leaving black holes
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From: bz on 2 Oct 2009 21:38 Bernhard Kuemel <bernhard(a)bksys.at> wrote in news:4765c$4ac657af$557f726a $27558(a)news.inode.at: > bz wrote: >> carlip-nospam(a)physics.ucdavis.edu wrote in news:ha2lvp$f4d$1 >> @skeeter.ucdavis.edu: >> >>> If she now sticks her hand toward the horizon, she's in trouble. Her >>> hand needs a huge acceleration to remain at rest, but it doesn't have >>> a rocket attached; it's accelerating only because it's connected to the >>> rest of her body, which presumably is in her spacecraft. Bones aren't >>> strong enough to transmit a near-infinite acceleration; nothing is. >> >> What if the black hole were the size and mass of our universe? > > Who do you think might stick her hand into an infinite universe? :) Someone that was outside it. There is no way to prove that it is infinite. If I remember correctly, "someone" has calculated that the amount of matter is "close" to the amount that would be needed for a black hole the size of the known universe. Perhaps we live inside a black hole. http://www.mathpages.com/home/kmath339.htm > > Bernhard > -- bz please pardon my infinite ignorance, the set-of-things-I-do-not-know is an infinite set.
From: eric gisse on 2 Oct 2009 22:28 bz wrote: > Bernhard Kuemel <bernhard(a)bksys.at> wrote in news:4765c$4ac657af$557f726a > $27558(a)news.inode.at: > >> bz wrote: >>> carlip-nospam(a)physics.ucdavis.edu wrote in news:ha2lvp$f4d$1 >>> @skeeter.ucdavis.edu: >>> >>>> If she now sticks her hand toward the horizon, she's in trouble. Her >>>> hand needs a huge acceleration to remain at rest, but it doesn't have >>>> a rocket attached; it's accelerating only because it's connected to the >>>> rest of her body, which presumably is in her spacecraft. Bones aren't >>>> strong enough to transmit a near-infinite acceleration; nothing is. >>> >>> What if the black hole were the size and mass of our universe? >> >> Who do you think might stick her hand into an infinite universe? :) > > Someone that was outside it. > There is no way to prove that it is infinite. > > If I remember correctly, "someone" has calculated that the amount of > matter is "close" to the amount that would be needed for a black hole the > size of the known universe. > > Perhaps we live inside a black hole. Which direction is the singularity? > > http://www.mathpages.com/home/kmath339.htm > >> >> Bernhard >> > > > > >
From: Omega on 3 Oct 2009 05:37 eric gisse wrote: > bz wrote: > >> Bernhard Kuemel <bernhard(a)bksys.at> wrote in >> news:4765c$4ac657af$557f726a $27558(a)news.inode.at: >> >>> bz wrote: >>>> carlip-nospam(a)physics.ucdavis.edu wrote in news:ha2lvp$f4d$1 >>>> @skeeter.ucdavis.edu: >>>> >>>>> If she now sticks her hand toward the horizon, she's in trouble. >>>>> Her hand needs a huge acceleration to remain at rest, but it >>>>> doesn't have a rocket attached; it's accelerating only because >>>>> it's connected to the rest of her body, which presumably is in >>>>> her spacecraft. Bones aren't strong enough to transmit a >>>>> near-infinite acceleration; nothing is. >>>> >>>> What if the black hole were the size and mass of our universe? >>> >>> Who do you think might stick her hand into an infinite universe? :) >> >> Someone that was outside it. >> There is no way to prove that it is infinite. >> >> If I remember correctly, "someone" has calculated that the amount of >> matter is "close" to the amount that would be needed for a black >> hole the size of the known universe. >> >> Perhaps we live inside a black hole. > > Which direction is the singularity? As the "direction" of the big bang is in to our past, the direction of the singularity (The Eye of Harmony) of our local black hole (Harmony) is to our future. ( That is, is not so much where, as when. And to account for the Hubble Constant and the negative deceleration paramenter as being due to its tidal force, its minimum mass is ~3.18619 x 10^53 kg). > >> >> http://www.mathpages.com/home/kmath339.htm >> >>> >>> Bernhard
From: eric gisse on 3 Oct 2009 04:44 Omega wrote: > eric gisse wrote: >> bz wrote: >> >>> Bernhard Kuemel <bernhard(a)bksys.at> wrote in >>> news:4765c$4ac657af$557f726a $27558(a)news.inode.at: >>> >>>> bz wrote: >>>>> carlip-nospam(a)physics.ucdavis.edu wrote in news:ha2lvp$f4d$1 >>>>> @skeeter.ucdavis.edu: >>>>> >>>>>> If she now sticks her hand toward the horizon, she's in trouble. >>>>>> Her hand needs a huge acceleration to remain at rest, but it >>>>>> doesn't have a rocket attached; it's accelerating only because >>>>>> it's connected to the rest of her body, which presumably is in >>>>>> her spacecraft. Bones aren't strong enough to transmit a >>>>>> near-infinite acceleration; nothing is. >>>>> >>>>> What if the black hole were the size and mass of our universe? >>>> >>>> Who do you think might stick her hand into an infinite universe? :) >>> >>> Someone that was outside it. >>> There is no way to prove that it is infinite. >>> >>> If I remember correctly, "someone" has calculated that the amount of >>> matter is "close" to the amount that would be needed for a black >>> hole the size of the known universe. >>> >>> Perhaps we live inside a black hole. >> >> Which direction is the singularity? > > As the "direction" of the big bang is in to our past, the direction of the > singularity (The Eye of Harmony) of our local black hole (Harmony) is to > our future. ( That is, is not so much where, as when. And to account for > the Hubble Constant and the negative deceleration paramenter as being due > to its tidal force, its minimum mass is ~3.18619 x 10^53 kg). Ok, people whose knowledge of physics consists of terminology grokked from doctor who have no right to contribute. > >> >>> >>> http://www.mathpages.com/home/kmath339.htm >>> >>>> >>>> Bernhard
From: Tom Roberts on 3 Oct 2009 10:44
Juan R. González-Álvarez wrote: > Tom Roberts wrote on Fri, 02 Oct 2009 09:34:18 -0500: >> Using different >> coordinates does NOT "move" the horizon, or make it be at a "different >> place", it makes the (fixed) locus of the horizon be at a DIFFERENT >> VALUE OF THE COORDINATE YOU HAPPEN TO LABEL WITH THE SAME SYMBOL, "r". > > Unfortunately you get totally confused again by your superfitial > knowledge of those topics Tom. It is not my "superficial knowledge" here, it is YOURS, and/or your failure to keep your theoretical context straight. > In my original message I refered *explicitely* to renormalized coordinates, > which do NOT describe "the same manifold". Look to the earlier posts in this thread. The context is the Schwarzschild solution of GENERAL RELATIVITY, not some other theory you might wish to discuss. In GR, a change of coordinates has NO EFFECT WHATSOEVER on the manifold, and a different set of coordinates always describes THE SAME manifold. This is just VERY basic geometry, applied to GR. Indeed, it is difficult indeed to have some other theory in which a change of coordinates changes the manifold, as you seem to be claiming. That would violate cherished beliefs that go far deeper than GR: that the world we inhabit does not depend on humans or their descriptions of it. Indeed, without this being valid it is not clear how there could be any physics at all. While YOU might mean something rather special by "renormalized coordinates", to the rest of us that phrase suggests a re-scaling of the coordinates, which clearly does nothing special IN THE CONTEXT OF GR. > In fact for r<<2M there is a large difference between both coordinates > (in the renormalized spacetime there is NOT central singularity for instance). Again, in GENERAL RELATIVITY this is nonsense. A mere change of coordinates cannot possibly affect the singularities of Schwarzschild spacetime. And how did you switch from "renormalized coordinates" to "renormalized spacetime" -- those phrases appear incommensurate. In the context of GR, there is a single manifold (a single spacetime), but an arbitrary number of coordinate systems that map regions of the (one) manifold onto regions of R^4 in different ways. I repeat: you have a lot of misinformation about GR in your head. You need to STUDY the actual theory. And if you are trying to discuss some other theory, you must EXPLICITLY state so. Tom Roberts |