Is the Universe expanding faster than the speed of light?

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Daniel Hötzel

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Daniel Hötzel  asked the Naked Scientists:
Hello to you all.
I listen to your podcast every week and it's a fantastic show.
I have a question for you.
I've been told that at the time of the big bang the universe expansion speed was enormous, even higher than the speed of light. Is this correct? and if so, how could that be, if light speed is the limit?
Have a nice day.

Daniel, Malmoe, Sweden 

What do you think?


Offline peppercorn

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Is the Universe expanding faster than the speed of light?
« Reply #1 on: 11/11/2009 10:22:31 »

The light-speed restriction only applies to matter or energy, not to space itself, which is neither matter nor energy.  Also, I understand that at this phase of the BB there wasn't any matter; it wasn't created until after the cosmic expansion phase.

Even now though, matter and energy at the opposite sides of the observable universe is receding from each other at > 'c'.  This isn't due to the matter and energy moving through space though, but once again, because space itself is expanding and carrying the matter and energy with it.

If we imagined that there was a maximum speed that boats could travel on water, then if the water was in a lake, with no flow, nothing could travel faster than the maximum water speed.  However, if the water is in a river and has it's own flow then the maximum water speed could be exceeded with reference to the river bank, but not with respect to other boats.