On Fri, Jan 24, 2020 at 5:21 PM Bruce Kellett <[email protected]> wrote:
>> And I've heard a bunch of bad analogies but I still haven't heard a >> direct answer to my question: >> What is the difference between a "finite" universe that is expanding and >> accelerating forever and an infinite universe that is expanding and >> accelerating forever? >> > *> If you don't understand Brent's answer in terms of the range of values > in coordinate maps, then you will never understand the difference.* > Then I guess I'll never understand the difference. > > A finite universe has a finite range of coordinate values. > NOPE! Brent specifically said "*I'm assuming a continuum spacetime. So even a 1cm interval takes an infinite number of labels*". Thus even if the universe is not expanding at all and even if it's only 1cm across a infinite number of labels with a infinite rage of coordinate values printed on them would be needed. > * > Even if it is expanding exponentially, the range of coordinate values > only ever increases at the same exponential rate -- i.e., never becomes > infinite.* > For the sake of argument let's take the opposite of Brent's assumption and say that spacetime is not a continuum but is composed of discrete chunks. It doesn't help. Any finite range of values you name regardless of how huge it is will soon (very soon, the universe is after all accelerating) be shown to be insufficiently large. So I have to ask my question yet again: What exactly is so finite about this finite universe of yours? How can I tell the difference between a "finite" universe that is expanding and accelerating forever and an infinite universe that is expanding and accelerating forever, and if I can't tell the difference is there any difference? John K Clark -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAJPayv09HrNCxwDW39sji4haGZ1XHa7vWMxdtSfrYMnv4D5e-A%40mail.gmail.com.
