On Friday, August 23, 2019 at 11:16:36 PM UTC-6, Alan Grayson wrote: > > > > On Friday, August 23, 2019 at 8:12:55 PM UTC-6, Lawrence Crowell wrote: >> >> On Friday, August 23, 2019 at 9:01:42 PM UTC-5, Alan Grayson wrote: >>> >>> >>> >>> On Friday, August 23, 2019 at 7:48:19 PM UTC-6, Lawrence Crowell wrote: >>>> >>>> On Friday, August 23, 2019 at 5:48:13 PM UTC-5, Alan Grayson wrote: >>>>> >>>>> >>>>> >>>>> On Friday, August 23, 2019 at 3:31:36 PM UTC-6, Lawrence Crowell wrote: >>>>>> >>>>>> On Thursday, August 22, 2019 at 12:37:40 AM UTC-5, Alan Grayson wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Wednesday, August 21, 2019 at 7:12:14 PM UTC-6, Alan Grayson >>>>>>> wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On Wednesday, August 21, 2019 at 3:13:11 PM UTC-6, Lawrence Crowell >>>>>>>> wrote: >>>>>>>>> >>>>>>>>> On Tuesday, August 20, 2019 at 4:56:23 PM UTC-5, Alan Grayson >>>>>>>>> wrote: >>>>>>>>>> >>>>>>>>>> https://en.wikipedia.org/wiki/Conformal_cyclic_cosmology >>>>>>>>>> >>>>>>>>>> Is this a viable theory for avoiding a BB interpreted as a >>>>>>>>>> singularity? AG >>>>>>>>>> >>>>>>>>> >>>>>>>>> Penrose proposed a conformal identification of spatial infinity in >>>>>>>>> the past and future i^±∞ of FLRW spacetimes. A cosmology expands and >>>>>>>>> in the >>>>>>>>> limit time → ∞ it transitions into a new cosmology. The de Sitter >>>>>>>>> vacuum is >>>>>>>>> not eternally stable, so the idea may have some germ of relevancy. I >>>>>>>>> am not >>>>>>>>> sure about how this would work with vacuum to vacuum transitions. The >>>>>>>>> exponential expansion of the universe is a sort of time dependent >>>>>>>>> conformal >>>>>>>>> transformation with a small vacuum expectation for the scale field. >>>>>>>>> To >>>>>>>>> transition to a new cosmology, say with inflationary expansion, this >>>>>>>>> means >>>>>>>>> the vacuum expectation is increased. >>>>>>>>> >>>>>>>>> The overall physics community response to this has been tepid at >>>>>>>>> best. There are some possible conflicts with observed data. >>>>>>>>> >>>>>>>>> LC >>>>>>>>> >>>>>>>> >>>>>>>> FWIW, ISTM that what GR might be indicating about the BB, is that, >>>>>>>> insofar as it's a singularity, it couldn't have occurred, and didn't >>>>>>>> occur. This is to say the universe didn't become infinitely small in >>>>>>>> spatial extent, like a mathematical point, but rather that there was a >>>>>>>> maximal finite value of its energy density, hugely high but not >>>>>>>> infinite. >>>>>>>> For this reason I find the cyclic models promising, although, as you >>>>>>>> rightly indicate, they're far from complete or bug-free. AG >>>>>>>> >>>>>>> >>>>>>> Which brings up a possibly relevant question: If the total energy of >>>>>>> the universe occupied zero spatial volume (the presumed condition of >>>>>>> the >>>>>>> universe at t=o according to the BB theory), wouldn't that contradict >>>>>>> the >>>>>>> Uncertainty Principle? AG >>>>>>> >>>>>> >>>>>> The total mass-energy content of the universe is zero. >>>>>> >>>>>> LC >>>>>> >>>>> >>>>> Is that a provable fact, or something that can be measured? TIA, AG >>>>> >>>> >>>> It is provable, because in general spacetimes there does not exist a >>>> Gaussian surface to define mass. This sets the energy to zero. Think of it >>>> as meaning gravitational potential energy as negative is equal in >>>> magnitude >>>> to positive mass-energy. >>>> >>>> LC >>>> >>> >>> If, using E=mc^2, one computes the rest energy of the material Earth, it >>> seems implausible that this equals the negative potential energy of the >>> Earth's gravitational field, to yield a net energy sum of zero. AG >>> >> >> Consider the gravitation with expansion and cosmological constant. This >> was first pointed out by Tolman many decades ago. >> >> LC >> > Do you have links on this specific topic? TIA, AG
> > I will. But maybe in the meantime you could explain how, using E=mc^2 and > the negative potential energy of Earth's gravity field , you can get them > to cancel out for an isolated Earth. Something very puzzling here. > Additionally, ISTM that one would have an impossible task making a nuclear > weapon from negative potential energy. What am I doing wrong, if anything? > 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/7082dbe8-f597-440c-85ed-7ce1655a706a%40googlegroups.com.
