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.
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
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