pharos at gmail.com
Wed Aug 25 06:22:05 UTC 2021
On Wed, 25 Aug 2021 at 01:22, spike jones via extropy-chat
<extropy-chat at lists.extropy.org> wrote:
> Adrian, this isn’t the way I understand it. In a finite (or gravitationally closed ) universe. There is not a place anywhere in space where one can go (ignoring the logistics of getting there) face one direction, there is everything, face the other direction, there is nothing. The big bang model kinda makes it sound like there should be a surface where everything appears to be inboard and nothing appears to be outboard. But that is misleading really. It makes it sound like everything started out as part of a big firecracker and now the bits are flying out everywhere. That isn’t what happened.
> The inflationary model suggests that absolutely regardless of where and when you are in spacetime, you will see stuff in every direction.
Yes, Ethan has an explanation here:
This boundary, however, is not an “edge” to the Universe in any
conventional sense of the word. It is not a boundary in space at all;
if we happened to be located at any other point in space, we would
still be able to detect and observe everything around us within that
46.1 billion light-year sphere centered on us.
This is because that “edge” is a boundary in time, rather than in
space. This edge represents the limit of what we can see because the
speed of light — even in an expanding Universe governed by General
Relativity — only allows signals to travel so far over the Universe’s
13.8 billion year history. This distance is farther than 13.8 billion
light-years because of the Universe’s expansion, but it’s still
finite. However, we cannot reach all of it.
But thinking about infinities still makes my brain hurt! :)
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