On Tuesday, July 14, 2020 at 2:50:12 PM UTC-6, Brent wrote: > > > > On 7/14/2020 12:22 PM, Alan Grayson wrote: > > > > On Tuesday, July 14, 2020 at 11:31:42 AM UTC-6, Brent wrote: >> >> >> >> On 7/14/2020 3:34 AM, Lawrence Crowell wrote: >> >> On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote: >>> >>> >>> >>> 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 >>>> >>> >>> About the EP; I merely stated that it demonstrates that acceleration is >>> locally indistinguishable from gravity, and then I stated what "locally" >>> means. This is what Wiki and other sources say. Yet you say I am confused. >>> How so? About masses of BH's, I watch documentaries which feature >>> astrophysicists offering their opinions, and they *uniformly* claim >>> that BH's have mass. How could it be otherwise if they're remnants of >>> massive collapsed stars? Not one makes Brent's claim, that they're just >>> geometric manifestations. AG >>> >> >> I didn't say they lacked mass. I said they lacked matter. Thus >> countering your assumption that gravity requires matter. >> >> Brent >> > > I could have said that gravity requires mass/energy. What's the > distinction between matter and mass? TIA, AG > > > Some things, e.g. black holes, have mass without matter (at least as far > as GR goes). > > Brent >
What's the distinction between matter and mass? 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/63bdb91a-8c21-4e13-a97b-053a50762926o%40googlegroups.com.
