If the universe is infinite, how is it expanding?

[glader]

The exact same question had been asked and answered multiple times in your previous threads.

The universe is not expanding, the space between everything within the universe is.

What's the point of making threads on the same topics over and over if you never actually want to learn anything from them?


---------- Post added 2012-10-11 at 02:56 AM ----------


No, that is completely wrong. There is nothing stopping the universe from expanding faster than the speed of light.

The only thing stopping it from doing so is the fact that nothing can travel faster than light in a vacuum. Unless you'd like to contradict a large amount of data that'll claim that nothing, other then things that carry no information and are massless, can travel faster than with a data set that is empty then I suggest you refrain from tearing down a central part of Physics.

[Deleted]

The matter in the universe is expanding, not the boundary.

If there is a boundary! Three-dimensional humans thinking about the multiverse.

[semaphore]

Everything we know, says that matter should be drawn together, but with a metaphorical middle finger, galaxies are actually moving apart. No-one knows why, but one thesis is called Dark Matter. Dark Matter is there to fill in a hole, both literally and figuratively, and we don't know if it excists.

You mean dark energy.

Also because the figurative hole is there, we're pretty sure something like that do exist, even though we know awfully little about it.

[semaphore]

Would his statement be related to that we know of no particle that can travel faster than the speed of light? Wouldn't that mean that the universe can't have expanded faster than the speed of light?

No it wouldn't, because what does that have to do with the expansion of space? The fabric of spacetime is not "travelling", and so it does not have to obey the universal speed limit. The whole reason we have an observable universe is because the rest of the unverse has moved away faster than light from those galaxies can reach us.

---------- Post added 2012-10-11 at 03:20 AM ----------

The only thing stopping it from doing so is the fact that nothing can travel faster than light in a vacuum.

Except the fact that it is completely irrelevant to the metric expansion of space.

[glader]

The universe is generally defined as all that exists.


Matter is not derived from the big bang. The big bang was a point in time when all matter in the universe was at one point.

Though I suppose given that we appear to be in a flat universe, the big bang could be around the point where our universe and by extension all matter in it came from nothing.

No, you can claim that all matter is derived from the Big Bang as a location. In what other sense were you implying that derived meant?

[Malcho]

Maybe some surrounding forces are pulling on it? Since we cannot see the end of the universe, we cannot see if there is an outer force yanking and stretching our dimensional fabric.

[glader]

No it wouldn't, because what does that have to do with the expansion of space? The fabric of spacetime is not "travelling", and so it does not have to obey the universal speed limit. The whole reason we have an observable universe is because the rest of the unverse has moved away faster than light from those galaxies can reach us.

---------- Post added 2012-10-11 at 03:20 AM ----------


Except the fact that it is completely irrelevant to the metric expansion of space.

Thankfully this has been validated with something such as observational data and/or mathematics yes?

[semaphore]

No, you can claim that all matter is derived from the Big Bang as a location. In what other sense were you implying that derived meant?

The normal sense of the world would imply you said the big bang created matter. If that's not what you meant, then cool. I'm biased to think you are mistaken because you think space cannot expand faster than light when we know for a fact that it does.

---------- Post added 2012-10-11 at 03:24 AM ----------

Thankfully this has been validated with something such as observational data and/or mathematics yes?

Indeed it has.

Don't use your mistaken understanding of what expansion space means to try tie it to the speed of light.

[glader]

The normal sense of the world would imply you said the big bang created matter. If that's not what you meant, then cool. I'm biased to think you are mistaken because you think space cannot expand faster than light when we know for a fact that it does.

---------- Post added 2012-10-11 at 03:24 AM ----------


Indeed it has.

Don't use your mistaken understanding of what expansion space means to try tie it to the speed of light.

Well you're going to need to provide credible journals for this as it contradicts many upheld observations and the implications would be that, well something I've not pondered. I'm not daft enough to claim the Big Bang 'created' matter but I will openly claim that, as far back as we're able to trace it, that is the origin of observable matter.

[Giants41]

My Mind=Blown

[semaphore]

Well you're going to need to provide credible journals for this as it contradicts many upheld observations

No it doesn't. What obersvation is it contradicting?

(Also I'm not actually sure which or both conversations you are replying to).

[iscalio]

The only thing stopping it from doing so is the fact that nothing can travel faster than light in a vacuum. Unless you'd like to contradict a large amount of data that'll claim that nothing, other then things that carry no information and are massless, can travel faster than with a data set that is empty then I suggest you refrain from tearing down a central part of Physics.

He is not tearing down any part of physics, central or otherwise. In fact, he is the only one in this thread so far who displays an understanding of what he is talking about.

Consider the following analogy: You have a piece of white fabric, and on that fabric you have several black dots. The speed limit for those black dots on the fabric is zero, as they cannot move. We will call this speed c (ergo c = 0). Now we pick out two random dots and measure their distance from each other, and find it is x. Now picture the fabric being stretched - if you measure the distance between the same two spots again now, then the new distance will be larger than x.
For an inhabitant of the fabric making these measurements, it would appear as if the dots had moved (as he had no way of witnessing the stretching of his world directly), and thus it would seem to him as if the dots had exceeded their speed limit c (which he knows is impossible, as he is a physicist).

It's the same with our universe. The different dots (let's say galaxies) on the fabric (spacetime) seemingly move away from each other with speeds higher than c (the speed of light), even though in reality they don't (since they can't, as all physicists know). But the fabric was stretched (expanded) between them, so there was still distance created between them at a rate of expansion that can surpass c.

Did this help?


A lot of people in this thread seem to believe that the universe is something expanding into something else ("empty space"). That is nonsense. There is nothing outside of the universe as the universe is all space by definition. It is infinite insofar as it is not finite - there is no "border" behind which the universe ends. It does not end at all. And yet it expands. There is no contradiction here once you understand what is meant by these words.

[glader]

No it doesn't. What obersvation is it contradicting?

(Also I'm not actually sure which or both conversations you are replying to).

It's contradicting all the observations which have turned up supporting the notion that nothing, unless massless without information, exceeds the speed of c. How could matter such as a gas travel faster than light at the birth of the known universe?

[iscalio]

It's contradicting all the observations which have turned up supporting the notion that nothing, unless massless without information, exceeds the speed of c. How could matter such as a gas travel faster than light at the birth of the known universe?

Check my post right before yours.

[This name sucks]

Let me make it really simple:

Infinity + 1 = Infinity.

I hope that clears some stuff up for you.

Isn't that actually

Infinity + 1 = Infinity +1

[Itisamuh]

I always find these science debate threads very amusing. Further proof that we know nothing.

[semaphore]

It's contradicting all the observations which have turned up supporting the notion that nothing, unless massless without information, exceeds the speed of c.

No it isn't. As has been repeatedly stated, space itself is expanding. The galaxies themselves are not moving any faster and so the speed of light is not surpassed. See iscalio's post for a good explaination from someone with far more patience and friendliness than me.

Again, you're using your own mistaken understanding of what expansion space means to try argue a blatantly wrong point.

How could matter such as a gas travel faster than light at the birth of the known universe?

Do a google search for the size of the observable universe.

[Klingers]

I think a more theoretically accurate way to explain this (and I could be wrong, I won't claim to be an expert on something I only have an interest in) might be that the universe does have an effective four-dimensional outer-edge, but its expansion capability is effectively infinite.

[Matchu]

It's contradicting all the observations which have turned up supporting the notion that nothing, unless massless without information, exceeds the speed of c. How could matter such as a gas travel faster than light at the birth of the known universe?

You're confusing "expansion". When we say the Universe is "expanding", it's not meant in the traditional sense of speed (it moves from point A to B at Xmph). We think light is the fastest thing in the universe, but it still travels across spacetime, the fabric of the universe. In the expansion of the universe, it's the very fabric itself that's expanding and stretching. It doesn't obey the same rules as light, because...well they're not in the same game.

[iscalio]

I think a more theoretically accurate way to explain this (and I could be wrong, I won't claim to be an expert on something I only have an interest in) might be that the universe does have an effective four-dimensional outer-edge, but its expansion capability is effectively infinite.

Nope. It does not have an outer edge. What would be behind it?