On Wednesday, September 4, 2019 at 9:03:44 AM UTC-6, John Clark wrote: > > On Tue, Sep 3, 2019 at 11:01 PM Alan Grayson <[email protected] > <javascript:>> wrote: > > *> Just sum over the estimated total of 10^80 particles, using mc^2 by >> first estimating the average mass of those particles for the rest energy, >> adding their average potential gravitational energy and their average >> kinetic energy. Why not? AG* >> > > What about the energy in light, it's being redshifted by the expanding > universe and thus becoming weaker, where did all that energy go? I would > maintain the energy went nowhere it was just destroyed. When looked at > at the scale of the entire universe why would anyone even expect energy to > be conserved? Noether's Theorem says if there is time-translation > invariance, that is to say if things generally look about the same from one > time period to another, then matter-energy is conserved, but in our > expanding accelerating universe things don't look the same. So it might be > better to say that in general relativity spacetime can create energy, as it > does when it accelerates the expansion of the universe, or destroy energy, > as it does when it redshifts photons in a expanding universe). So energy > simply isn’t conserved globally at the level of the entire cosmos, although > it is locally at least approximately. > > John K Clark >
It's claimed the energy is undefined in GR. Regardless, what I am trying to do is estimate what the total energy is, not whether it's conserved for an expanding or contracting universe. 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/161ef99b-246d-4d0c-a012-b68f1cdcd1ee%40googlegroups.com.
