Ben Rudiak-Gould wrote:
Yousuf Khan wrote:

If the universe is
expanding, and the further an object (e.g. a galaxy) is away from us,
the faster it is moving away from us. Are there parts of space so far
away from us that it's expanding away from us *faster* than the speed
of light?


You have to be careful of what you mean by "speed". It has units of
distance over time, but it's not the same as speed in special
relativity. With that caveat, the answer is yes.

Therefore the Cosmic Microwave Background Radiation isn't the cloak
that surrounds the secrets of the Big Bang, but just the curtain around
a part of the universe that is now out of contact with us.


The "speed" of the CMBR, in units of comoving distance over cosmological
time, is much larger than the speed of light. I think it's about 3.2c.
This means essentially nothing, since the speed of light has no special
status when talking about cosmological recession velocities.

-- Ben

I'm not sure I understand: Does that mean that there are portions of
the universe that we can never see because they are in effect moving
away from us faster than the speed of light? I thought that was
impossible--that the light just got more red-shifted at greater
distances.