Big Bang and the speed of light

[Alpinestars]

Noddy question about the speed of light and the Big Bang.

Just listening to 5 live this morning and a caller asked how we, at the "edge" of the Big Bang are able to look back to its origin. The "expert" explained that we were all part of the Big Bang in that everything was at the same place? and the Big Bang caused an expansion of space and therefore created distance between objects. We can now look back, I assume at things that didn't expand as quickly?? I must have that wrong, because wouldn't that mean we would have travelled faster than the speed of light to be able to look back at things which are billions of years old (via the light they emitted billions of years ago)?

Hope that makes sense?

What have I misunderstood?

Thanks

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Alapeno said:

This is as basic as it comes I think, someone will probably be along to expand on this.

Inflation theory says that Space actually expanded rather than objects moving at relative speed and distance to one another. A basic way of looking at it is to draw 2 dots on a balloon and then inflate it. The dots haven't moved from their original position in space (on the ballon) but the space between them has.

Hopefully that makes a little bit of sense.

ETA - think of space as the material that makes up the balloon in 2D (the rubber) rather than the air inside. Then apply that to 3D and you'll get the idea.

Edited by Alapeno on Friday 12th February 09:38

That's helpful.

Did the space expand quicker than the speed of light? Which still takes me back to my original confusion. Ie, what's the relationship between the expansion and the speed of light? To a layman like me, it seems as if light got "left behind". Otherwise I can't reconcile that everything started in the same place, or came to being in the same place, expansion created the distance, but light from the earlier objects (ones where expansion didn't create the same distance?) is still observable. If speed is limited to the speed of light, how can we look back at light?

I'm probably not articulating it well but hopefully someone understands my ramblings.

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I still don't understand if space expanded quicker than the speed of light.

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Halmyre said:

According to theory, yes, shortly after the big bang it goes through a period where it expands faster than light. It's the reason why the universe is lumpy (i.e. has structure), like overheating a beurre blanc; it splits and curdles.

Wow. So something did travel quicker than the speed of light? What was that something and why are we no (theoretically and practically) limited to the speed of light?

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davepoth said:

Travelled faster than the speed of light now and here. In areas of extreme gravity both the concepts of metres and seconds become a bit flaky, and we'd expect extreme gravity at the point of the big bang.

Sorry I still don't understand. If both the Earth and say a distant star started in the "same" place. How did expansion create space between light emitted bu the star and the Earth, when both the Earth and light were subject to the same extreme gravity? Did it only act on matter (Earth) and not on light? I know we can't recreate Big Bang, but can extreme gravity not be created on a small scale to show expansion taking place quicker than the speed of light?

Apologies if I'm being slow.

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davepoth said:

You aren't being slow - Anyone who announces that they fully understand it doesn't really understand it at all; even Stephen Hawking makes it up as he goes along.

The answer to that question is really that nobody is entirely sure. Hopefully further study of gravitational waves will lead us to some more information about what happened at the creation of the universe, bearing in mind that the Big Bang still hasn't been proven.

Thanks. No idea what made me think of the question in the first place!