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LHC and partical decay  time question  
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#1
Jan713, 12:18 PM

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If time itself slows down near the speed of light, why don't they prove this by sending a partical which decays over a short period of time around the LHC and see if it decays at the same rate as a partical not moving around the LHC?
Would this not prove that time really does slow down and things "age slower" when moving at near the speed of light? 


#2
Jan713, 12:25 PM

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#3
Jan713, 12:27 PM

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See: http://www.eduobservatory.org/physi...icle_lifetimes http://www.eduobservatory.org/physi...ts.html#Bailey 


#4
Jan713, 12:28 PM

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LHC and partical decay  time question 
Also, there are the cosmic ray muon experiments and other like it. take a look at the FAQ at the top of this forum, on experimental support for relativity. This particular result is about as well as established as the fact that if I let heavy objects fall when dropped from the top of a building. 


#5
Jan713, 12:37 PM

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When I was a graduate student 3035 years ago, one of my friends worked on an experiment involving beams of highenergy sigma and xi hyperons at Fermilab. Their lifetimes at rest are short enough that if they hadn't been timedilated, they wouldn't have made it into and through the detector!



#6
Jan713, 01:23 PM

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#7
Jan713, 01:30 PM

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If you had done any kind of a search on something like that, you would have you easily come up with a number of results that would have answered your question, including something like this: http://www.nature.com/nphys/journal/.../nphys778.html Zz. 


#8
Jan713, 02:29 PM

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In the case of "one frame's near speed of light is another frame's rest" there is no difference between comparative motion & in turn "aging". 


#9
Jan713, 02:31 PM

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#10
Jan713, 03:24 PM

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#11
Jan713, 04:25 PM

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#12
Jan713, 07:55 PM

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#13
Jan713, 08:20 PM

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The atmospheric muon never gets to compare its 'clock' repeatedly to the same earth clock. The particle in a ring does. Each time it passes the same hypothetical clock on the ring it sees the ring clock further and further ahead, i.e. faster. There is no interpretation that it make to say the clock it repeatedly encounters and sees running ahead is really slower. There is no doppler, simultaneity, length conrraction, or time dilation interpretation that is involved  you have a direct comparison of colocated clocks. This makes it analagous to the invariant differential aging of the twin paradox, rather than the symmetric time dilation between relatively moving inertial frames. I think we've gone over this in different threads: you have to let go of any notion that an noninertial path is equivalent to an inertial path. This is false both in SR and GR. Another is that the muon never changes inertial frames. The particle in the ring has, at every point around the ring, a different instantly comoving inertial frame, with different simultaneity. This is fundamentally different from the fixed simultaneity for the muon. If you build a coordinate system in which the ring particle is at rest, is has a different metric from the standard Minkowski metric. Using this metric, the ring particle would compute that a lab clock is running fast on average, not slow. [Edit: Is it possible you didn't know the LHC is a ring? However, even if we talk about a linear accelerator, the situation is different from the atmospheric muon case, in that acceleration is involved. All three of these cases (muon, LINAC, LHC) look similar from earth lab frame; however, each is quite different from the particle's point of view. ] 


#14
Jan713, 08:30 PM

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For example, instead of a circular ring, we could (theoretically) give the LHC particle a long straight tunnel... (Edit: I see you already referred to this, but why should the initial acceleration matter?) Alternatively, we could provide the cosmic muon a set of stationary clocks (synchronized with Earth clock) along its path... I am not talking about the physical feasibility of such set ups, just the 'thought experiment' side of it. (I did know it was a ring). 


#15
Jan713, 09:00 PM

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Now consider the circular moving particle trying to do this. First issue is how to synchronize their ring of clocks (for example), to compare to lab clocks along the ring. If they use Einstein synchronization from the particle clock as origin, then the result will be that the particle ring of clocks will conclude that each lab ring clock (compared to successive particle ring of clocks) will vary in speed but, on average, run very fast. [Edit: The idea above is to remove all aspects of Doppler, and visual appearance; and use only direct comparison of instantly collocated clocks; every system of clocks is synchronized with the Einstein or radar convention. The results for the circular case are radically different.  for the particle point of view] 


#16
Jan713, 09:42 PM

P: 181

I think the underlying physics is the same in both cases (LHC particle and cosmic muon) and the same set of explanations apply to both. What you are explaining looks more like the 'method of measurement' ascribed to observers in the particular experimental set ups. In the end, it is purely about the velocity and the Lorentz factor 1/√(1v^{2}/c^{2}) in both cases. The apparent differences in the experimental situation does not affect the results at all. As Bailey et. al. concluded (I believe) that the rather large acceleration (and therefore the noninertial frame) in the muon storage ring plays no role in the differential aging, only the velocity makes the difference. Ditto the cosmic muon experiments. These are supposed to be straight forward validations of SR, not involving any particular points of view. I will not argue further, since you are much more knowledgeable in these things, of course. 


#17
Jan713, 10:01 PM

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I am quite sure I have no disagreement with Baily. It is you that does not understand SR well enough to see the whole picture. 


#18
Jan713, 10:26 PM

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