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Are comoving distances time-independent?

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A comoving reference frame expands along with the universe, factoring out the effect of the Hubble expansion. Suppose a galaxy has a redshift z=1 and its comoving distance DM is 11Gly=const. . This is also the distance we measure today. After 1000 years the distance to that galaxy is measured again:
- will its comoving distance still be considered 11Gly ?, or
can the comoving distance be redifined? Then it will be larger than 11Gly since the reference frame has expanded, stretching the distances?

asked May 25 in Astronomy by rhkail (0 points) [ no revision ]

Do not confuse coordinate differences with proper physical distances. The co-moving coordinates of an object need not be constant, as the object's motion need not be determined by the expansion of the universe only. For example, two galaxies can attract each other and collide.

commented May 25 by Flamma (90 points) [ no revision ]

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