Re: The Big Crunch may be a possibility

On 3/20/2025 5:27 PM, Kestrel Clayton wrote:

  On 20-Mar-25 17:33, RonO wrote:

https://www.nbcnews.com/science/science-news/dark-energy-changing- understanding-rcna197386
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Dark energy may be waning, and the acceleration of our galaxies may one day end.

 That's interesting. I couldn't tell from the Berkeley Lab public release whether this new data suggest the rate of expansion is dropping, or if the acceleration of the rate of expansion is decreasing (instead of increasing, which is the current consensus). In other words, is it slowing down, or just not speeding up quite as fast?
 

What would happen after the big crunch?  Would all the matter in the universe eventually fall into one large black hole?  How much matter can a black hole contain before something like the Big Bang happens?  There is already "evaporation" from black holes.  Would anything send the evaporation out of control?  Could anything like a Big Bang occur within a black hole to create a new universe within the event horizon?

 I'm fairly out of date on this, but before the discovery of dark energy, the consensus was that the universe is either flat, or so close to spherical as to be indistinguishable. That would indicate the expansion of the universe would eventually halt, but the universe would not really collapse. Instead, given enough time, the stars would all burn out, all protons would eventually decay, and even the black holes would evaporate, until all that remains are photons, electrons, and some other, weirder particles. (However, I know photon decay is currently considered less certain a prospect than in the 1990s, so YMMV.)
 Everything collapsing into a massive black hole still seems unlikely, but if it did, that would simply be a different route to the photon age. Eventually energy states are so low that quantum phenomena become the biggest movers and shakers in the universe, and after that... we really don't know. It's simply off the map, as far as modern physics goes.
 Fascinating stuff. Thank you for sharing the article!
 

Google thinks that there might be enough dark matter and regular matter in the universe so that the collapse would happen if the expansion stops.
One science article that I read recently noted that inflation predicted that there are parts of the universe that would not be visible to the Webb telescope.  The fringe of our universe expanded away so fast that there would be a sort of event horizon past which light has not reached us inside the visible universe.  Sounds weird, but is all matter further away than that horizon, part of the calculations about whether the universe will collapse or not?
Ron Okimoto