. Perhaps we are all trapped in the lungs of God and at present things are expanding because he is breathing in. The collapse will be when he breaths out. Hope the bugger doesn’t sneeze.

Unless of course it is infinitely small compared to a wing feather of the Giant Yellow Mutant Space Chicken. Perhaps we are all trapped in the gizzard of the Giant Yellow Mutant Space Chicken and at present things are expanding because he is eating. The collapse will begin when he stops.

LLH

[Melendwyr]

Wrong. Wrong.

Sure there is. Distant galaxies really are moving away from us. The source of that movement is the expansion of the Universe, but the movement is real. No. Those galaxies aren't moving, they're just getting farther away. Moving requires passage through space.

The problem with "tired light" is that it (a) it contravenes the First Law of Thermodynamics (it is impossible) and Quantum Mechanics (it is impossible) and it makes predictions which are not borne out by evidence (it is wrong). (a) No, and (b) no.

In the expanding universe hypothesis, light does vibrate more slowly the farther it travels.

It's not a restatement of the Doppler Effect, it's just plain wrong. Who's said it's the Doppler Effect? Doppler shifting is due to relative motion. There IS no relative motion between us and distant parts of the universe (not on a universal scale, at least - other galaxies are of course moving all around). Universal expansion is not movement.

[SpaceFluffer]

Melendwyr, please go read up on this stuff before spewing your lack of knowledge onto hapless, unsuspecting individuals who are just trying to learn. Your questions have been well answered by PixyMisa, now go read a book on General Relativity.

You may also like to read: http://sciencenow.sciencemag.org/cgi/content/full/2001/628/1. If you still insist on this hypothesis, you'd better have some damn good reasons why it failed these tests.

As yet further reading, may I suggest that you read your own sig line? FYI, I have some rope and can probably get hold of some oil.

[CurtC]

super novi"Supernovas," please.

[Melendwyr]

Melendwyr, please go read up on this stuff before spewing your lack of knowledge onto hapless, unsuspecting individuals who are just trying to learn. Your questions have been well answered by PixyMisa, now go read a book on General Relativity. Oh, really? If expansion leads to actual movement through space, how can you reconcile galaxies that are moving away faster than light with Relativity? That's what the expansion implies, after all.

[SpaceFluffer]

The galaxies are not moving through space faster than light (which would indeed be prohibited by Special Relativity), but the spacetime itself is expanding in such a way, that from a great distance the net effect is a recession greater than c. Again, the spacetime is not expanding faster than c, but when everything is expanding in this way, the further away from something you are, the faster it's recession will appear to be. I'm afraid that the reality of the situation will not change just because you don't seem to like it.

Like I said, go read some GR because you've just demonstrated once again that you have no idea what you're talking about. I'm perfectly fine with someone not knowing about this stuff, but I'm not fine with a dullard such as yourself talking like he/she knows all about it when there are posters around who are genuinely interested in learning. Your arrogance and lack of understanding does them no favors.

Another link: http://www.astro.ucla.edu/~wright/tiredlit.htm

[Melendwyr]

The galaxies are not moving through space faster than light (which would indeed be prohibited by Special Relativity), but the spacetime itself is expanding in such a way, that from a great distance the net effect is a recession greater than c. Yes! The whole point is that the galaxies themselves are not moving away from us. They're just getting farther away, because more space is appearing between us and them all the time. Or so goes the hypothesis.

Given that hypothesis, light waves will also have more space popping up inside them, slowly causing their vibrational nodes to become farther and farther apart. This is equivalent to slowing their vibration, which is equivalent to their losing energy. Therefore, the longer a photon travels in the expanding universe, the more energy it will seem to have lost. Tired light hypothesis, right there.

Like I said, go read some GR because you've just demonstrated once again that you have no idea what you're talking about. I'm perfectly fine with someone not knowing about this stuff, but I'm not fine with a dullard such as yourself talking like he/she knows all about it when there are posters around who are genuinely interested in learning. Your arrogance and lack of understanding does them no favors. Your "corrections" argue the points I've been making. I think you should reexamine the question of who doesn't know what, here.

[SpaceFluffer]

Kindly explain why the 'tired light' hypothesis failed the tests that I referenced earlier.

[Melendwyr]

"Tired Light Hypothesis": Light will vibrate more slowly with time.

"Expanding Universe Hypothesis": Space is constantly expanding, causing the space between distant objects to become greater at a rate proportional to the distance between them.

One of the side effects of #2 is that the wavelengths of light waves will become stretched out over time. Thus, they will vibrate more slowly the longer they travel. That is essentially the assertion that #1 makes. Thus, #1 is actually a subset of #2.

[SpaceFluffer]

Wow, you can't even get your pseudoscience correct.

Once again, please explain why the predictions of the tired light hypothesis do not match supernova and CMB data, as described in the links I've posted.

[Melendwyr]

The site you linked to explicitly says that light traveling around an expanding universe will be redshifted, SpaceFluffer.

Combining the hypotheses that light vibrates more slowly AND that the universe is static leads to contradictions with observation, as those sites point out. The hypothesis that light vibrates more slowly with time is a necessary consequence of the expanding universe hypothesis, however.

This will be the last time I attempt to explain this extremely simple point to you.

[SpaceFluffer]

Yes, but redshifted by THE WRONG AMOUNT.

But don't worry - there's no need to explain your 'extremely simple' (yet wrong) point again to this lowly Ph.D. I have far better things to do than exchange words with arrogant fools.

Congratulations on making my ignore list - only a select few, carefully handpicked idiots make it there. You should feel special.

[Genesius]

Oh, really? If expansion leads to actual movement through space, how can you reconcile galaxies that are moving away faster than light with Relativity? That's what the expansion implies, after all.

From http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html


According to the Hubble Law, two galaxies which are a distant D apart are moving away from each other at a speed HD where H is Hubble's constant. In that case two galaxies which are a distance greater than c/H apart are moving away from each other faster than the speed of light. This is quite correct. The distance between two objects can be increasing faster than light because of the expansion of the universe. However, it is meaningless to say that the universe is expanding faster than light because the rate of the expansion is measured by Hubble's constant alone which does not even have the units of speed.
As was mentioned above, in special relativity it is possible for two objects to be moving apart by speeds up to twice the speed of light as measured by an observer in a third frame of reference. In general relativity even this limit can be surpassed but it will not then be possible to observe both objects at the same time. Again, this is not real faster than light travel. It will not help anyone to travel across the galaxy faster than light. All that is happening is that the distance between two objects is increasing faster when taken in some cosmological reference frame.

[Melendwyr]

That's what I've been saying. Expanding space does not cause things to move.

How many times do I have to repeat it?

[Genesius]

That's what I've been saying. Expanding space does not cause things to move.

How many times do I have to repeat it?

Until you get it right? :D

For much better info on this topic than I am able to provide, I suggest you read http://www.astro.ucla.edu/~wright/cosmology_faq.html#FTL , especially the section headed "Are galaxies really moving away from us or is space just expanding?"

Hey, I'm no astrophysicist, but I can Google with the best of 'em. :cool:

[SpaceFluffer]

Well, apparently being an astrophysicist doesn't help anyway. Nothing to see here, folks.

[Genesius]

Well, apparently being an astrophysicist doesn't help anyway. Nothing to see here, folks.
And here I was wishing the Bad Astronomer would show up and smite the fool, not knowing that an astrophysicist was amongst us!

I'll be real quiet now, and let those who know the subject handle the situation. . .
:boxedin:

[Melendwyr]

Until you get it right? :D

For much better info on this topic than I am able to provide, I suggest you read http://www.astro.ucla.edu/~wright/cosmology_faq.html#FTL , especially the section headed "Are galaxies really moving away from us or is space just expanding?"

Hey, I'm no astrophysicist, but I can Google with the best of 'em. :cool:


You can Google, but it seems you can't understand the results you get.

The Tired Light Hypothesis is not sufficient to explain the observations we see. But the Expanding Space Hypothesis predicts the same things the Tired Light Hypothesis does, AND MORE.

[LordoftheLeftHand]

The part of the Big Bang I never understood is why is the universe lumpy? Why are there planets and stars, and not just a thinly dispersed fog of hydrogen gas?

LLH

[Melendwyr]

The part of the Big Bang I never understood is why is the universe lumpy? Why are there planets and stars, and not just a thinly dispersed fog of hydrogen gas?

LLH Short answer: no one really knows.

[Genesius]

You can Google, but it seems you can't understand the results you get.

The Tired Light Hypothesis is not sufficient to explain the observations we see. But the Expanding Space Hypothesis predicts the same things the Tired Light Hypothesis does, AND MORE.

I've been trying to find info on the "Expanding Space Hypothesis" online, and not coming up with anything. Do you have a link to a site which discusses it? Was this hypothesis created by anything approaching a respected scientist, or is it the product of your fevered mind?

[Melendwyr]

I've been trying to find info on the "Expanding Space Hypothesis" online, and not coming up with anything. Do you have a link to a site which discusses it? Was this hypothesis created by anything approaching a respected scientist, or is it the product of your fevered mind? It's the standard explanation for the Big Bang. The existence of a singularity is inferred from the hypothesis that the universe is expanding - that hypothesis is what is needed to explain our observations.

We had one person claim that light could not be vibrating more slowly because it violated the laws of physics, and the sources brought up by others have refuted that. Those sources explicitly demonstrated how expanding space produces results consistent with the idea of "tired light". As an ad hoc explanation, the TLH fails. But it's implied by the EUH.

[KingMerv00]

This thread isn't about Mel. Back to the topic at hand.

Thanks for the reply. Think I understand the mechanics/physics of a constant, uniform 3D expansion. I appreciate that it’s often hard to express ideas in words, so I hope I’m not being too pedantic here. The singularity (clump) is often described as being infinitely small and infinitely dense but surely it would defy description as being all of existence there would nothing else to draw a comparison with. Perhaps one could say that the matter component of the universe was more compact than it is now. Unless of course it is infinitely small compared to the little finger of God. Perhaps we are all trapped in the lungs of God and at present things are expanding because he is breathing in. The collapse will be when he breaths out. Hope the bugger doesn’t sneeze. Can you give an example of “empty space” (absolute nothing)? What we call space within the universe is not empty. As the theists say “well how do you explain the unexplainable”.

That is the difference between theism and science. A scientist will come across a mystery and say, "I don't have enough information yet. Maybe we'll get it one day." A theist will say, "Wow. I don't have information yet. God must have done it."

The balloon analogy works for me if you use it to explain the expansion but not the lack of an edge. The natural direction of motion is linea. The circumference of a balloon is circular. A line has ends (edges) a circle doesn’t. Also the balloon has an edge in that it has a surface. The universe does not have a surface.

The balloon is just an illustration. The concept is that 3D space is curved in a "higher" dimension. There are actually attempts underway to measure the curvature of space. (I don't know how, I know they are trying it.) Alot of this stuff is still in the hypothetical stage. We are just trying to understand the universe.

The idea (that some people have) that, if you travel through the universe in a straight line you will eventually end up where you began, is the stuff of theists as far as I’m concerned.

Why? You can't let personal feelings dictate reality. Just because something is counter intuitive does not mean it isn't true. Quantum physics is mindbending stuff, but it is testable. Weird things exist. The end.

Just had an idea from something I said above (probably been done before and discarded as tripe). Maybe all the matter of the universe was the singularity and everything else of existence that is not matter (maybe even anti-matter) was external to the singularity. Matter is now expanding in to the infinite space that this other “non-matter stuff” occupies. Maybe as the matter is expanding, the “non-matter stuff” is contraction at the same rate to preserve a balance.


Well you'd have to have a way to observe "non-matter" before we go any further.

[Genesius]

The part of the Big Bang I never understood is why is the universe lumpy? Why are there planets and stars, and not just a thinly dispersed fog of hydrogen gas?

LLH

I think that is one of the things that led Guth to create his Inflation model. From the Wikipedia article http://en.wikipedia.org/wiki/Cosmic_inflation
Cosmic inflation is the idea, first proposed by Alan Guth (http://en.wikipedia.org/wiki/Alan_Guth) in 1981, that the nascent universe (http://en.wikipedia.org/wiki/Universe) passed through a phase of exponential expansion (http://en.wikipedia.org/wiki/Exponential_growth) (the inflationary epoch (http://en.wikipedia.org/wiki/Inflationary_epoch)) that was driven by a negative pressure vacuum (http://en.wikipedia.org/wiki/Vacuum) energy density. This expansion is similar to a de Sitter universe (http://en.wikipedia.org/wiki/De_Sitter_universe) with positive cosmological constant (http://en.wikipedia.org/wiki/Cosmological_constant). As a direct consequence of this expansion, all of the observable universe originated in a small causally-connected (http://en.wikipedia.org/wiki/Causality_%28physics%29) region. Quantum fluctuations (http://en.wikipedia.org/wiki/Quantum_fluctuation) in this microscopic region, magnified to cosmic size, then became the seeds for the growth of structure in the universe

The question of Guth's theory being correct or not is left to intellects much more advanced than mine.

[Complexity]

Short answer: no one really knows.

Melendwyr - You were asked to stop pretending to be knowledgable about things that you are pretty ignorant about.

I'm asking you again to keep quiet on this subject - you've been wrong more than right.

It would be admirable if you were to say "I don't know" - that is accurate.

To say that "no one really knows" is outside of your knowledge and is irresponsible - someone might take you seriously. As it happens, some people think they've got some good ideas about how the lumpiness came to be.

One very accessible book on how the lumpiness may have come to be is How the Universe Got Its Spots by Janna Levin.

[Melendwyr]

Melendwyr - You were asked to stop pretending to be knowledgable about things that you are pretty ignorant about. And that request came from people who confirm what I've said and then insist that they've shown me to be wrong.

To say that "no one really knows" is outside of your knowledge and is irresponsible - someone might take you seriously. As it happens, some people think they've got some good ideas about how the lumpiness came to be. 'Thinking you've got some good ideas' and 'knowing' are quite different states. Given that this is one of the Big Problems science is attempting to understand, representing any of the many unconfirmed and usually currently unverifiable hypotheses on the matter as an explanation is irresponsible.

[ynot]

Your conveyor belt analogy isn't right. In order to see more lower spectrum (red) light, the star would have to emit more of it. Also, if the lower spectrum light traveled faster, it would appear disproportionately dimmer compared to the higher spectrum.

Why dimmer? Hmm...how do I explain this.

Ok you have two belts. One moving at rate X and the other moving at 2X. At the start of each, you have a guy who places a red photon on it at the rate of one per second. Now imagine you are at the end of each belt, what do you see?

The X belt's photons are coming of more densely packed than the 2X belt. Densely packed photons means more energy is striking your eye at any given moment, and therefore appears brighter. In order to appear just as bright as the X belt, the 2X belt guy would have to double his rate.

WARNING: NOT a cosmologist. I am but a mere chemist. I really don't know anything useful. I am willing to be corrected.

-----------------------------------------------------------------
Another thing to think about:

I plan on beating the rotating galaxy example to death, so bear with me.

Say we have two identical stars (sample spectum emitted, same size, etc) in the same galaxy that are both the same distance away from us. The only difference ... one rotate towards us and one rotates away. What would we expect to see?

In your theory, they would appear identical because they are both the same distance away.

In the Big Bang Theory, we would observe one red shifted and the other blue shifted.

We see the latter.

Not sure I can follow (or agree) with what you have said here. To simplify things, lets imagine that the galaxy is a flat disc and we draw two diametrically opposed dots on the outer edge of one surface of the disc. We then spin the disc on a fixed point and on a flat plane (edge on and stationary to our view-point). As the disc rotates, the disc overall would remain the same distance away but one dot would be moving away from our view-point while the other would be moving closer. Whether a particular dot was moving away or closer would depend on which half of the disc it was on as the disc spins in relation to our view point. As long as the spin was fast and large enough, the moving away could cause the red shift and the moving towards the blue (as in my theory)

If the spinning disc was then caused to move away from our view-point (as in an expanding universe), the moving away effect of half of the spinning motion, combined with the overall moving away motion of the disc, would speed-up the overall moving away motion of the dot that was on the moving away side of the spinning disc. In other words, the red shift effect would be increased.

Exactly the opposite effect however would occur to the other dot. The moving towards motion of the half the spinning motion would be slowed down by the speed of overall moving away motion of the disc. If the overall moving away motion of the disc was greater than the rotational speed of the disc, then no part of the spinning disc would be moving toward the observer. Surely this would make it harder for the blue shift to occur in an expanding universe that a relatively stationary one. That is, if it is the spinning motion of galaxies the causes blue shift.

Bit of a ramble - Hope it makes some sense

[ynot]

This thread isn't about Mel. Back to the topic at hand.

[/size][/font]

[font=Verdana][size=2]That is the difference between theism and science. A scientist will come across a mystery and say, "I don't have enough information yet. Maybe we'll get it one day." A theist will say, "Wow. I don't have information yet. God must have done it."

I can make any piece of the jigsaw fit if I have a pair of sissors.

EDIT - Sorry - should read scissors of course.



The balloon is just an illustration. The concept is that 3D space is curved in a "higher" dimension. There are actually attempts underway to measure the curvature of space. (I don't know how, I know they are trying it.) Alot of this stuff is still in the hypothetical stage. We are just trying to understand the universe.

Starting to dance a bit far from the band for me.



Why? You can't let personal feelings dictate reality. Just because something is counter intuitive does not mean it isn't true. Quantum physics is mindbending stuff, but it is testable. Weird things exist. The end.

Sometimes I am sceptical that the tests may be a pair of sissors.

(scissors)

Well you'd have to have a way to observe "non-matter" before we go any further.

Is light, heat or radiation matter?

[c4ts]

Multi-Speed Light - This is my favoured concept. Perhaps different parts of the light spectrum travel at different speeds, and the infrared end of the spectrum travels faster than the ultraviolet. If this were so, it would cause a “red shift” effect. The greater the distance, the greater the effect.

According to you, if you filmed two simultaneous and synchronous actions, one in red light, and one in blue-white light, and they were equidistant from the camera, the red event would happen before the white.

You can test it, but you'll find it doesn't work that way.

[ynot]

According to you, if you filmed two simultaneous and synchronous actions, one in red light, and one in blue-white light, and they were equidistant from the camera, the red event would happen before the white.

You can test it, but you'll find it doesn't work that way.

Yes - This is essentially what I'm suggesting. Given the overall speed of light however, the effect would not be apparent (or perhaps even measurable) at close distance. In other words, immense distances would be required to see the effect.

[ynot]

According to you, if you filmed two simultaneous and synchronous actions, one in red light, and one in blue-white light, and they were equidistant from the camera, the red event would happen before the white.

You can test it, but you'll find it doesn't work that way.

To put it another way, if the film was projected on to a screen, the screen would need to be an immense distance away to see the effect. Or perhaps I mean that the images would have to be projected on to the from an immense distance away.

(on to the screen)

[PixyMisa]

Oh, really? If expansion leads to actual movement through space, how can you reconcile galaxies that are moving away faster than light with Relativity? That's what the expansion implies, after all.

Yes, that's what it implies.

But you cannot see them. You cannot measure them. No signal can pass from you to those distant galaxies, under any circumstances whatsoever.

So there is no observation that needs to be reconciled with Relativity.

[Melendwyr]

Yes, that's what it implies.

But you cannot see them. You cannot measure them. No signal can pass from you to those distant galaxies, under any circumstances whatsoever.

So there is no observation that needs to be reconciled with Relativity. Except that it's not possible to accelerate things past the speed of light. If the galaxies are moving through space, instead of space increasing between them, then there's a whole lot of nasty problems. You have to start drawing odd conclusions about the nature of space-time, instead of accepting the much simpler explanation that space is expanding and those galaxies are remaining still.

It's possible to adopt the view that the Earth really is staying still while the rest of the solar system orbits around it, but it's ridiculously difficult and not very useful. Same deal.

[ynot]

Am I right in assuming that, if the universe is expanding uniformly in all directions, and it has no edge, that it is impossible to define a centre or start point of the expansion?

[PixyMisa]

We had one person claim that light could not be vibrating more slowly because it violated the laws of physics, and the sources brought up by others have refuted that. Those sources explicitly demonstrated how expanding space produces results consistent with the idea of "tired light".
:notm

The "Tired Light" hypothesis is a specific statement intended as a counter to the idea that the Universe is expanding. It says that the cosmological red shift is not due to relative movement, but due to the distance travelled by the light in a static Universe.

That's why SpaceFluffer said "you can't even get your pseudoscience correct". Your statement of the tired light hypothesis bears no relation to what the hypothesis actually says.

Please look at my link this time. (http://www.astro.ucla.edu/%7Ewright/tiredlit.htm)

[c4ts]

To put it another way, if the film was projected on to a screen, the screen would need to be an immense distance away to see the effect. Or perhaps I mean that the images would have to be projected on to the from an immense distance away.

(on to the screen)

Why? Are you suggesting that light is not only slower, but it decellerates?

[PixyMisa]

Except that it's not possible to accelerate things past the speed of light. If the galaxies are moving through space, instead of space increasing between them, then there's a whole lot of nasty problems.

Sure.

But they're not.

Now this is why I made my other comment - that I'm not married to this description. There are reasons not to speak of movement in this situation, or to qualify the term, but that's not what you're addressing.

It's possible to adopt the view that the Earth really is staying still while the rest of the solar system orbits around it, but it's ridiculously difficult and not very useful. Same deal.

What problems arise when you treat those distant galaxies as actually moving away from us?

If the relative motion is less than the speed of light, the red shift is precisely what it should be. Time dilation is what it should be.

If the relative motion is greater than the speed of light, you can't see them.

Where are those nasty problems?

[Melendwyr]

If the relative motion is greater than the speed of light, you can't see them. How would you get two things moving away from each other, from their own perspectives, faster than the speed of light?

[ynot]

Why? Are you suggesting that light is not only slower, but it decellerates?

No - I am suggesting that different parts of the light spectrum might travel at different speeds. Red faster than blue.

[chipmunk stew]

Sometimes I am sceptical that the tests may be a pair of sissors.

(scissors)And sometimes, scientists being as human as anyone else (although some may argue that point), this is true. However, one thing to remember is that scientists as a group are an insecure lot in the sense that they are never quite sure their methods are not flawed in some way and so they try to be very fastidious in their work. They also like finding flaws in other people's work. Look at how quickly the flaws in Whatsizname's study on stem cells was exposed (someone help me out here).

So, typically, when consensus forms around a particular topic in the scientific community, it happens not by cursory support of ideas that sound nifty or because it provides a convenient basis for a pet idea, but rather by begrudging and reluctant admission that they can't find any flaws. Only then is it considered a nifty idea.


Is light, heat or radiation matter?Yes. In the technical sense, if not the vernacular. Remember: E=MC^2

[Melendwyr]

Your statement of the tired light hypothesis bears no relation to what the hypothesis actually says.Tired light models invoke a gradual energy loss by photons as they travel through the cosmos to produce the redshift-distance law. With expanding space, the longer photons travel, the more space there is between their vibrational nodes. Therefore they have less energy than they did when they were originally released.

If you invoke Tired Light to explain the observations, you don't get anywhere. If you invoke the expansion of space, one of the consequences of that is that photons will gradually lose their energy as they travel.

What objection do you have with this reasoning?

[chipmunk stew]

Am I right in assuming that, if the universe is expanding uniformly in all directions, and it has no edge, that it is impossible to define a centre or start p