February 17th, 2014, 10:02 PM

Originally Posted by
mrjc99
but thats not the speed that they are travelling at now...thats the speed they were travelling in the past. maybe they have slowed down since then. could this explain why we believe that the universe is expanding faster than it actually is? thanks for the help.
It the very fact that we are looking at these galaxies as they were in the past that allows us to determine that the the rate at which the Universe is expanding is accelerating. The further we look into the universe, the further we look back in time. By measuring the distances of the galaxies and how fast they were receding, and doing this for galaxies at different distances from us, its like taking a series of snapshots of the universe over a range of time. A pattern is formed,and that pattern gives us a picture of how the universes expansion has changed over time.
"Men are apt to mistake the strength of their feelings for the strength of their argument.
The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone
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