Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

When accelerated expansion of universe was discovered, the astronomers used redshift of ancient stars. Say if star is 10 billion years in the past, then it should be moving faster than star from 5 billion years ago because of distance. But not 100% faster, only close to 100% faster. So red shift for 10 bln star is slightly less than two redshifts of 5 bln year star. Is it what was measured in the discovery of accelerated cosmological expansion ?

share|cite|improve this question
up vote 0 down vote accepted

In practice, its much more complicated than that, but you definitely have the right basic idea. Redshift vs. time is non-linear even at much lower redshifts, see this figure:

enter image description here

The page it comes from might also be helpful:

share|cite|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.