How Universe is expanding faster than speed of light?

[SecretOfnumber]

Hi Guys ,

Just read this at The NASA site:

http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/070904a.html

""Q ...My question is if the universe is accelerating, eventually should it not reach a speed faster than the speed of light? Has anyone investigated the question as to what will happen if the expansion of the universe breaks the light speed barrier?

The Answer

A :Thanks for your question. It is true that nothing can go faster than the speed of light. And it is also true that our universe is expanding faster than the speed of light today. This sounds like a contradiction, but..."""

Could some one explain this to me please ?perhaps a little about length contraction... !sorry I just don't get it!

Cheers,

 

[Chronos]

Its a metric thing. Coordinates on the graph paper are not constrained.

 

[SecretOfnumber]

Thanks ,I guess I know what you mean, but does this is "actually "is happening in a physical world?

 

[Bandersnatch]

It means that even though the far away parts of the observable universe do indeed recede at velocities higher than c, nothing is ever overtaking light.

Here are two very good articles explaining the misconceptions about superluminal recession(among others):

http://www.mso.anu.edu.au/~charley/papers/LineweaverDavisSciAm.pdf
(page 40; the first page is blank)

http://arxiv.org/pdf/astro-ph/0310808.pdf
(chapter 3; more technical than the previous one)

 

[Mordred]

Along with Bandersnatch's excellent links. You can find more answers on this related and recent thread.

https://www.physicsforums.com/showthread.php?t=685265