On Sunday, March 9, 2025 at 2:54:12 PM UTC-6 Brent Meeker wrote:
On 3/9/2025 7:38 AM, Alan Grayson wrote: On Sunday, February 2, 2025 at 3:24:53 PM UTC-7 Brent Meeker wrote: On 2/2/2025 12:42 AM, Alan Grayson wrote: Einstein claimed that when his GR field equations predicted an explanding universe when he believed in the Steady State theory, he added the CC to GR to make it consistent with his belief. That's not quite accurate. He saw that solutions to the GR equations for a universe contained an undetermined constant, the Cosmological Constant. So he sought to determine it from the observed data. He consulted the best astronomers of his time and they assured him that the universe consisted of Milky Way and a some scattered nebula and it was unchanging. So he set the CC value to make the universe in equilibrium. What value would that be; CC=0? AG No it would be positive. As soon as he published this, it was pointed out to him that this would be an unstable equilibrium and was not consistent with the observed existence of the universe. Are you saying he was told by astromers that the universe is in stable equilibrium? Do you have a reference which shows why, presumably with CC=0, the equilibrium would be unstable? AG Why would you need a reference. Think for yourself. If you have a constant repulsive force balancing an inverse square attractive force... *I don't think you understand my question. Without a CC, or equivalently setting it to zero, don't we get a universe which is in UNSTABLE equilibrium, like balancing a pencil of its writing tip, so the universe expands or contracts in a very short time interval? Isn't this the issue Einstein faced? If so, why would he choose a positive CC? AG * About the same time Hubble published his discovery that the universe was expanding and Einstein called the CC, "My greatest blunder." If not for the astronomers he might have predicted the expansion of the universe before Hubble observed it. What a coup that would have been. What value for CC would he have needed to predict an expanding universe? Was this the value he originally set CC to? AG None. CC=0 It was just expanding due to the initial motion of bodies. *So what about the claim of UNSTABLE equilibrium if CC=0? AG* Brent But I recall a remark by Vic Stenger that the constant could have arisen naturally as the constant in an indefinite integral. Is there any substance to Stenger's claim? Sure. But the value of the constant can't be derived from the equation. Like any constant of integration it has to be determined by something else, usually boundary conditions. Brent That is, in the opaque process of creating the GR field equations, do INDEFINITE integrals play a role? AG. -- 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 visit https://groups.google.com/d/msgid/everything-list/67f877f8-4c33-4356-9f2e-69211ca52296n%40googlegroups.com.
