Known physics defeated by simple puzzle?
in [Relativity]
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From: dlzc on 17 Feb 2010 12:13 Dear J. Clarke: On Feb 17, 7:51 am, "J. Clarke" <jclarke.use...(a)cox.net> wrote: .... > Make some reasonable assumptions about the > difference in speed in different directions and > then calculate the effect on the measurement > based on the motion of Jupiter's moons and get > back to us. Ignorance of the impossibility of making one way light speed measurements is not my problem. Pull your head out, then get back to us. Not not. Posture more, and impress us all with your witticisms. David A. Smith
From: Ste on 17 Feb 2010 15:57 On 17 Feb, 15:53, PD <thedraperfam...(a)gmail.com> wrote: > On Feb 17, 9:13 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > Translations in relativity--or in fact, even in pure mathematics--are > > > > > very different things than rotations, and picking the detector up and > > > > > putting it somewhere else without changing the speed is a pure > > > > > translation. You don't even need relativity in this scenario, where > > > > > everything is at rest with respect to everything else. > > > > > Yes, but we're going to get to the bit where relativity is required in > > > > a moment. > > > > > Now, let us suppose we have two source and two detectors again: > > > > > D1 D2 D3 > > > > > S1 S2 S3 > > > > > S1 and D1 are stationary in the frame, and do not move. D2 is also > > > > stationary in the frame. S2, S3, and D3 are all moving in the y+ > > > > direction (i.e. same as the previous scenario) at a constant speed > > > > (which is close to 'c'). Just to be sure we understand, the same setup > > > > a few moments back in time would have looked like this: > > > > > D1 D2 > > > > > D3 > > > > > S1 > > > > > S2 S3 > > > > > Now, when all sources come into line with each other (as per the first > > > > illustration above), a pulse is emitted towards the respective > > > > detectors. After emission, S2 would continue towards D2, but in > > > > reality we remove S2 from the picture before any collision (and we've > > > > already established that any transformation of the sources after > > > > emission has no effect on photons already emitted). > > > > > Now, based on the previous scenario, I presume that in SR, D3 receives > > > > its pulse long after D1. However, this time, does D2 receive its pulse > > > > at the same time as D1? > > Yes, and yes. Ok. Consider yet another setup: D1 D3 S1 D2 S2 D4 In case it isn't clear, D1 and D2 are equidistant from S1, and D3 and D4 are equidistant from S2. The S1 group (i.e. comprising S1, D1, and D2) are always stationary in the frame, and S1 is emitting a pulse towards both D1 and D2. There is a similar setup for the S2 group, except that after the emission of the pulse, the S2 group moves in the y+ direction, so that S2 is now in the former place of D3 (again, the whole group accelerates rapidly, and is stationary again by time of detection). Now, I assume D1 and D2 receive their signals simultaneously. But what of D3 and D4? By the previous answers, I presume D4 receives it's signal before D3?
From: J. Clarke on 17 Feb 2010 15:49 dlzc wrote: > Dear J. Clarke: > > On Feb 17, 7:51 am, "J. Clarke" <jclarke.use...(a)cox.net> wrote: > ... >> Make some reasonable assumptions about the >> difference in speed in different directions and >> then calculate the effect on the measurement >> based on the motion of Jupiter's moons and get >> back to us. > > Ignorance of the impossibility of making one way light speed > measurements is not my problem. Pull your head out, then get back to > us. Not not. Posture more, and impress us all with your witticisms. If the "two way effects" do not introduce significant error then what relevance do they have? And if you can't calculate the effects then you are a damned fool for pontificating on a physics forum.
From: Inertial on 17 Feb 2010 16:10 "dlzc" <dlzc1(a)cox.net> wrote in message news:f2cd2caa-9ec8-4930-a824-9743d8a3f4eb(a)t17g2000prg.googlegroups.com... > Dear J. Clarke: > > On Feb 17, 7:51 am, "J. Clarke" <jclarke.use...(a)cox.net> wrote: > ... >> Make some reasonable assumptions about the >> difference in speed in different directions and >> then calculate the effect on the measurement >> based on the motion of Jupiter's moons and get >> back to us. > > Ignorance of the impossibility of making one way light speed > measurements is not my problem. Pull your head out, then get back to > us. Not not. Posture more, and impress us all with your witticisms. It is not impossible, as it has been done, but it does involve some assumptions about how to keep to clocks synchronized (eg move them apart with the same speed profile). The same is true, of course, for any speed measured with a pair of clocks. One wonders if there is a way to measure the speed of light without a pair of clocks (without any assumptions about time at different locations). We can, for example, measure the speed of a car with a speedometer that doesn't involve a pair of clocks (either directly in measurement, or in the calibration of the instrument).
From: dlzc on 17 Feb 2010 16:11
Dear J. Clarke: On Feb 17, 1:49 pm, "J. Clarke" <jclarke.use...(a)cox.net> wrote: > dlzc wrote: > > Dear J. Clarke: > > > On Feb 17, 7:51 am, "J. Clarke" <jclarke.use...(a)cox.net> wrote: > > ... > >> Make some reasonable assumptions about the > >> difference in speed in different directions and > >> then calculate the effect on the measurement > >> based on the motion of Jupiter's moons and get > >> back to us. > > > Ignorance of the impossibility of making one > > way light speed measurements is not my > > problem. Pull your head out, then get back to > > us. Not not. Posture more, and impress us all > > with your witticisms. > > If the "two way effects" do not introduce > significant error then what relevance do they have? They have potentially significant error / signal that cannot be eliminated / obtained. Of course, you know that, so then you say... > And if you can't calculate the effects then you are > a damned fool for pontificating on a physics forum. Then I appear to be in excellent company, since it has f*ck-all to do with even "one-way" light speed measurements in the lab. But you know it all, so we all prostrate ourselves before your sagacity and infinitessimal wit. David A. Smith |