On Sun, Apr 14, 2024 at 5:53 PM Jesse Mazer <laserma...@gmail.com> wrote:
*> "The article > at > https://arstechnica.com/science/2024/04/dark-energy-might-not-be-constant-after-all/ > <https://arstechnica.com/science/2024/04/dark-energy-might-not-be-constant-after-all/> > says: 'One alternative theory proposes that the universe may be filled with > a fluctuating form of dark energy dubbed “quintessence.” There are also > several other alternative models that assume the density of dark energy has > varied over the history of the universe.'I'd heard of "quintessence" (a > dynamical scalar field throughout space) as an alternative to a > cosmological constant, does anyone know what the "several other alternative > models" with variable dark energy might be?"* > *The word "Quintessence"covers a lot of ground, it's just a placeholder name for a hypothetical fifth fundamental force of nature that produces a field with a negative pressure (stress) and thus, according to Einstein's General Relativity, would cause the universe to accelerate. If the recent observations made by the Dark Energy Spectroscopic Instrument (DESI) in Arizona about the expansion of the universe turn out to be valid (it only has a 3 sigma and you need a 5 sigma or more to claim a discovery) and the strength of Dark Energy really does change over time, then it cannot be an inherent property of space itself as most had thought. So it must be caused by some form of Quintessence. * *One very popular type of Quintessence is called, for reasons not entirely clear to me, "Phantom Dark Energy"; it hypothesizes that Dark Energy is a field that contains negative kinetic energy. But there are problems with this idea, it is very difficult to reconcile negative kinetic energy with standard Quantum Mechanics. And in the lab nobody has ever found anything that has negative kinetic energy. And if the DESI observations turn out to be true then Dark Energy is getting weaker overtime, but Phantom Dark Energy predicts it should get stronger leading eventually to the Big Rip.* John K Clark See what's on my new list at *Extropolis* <https://groups.google.com/g/extropolis> edp -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAJPayv1mdnd%2BmFbQa6tQp3qYkWAVa4shQZSrEeiDhfEbwej%3DGw%40mail.gmail.com.
