On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote: > > On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan Grayson wrote: >> >> >> >> On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote: >>> >>> >>> >>> On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote: >>>> >>>> >>>> >>>> On 7/12/2020 11:50 PM, Alan Grayson wrote: >>>> >>>> There can be because it's consistent with the equations. A black hole >>>>> doesn't include any matter. General relativity is non-linear, that's why >>>>> there can be non-flat cosmologies that contain no matter. Of course >>>>> there >>>>> may be some different, better theory in which spacetime can't be curved >>>>> without matter...but it seems unlikely since we have good evidence that >>>>> gravitational waves exist. >>>>> >>>>> Brent >>>>> >>>> >>>> Yes, good evidence that gravitational waves exist, but as far I know >>>> they're always associated with material interactions such as collisions of >>>> black holes. In the case of EM waves, I'd be more receptive of your claim >>>> that they can exist independent of charges and/or currents, but as far as >>>> I >>>> know there's no evidence of that. AG >>>> >>>>> >>>> But a collision of black holes does NOT involve matter. Black holes >>>> (as far as the theory goes) are purely geometric things, i.e. made of >>>> empty >>>> space. >>>> >>>> Brent >>>> >>> >>> How then does the BH at the center of our galaxy weigh in at 4 million >>> solar masses? AG >>> >> >> It's measured by observing the rotation rates of stars near the galactic >> core, and not so small by comparison with other BH's at the center of >> galaxies, called Super Massive BH's. AG >> > > It is unfortunately apparent that you are pretty highly confused by some > of this. You need to sit down and read a comprehensive book or text on GR > and related subjects. It is not going to be possible to clear this up with > dozens of email posts. > > LC >
In reviewing Wiki's article on the Equivalence Principle, I see the details there are not exactly what I stated. But it doesn't really matter, except possibly for a purist, in the sense that I was trying to see how Einstein could have inferred curvature of space-time from the EP, using the enclosed elevator example subject to uniform acceleration. What I wrote seems sufficient to my objective. I am not confused. 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/c0e87cd8-af85-4cae-82c7-2d47e436cf80o%40googlegroups.com.
