Fun with black holes
in [Relativity]
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From: Edward Green on 24 May 2010 18:19 On May 24, 2:42 am, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > eric gisse wrote: <...> > > The event horizon is isn't a membrane. It is not a material surface. It is > > not 'there'. Nothing special happens when something passes through it, other > > than the certainty of never leaving the black hole. > > Yes to all that. But the horizon is a geometrical locus, and when spacetime is > foliated into space and time, the spatial locus at a given time can change over > time. Again I have reference to Thorne (1994), the popular book mentioned earlier, and which I unaccountably have actually read, pretty much cover to cover (so much easier than even reading the words of all of MTW, much less grokking the equations): p. 405 ff "Sometimes people who are new to a field of research are more open- minded than the old hands. Such was the case in the 1970's, when new people had insights that led to a new paradigm for black holes, the _membrane paradigm_". ... Yes, I hasten to add, I understand that that doesn't mean a material membrane! "When I, as an old hand at relativity theory, heard this story, I thought it ludicrous". ... But... "Unable to resist its allure, I spent much of the 1980's, together with ... bringing it into a polished form a writing a book on it, _Black Holes, The Membrane Paradigm_. I notice that MTW was copyright 1970 - 1973, so Thorne (1994) at least brings us half way to current research.
From: BURT on 24 May 2010 18:27 On May 24, 3:19 pm, Edward Green <spamspamsp...(a)netzero.com> wrote: > On May 24, 2:42 am, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > > > eric gisse wrote: > > <...> > > > > The event horizon is isn't a membrane. It is not a material surface. It is > > > not 'there'. Nothing special happens when something passes through it, other > > > than the certainty of never leaving the black hole. > > > Yes to all that. But the horizon is a geometrical locus, and when spacetime is > > foliated into space and time, the spatial locus at a given time can change over > > time. > > Again I have reference to Thorne (1994), the popular book mentioned > earlier, and which I unaccountably have actually read, pretty much > cover to cover (so much easier than even reading the words of all of > MTW, much less grokking the equations): > > p. 405 ff > > "Sometimes people who are new to a field of research are more open- > minded than the old hands. Such was the case in the 1970's, when new > people had insights that led to a new paradigm for black holes, the > _membrane paradigm_". ... > > Yes, I hasten to add, I understand that that doesn't mean a material > membrane! > > "When I, as an old hand at relativity theory, heard this story, I > thought it ludicrous". ... > > But... > > "Unable to resist its allure, I spent much of the 1980's, together > with ... bringing it into a polished form a writing a book on it, > _Black Holes, The Membrane Paradigm_. > > I notice that MTW was copyright 1970 - 1973, so Thorne (1994) at least > brings us half way to current research. Black holes are a theoretical failure and we are not seeing them. It is going to take time for the stupid people to figure this out. Mitch Raemsch
From: Edward Green on 24 May 2010 20:40 On May 24, 6:27 pm, BURT <macromi...(a)yahoo.com> wrote: > Black holes are a theoretical failure and we are not seeing them. It > is going to take time for the stupid people to figure this out. The people involved are hardly stupid. I do notice a deafening silence from the gravitational wave detectors, however. Am I missing something?
From: BURT on 24 May 2010 20:46 On May 24, 5:40 pm, Edward Green <spamspamsp...(a)netzero.com> wrote: > On May 24, 6:27 pm, BURT <macromi...(a)yahoo.com> wrote: > > > Black holes are a theoretical failure and we are not seeing them. It > > is going to take time for the stupid people to figure this out. > > The people involved are hardly stupid. I do notice a deafening silence > from the gravitational wave detectors, however. Am I missing something? They aren't smart. But they think they are. Mitch Raemsch
From: Edward Green on 24 May 2010 20:51
On May 21, 9:21 pm, eric gisse <jowr.pi.nos...(a)gmail.com> wrote: > Edward Green wrote: > > On May 21, 6:41 pm, eric gisse <jowr.pi.nos...(a)gmail.com> wrote: > >> Edward Green wrote: > > > <...> > > >> > Thereafter the black hole rings out like a bell until > >> > the perturbation to its horizon has been absorbed. > > >> No again. There is no analysis anywhere which supports this. > > > MTW p.886 > > > "When matter falls down a black hole, it can excite the hole's > > external spacetime geometry into vibration. The vibrations are > > gradually converted into gravitational waves..." > > Which does not mean the horizon itself changes. I suspect neither of us knows enough to answer this definitively, but analyticity suggests to me that if the spacetime curvature immediately adjacent to the horizon is vibrating, then so is the horizon. And BTW, the above quote also supports my contention that black holes can have hair, they just tend to radiate it away. The theorems refer to _stationary_ black holes, not excited ones. An excited black hole is obviously not solely characterized by mass, charge and angular momentum. |