Re: Spacetime

On Tue, 25 Jun 2024 12:20:20 +0000, gharnagel wrote:

>
“spacetime is likely to be an approximate description of
something quite different.” – Steven Carlip
>
It's interesting how most physicists describe spacetime
as an actual "fabric."  It's really a mental model that
may not have any existence at all.  The equations of
relativity describe what actually happens quite well,
but the "fabric" of spacetime may be an invention.
>
I think the things that are real are THINGS.  I find the
basic concept of string theory very compelling: that is,
elementary particles are not points as the standard model
posits.  In the real world there are no such things as
dimensionless points.  It's a very good assumption because
the string theory particles are way smaller than we can
detect, but presuming elementary particles have extension
in space is surely correct, even though strings may not be.
>
Some of the things that string theory leads to, however,
are very interesting, such as M-theory and branes.  The
ekpyrotic theory is one that sets forth a reason why the
big bang happened:
>
https://en.wikipedia.org/wiki/Ekpyrotic_universe
>
although I disagree with a cyclic universe as presented.
Anyway, that's not necessarily a given in the theory.
The universe may still be cyclic without a contraction
(in agreement with the present information that the
expansion is accelerating).  The energy for a bang comes
from the bashing of an adjacent brane into ours, as
proposed in the original theory and, if it happened once,
why couldn't it happen again?  And again, and again, and
again?
>
This would shoot down the idea that spacetime (and space)
only extends as far as the last bang (the one nearest and
dearest to our hearts) has had time to expand.
>
So then the question arises:  what would be the effects
of a previous bang on us?  If we applied GR to that model,
might it not explain some mysteries we are dealing with?

>
It seems that everyone is married to their own vision.
That's fine, but it seems to me that they should start
their own thread to discuss it.  Then everyone can decide
if they want to discuss it there.  I want arguments
against the ideas I've presented above.
>
“I never learned from a man that agreed with me.”
– Robert A. Heinlein
>
OTOH, I never learned much from an idiot, either.
>
All ideas fall short of reality, so Carl Sagan suggested
a way to get closer:
>
"Spin more than one hypothesis. If there’s something to
be explained, think of all the different ways in which
it could be explained. Then think of tests by which you
might systematically disprove each of the alternatives.
What survives, the hypothesis that resists disproof in
this Darwinian selection among “multiple working
hypotheses,” has a much better chance of being the right
answer than if you had simply run with the first idea
that caught your fancy.
>
"Try not to get overly attached to a hypothesis just
because it’s yours."