According to Hubble, the more distant galaxies are moving faster than those close to us. But, because light takes time to arrive on Earth, we’re seeing how galaxies *used* to be, the more distant in space the further back in time. I guess I’m asking how couldn’t it be argued that cosmic expansion is slowing down, since light from "more recent" galaxies shows less red shift than "older" galaxies? Sorry, this is just a weird question that’s been hanging around in the back of my brain for a while. Comments?
Some distant galaxies appear to be accelerating away from us, not just moving at a uniform speed.
And the most distant galaxies are probably expanding away from us at more than the speed of light. This does not violate the special theory since no information is being transferred (see reference).
November 30th, 2009 at 7:21 pm
It is not known whether the universe is expanding indefinitely, approaching a stable expansion or destined to cease expanding and begin contracting. Calculations depend on the amount of matter (mass) in the universe. It is especially difficult to assess the mass of dark matter which can not be "seen" by normal means.
It is also difficult to gage the ages of the galaxies. Hubble is celebrated for discovering that the more distant a galaxie is from the earth the faster it seems to be moving away from us (based on red shift, etc.). Some explain this as a uniform expansion – similar to the expansion between equally spaced dots on the surface of a balloon that is being inflated. The further away from us a "dot" is the faster it seems to be moving away from us; even though all dots are expanding the same amount compared with its nearest neighbors.
References :
November 30th, 2009 at 7:31 pm
Some distant galaxies appear to be accelerating away from us, not just moving at a uniform speed.
And the most distant galaxies are probably expanding away from us at more than the speed of light. This does not violate the special theory since no information is being transferred (see reference).
References :
http://www.sciam.com/article.cfm?articleID=0009F0CA-C523-1213-852383414B7F0147&sc=I100322