On Tuesday, July 14, 2020 at 9:43:11 AM UTC-6, Lawrence Crowell wrote: > > On Tuesday, July 14, 2020 at 5:55:52 AM UTC-5, Alan Grayson wrote: >> >> >> >> On Tuesday, July 14, 2020 at 4:34:00 AM UTC-6, 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 >>>> >>> >>> 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. >>> >> >> Generally, what resides inside a BH interacts gravitationally with what's >> exterior and is the remnant of a Type 1A supernova. It's unreachable, but >> has some correspondence with normal mass, which is why its mass can be >> estimated by its exterior effects, say for the one residing at the core of >> the Milky Way. I don't know how their masses are estimated when they are >> cores of distant galaxies. AG >> > > The interior does not interact with the exterior. The event horizon > prevents that. >
Then how can a BH interact gravitationally with objects external to the event horizon, or do you deny that? AG > From the perspective of anyone in the exterior the interior of a black > hole is nothing more than a theoretical abstraction. It only exists as a > counter factual situation, where instead of remaining outside an observer > enters the BH/ > > 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]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/236ec928-6fd9-42ff-ada6-cd1387c61aa1o%40googlegroups.com.
