# Universe expansion

SmallChristian
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Universe expansion

It has been described to me that the universe expanding exponentially; faster and faster and faster and faster.  So could the universe or is the universe already expanding faster than the speed of light?  If so, doesn't this prove that the speed of light can be broken without having to "fold" space?

Thomathy
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The expansion of the

The expansion of the universe is an accelerating phenomenon.  The phenomenon is not relative to the objects at the edge to the edge (or the expansion of the edge outward), it's relative to the increasing distance from contiguous bodies in the universe from each other (galaxies to other galaxies).  The universe did expand faster than the speed of light initially, through some mechanisms that deludedgod (and others) can explain.  I don't think that the expansion is currently faster or can necessarily exceed the speed of light.

As a note, folding space isn't equivalent to going faster than the speed of light.

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SmallChristian
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Thomathy wrote:As a note,

Thomathy wrote:

As a note, folding space isn't equivalent to going faster than the speed of light.

Rightl because it's not moving any faster, it's just getting there by a different means.

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OK, where to begin is a

OK, where to begin is a good question. What you are asking about is not really accurate. The answer can't really be stated simply. As Einstein was noted for saying, “Any explanation of the universe should be as simple as possible but no simpler”.

Let me start by covering some basic theories.

Special Relativity (SR) is a theory of motion in general and where the notion that you can't exceed the speed of light comes from.

General Relativity (GR) is a theory of gravity and carries implications for the expansion of the universe.

The two theories above are really two aspects of the same theory but they cover separate domains of inquiry and it is best not to confuse them.

Quantum Mechanics (QM) is a theory of the universe on the smallest scale. It is just as accurate as both versions of relativity (which is to say stunningly accurate). However, as far as anyone can tell, it simply cannot be reconciled with SR/GR. Many scientists have tried and every one of them has failed. Except for String Theorists (ST). But I will not be using either QM or ST any farther as it will not help and will just confuse the question terribly.

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That being said, your main point of confusion seems to be an unwarranted interpretation of SR/GR.

For your purpose, we can just go with the idea that the expansion of the universe is a sort of special reserved category of motion.

Basically, SR provides that you cannot exceed the speed of light but only if you were not past that point from the very beginning of the universe. On the other hand, GR does allow distant galaxies to recede at faster than the speed of light but only if they were already doing that at the very beginning of the universe.

I suspect that your confusion lies in reading the wrong sources or in a poor reading of the right ones. GR carries an implication that the expansion of the universe must decrease over time. However, QM seems to require an increase in the rate of expansion.

Add to that that our best observations are showing us that there remain a number of great unanswered questions in science and whatever the answers to them may be has implications for all of the above mentioned theories.

If you are reading popular science types of work, you will hear the terms Dark Matter, Dark Energy and the Cosmological Constant being used. As I say, the observational evidence is that there is something going on that we still have not figured out. However, the above terms are not really offered by scientists as final answers to the questions. They are more or less place holder terms that are used as a good place to start the next great lines of inquiry.

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SmallChristian
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Well this is where a

Well this is where a theist should jump in and go "ah ha! contradictions!" and "god did it" with all the loopholes and gaps and all..... Just sayin'

I hate to admit it, but my confusion just increased!

So we have a contradiction between SR and SG, then both can't be right!  Both are most likely wrong, then?

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The two theories above are really two aspects of the same theory but they cover separate domains of inquiry and it is best not to confuse them.

Amen bro

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Basically, SR provides that you cannot exceed the speed of light but only if you were not past that point from the very beginning of the universe. On the other hand, GR does allow distant galaxies to recede at faster than the speed of light but only if they were already doing that at the very beginning of the universe.

Then why do all the zillions of articles about space expansion say "the expansion rate is increasing, faster and faster, and faster, and faster"  and they never put a "cap" or "limit" on it's acceleration??????????

Quote:

I suspect that your confusion lies in reading the wrong sources or in a poor reading of the right ones. GR carries an implication that the expansion of the universe must decrease over time. However, QM seems to require an increase in the rate of expansion.

I would say you're right for the most part.  I mean, I tend to read popular science, watch the science channel and read NASA articles on the web.  I'm sure they're simplifying things, and I'm sure I'm misreading some of them.

Quote:

Add to that that our best observations are showing us that there remain a number of great unanswered questions in science and whatever the answers to them may be has implications for all of the above mentioned theories.

Perhaps there is a missing theory to bridge the gap?  How about "God did it?" JK lol, but you see where I'm getting at?

Quote:

If you are reading popular science types of work, you will hear the terms Dark Matter, Dark Energy and the Cosmological Constant being used. As I say, the observational evidence is that there is something going on that we still have not figured out. However, the above terms are not really offered by scientists as final answers to the questions. They are more or less place holder terms that are used as a good place to start the next great lines of inquiry.

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SmallChristian wrote:

SmallChristian wrote:
Well this is where a theist should jump in and go "ah ha! contradictions!" and "god did it" with all the loopholes and gaps and all..... Just sayin'

I hate to admit it, but my confusion just increased!

Well, if it helps, my earlier post actually grew to like 5 pages in my word processor and probably answered some of your questions. Then I shortened it massively because I figured that it would be better to start a conversation than to just try to end it with one massive post.

Let me take some of your points but out of order and see where we can go.

SmallChristian wrote:
Perhaps there is a missing theory to bridge the gap? How about "God did it?" JK lol, but you see where I'm getting at?

Well, it makes a whole lot of sense to think that there really ought to be one master theory of the universe. Not simply one that serves as a bridge between competing theories but one under which it is clear that the other, earlier theories are really smaller parts of the new master theory.

It may help to think about how Newton's work fits neatly into relativity. Now you don't need relativity to aim a cannon or lift a load of lumber to the top of a building. For such relatively simple tasks, that is just adding a huge level of complexity and the answers that you get will not be any better than if you had done simple Newtonian math instead. Even so, the work of Newton can be considered to be a special case of Einsteinian Relativity that only works at very low speeds, where as relativity works at all speeds.

SmallChristian wrote:

To be honest, there really is not a test to determine if something is a place holder or not. I suppose that you could go with how new to science in general any given idea is. Newer stuff is far more likely to be place holder material. However, you should also know that some of the place holder material has been around for quite a long time.

However, let me note that the difference between “god did it” and a place holder is that the god thing just shuts down any meaningful discussion but a place holder term keeps the discussion open until better ideas come along.

SmallChristian wrote:
Then why do all the zillions of articles about space expansion say "the expansion rate is increasing, faster and faster, and faster, and faster" and they never put a "cap" or "limit" on it's acceleration?

Well, you should make a distinction between “all the zillions of articles” that turn up in places like Discover magazine and the actual articles that get submitted to respected scientific journals for peer review.

As far as the real science goes, there are probably less than a half dozen telescopes in the whole world that can take the really sensitive measurements needed to make such an observation. There may well be hundreds of astronomers competing for time on them but only a few want to do that specific type of observation. Other scientists was to look at other things. Honestly, there are probably only a scant few dozen papers that have material like you are talking about. You may have seen lots of article that are rewrites of that original material but the actual original material is probably a much smaller body of work than you are thinking.

Then too, there is no real reason why the people who work out on the bleeding edge of science must agree on everything. In fact, it probably helps if they don't agree with each other all the time. Only when an idea has been around for a few decades does it really become accepted as really a real thing. Along the way, it will be thought about by theorists and it will be tested by experimentalists. Ideas that turn out to be just plain wrong, eventually become scientific road kill. Ideas that are pretty close but need to be modified as new data comes in will be.

Ideas that are just so right that scientists can't fall over themselves fast enough to accept them? Well they have happened but they are pretty rare. Usually, they depend on earlier scientists doing lots of related work for many years. Then, when the likes of Newton or Einstein come along and have the temerity to take all of that earlier work and tie it together in a neat package do the other scientists look over the new theory and realize that not only is it probably right but it was also primed to be discovered by someone.

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DanMullin
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SmallChristian wrote:So

SmallChristian wrote:

So could the universe or is the universe already expanding faster than the speed of light?

From Wikipedia on metric expansion of space:

The metric expansion of space is the averaged increase of metric (i.e. measured) distance between objects in the universe with time. It is an intrinsic expansion—that is, it is defined by the relative separation of parts of the universe and not by motion "outward" into preexisting space. Metric expansion is a key feature of Big Bang Cosmology and is modeled mathematically with the FLRW metric. This model is valid in the present era only at relatively large scales (roughly the scale of galactic super clusters and above). At smaller scales matter has clumped together under the influence of gravitational attraction and these clumps do not individually expand, though they continue to recede from one another. The expansion is due partly to inertia (that is, the matter in the universe is separating because it was separating in the past) and partly to a repulsive force of unknown nature, which may be a cosmological constant. Inertia dominated the expansion in the early universe, and according to the ACDM model the cosmological constant will dominate in the future. In the present era they contribute in roughly equal proportions.

The metric expansion leads naturally to recession speeds which exceed the "speed of light" c and to distances which exceed c times the age of the universe, which is a frequent source of confusion among amateurs and even professional physicists.  The speed c has no special significance at cosmological scales.

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