No_Spam wrote in
m:

Maybe some kind soul can answer this for me and tell me what I'm
missing ?
If the universe is just under 14 billion years old how can it be (from
what I've read) 93 billion light years across ?
If nothing can exceed the speed of light then shouldn't the maximum
diameter be no more than the age x2 (assuming the universe expands at
the speed of light, which it doesn't).
I have a feeling the explanation will be something to do with the
early universe not obeying the laws we observe now, but I can't find
any info on the sites I found so far and it's bugging me !!
Thanks...

See Wright's Cosmology FAQ at:
http://www.astro.ucla.edu/~wright/cosmology_faq.html#DN

It is the difference between distance-then and distance-now. Most
galaxy distances in popular media are described in terms of distance-
then. It takes 2.4 million years for light to travel from the Andromeda
galaxy to reach Earth, so its distance is 2.4 million light-years.

This measurement of distance leaves out two factors:

1) The universe itself - the fabric of space and time - expands at
superluminal speeds. The speed-of-light limitation means that light
cannot move through normal vacum space at more than a set speed. It
does not mean that the fabric of space itself cannot be expanding at
more than the speed of light. Many distant galaxies are so red-shifted
that their apparent speed relative to the Earth appears to exceed the
speed of light. This is not actual measurement of light traveling at
superluminal speed. It is an artifact of the space through which the
light is transiting expanding at superluminal rates. Confused? I am.

2) A very distant galaxy - let's say one 1 billion light years distant -
has been moving for a billion years and is no longer physically located
at the same spot when the light left a billion years ago.

The comoving distance - or distance-now - is usually much larger than
the more oft quoted distance-then.

Distance-then and distance-now measure the same thing - how far away a
distant galaxy is - just by different methods.

- Canopus56

A more complicated explanation at wikipedia
http://en.wikipedia.org/wiki/Comoving_distance

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