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 > > > Black hole mass is a pure spacetime physics. There is no material stuff > anyone can get their hands on. With the tortoise coordinate the distant > observer might say the matter-fields that made of a black hole exist, but > if one tried to reach them they always recede away. Black holes do not have > mass in a standard sense, though they have an ADM mass defined by the > curvature of spacetime. > > LC > -- > 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] <javascript:>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/73eaaefd-b59a-4c4e-88bd-7b2aac7c1d0bo%40googlegroups.com > > <https://groups.google.com/d/msgid/everything-list/73eaaefd-b59a-4c4e-88bd-7b2aac7c1d0bo%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > > -- 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/6375f7ec-2c0d-4291-8015-37446201039ao%40googlegroups.com.
