Known physics defeated by simple puzzle?
in [Relativity]
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From: Ste on 15 Feb 2010 10:02 On 15 Feb, 13:29, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > news:f3b13712-7e39-4005-ad5d-d0ce7f04e40f(a)k19g2000yqc.googlegroups.com... > > > On 15 Feb, 07:35, Owen Jacobson <angrybald...(a)gmail.com> wrote: > >> Subject: Known physics defeated by simple puzzle? > > >> If you're serious about actually learning something about physics, as > >> opposed to being serious about winding people up, don't take this > >> approach. It discourages others from taking you seriously. > > > I dare say it is the preconceptions of many of those here that prevent > > them taking any questioning seriously. It's often like being > > surrounded by a bunch of ideological crackpots. > > No, its like being surrounded by people who know vastly more about the > subject than you do, and telling them they are wrong. Of course some of them > get pissed off. But I haven't said anyone is wrong. I'm simply said that many, if not all, people here who claim to know anything about relativity, don't seem to be able to explain it except in its own existing mathematical terms. > >> We already > >> have enough "physics is wrong!" threads kicking around. > > > As I say, I don't think it is wrong. Relativity clearly works - or at > > least to a sufficiently precise approximation. > > No, you repeatedly claim that key tenets of SR are wrong, including length > contraction, intertial frame invariance of c, absolute simultaniety etc. No, I said there was *no direct observation* of length contraction. As for the invariance of 'c' within an inertial frame, I accept that this is consistent with observation, while arguing that this poses an apparent physical contradiction. As for absolute simultaneity, as I said I would simply define it as that simultaneity which would manifest itself to the senses if information could travel instantaneously. By this measure, if an obsever is equidistant from two events and reckons they are simultaneous, then he should also reckon that they are simultaneous if he is not equidistant from the two events. This obsession with insisting that things do not happen until they are observed is as ludicrous and toxic for understanding as a blind man arguing that a gun was not fired until he heard it (and going on to lecture about how it's "impossible to prove" that the gunshot ever happened before he heard it). > You can't now pretend you believe SR is correct, after 600 posts saying the > exact opposite. I'm not sure that I did. > > The point is that no > > one seems to be able to explain some of its more esoteric assumptions > > in physical terms > > There have been many explanations. After the first 200 or so, you just > started quibbling inconsistently about what was "physical"; playing word > games. Whenever anybody said that the real explanation was in the > mathematics, you said you weren't very good at maths. Learn some maths. I haven't quibbled about "physical". I know what its essential features are, as apparently do a number of other posters. As for the "real explanation", mathematics is not a "real explanation", and even if I learned it I would not be satisfied with it as an explanation - I would still want to know why it worked physically. And I've finally got to the point that there is no point asking for an explanation, but that instead I should simply ask for the answers to some simple examples, and try and derive some sort of explanation for myself.
From: PD on 15 Feb 2010 10:18 On Feb 14, 1:42 pm, Ste <ste_ro...(a)hotmail.com> wrote: > No takers for this simple question then? > > Consider this setup: > > S1 D2 > > D1 S2 > > We've got sources S1 and S2, paired with detectors D1 and D2. They're > all mechanically connected, so that a movement in one of them > produces > a movement in all the others - in other words, their relative > distances are always maintained. Each source is transmitting a > regular > pulse of light to its counterpart detector (so S1 is transmitting to > D1, etc.), and both sources are transmitting simultaneously with each > other. > > Now, we calculate that a pulse has just been emitted from both > sources, and we suddenly accelerate the whole setup "upwards" (i.e. > relative to how it's oriented on the page now) to near the speed of > light, and we complete this acceleration before the signals reach > either detector. > > Now, do both detectors *still* receive their signals simultaneously, > or does one receive its signal before the other? And are the signals > identical, or do they suffer from Doppler shifting, etc? In what frame do you want the answer? The frame into which the set-up is accelerating, or the frame from which the set-up is accelerating? The answer is dependent on that choice.
From: Ste on 15 Feb 2010 11:05 On 15 Feb, 15:18, PD <thedraperfam...(a)gmail.com> wrote: > On Feb 14, 1:42 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > No takers for this simple question then? > > > Consider this setup: > > > S1 D2 > > > D1 S2 > > > We've got sources S1 and S2, paired with detectors D1 and D2. They're > > all mechanically connected, so that a movement in one of them > > produces > > a movement in all the others - in other words, their relative > > distances are always maintained. Each source is transmitting a > > regular > > pulse of light to its counterpart detector (so S1 is transmitting to > > D1, etc.), and both sources are transmitting simultaneously with each > > other. > > > Now, we calculate that a pulse has just been emitted from both > > sources, and we suddenly accelerate the whole setup "upwards" (i.e. > > relative to how it's oriented on the page now) to near the speed of > > light, and we complete this acceleration before the signals reach > > either detector. > > > Now, do both detectors *still* receive their signals simultaneously, > > or does one receive its signal before the other? And are the signals > > identical, or do they suffer from Doppler shifting, etc? > > In what frame do you want the answer? > The frame into which the set-up is accelerating, or the frame from > which the set-up is accelerating? > The answer is dependent on that choice. The answer will be according to an observer that is attached to the setup and is equidistant from both detectors. And remember, the acceleration is complete before the detection occurs.
From: dlzc on 15 Feb 2010 11:27 Dear Ste: On Feb 15, 4:34 am, Ste <ste_ro...(a)hotmail.com> wrote: > On 15 Feb, 03:04,dlzc<dl...(a)cox.net> wrote: > > > > Now, do both detectors *still* receive their > > > signals simultaneously, or does one receive > > > its signal before the other? > > > S2 should get its signal first. The path length is > > shorter, due to the acceleration. Acceleration is > > not really part of SR, and your imaginary setup > > isn't helping. > > Forget the imaginary setup. The purpose of my > questions are to establish and distill out the > essential truths that are captured in relativity. They are called "postulates". Their number is two: 1) physics is the same for all inertial observers 2) the equivalence principle Other theories derive the constant local speed of c. And the logic- set of mapping problem-space to solution-space has a long and hoary tradition (aka. mathematics). > It doesn't matter that no real device in the Universe > could conceivably carry out such an acceleration. It does if one starts depending on instantaneous signal transmission via "perfectly rigid structures". You aren't quite there yet, but there was significant deformation of the structure you placed your emitters and detectors on, causing ringing to boot (oscillating distances), and you simply don't care about it... David A. Smith
From: PD on 15 Feb 2010 11:49
On Feb 15, 10:05 am, Ste <ste_ro...(a)hotmail.com> wrote: > On 15 Feb, 15:18, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 14, 1:42 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > No takers for this simple question then? > > > > Consider this setup: > > > > S1 D2 > > > > D1 S2 > > > > We've got sources S1 and S2, paired with detectors D1 and D2. They're > > > all mechanically connected, so that a movement in one of them > > > produces > > > a movement in all the others - in other words, their relative > > > distances are always maintained. Each source is transmitting a > > > regular > > > pulse of light to its counterpart detector (so S1 is transmitting to > > > D1, etc.), and both sources are transmitting simultaneously with each > > > other. > > > > Now, we calculate that a pulse has just been emitted from both > > > sources, and we suddenly accelerate the whole setup "upwards" (i.e. > > > relative to how it's oriented on the page now) to near the speed of > > > light, and we complete this acceleration before the signals reach > > > either detector. > > > > Now, do both detectors *still* receive their signals simultaneously, > > > or does one receive its signal before the other? And are the signals > > > identical, or do they suffer from Doppler shifting, etc? > > > In what frame do you want the answer? > > The frame into which the set-up is accelerating, or the frame from > > which the set-up is accelerating? > > The answer is dependent on that choice. > > The answer will be according to an observer that is attached to the > setup and is equidistant from both detectors. And remember, the > acceleration is complete before the detection occurs. |