Quote:
Originally Posted by Archy
What is clearly incorrect:
1) For the cosmological model postulated by CraigS it is possible the the two galaxies will blink out at the same time.
2) However, the entire universe can only blink out if Y is a photon from the galaxy furthest from us and X is a photon from the galaxy nearest to us and all galaxies are receding so fast that light cannot reach us.
3) However some galaxies are not moving away from us. So the universe will not blink out all at once.
|
Try re-reading my previous post.
Quote:
[/I]You mention the Hubble sphere. As I understand Hubble sphere is the region of the Universe surrounding an observer beyond which objects recede from the observer at a rate greater than the speed of light, due to the expansion of the Universe.
There has been no empirical evidence of anything moving at a rate greater than the speed of light.
|
Of course there is empirical evidence.
Any object that has a cosmological redshift z> 1.46 has a recessional velocity greater than c.
The reason we see some of the photons emitted was explained in my previous post.
Objects formed in this era occurred at a time
before there was an acceleration in the expansion of the Universe. Photons that are intially superluminal become subluminal as the velocity of the Hubble sphere can eventually exceed the scale velocity of the Universe. These subluminal photons become observable.The objects themselves however continue to recede at superluminal velocities.
For a more technical explanation.
http://arxiv.org/abs/astro-ph/0310808
The Wikipedia article regarding the speed of light refers to
objects travelling in space-time. When we refer to recessional velocities of objects, the objects are in fact
stationary in space-time but are being carried by the Hubble flow or the expansion of space-time.
The Wikipedia article has no relevance.