Fun with black holes
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From: eon on 15 May 2010 05:22 On May 14, 3:44 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > eon wrote: > > On May 14, 6:04 am, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > >> But once it reaches the horizon, there is no possible amount of thrust that can > >> make it return. > > > not true, before event horizon you must > > have infinite angular velocity, from the > > flush, which by integration gets even > > more infinite position > > these two quantities would easy cancel a > > black hole > > You are confused: > 1. I was discussing an object on a straight radial path, so its angular fluid dynamics says you have a sink, a radial path is unreal > 2. There is no "flush" (whatever that is supposed to mean). how not, you have a sink, with angular velocity component must be much higher than its radial i saw this in a move sold by a Brian, or was is it Stephan or something > 3. Integration does not work that way. how not? > 4. One cannot "cancel" a black hole, because it is a geometrical property > of the manifold. is not it an object, but only a property of an object ??? how come? > Tom Roberts thanks
From: Daryl McCullough on 15 May 2010 12:36 eon says... > >On May 14, 3:44 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: >> You are confused: >> 1. I was discussing an object on a straight radial path, so its angular >> velocity (wrt the black hole) is zero. > >fluid dynamics says you have a sink, >so a radial path is unreal > >> 2. There is no "flush" (whatever that is supposed to mean). > >how not, you have a sink, with angular velocity >component must be much higher than its radial You are confused. There is no "flush" associated with a sink. A flush is associated with a toilet. -- Daryl McCullough Ithaca, NY
From: eon on 15 May 2010 12:43 On May 15, 6:36 pm, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > eon says... > > > > >On May 14, 3:44 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > >> You are confused: > >> 1. I was discussing an object on a straight radial path, so its angular > >> velocity (wrt the black hole) is zero. > > >fluid dynamics says you have a sink, > >so a radial path is unreal > > >> 2. There is no "flush" (whatever that is supposed to mean). > > >how not, you have a sink, with angular velocity > >component must be much higher than its radial > > You are confused. There is no "flush" associated with a sink. > A flush is associated with a toilet. > > -- > Daryl McCullough > Ithaca, NY untrue, you just been falsified and flushed down through the sink of a toilet good bye, and learn physics
From: BURT on 15 May 2010 15:20 On May 15, 9:43 am, eon <ynes9...(a)techemail.com> wrote: > On May 15, 6:36 pm, stevendaryl3...(a)yahoo.com (Daryl McCullough) > wrote: > > > > > > > eon says... > > > >On May 14, 3:44 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > > >> You are confused: > > >> 1. I was discussing an object on a straight radial path, so its angular > > >> velocity (wrt the black hole) is zero. > > > >fluid dynamics says you have a sink, > > >so a radial path is unreal > > > >> 2. There is no "flush" (whatever that is supposed to mean). > > > >how not, you have a sink, with angular velocity > > >component must be much higher than its radial > > > You are confused. There is no "flush" associated with a sink. > > A flush is associated with a toilet. > > > -- > > Daryl McCullough > > Ithaca, NY > > untrue, you just been falsified and flushed > down through the sink of a toilet > > good bye, and learn physics- Hide quoted text - > > - Show quoted text - Light never slows down from C in empty space. There is no escape speed for light as there is for gravity slowing matter. Light always overcomes gravity. Mitch Raemsch
From: Edward Green on 15 May 2010 20:01
On May 14, 9:08 pm, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > Edward Green says... > > >Consider an ensemble of rocket probes dropped into a black hole. These > >probes have the property that some of them will fire their rockets off > >at a random r_closest and return to us, others will fall in without > >firing their rockets. > > >No matter how long we wait, some fraction of the ensemble (all dropped > >from the same height at the same time) will continue to trickle back > >home. Therefore there is no time we can wait until we can say "OK, by > >now, the remaining probes have all crossed the event horizon, and no > >more will return. This strongly suggests to me that the probes never > >cross the event horizon, in a sense that doesn't depend on ambiguities > >in simultaneity and time dilation. But you need the continued stream > >of returning probes to see this clearly. > > But there is the analogous situation with the rocket undergoing > constant proper acceleration. You have a huge mothership that is > accelerating continually. Then, in the accelerated coordinate > system of the mothership, there will be a distance, L, below > the mothership such that no signal sent from farther away than > that will ever reach the mothership. This is the Rindler event > horizon. > > You can then release a bunch of rocket probes, which will drop > behind the mothership and get arbitrarily close to the Rindler > horizon. Then the probe will accelerate and return to the mothership. > The time required for the round trip goes to infinity as the > probes get closer and closer to the Rindler horizon. > > But in this case, we know that life goes on past the Rindler > horizon. Because the horizon is just an artifact of using > accelerated coordinates. Nothing changes when something > crosses the horizon, except that there is a point at which > it becomes impossible to catch up to the mothership (unless > the mothership stops accelerating). Given the equivalence principle, your counter-example seems to trump my intuition. I do note hopefully that the two situations are not strictly equivalent, even locally: one occurs in flat spacetime, the other in a spacetime which is definitely not flat. How important this is, I do not know. |