h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

i read somewhere that the universe is expanding faster than the speed of light ( C ) so what is the universe made of that could travel faster than C or am i mistaken?

I think you mean c.



It's a good question. If the universe is expanding faster than the speed of light - what's in the new bit of space?

Liam.

Maybe the universe is already there and light is only just reaching it now Until later....
BCNU - Crescent

I'm told that things traveling faster than the speed of light is only impossible in relation to the immediate vicinity. One theory on how interstellar travel might be possible is by warping space (hence the 'warp engines' in Star Trek) by greatly compressing the space in front of your ship and stretching the space behind it. In relation to the immediate vicinity of the ship, it is not moving at all, but in relation to the rest of the universe it is moving faster than the speed of light.

The universe certainly expanded faster than light at the start, just after the big bang. The universe is made of space-time, which is able to expand faster than light.

The universe is not a lump of matter which is expanding into a big empty space. It is the space itself which is expanding.

Don't worry, I don't really understand it either.

It is also the case that the speed of light only applies to information-carrying species. Something can travel faster than 2*10^8 ms^-1, but only something incapable of carrying information.

Such as?

Hmm, not heard this one before. I had it explained to me that the universe is everything that came from the Big Bang, rushing outwards. This is made up of energy and matter with the outmost edge being the fastest travelling stuff i.e. light. Hence, in that explanation the edge of the universe travels at the speed of light. Due to us not being able to look past this edge (technically an event horizon because nothing escapes from it) we don't know what is outside and, for all we know, the rules could be entirely different. It also means that technically the universe is a black hole, as no light can escape. I gave up on cosmology rather quickly.

The Universe doesn't have an edge. It is infinite. But it is expanding, so everything in it is getting further from everything else.

Tompkins In Paperback is a good place to start as is Time Travel in Einstein's Universe. I can't remember either author - though the first one begins with G.

Czerenkov radiation is where a particle is travelling through a medium at faster than the speed of light in that medium. It gives of an eerie blue glow. Seen in cooling ponds at nuclear power stations.

Liam.

I heard recently, that the latest theory is that the speed of light, due to the bending or *warping* of space-time, is not constant. I think this means that although something may travel faster than light travels here, it isn't in fact travelling faster than the speed of light in it's own vicinity.

Seamus

I've also heard it said that there are things beyond what we can see because they are travelling faster than the speed of light in relation to us and so the light coming from them will never reach us.

I saw an episode of Horizon about something like that. The scientist working on it was a guy called Joao Magueijo.

I think Einstein's theory never says you can't go faster than the speed of light. It just says that a massive accelerating body can never reach the speed of light.

Or that a mass can reach the speed of light given infinite energy.

sorry just to clear up some points:
The universe expands below the speed of light(3x10*8) although space-time is not like a piece of matter so somewhat strange rules apply,for example there is no expanding edge but every piece is expanding(there is some debate about the speed at the time of the big bang as normal physics breaks down at a singularity)
The speed of light is a speed that can never be reached, you can can get closer and closer to it but never actually reach reach it as relativity says you would require an infinity amount of energy to do so, the theroised particle tachyons supposed contantly travel faster then light but they can never reach the speed of light either for the same reason.
Also space is finite there is not an infinite amount of it, if you set of in a straight line you will eventually reach the point where you started, the matter in the universe distorts space-time amking the universe finite but unbounded.

I agree with much of what DarthWibble says, but I disagree with the following:

Space is finite and unbounded - No. The scientists have been desperately trying to show this for years despite all the evidence that it is infinite and unbounded. We do not live in a closed finite universe, we live in an open inifinite one. There is not enough matter in the universe to bend it round into a closed shape.

nasa (i think) recently relesed a picure that they got taken by MAP it was a microwave background of the early universe, it showed a finite universe with edges, but wat were those edge's made of or is it just an illution because of the space behind it?

I had a quike read over a brief history of time to the part where it said that the universe expanded faster than light, because the imformation couldnt get between the ends of the universe in light because light wasnt fast enough to catch up with the universe which expanded fast.

and i also saw an article about how the speed of light might be slowing down, but i didnt read it

Ummm, the microwave background is the residue of the energy from the Big Bang and as such is just a bunch of photons hurtling through space from a central event. Hence they will be going at the speed of light, so it seems reasonable to think it will have an edge. I get the feeling, from what has been said here, that this is not synonomous with the edge of the Space-Time Univers thingy. Does anyone have a definition for what is "The Universe" as certainly that is where I always fell down, not considering it all but just one bit and so coming up with false reasoning.

Munchkin, answered a question on this for his degree, and you wouldn't know it.

Dr M, that's really thinking big! Define the Universe!