September 05, 2009


From Sijin N K:

Re: Something beyond visible universe detected? (Sept. 23): As far as I can understand, Unexpected motion in distant clusters of galaxies, being caused by a thing outside visible universe contradicts basic physics. Reason: We believe, there are objects outside the edge from where light has not got time to reach us since the big bang. So if visible universe edge is currently X light years away, so we see things there not more than X years old, and the invisible objects causing the motion on the clusters is X+Y light years away from us. The effect of any kind of information (Say gravity) to reach the edge will take at least Y years. So the effect of gravity or electromagnetic force or any other force will make the visible universe move after Y years. Then it will take X more years so that we can see, which means, we’ll see it after X+Y years minimum. But this contradicts to the original fact that we are seeing things at most X years old.

Please help throw some light on this if possible.

1 Comments:

Blogger sijin said...

Got clarification from http://en.wikipedia.org/wiki/Observable_universe
The basic assumption is not correct. This was my misconception that the objects in the universe wont go apart faster than light. Since the space itself is expanding faster than light (in the 4D time-space), the calculations wont hold good. So there can be things in the past visible universe which would have affected the motion in distance galaxies(which we may be seeing now), and these affecting objects have now gone out of visible universe..

September 09, 2009 2:19 AM  

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