We all know that the velocity of a point in the proper distance
increases since it keeps changing, what about velocity of a point in the comoving distance?
Lets assume we are observing a galaxy at point A and we record it's velocity, after sometime it moves on and that same point is replaced by galaxy B. Will there be any differences in velocity between galaxy A and B basing on the current model of the Universe?
Comoving distance is constant by definition so I'm not clear what you are asking.
Lets assume we are observing a galaxy at point A and we record it's velocity, after sometime it moves on and that same point is replaced by galaxy B. Will there be any differences in velocity between galaxy A and B basing on the current model of the Universe?
ME: Lets assume we are observing a galaxy at point A
ME: Will there be any differences in velocity between galaxy A and B
What is "A"? Is it a location, described by a distance from us which doesn't change, or is it the label of a galaxy which gets farther away? You need to be more careful in how you ask your questions.
ME: Lets assume we are observing a galaxy at point A and we record it's velocity, after sometime it moves on and that same point is replaced by galaxy B. Will there be any differences in velocity between galaxy A and B basing on the current model of the Universe?
Let's ignore local peculiar motion and consider comoving galaxies so galaxy A is at a fixed comoving distance and galaxy B is at a fixed but smaller comoving distance, and we can define a location X as being at some fixed proper distance D.
At some time t1, galaxy A is at location X receding at proper speed VA1. At some later time t2, galaxy B passes location X receding at speed VB2.
The Hubble law says the speed is proportional to the distance D but the coefficient is falling with time so VB2 < VA1.
If these terms aren't clear, I would recommend reading the Lineweaver paper which clears up a lot of confusion.
https://en.wikipedia.org/wiki/Comoving_distance#Comoving_distance_and_proper_distance
http://arxiv.org/abs/astro-ph/0310808v2
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