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|    sci.physics.research    |    Current physics research. (Moderated)    |    17,516 messages    |
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|    Message 16,358 of 17,516    |
|    Tom Roberts to Nicolaas Vroom    |
|    Re: The behaviour of a clock in a linear    |
|    26 Sep 18 11:42:01    |
      From: tjroberts137@sbcglobal.net              On 9/23/18 4:57 PM, Nicolaas Vroom wrote:       > Any clock in a centrifuge is not in an inertial frame. My point is to       > simulate the behaviour of a clock undergoing acceleration. What the       > simulation shows is that the behaviour is very complex using the clock as       > described on page 12 (as a function of v)              IIRC that is a light clock with a light pulse bouncing between two mirrors.       Remember that the mirrors are accelerated but the light is not -- the light       pulse moves in straight lines between bounces (relative to any INERTIAL frame).               For instance, while they are being accelerated you must tilt the        mirrors so the light pulse continues to bounce between them.        Parallel mirrors work only when they are moving inertially.              Let me assume a light clock in a centrifuge, and [#]:        a) the center of the centrifuge is at rest in the lab        b) the lab is at rest in an inertial frame        c) we can ignore the size of the light pulse        d) the light clock is constructed so at every bounce its mirrors'        centers are at rest in the same instantaneously co-moving inertial        frame, and the distance between their centers remains fixed in        each of those frames (i.e. the mirrors adjust themselves to make        this so, independent of any strains in their support structures)        e) the light clock is constructed so the light pulse always bounces        from the exact center of each mirror (i.e. the mirrors adjust        themselves to make this so)        f) all bounces are perfect, with no light loss       Then it is straightforward to see that the trajectory of the light pulse       relative to the lab is a series of straight lines with corners at the       successive       locations of the mirrors' centers when it bounces. It is quite clear that the       rate of bouncing measured in the lab depends ONLY on the size of the clock and       how fast the mirrors move relative to the lab (i.e. how far apart the       corners/bounces are); the mirrors' acceleration DOES NOT MATTER (i.e. it does       not matter how they get to successive positions of the bounces/corners). This       is       just basic geometry, and if your simulation does not show this then it is       wrong.               Independence of acceleration is obvious, but it is not so        obvious that for a given clock speed relative to the lab that        the bounce rate is independent of the orientation of the        clock -- a detailed calculation MUST show that it is (because        we are using SR as the basis of the calculation, and SR        clearly predicts independence of clock orientation).               [#] This is a gedanken; I know of no way to actually implement        it; I do not think these assumptions are unreasonable.              > My point is also that allmost all clocks in principle have this problem.              I doubt it: SR predicts that NO clock has this "problem", and I see no reason       to       doubt that prediction. For instance, muons in a "relativistic centrifuge" (aka       storage ring), undergoing the enormous proper acceleration of 10^18 g, are       observed to decay at the rate SR predicts; that prediction depends on only       their       speed relative to the lab and their proper lifetime (see equation given earlier       in this thread); in particular it is completely independent of their       acceleration.               Bailey et al., “Measurements of relativistic time dilation for        positive and negative muons in a circular orbit,” Nature 268        (July 28, 1977) pg 301.        Bailey et al., Nuclear Physics B 150 pg 1–79 (1979).              > My point is also that accelaration is the primary influence of the behaviour       > of a clock.              Not in SR. (Also not in GR.) And apparently not in the world we inhabit.              As I said before: your simulation is wrong.              Tom Roberts              --- SoupGate-Win32 v1.05        * Origin: you cannot sedate... all the things you hate (1:229/2)    |
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