On Saturday, February 15, 2025 at 9:20:55 PM UTC-7 Alan Grayson wrote:
On Saturday, February 15, 2025 at 9:11:22 PM UTC-7 Brent Meeker wrote:
On 2/15/2025 7:03 PM, Alan Grayson wrote:
On Saturday, February 15, 2025 at 1:56:14 PM UTC-7 Brent Meeker wrote:
On 2/14/2025 11:36 PM, Alan Grayson wrote:
On Friday, February 14, 2025 at 11:06:42 PM UTC-7 Brent Meeker wrote:
On 2/14/2025 3:23 PM, Alan Grayson wrote:
On Wednesday, February 12, 2025 at 12:36:38 PM UTC-7 Brent Meeker wrote:
On 2/12/2025 12:55 AM, Alan Grayson wrote:
If the age of the universe is finite, which is generally believed, then no
matter how fast it expands, it can never become spatially infinite, So,* IF*
it is spatially infinite, this must have been its initial condition at or
around he time of the Big Bang (BB). But this contradicts the assumption
that it was at a super high temperature at or around the time of the BB.
No it doesn't. I can be infinite and high temperature. What gave you idea
it couldn't?
IOW, if we run the clock backward, the universe seems to get incredibly
small,
If the universe is infinite, then it is only the Observable Universe that
gets incredibly small.
*Is there any principle you are aware of, which prevents an infinite
universe from becoming incredible small? *
*It would have to undergo an infinite change in size in a finite time,
which would require infinite relative velocities. Brent*
*I can't imagine a universe starting as infinite in spatial extent -- can
you? -- *
As well as I can imagine any infinite thing. Imagination can be trained.
My supervising professor, Englebert Schucking, could visualize four
dimensional objects and draw their projection on the blackboard. If you
can't do that, you just have to suppress some dimensions; then in the (t,r)
plane there's an infinite line, the t-axis, and to the right of this line
is the (t,r) plane and in that plane everything is moving apart. Just look
at Ned Wright's cosmology tutorial:
https://www.astro.ucla.edu/~wright/cosmolog.htm
Brent
The problem is this; how does one imagine a universe which suddenly comes
into being, initially resumably with zero spatial extent, and when it does,
it's infinite in spatial extent? IMO, this would be a singularity implying
infinite spatial expansion instantaneously. I have no alternative but to
reject this model for a finite one, starting small and hot, and expanding,
since I have no idea what it means to begin infinitely. I am open to
suggestions. AG
Expand your imagination. Remember "infinite" just means without bound.
You don't have to imagine the whole infinite line, just imagine a line
without imagining it's ends.
Not saying I believe it, but the best bet at this point in time, is that
the universe began as a quantum fluctuation, thus small, very small! AG
BTW, since a finite volume such as the observable universe, can originate
from a point, those pictorial models of the evolution of the universe,
starting from a point, aka the BB, are apparently accurate in their
descriptions. That is, they're not necessarily simplifications of the
evolution. AG
Probably they are since they don't take account of quantum mechanics; but
we don't know exactly how they are wrong.
Brent
Consider this: For Nothing to become Something and also be infinite in
spatial extent, that Something must have that infinity as its initial
condition, given that it now has a finite age. But transforming from
Nothing to Something and having that infinity as its initial condition as
infinite in spatial extent, is, if you think about, not remotely
intelligible. For this reason, I conclude it can't have this infinity as
its initial condition and can't be flat, which implies this infinity. AG
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