Quote:
Originally Posted by Solanum
And my simple understanding of it is firstly that the expansion is not from one point, so you can't think of a small sphere getting larger and that by looking backwards in time we are looking towards the 'origin'/middle. The expansion of the universe is in every direction, not just one, so we haven't travelled 'out' from a centre point, but simply apart. The classic example is to draw points on an uninflated balloon and then blow it up. Considering only the surface of the balloon, the points are now all further apart than they were, but haven't moved from a common origin.
Although we can see more and more of the universe as time goes on (in absolute volume terms) due to the time from the universe changing from being opaque to transparent being further away from the time of observation (i.e. the present), we see proportionally less and less of it as (in relative volume terms), because due to the expansion less and less of the light from the rest of the universe can 'catch up' with us due to light having a finite speed.
Anyone feel free to correct me if my simple interpretation is wrong!
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The first part of what you wrote is correct. There is no centre to the Universe, as such. However, if you were talking about the centre of the expansion, you would have to move outside of spacetime to find it...i.e. you would have to jump to a higher dimensional state to view it. In effect you'd be placing yourself in superspace, or the space of all spaces. Which is, as far as supersymmetry is concerned, an 11 dimensional object.
The second part is a little harder. We do see more and more of the Universe over time, in terms of an increasing horizon distance bringing more of the Universe within the horizon. However, what we see is in effect a mirage, because those objects we see are only what we see of those objects as they were "x" billion years before. What they are now will be unknown as those objects now are much farther away from us than what they were then, and beyond the horizon limit. In effect we never catch up with those objects and by the time we did reach where they are "now", those objects would most likely no longer exist.