Thermodynamics and The Universe

If you had browsed, tediously, the cosmology threads you would find reference to the fact that the expansion of the universe is NOT anything moving through space (which is limited to light speed). It is the expansion of space itself. This is not limited to light speed.The expansion between two points in space is proportional to the distance between them. At some point this means that two galaxies may be receding from each other at greater than light speed even if they are not moving.If that is confusing try this analogy.Put ants on a big sheet of rubber. Now stretch the rubber bigger and bigger. The ants get further apart without 'moving' (on the sheet) at all.Ants that started further apart have more stretching rubber between them so they move apart faster than ants that started closer together.

Yes, this is the "red shift" you read about a lot. As the recession velocity goes up the light from a given galaxy is shifted (stretched) to longer and longer wave lengths. As the recession velocity approaches c (light speed) the wave length is stretched to infinity and the galaxy is no longer visible.(warning: I'm an amateur so wait for cavediver's corrections before swallowing completely)

I think the reason for this is that (off the top of my head or made up a bit) some light can get "left behind". It starts off before the speed of recession is too much and can get to us after the galaxy is "out of range".I have a proper explanation in some book here but, as usual, can't remember where. Edited by NosyNed, : spelling