Fun with black holes
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From: BURT on 24 May 2010 20:55 On May 24, 5:51 pm, Edward Green <spamspamsp...(a)netzero.com> wrote: > 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.- Hide quoted text - > > - Show quoted text - Light has no escape speed because it doesn't change from C. What applies to matter does not apply to light. Light always overcomes gravity. Matter while leaving slows down. Light does not. Stephen Hawking quoted me "There are no local boundaries to light." The no boundary proposal applies to gravity and light. Mitch Raemsch
From: Edward Green on 24 May 2010 21:19 On May 24, 8:55 pm, BURT <macromi...(a)yahoo.com> wrote: > Light has no escape speed because it doesn't change from C. What > applies to matter does not apply to light. Light always overcomes > gravity. Matter while leaving slows down. Light does not. > > Stephen Hawking quoted me "There are no local boundaries to light." > The no boundary proposal applies to gravity and light. I'm degrading my cred by replying to you. But I mention that I think I can understand how light can fail to escape from a collapsing start -- there is sort of a radial frame dragging. I'm not sure is the same can be said for a static black hole. A radial frame dragging can explain how objects which never seem to quite fall in from the outside nonetheless do fall in: cf. Thorne (1994) p. 247.
From: Edward Green on 24 May 2010 21:24 On May 24, 9:19 pm, Edward Green <spamspamsp...(a)netzero.com> wrote: > On May 24, 8:55 pm, BURT <macromi...(a)yahoo.com> wrote: > > > Light has no escape speed because it doesn't change from C. What > > applies to matter does not apply to light. Light always overcomes > > gravity. Matter while leaving slows down. Light does not. > > > Stephen Hawking quoted me "There are no local boundaries to light." > > The no boundary proposal applies to gravity and light. > > I'm degrading my cred by replying to you. > > But I mention that I think I can understand how light can fail to > escape from a collapsing start I meant "star". > -- there is sort of a radial frame > dragging. I'm not sure is the same can be said for a static black > hole. A radial frame dragging can explain how objects which never seem > to quite fall in from the outside nonetheless do fall in: cf. Thorne > (1994) p. 247.
From: BURT on 24 May 2010 21:30 On May 24, 6:24 pm, Edward Green <spamspamsp...(a)netzero.com> wrote: > On May 24, 9:19 pm, Edward Green <spamspamsp...(a)netzero.com> wrote: > > > On May 24, 8:55 pm, BURT <macromi...(a)yahoo.com> wrote: > > > > Light has no escape speed because it doesn't change from C. What > > > applies to matter does not apply to light. Light always overcomes > > > gravity. Matter while leaving slows down. Light does not. > > > > Stephen Hawking quoted me "There are no local boundaries to light." > > > The no boundary proposal applies to gravity and light. > > > I'm degrading my cred by replying to you. > > > But I mention that I think I can understand how light can fail to > > escape from a collapsing start > > I meant "star". > > > > > -- there is sort of a radial frame > > dragging. I'm not sure is the same can be said for a static black > > hole. A radial frame dragging can explain how objects which never seem > > to quite fall in from the outside nonetheless do fall in: cf. Thorne > > (1994) p. 247.- Hide quoted text - > > - Show quoted text - Light cannot be dragged backwards. Light will always escape gravity because it does not slow from C. What applies to matter does not apply to light. So hows your cred now? Kip Thorne made the excuse for everyone. He said matter can fall at the speed of light but no faster. But that is just another contradiction since SR says matter cannot reach it. And by the way if there is even stronger acceleration inside then matter will fall faster than light. Mitch Raemsch
From: Edward Green on 24 May 2010 21:47
On May 24, 2:18 am, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > Edward Green wrote: > > Finite proper time either means it actually > > falls in, or actually freezes. > > No. Finite proper time means a finite time to a comoving observer. An object > that crosses the horizon in a finite proper time after a given point on its > trajectory outside the horizon definitely DOES fall into the BH, according to a > comoving observer. This is not "debatable". > > You seem to be hung up on the notion that any observer ought to be able to > observe all aspects of "reality" -- that's quite naive. I remind you of the class of trajectories in SR of unbounded (but always finite) acceleration which accumulate only finite proper time on their trip to infinity. How do I know something similar is not happening here? In some sense the free fall acceleration becomes unbounded here also, because to stop it would require unbounded acceleration. However, I thought you agreed with me that for a massive test particle, the horizon will rise to meet it, which renders the question moot. |