Re: The Big Crunch may be a possibility

On Thu, 27 Mar 2025 10:19:43 -0400, Kestrel Clayton
<richZIG.e.clayZIGton@gmail.com> wrote:

On 27-Mar-25 01:53, jillery wrote:

On Wed, 26 Mar 2025 09:31:10 -0400, Kestrel Clayton
<richZIG.e.clayZIGton@gmail.com> wrote:
 

Here's a source I found useful, as a first-pass primer:
>
https://newscenter.lbl.gov/2025/03/19/new-desi-results-strengthen-hints-that-dark-energy-may-evolve/
>
It's still pop science, but at least it's pop science written by actual
scientists. The page is careful to state "the preference for an evolving
dark energy has not risen to '5 sigma,' the gold standard in physics
that represents the threshold for a discovery." Also it does not claim
that cosmic expansion is slowing; only that the *rate of increase* in
expansion due to dark energy may have slowed in the past (and is
presumably still slowing). In other words, the car isn't slowing down,
but dark energy is very slowly easing up on the throttle.

 
 
IIUC you distinguish between "rate of increase" aka acceleration and
plain vanilla increase.  If dark energy is constant, then rate of
increase would be proportional to the distance between objects aka
Hubble's Law.  If distant objects accelerate more slowly than
expected, then some other factor besides dark energy or gravity is
involved (gravity weakens over distance).
 
I have speculated in the past that dark energy might weaken over time
due to some quantum effect, which suggests that spacetime isn't doomed
to expand forever, and instead, some googolplexian years from now,
collapse cyclically back onto itself.

>
Could well be. We're far off the map from what I know — when I was a
physics student, the phrase "dark energy" hadn't even been coined yet.

You and me both.  A challenge for mere mortals like us is that
cosmology is still on the bleeding edge of ignorance, so new
discoveries almost necessarily create controversies and paradigm
shifts among those who are paid to know what they're talking about. It
(almost) makes me long for the mindless simplicity of Genesis:

"In the beginning, the earth was formless and void, and darkness
covered the face of the deep.  Then God said, 'Let there be light',
and there was light.  Of course the earth was still formless and void,
but now you could see it better."  (Woody Allen?)




--
To know less than we don't know is the nature of most knowledge