Cantor Confusion
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From: David Marcus on 2 Nov 2006 03:06 Han de Bruijn wrote: > Virgil wrote: > > In article <dec9e$454858d1$82a1e228$21143(a)news1.tudelft.nl>, > > Han de Bruijn <Han.deBruijn(a)DTO.TUDelft.NL> wrote: > > >> A large mass (as with the balls in a vase close to noon) surely _will_ > >> halt time, according to the General Theory of Relativity. > > > > As those infinitely many balls are required to exist before any are put > > in the vase, if they are going to stop time at all, they will stop it > > before any of them are to be put into the vase. So the need for a > > discontinuity at noon will be no problem. > > Ah, that's true! So time has stopped well before the experiment has even > started. So the balls in a vase problem is ill-posed from the beginning, > as I've always said. It is ill-posed if it is a physics problem. However, most of us have been saying all along that it is not a physics problem. In fact, most of us can't understand how anyone could have ever mistaken it for a physics problem. -- David Marcus
From: Han de Bruijn on 2 Nov 2006 03:11 Virgil wrote: > In article <335f8$45489012$82a1e228$29179(a)news2.tudelft.nl>, > Han de Bruijn <Han.deBruijn(a)DTO.TUDelft.NL> wrote: > >>Randy Poe wrote: >> >>>Han de Bruijn wrote: > >>>>A large mass (as with the balls in a vase close to noon) surely _will_ >>>>halt time, according to the General Theory of Relativity. >>> >>>You are no doubt remembering something you heard about >>>time inside the Schwarzchild radius of a black hole. >>> >>>Point to ponder: Black holes exist in our galaxy. Yet here we >>>are, with time ticking on regardless. Is it possible you remember >>>something wrong? >> >>That's besides the point. First of all, it has NOT been established that >>black holes indeed exist in our galaxy. > > It has been established beyond reasonable doubt that huge black holes > exist at the center of a great many galaxies, including our own. An astronomer, a mathematician and a physicist are riding a train through the countryside when one of them spots a black sheep from the window. "What can we conclude from that?" he says. "All sheep are black," says the astronomer, with his traditional habit of generalizing from one star (our sun) to all the others. "Some sheep are black," says the physicist, who is a very practical person. "There exists at least one sheep which is black," says the mathematician, "on one side." As quoted from: http://groups.google.nl/group/sci.math/msg/727176a34d254af1?hl=en& > If HdB is to pose as a physicist, he should keep up on his physics. Han de Bruijn
From: Virgil on 2 Nov 2006 03:22 In article <dc0ee$4549a5a2$82a1e228$10529(a)news2.tudelft.nl>, Han de Bruijn <Han.deBruijn(a)DTO.TUDelft.NL> wrote: > Virgil wrote: > > > In article <dec9e$454858d1$82a1e228$21143(a)news1.tudelft.nl>, > > Han de Bruijn <Han.deBruijn(a)DTO.TUDelft.NL> wrote: > > >>A large mass (as with the balls in a vase close to noon) surely _will_ > >>halt time, according to the General Theory of Relativity. > > > > As those infinitely many balls are required to exist before any are put > > in the vase, if they are going to stop time at all, they will stop it > > before any of them are to be put into the vase. So the need for a > > discontinuity at noon will be no problem. > > Ah, that's true! So time has stopped well before the experiment has even > started. So the balls in a vase problem is ill-posed from the beginning, > as I've always said. Not in the world of mathematics, in which massless balls are as easy to conjure up as the massless natural numbers which move with them.
From: Virgil on 2 Nov 2006 03:29 In article <c014a$4549a6a3$82a1e228$10625(a)news2.tudelft.nl>, Han de Bruijn <Han.deBruijn(a)DTO.TUDelft.NL> wrote: > Virgil wrote: > > > In article <57d64$45485a34$82a1e228$21322(a)news1.tudelft.nl>, > > Han de Bruijn <Han.deBruijn(a)DTO.TUDelft.NL> wrote: > > > >>Virgil wrote: > >> > >>>In article <bdc92$45476e9e$82a1e228$30478(a)news1.tudelft.nl>, > >>> Han de Bruijn <Han.deBruijn(a)DTO.TUDelft.NL> wrote: > >>> > >>>>It's easy to come up with a correct physical problem and > >>>>solve it with the wrong mathematics. As you did. > >>> > >>>HdB has come up with a mathematical problem which he claims can end the > >>>world: > >>> > >>>HdB claimed that a discontinuity in a mathematical function of time > >>>causes time to stop. And he claimed this followed from physics. > >>> > >>>Thus, if HdB is right, the vase problem will cause the end of the > >>>world. > >> > >>Yes. If it came into _existence_, it would cause the end of the world. > >>Because an infinite mass would be no less than a Cosmic Disaster. > > > > Since it _exists_ only as a gedankenexperiment, a sort of mental game, > > such fears are irrelevant. > > Other fears are more relevant. Such as the fear that infinities in > mathematics may easily lead to irrelevancies in physics (like e.g. > with Black Holes or String Theory) As the almost universal consensus of astronomers now is that the center of many, possibly most, galaxies is a huge black hole, and that many larger stars too big to eventually collapse into neutron stars collapse into black holes when they run out of fuel, it appears that HdB is the unaware of what are irrelevancies in physics. So that HdB is hardly in a position to dictate what should be considered irrelevancies in areas outside of his supposed area of expertise.
From: Virgil on 2 Nov 2006 03:34
In article <6c953$4549a822$82a1e228$10849(a)news2.tudelft.nl>, Han de Bruijn <Han.deBruijn(a)DTO.TUDelft.NL> wrote: > Virgil wrote: > > > In article <335f8$45489012$82a1e228$29179(a)news2.tudelft.nl>, > > Han de Bruijn <Han.deBruijn(a)DTO.TUDelft.NL> wrote: > > > >>Randy Poe wrote: > >> > >>>Han de Bruijn wrote: > > > >>>>A large mass (as with the balls in a vase close to noon) surely _will_ > >>>>halt time, according to the General Theory of Relativity. > >>> > >>>You are no doubt remembering something you heard about > >>>time inside the Schwarzchild radius of a black hole. > >>> > >>>Point to ponder: Black holes exist in our galaxy. Yet here we > >>>are, with time ticking on regardless. Is it possible you remember > >>>something wrong? > >> > >>That's besides the point. First of all, it has NOT been established that > >>black holes indeed exist in our galaxy. > > > > It has been established beyond reasonable doubt that huge black holes > > exist at the center of a great many galaxies, including our own. > > An astronomer, a mathematician and a physicist are riding a train > through the countryside when one of them spots a black sheep from > the window. "What can we conclude from that?" he says. > > "All sheep are black," says the astronomer, with his traditional > habit of generalizing from one star (our sun) to all the others. > > "Some sheep are black," says the physicist, > who is a very practical person. > > "There exists at least one sheep which is black," > says the mathematician, "on one side." > > As quoted from: > > http://groups.google.nl/group/sci.math/msg/727176a34d254af1?hl=en& > > > If HdB is to pose as a physicist, he should keep up on his physics. > > Han de Bruijn That joke demonstrates that it is the physicists, rather than the mathematicians, who jump to conclusions on less than complete evidence. So in questions of reliability of conclusions, HdB is conceding that the mathematicians win. |