Is Length Contraction in SR physical??
in [Relativity]
|
Prev: Simultaneous events and Einstein's absolute time
Next: New Theory --- The Theory of Quantum Wave Sources
From: Uncle Ben on 2 Feb 2010 07:56 On Feb 2, 7:43 am, "Pete" <P...(a)b.c> wrote: > Imagine two speres joined by a thread which is extended to its full length > but not under tension > Gently accelerate the two spheres at exactly the same rate. > Does Lorentz contraction increase the tension in the thread (and eventually > cause it to break)? If the spheres are massive enough to move without influence of the thread, then yes, it will break. See Wikipedia, "Bell's Spaceship paradox", which is not a paradox. Also see my discussion at www.greenba.com Uncle Ben
From: Uncle Ben on 2 Feb 2010 08:07 On Feb 1, 11:36 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > kenseto wrote: > > On Feb 1, 6:42 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > >> This is a LINGUISTIC issue. When someone asks "Is length contraction in SR > >> physical?", they invariably don't have a definite meaning of "physical" in mind > >> (if they did, they could answer the question themselves). Generally, they would > >> consider a "physical length contraction" to mean that the object ITSELF gets > >> physically shorter. This is manifestly not so in SR. But it is indeed what > >> kenseto has repeatedly failed to understand. > > > The general public know what physical length means.....the length of a > > ruler is physical. > > You clearly haven't a clue. In SR, length is most definitely not "physical" in > the usual sense. In the USUAL sense, physical attributes of an object do not > change with the way someone looks at it. But the length of an object DOES change > with the way one looks at the object (i.e. which inertial frame one uses to > measure its length). The related PHYSICAL attribute is proper length -- that is > an attribute of an object that is intrinsic to the object (and does not change > with how one looks at it -- it is an invariant). > > > If you don't like the word physical how about > > "material" length contraction? In any case you stated above that > > material length contraction does not occur in SR and I agree with that > > fully. So I don't know why you accused me of repeatly failed to > > understand!!!!!! > > Indeed, you clearly do not understand why I say you fail to understand this, > because you STILL don't understand it. Your statement three sentences earlier > ("the length of a ruler is physical") CONTRADICTS your claim here. > > The word "physical" has at least two different meanings that could be applied here: > A) the object itself contracts > B) the object itself does not change, but the measurements have > physical consequences (such as a long pole fitting in a short barn > when moving rapidly enough wrt the barn). > > (A) is not correct in SR; (B) is correct in SR. Both COULD be called "physical" > so one MUST specify what they mean when they use that word in this context. > > When you use the word "physical" without saying what you mean by it, people get > confused. ESPECIALLY YOURSELF. > > Ditto for "material"-- changing the word does not change the problem. > > > BTW your SR brothers PD and other disagree with you. They insisted > > that a moving meter stick itself gets physically (materially) > > shorter. > > Again you demonstrate your inability to read or understand. PD most definitely > did NOT say that. I'm not sure what "others" you mean. In any case, you _REALLY_ > _REALLY_ _REALLY_ need to learn how to read. You have no hope whatsoever of > understanding subtle concepts like SR until you learn how to read. > > [I give up. It's hopeless until you LEARN how to read.] > > Tom Roberts Tom Robrts takes the conservative position on what is "physical." To be consistent, he would have to deny physicality to kinetic energy and to the magnetic field of a moving charge. Or even motion itself. Or do I not understand? Uncle Ben
From: JT on 2 Feb 2010 08:11 On 2 Feb, 07:46, Sebastian Garth <sebastianga...(a)gmail.com> wrote: > On Feb 1, 8:03 pm, kenseto <kens...(a)erinet.com> wrote: > > > I suggest that you go argue with your SR brother Tom Roberts. He said: > > "Generally, they would consider a "physical length contraction" to > > mean that the object ITSELF gets > > physically shorter. This is manifestly not so in SR". > > Not true. Length contraction is a truly physical phenomena which is > absolutely measurable. Fire two laser beams perpendicularly across the > front and rear of the moving object; the change in length is not an > illusion - within the observer's frame of reference, the object indeed > occupies less space. That certainly would mean that distance is observer dependent, two objects at same distance but with relative measured distance, no it do not make sense. But who cares SR is a silly theory to start with. JT
From: Androcles on 2 Feb 2010 08:41 "Uncle Ben" <ben(a)greenba.com> wrote in message news:1d101d4f-7e5e-449b-a73e-2326d84d9c3d(a)b2g2000yqi.googlegroups.com... On Feb 2, 7:43 am, "Pete" <P...(a)b.c> wrote: > Imagine two speres joined by a thread which is extended to its full length > but not under tension > Gently accelerate the two spheres at exactly the same rate. > Does Lorentz contraction increase the tension in the thread (and > eventually > cause it to break)? If the spheres are massive enough to move without influence of the thread, then yes, it will break. See Wikipedia, "Bell's Spaceship paradox", which is not a paradox. Uncle Ben =================================== Just what IS a paradox, integrity-less Uncle Bonehead? SANITY WARNING (Bonehead Green) On March 7th 2009 Bonehead Green claimed Einstein's first postulate: "relative motion" implies that space and time is homogeneous and space is isotropic. Einstein's 2nd postulate: "light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body" bears no resemblance whatsoever to Green's: "Einstein's 2nd postulate of SR says that the speed of light is c in every inertial frame." Green makes no apology for misrepresenting Einstein, instead he mumbles "I insist on using a modern form of the 2nd postulate." Einstein himself says "Nun bewegt sich aber der Lichtstrahl relativ zum Anfangspunkt von k im ruhenden System gemessen mit der Geschwindigkeit V - v, so da� gilt: t = x'/(V-v)." "But the ray moves relatively to the initial point of k, when measured in the stationary system, with the velocity c-v, so that t = x'/(c-v)." Green cannot distinguish a postulate from a conclusion or realize his assertion conflicts with Einstein's statement. Green is guilty of lying and has lost all credibility by attempting to excuse himself. He is a cheat with zero integrity to be treated with contempt by all. Even if what he says on other subjects were to be proven true he cannot be trusted, one would always need to check the source for verification or denial. Green has been invited to sue for defamation of character but has declined the offer to test the outcome. He has no defence.
From: Androcles on 2 Feb 2010 08:47
"Uncle Ben" <ben(a)greenba.com> wrote in message news:3a089afd-817e-4170-b023-21dc1b704a07(a)21g2000yqj.googlegroups.com... On Feb 1, 11:36 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > kenseto wrote: > > On Feb 1, 6:42 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > >> This is a LINGUISTIC issue. When someone asks "Is length contraction in > >> SR > >> physical?", they invariably don't have a definite meaning of "physical" > >> in mind > >> (if they did, they could answer the question themselves). Generally, > >> they would > >> consider a "physical length contraction" to mean that the object ITSELF > >> gets > >> physically shorter. This is manifestly not so in SR. But it is indeed > >> what > >> kenseto has repeatedly failed to understand. > > > The general public know what physical length means.....the length of a > > ruler is physical. > > You clearly haven't a clue. In SR, length is most definitely not > "physical" in > the usual sense. In the USUAL sense, physical attributes of an object do > not > change with the way someone looks at it. But the length of an object DOES > change > with the way one looks at the object (i.e. which inertial frame one uses > to > measure its length). The related PHYSICAL attribute is proper length -- > that is > an attribute of an object that is intrinsic to the object (and does not > change > with how one looks at it -- it is an invariant). > > > If you don't like the word physical how about > > "material" length contraction? In any case you stated above that > > material length contraction does not occur in SR and I agree with that > > fully. So I don't know why you accused me of repeatly failed to > > understand!!!!!! > > Indeed, you clearly do not understand why I say you fail to understand > this, > because you STILL don't understand it. Your statement three sentences > earlier > ("the length of a ruler is physical") CONTRADICTS your claim here. > > The word "physical" has at least two different meanings that could be > applied here: > A) the object itself contracts > B) the object itself does not change, but the measurements have > physical consequences (such as a long pole fitting in a short barn > when moving rapidly enough wrt the barn). > > (A) is not correct in SR; (B) is correct in SR. Both COULD be called > "physical" > so one MUST specify what they mean when they use that word in this > context. > > When you use the word "physical" without saying what you mean by it, > people get > confused. ESPECIALLY YOURSELF. > > Ditto for "material"-- changing the word does not change the problem. > > > BTW your SR brothers PD and other disagree with you. They insisted > > that a moving meter stick itself gets physically (materially) > > shorter. > > Again you demonstrate your inability to read or understand. PD most > definitely > did NOT say that. I'm not sure what "others" you mean. In any case, you > _REALLY_ > _REALLY_ _REALLY_ need to learn how to read. You have no hope whatsoever > of > understanding subtle concepts like SR until you learn how to read. > > [I give up. It's hopeless until you LEARN how to read.] > > Tom Roberts Tom Robrts takes the conservative position on what is "physical." To be consistent, he would have to deny physicality to kinetic energy and to the magnetic field of a moving charge. Or even motion itself. Or do I not understand? Uncle Ben ============================================== > In SR of course, the closing speed of light and star is c+v or c-v > (depending on > direction of star's motion). That is NOT the speed of light leaving the > star > measured in the star's instantaneously comoving inertial frame, which is > of > course c. > > > Tom Roberts You co-do co-not co-understand, co-inert co-Bonehead. It's co-hopeless until you COLEARN co-how to co-read. |