On Sun, Aug 24, 2025 at 1:16 AM Alan Grayson <[email protected]> wrote:
*>>> **but I want what you're not interested in; to have model which > explains the phenomenon.* > > > *>> What causes the cosmological redshift?* > *The expansion of space. * > *What causes the expansion of space? * > *Space expands because, according to Einstein's General Relativity, static > equilibrium is unstable, the slightest perturbation will cause space to > either expand or contract. * > > > *>Why did the universe expand, rather than contract?* > *That is unknown. However it could've been predicted that the universe had to be expanding rather than contracting for thermodynamic reasons and the arrow of time. The second law of thermodynamics can explain why tomorrow will have a higher entropy than today, there are simply more ways to be ordered than disordered so if tomorrow is different from today then it's astronomically more likely to be less ordered not more ordered. But by using the exact same reasoning yesterday should also have had a higher entropy then today, which is clearly untrue. However it would make sense if the universe started out in a small low entropy state. How the universe could've started out in such a state is perhaps the greatest mystery in physics, if not in all of science. * > *> Which equations of GR illustrate that static equilibrium is unstable? > TY, AG * > *Einstein knew from the day he finished General Relativity in 1915 that his theory's equations predicted a universe that was either expanding or contracting, and he considered that a major flaw in his theory because all his astronomer friends told him (incorrectly) that the universe was static. So in 1917 he added a "cosmological constant" that he thought would keep things static; Einstein later said that was the greatest scientific blunder of his life. In the 1930s Arthur Eddington proved mathematically that even with a cosmological constant any small perturbation would cause the delicate balance to break down and the universe would either collapse or expand. About the same time Hubble discovered the universe was expanding and Einstein abandoned the cosmological constant idea. * * John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>* -- 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 [email protected]. To view this discussion visit https://groups.google.com/d/msgid/everything-list/CAJPayv0oQ%2BGzBsj7F2qLwjYoroYi0z1hGzi-mWq2Be5pVRst7g%40mail.gmail.com.
