Re: Faster than c expansion

Posted by DickT on January 23, 2003 at 20:44:39:

In Reply to: Re: Faster than c expansion posted by dlgoff on January 23, 2003 at 10:49:23:

Don,

I think it's quite possible that there are galaxies "over the horizon" from us. Their light will never reach us. And if gravity propagates at c, their gravity will never affect us either.

Matter doesn't make the universe expand, it tends to make it shrink. But apparently there isn't enough matter to make the universe shrink, and it continues to expand.

There is another effect that matter has, which is different from expanding and shrinking. Matter determines the overall curvature of spacetime. The curvature can be negative, analogous to a saddle shape in two dimensions, or positive, analogous to a sphere, or it can be zero, analogous to a flat surface. Apparently there is just exactly enough matter that the overall curvature is precisely zero to several decimal places. This is an open question, where does this accuracy come from.

Regards,
Dick

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