Expanding Universe and the Red Shift

[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?

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.

 

[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!

 

[Melendwyr]

Until you get it right?

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.

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 in 1981, that the nascent universe passed through a phase of exponential expansion (the inflationary epoch) that was driven by a negative pressure vacuum energy density. This expansion is similar to a de Sitter universe with positive cosmological constant. As a direct consequence of this expansion, all of the observable universe originated in a small causally-connected region. Quantum fluctuations 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]

How the universe got its spots

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.