Fun with black holes
in [Relativity]
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From: BURT on 17 May 2010 01:11 On May 16, 8:58 pm, eric gisse <jowr.pi.nos...(a)gmail.com> wrote: > Edward Green wrote: > > [...] > > What's the point of this? You are rehashing a well known point that > observers outside a black hole's event horizon do not see the transit of an > object through the event horizon in finite observer time. > > It doesn't matter how you rephrase the question, the answer is always going > to be the same. What does an infinite red shift do to light? Black holes violate the laws of energy for light. MItch Raemsch
From: Don Stockbauer on 17 May 2010 01:18 On May 17, 12:11 am, BURT <macromi...(a)yahoo.com> wrote: > On May 16, 8:58 pm, eric gisse <jowr.pi.nos...(a)gmail.com> wrote: > > > Edward Green wrote: > > > [...] > > > What's the point of this? You are rehashing a well known point that > > observers outside a black hole's event horizon do not see the transit of an > > object through the event horizon in finite observer time. > > > It doesn't matter how you rephrase the question, the answer is always going > > to be the same. > > What does an infinite red shift do to light? The potential, or the actualized infinity?
From: BURT on 17 May 2010 01:44 On May 16, 10:18 pm, Don Stockbauer <donstockba...(a)hotmail.com> wrote: > On May 17, 12:11 am, BURT <macromi...(a)yahoo.com> wrote: > > > On May 16, 8:58 pm, eric gisse <jowr.pi.nos...(a)gmail.com> wrote: > > > > Edward Green wrote: > > > > [...] > > > > What's the point of this? You are rehashing a well known point that > > > observers outside a black hole's event horizon do not see the transit of an > > > object through the event horizon in finite observer time. > > > > It doesn't matter how you rephrase the question, the answer is always going > > > to be the same. > > > What does an infinite red shift do to light? > > The potential, or the actualized infinity? The infinite infinity don. Mitch Raemsch
From: Greg Neill on 17 May 2010 08:20 eric gisse wrote: > Edward Green wrote: > > [...] > > What's the point of this? You are rehashing a well known point that > observers outside a black hole's event horizon do not see the transit of an > object through the event horizon in finite observer time. > > It doesn't matter how you rephrase the question, the answer is always going > to be the same. How about a vaiation involving the observed gravitational field? Since gravitation is a manifestation of the curvature of space it doesn't have any problem "escaping" from a balck hole -- after all, black holes certainly present a strong gravitational influence outside of their event horizons. Suppose there's an observer situated a goodly distance from a black hole with a sensitive gravitational compass (like a small mass on a string that will point in the direction of the net gravitational force, only one as sensitive as can be made by the Gedankenwerks manufacturers). Using this apparatus the observer monitors the straight-line appoach and infall of a significantly massive body towards the black hole. He's watching the infall in profile, so the motion is perpendicular to his line of sight. During the infall, his "compass" points in a direction that is essentially the center of mass of the infalling body and black hole. The question that arrises is, at what point in time, if any, with the observed center of mass coincide with the center of the black hole? That is, when will the external observer conclude that the infalling mass has met its fate at the singularity?
From: PD on 17 May 2010 14:47
On May 12, 4:50 pm, Edward Green <spamspamsp...(a)netzero.com> wrote: > Consider an ordinary Schwarzschild black hole: > > (1) Let an object be dropped from an arbitrary value of the radial > coordinate above the event horizon. > > (2) Is there ever a case where the object has not reached the event > horizon where it is _not_ possible to reverse its trajectory and > escape back to its starting point, by means of a sufficiently powerful > thrust? > > (3) Assuming the answer to (2) is "no", let T be the greatest lower > bound on the time to make a return trip. > > (4) Does T tend to infinity as the distance from the event horizon > tends to zero? > > (5) Assuming the answer to (4) is "yes", in what sense does a distant > object ever finish falling into the event horizon? To the distant observer, it doesn't. This is well known. Of course, to clock falling alongside the object, there is a definite time that marks crossing the event horizon. |