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Natural Science Forum / Physics / General Physics / February 2007Relativistic paradox
Could someone give me a reference (on the web) for the paradox of the bar and the hole (that one in which the bar fall down in the hole in a reference system fixed with the hole, and don't fall down in the hole in the reference system fixed with the bar)? Thank you. > Could someone give me a reference (on the web) for the paradox of the > bar and the hole (that one in which the bar fall down in the hole in a > reference system fixed with the hole, and don't fall down in the hole in > the reference system fixed with the bar)? > Thank you. Physics FAQ A Special Relativity Paradox: The Barn and the Pole http://edu-observatory.org/physics-faq/Relativity/SR/barn_pole.html >Could someone give me a reference (on the web) for the paradox of the >bar and the hole (that one in which the bar fall down in the hole in a >reference system fixed with the hole, and don't fall down in the hole in >the reference system fixed with the bar)? >Thank you. You can learn it bottom up or from top down. I prefer the latter. Google for "Terrell rotation" Or you decide to learn nothing by reading Sorcerer Androcles' postings which will unavoidably appear here real soon now :-) w. > Could someone give me a reference (on the web) for the paradox of the > bar and the hole (that one in which the bar fall down in the hole in a > reference system fixed with the hole, and don't fall down in the hole in > the reference system fixed with the bar)? > Thank you. There is no paradox with the broomstick and the barn. The broomstick both fits and does not fit consistent with the point of view of the bosrver. There is no contradiction, either. http://bkocay.cs.umanitoba.ca/Students/Theory.html The distorted cube  SignatureUncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) http://www.mazepath.com/uncleal/lajos.htm#a2 In sci.physics, Uncle Al <UncleAl0@hate.spam.net> wrote on Fri, 23 Feb 2007 12:00:14 -0800 <45DF47CE.B718CCE8@hate.spam.net>: >> Could someone give me a reference (on the web) for the paradox of the >> bar and the hole (that one in which the bar fall down in the hole in a [quoted text clipped - 8 lines] > http://bkocay.cs.umanitoba.ca/Students/Theory.html > The distorted cube And even if there were a contradiction, it would last but a fraction of a microsecond at the usual specified velocities. After all, the broomstick is moving through the barn at a fraction of c, and, if one assumes a broomstick weight of, say, 1 kg, moving through the barn at 0.6 c would have the stick have more than 5 megatonnes TNT worth of kinetic energy, and would probably be illegal in most antiballistic treaties. :-) (This is about 1.5 megatonnes more than predicted by Newton.) I wouldn't want to get in the way. Signature#191, ewill3@earthlink.net /dev/signature: No such file or directory -- Posted via a free Usenet account from http://www.teranews.com >> Could someone give me a reference (on the web) for the paradox of the >> bar and the hole (that one in which the bar falls down in the hole in a [quoted text clipped - 8 lines] > http://bkocay.cs.umanitoba.ca/Students/Theory.html > The distorted cube What do you mean with "fits and don't fit consistent ..."? Do you mean that it falls down and not, consistent with the reference used? If you say so, I can't agree. In different reference systems, it must happen the same thing: or it falls down, or not. > >> Could someone give me a reference (on the web) for the paradox of the > >> bar and the hole (that one in which the bar falls down in the hole in a [quoted text clipped - 13 lines] > If you say so, I can't agree. In different reference systems, it must > happen the same thing: or it falls down, or not. It cannot fall - there isn't enough time during its translation over the hole. That is why the "paradox" is presented as a broomstick and two barn doors. You could go to a higher gravitational field to make it fall faster over the allotted time interval... but that brings in General Relativity. Add enough gravitation to recreate the paradox and the paradox disappears for the spacetime distortion that is gravitation. Get this through your thick stooopid head: 1) Special Relativity is a rigorously derived self-consistent hyperbolic geomtry. It contains no errors, it contains no paradoxes, it contains no contradictions. It has exactly zero empirical falsifications. 2) General Relativity is a non-linear elliptic-hyperbolic set of ten diffential equations. It contains no errors, it contains no paradoxes, it contains no contradictions. It has exactly zero empirical falsifications. If you do not like SR or GR you may only attack them at their founding postulates. Euclid is absolutely air-tight. That doesn't prevent Euclid from being wrong. Get a ball and on its surface draw Uncle Al a triangle with straight line sides (i.e., geodesics, great circles) whose interior angles sum to exactly 180 degrees. Hey stooopid - GPS works. You don't have the brains or the knowledge to mount a rational assault upon relativity. The universe does not scale linearly nor is it Galilean. "Principia" was wrong. Live with it. SignatureUncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) http://www.mazepath.com/uncleal/lajos.htm#a2 >>>> Could someone give me a reference (on the web) for the paradox of the >>>> bar and the hole (that one in which the bar falls down in the hole in a [quoted text clipped - 12 lines] >> If you say so, I can't agree. In different reference systems, it must >> happen the same thing: or it falls down, or not. I can't understand what you wrote. What do you mean with "bosrver"?? Perhaps "observer"? > It cannot fall Ah OK. Now I agree with you. > - there isn't enough time during its translation over > the hole. That is why the "paradox" is presented as a broomstick and [quoted text clipped - 3 lines] > and the paradox disappears for the spacetime distortion that is > gravitation. I know all that. I was only interested to references on the web. > Get this through your thick stooopid head: I can't understand. If with "stooopid" you mean "stupid", I say only that you have understood badly what I wrote. > 1) Special Relativity is a rigorously derived self-consistent > hyperbolic geomtry. It contains no errors, it contains no paradoxes, > it contains no contradictions. It has exactly zero empirical > falsifications. I agree with you. > 2) General Relativity is a non-linear elliptic-hyperbolic set of > ten diffential equations. It contains no errors, it contains no > paradoxes, it contains no contradictions. It has exactly zero > empirical falsifications. I know what GR and SR are. > If you do not like SR or GR you may only attack them at their founding > postulates. Euclid is absolutely air-tight. That doesn't prevent > Euclid from being wrong. Get a ball and on its surface draw Uncle Al > a triangle with straight line sides (i.e., geodesics, great circles) > whose interior angles sum to exactly 180 degrees. I "like" SR and GR. I'm not attacking them. But what do you mean with " ... draw Uncle Al a triangle ... " > Hey stooopid - GPS works. I know. Perhaps you have not understood. Who is stooopid, now? > You don't have the brains or the knowledge > to mount a rational assault upon relativity. The universe does not > scale linearly nor is it Galilean. "Principia" was wrong. Live with > it. In the better hypothesis, you haven't understood what I wrote. I'm not attacking relativity. Who said it to you??? > Could someone give me a reference (on the web) for the paradox of the > bar and the hole (that one in which the bar fall down in the hole in a > reference system fixed with the hole, and don't fall down in the hole in > the reference system fixed with the bar)? > Thank you. You're going to find in any explanation of this (Google "man and grate paradox", "bar and hole paradox") that the key assumption (and mistake) in the "paradox" is that the bar is rigid. Nothing *can* be rigid, not because of practical considerations, but precisely because of the limitation imposed by the speed of light. Interestingly, the orientiation of the hole is also observer dependent. Whether you view the result of the bar fitting into the hole as being due to the *rotation* of the hole or the *bending* of the bar is perhaps a matter of taste, or more precisely, a matter of exactly what measurements are made. Someone else made reference to the barn and pole paradox, which is a 1- D variant of the 2-D man and grate paradox. Same thing applies there. It is simply unphysical, even in principle, to assume that when the front of the pole stops, the back of the pole will stop at the same moment. For that to happen is simply impossible, physically. PD >> Could someone give me a reference (on the web) for the paradox of the >> bar and the hole (that one in which the bar fall down in the hole in a [quoted text clipped - 7 lines] > rigid, not because of practical considerations, but precisely because > of the limitation imposed by the speed of light. Consider a "strong form" of the rod-and-hole, where the rod starts to fall as soon as its centre-of-mass is over the hole (so the rod should fall in if its length is less than double the width of the hole). Consider the rest frame of the hole, and assume that the rod begins to tip into the hole the instant the centre-of-mass reaches the edge of the hole. At this point, it is educational to write down (t,x) for the two ends of the rod, and its centre of mass, these events are when the rod begins to tip. Transform these to the rod's rest frame. Oops! t was the same for all three in the hole frame, but t for these three events is different in the rod frame. This tells you that rigidity is a bad assumption - the rod that appears rigid in one frame does not appear rigid in all. Without rigidity, we can assume that the rod begins to bend downwards as soon as any of the rod goes over the hole. Given no clearance, the rod must always fall in. The only (significant) thing that varies between the frames is the relative timing of the near end hitting the edge of the hole, and the far end crossing the far edge. This is essentially identical to the barn-and-pole. > Interestingly, the > orientiation of the hole is also observer dependent. Aargh! The evil word "observer"! The apparent orientation of the hole depends on the position and motion of an observer _looking_ at it. Alas, much of the literature uses "observer" to mean "reference frame" aka coordinate system, which is very different from an observer-who-looks. The orientation of the hole is the same in all inertial reference frames, despite what observers see. Consider length contraction. The length measured in a coordinate system by finding the location of the ends of an object simultaneously depends on the speed of the object, and is given by the usual length contraction formula. What the observer-who-looks sees is different, with 1st order in v/c optical "illusions" due to the finite transit time of light from the two ends resulting in apparent expansion or larger contraction. SignatureTimo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/ E-prints: http://eprint.uq.edu.au/view/person/Nieminen,_Timo_A..html Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html >>> Could someone give me a reference (on the web) for the paradox of the >>> bar and the hole (that one in which the bar fall down in the hole in a [quoted text clipped - 19 lines] > three in the hole frame, but t for these three events is different in > the rod frame. f.cking garbage from a moron. You are dead from the neck up, Nieminen. "JanPB" <filmart@gmail.com> wrote in message news:1172078787.841294.4840@t69g2000cwt.googlegroups.com... Androcles asked: How far is it from A to A and how long will it take to get there... err... fuckhead? Bielwacky: It obviously depends Androcles asked: How far is it from A to A and how long will it take to get there... err... stupid fuckhead? Bielwacky: Saying "from A to A" Androcles asked: How far is it from A to A and how long will it take to get there... err... stoopid fuckheaded imbecile? Bielwacky: The question "How far is it from A to A" has infinitely many answers. Androcles: HAHAHA! Three strikes, you are out, stooopid. The answer was zero. Bielwacky: No, the answer is not zero. Androcles: HAHAHA! That's a keeper. "A-A <> 0" - Bilewacky. Bilewacky: Distance travelled by photon from A to A is not A-A. End of story. [Relativity works because] an error in Relativity "would be like Stephen Hawking dividing by zero or something equally trivial." -- Bielawski. Oops, how trivial, dumbfuck. On Feb 26, 8:27 am, "Androcles" <Engin...@hogwarts.physics.co.uk> wrote: > >>> Could someone give me a reference (on the web) for the paradox of the > >>> bar and the hole (that one in which the bar fall down in the hole in a [quoted text clipped - 26 lines] > Androcles asked: > How far is it from A to A and how long will it take to get there... err... fuckhead? I see. So you are still convinced that gold-medal Olympians running the 400m don't deserve a medal because they've run zero distance? How long do you repeat the same nonsense before giving up on it? > Bielwacky: It obviously depends > [quoted text clipped - 29 lines] > > - Show quoted text - > Could someone give me a reference (on the web) for the paradox of the > bar and the hole (that one in which the bar fall down in the hole in a > reference system fixed with the hole, and don't fall down in the hole in > the reference system fixed with the bar)? > Thank you. A subatomic "pole and barn" will behave ~about~ as advertised. See equation 511 http://farside.ph.utexas.edu/teaching/em/lectures/node50.html Time-independent Maxwell equations Time-dependent Maxwell's equations Relativity and electromagnetism http://farside.ph.utexas.edu/teaching/em/lectures/lectures.html Maxwell's equations in classic electrodynamics (classic field theory)_ a) Maxwell equations (no movement), b) Maxwell equations (with moved bodies) http://www.wolfram-stanek.de/maxwell_equations.htm#maxwell_classic_extended Problem is ya can't get much milk from a subatiomc cow. Propagation in a dielectric medium http://farside.ph.utexas.edu/teaching/em/lectures/node98.html http://en.wikipedia.org/wiki/Wave_impedance http://en.wikipedia.org/wiki/Free_space http://www-ssg.sr.unh.edu/ism/what.html Sue... Sue... ha scritto: >> Could someone give me a reference (on the web) for the paradox of the >> bar and the hole (that one in which the bar fall down in the hole in a [quoted text clipped - 27 lines] > > Sue... Thanks Sue, I've found those links. But it seems to me that they are not exactly that what I was trying. I was looking for a reference for non subatomic "pole and barn". But I've found something with "pole barn" in google. Thank you again. Sue... ha scritto: >> Could someone give me a reference (on the web) for the paradox of the >> bar and the hole (that one in which the bar fall down in the hole in a [quoted text clipped - 27 lines] > > Sue... Thanks Sue, I've found those links. But it seems to me that they are not exactly that what I was trying. I was looking for a reference for non subatomic "pole and barn". But I've found something with "pole barn" in google. Thank you again. Sue... ha scritto: >> Could someone give me a reference (on the web) for the paradox of the >> bar and the hole (that one in which the bar fall down in the hole in a [quoted text clipped - 27 lines] > > Sue... Thanks Sue, I've found those links. But it seems to me that they are not exactly that what I was trying. I was looking for a reference for non subatomic "pole and barn". But I've found something with "pole barn" in google. Thank you again. |
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