# Clock runs slower when speeding?

Discussion in 'Physics & Math' started by Saint, May 1, 2020.

1. ### originIn a democracy you deserve the leaders you elect.Valued Senior Member

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At the speed of light time equals 0 and length in the direction of travel is 0. So if that means to you that time is emergent then the same must be said about length. But I would disagree with calling either emergent.

3. ### Write4UValued Senior Member

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Let me put it this way .
Distance is an emergent measurement of geometric change, unless the start and end point are known at which time distance becomes fixed. An odometer records the emerging and total distance traveled.

Time is an emergent measurement of duration, unless the start and end of duration of change are known at which time the duration of travel is fixed. A stopwatch records the emerging and total duration of travel.

But like time, distance is a relative term depending on speed and duration of travel.

Length contraction
And what is it's proper length?
https://en.wikipedia.org/wiki/Length_contraction

Time dilation
For the man in the elevator time is dilated, due to the elevator's movement. The light beam itself travels @ "c" . Hence the phenomenon that in both cases the straight and the apparently curved light beam strike the opposite wall at the "same time".
What is a "proper" unit of time other than a decay rate of say a caesium atom, an arbitrary albeit very accurate measuring standard.

Caesium_standard
https://en.wikipedia.org/wiki/Caesium_standard

It seems then that nothing is fixed and all phenomena associated with speed, distance and duration are all emergent phenomena, dependent on their relative association.

There is an interesting conversation in this link; A question on Time as an emergent property
H Chris Ransford, Karlsruhe Institute of Technology
https://www.researchgate.net/post/A_question_on_Time_as_an_emergent_property

Last edited: May 6, 2020

5. ### Write4UValued Senior Member

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But mass becomes infinite? A singularity?

Einstein’s Theory of Relativity
What Does Mass-Energy Equivalence Mean?
https://www.scienceabc.com/pure-sci...en-if-you-traveled-at-the-speed-of-light.html

Last edited: May 6, 2020

7. ### exchemistValued Senior Member

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Do you agree more muons arrive at the earth's surface than would be expected from their lifetime in the lab, irrespective of whether anyone is watching?

8. ### Write4UValued Senior Member

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I don't know how many muons arrive at the earth's surface. Apparently they are hard to detect.

Cosmic Ray Muons & Muon Lifetime

Examples of pulses caused by the passage of a muon and the subsequent decay into an electron. The electron has high kinetic energy, and then leaves a trace of amplitude similar to that of the muon. In the first case the time interval is approximately 1600ns, in the second case approximately 5600ns.

Oscilloscope image that shows, with the display setting of infinite persistence, the muon trace on the left and on the right some electron traces produced by the muon decay

https://physicsopenlab.org/2016/01/10/cosmic-muons-decay/

9. ### exchemistValued Senior Member

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You don't need all that. Just read this and then answer my question:

"Muons arriving on the Earth's surface are created indirectly as decay products of collisions of cosmic rays with particles of the Earth's atmosphere.[7]

About 10,000 muons reach every square meter of the earth's surface a minute; these charged particles form as by-products of cosmic rays colliding with molecules in the upper atmosphere. Traveling at relativistic speeds, muons can penetrate tens of meters into rocks and other matter before attenuating as a result of absorption or deflection by other atoms.[8]

When a cosmic ray proton impacts atomic nuclei in the upper atmosphere, pions are created. These decay within a relatively short distance (meters) into muons (their preferred decay product), and muon neutrinos. The muons from these high-energy cosmic rays generally continue in about the same direction as the original proton, at a velocity near the speed of light. Although their lifetime without relativistic effects would allow a half-survival distance of only about 456 meters ( 2.197 µs × ln(2) × 0.9997 × c ) at most (as seen from Earth) the time dilationeffect of special relativity (from the viewpoint of the Earth) allows cosmic ray secondary muons to survive the flight to the Earth's surface, since in the Earth frame the muons have a longer half-life due to their velocity. From the viewpoint (inertial frame) of the muon, on the other hand, it is the length contraction effect of special relativity which allows this penetration, since in the muon frame its lifetime is unaffected, but the length contraction causes distances through the atmosphere and Earth to be far shorter than these distances in the Earth rest-frame. Both effects are equally valid ways of explaining the fast muon's unusual survival over distances."

From: https://en.wikipedia.org/wiki/Muon

To remind you, the question is: do you agree that this is a physically real effect, which takes place regardless of whether anyone observes it?

Write4U likes this.
10. ### Write4UValued Senior Member

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Is that fact of any importance?
If our labs are that far off the mark, does that not mean we need to perform more laboratory experiments to find the right answer to your question?

11. ### exchemistValued Senior Member

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So you refuse to answer, even though both the data (which is not in any doubt) and the explanation are now in front of your nose.

QED.

foghorn likes this.
12. ### foghornRegistered Senior Member

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379
If he don't like muons, then here are Lithium ions in an accelerator.
https://www.scientificamerican.com/article/einsteins-time-dilation-prediction-verified/

13. ### exchemistValued Senior Member

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It won't make any difference. He'll just duck and weave, post reams of diagrams he's looked up on the web, introduce red herrings etc., all to avoid conceding that his understanding was incorrect.

For some reason he's decided he wants relativity to be subjective and about the observer. On past form that is what he will now stick to, even though the evidence its effects are physically real and objective is staring him in the face.

14. ### Write4UValued Senior Member

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I am not refusing to answer any question. I don't know what I am supposed to answer here.

This is the question;
I don't know if I agree. Apparently here are a lot of muons, but I have no clue as to the question if "more muons
arrive at the earth's surface than would be expected from their lifetime in the lab, irrespective of whether anyone is watching." I believe I answered the question as best I could.

But I fail to see any relevance of the question to the behavior of muons in relation to clocks running faster or slower when speeding. Do I agree? Maybe. What am I supposed to agree with? That there are a lot of muons who apparently are unobservable except for a random probability? If a muon can burrow deep into the earth's crust without observation, that's really interesting and I wonder why they are so hard to detect to begin with.

15. ### Write4UValued Senior Member

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Who said I don't like muons?

btw. Thanks for the interesting tidbit that there are lithium ions in an accelerator. I didn't know that.

16. ### exchemistValued Senior Member

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Just in case you had trouble with the way I originally put the question, I even gave you a revised expression of the same question, in post 66, after giving you a short explanatory passage about the muons. Why can you not answer it, after reading the quoted passage of explanation?

17. ### Write4UValued Senior Member

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Did I give the impression that I do not agree with any of that?

I posited that in the thought experiment of the man in the elevator, it makes no difference if the elevator is stationary or in motion. The photon will arrive at the exact same time at the opposite wall in either scenario. It just wont hit the target in the accelerating elevator, but the difference in distance of the original target (straight) and the curved trajectory, will be the exact distance the elevator has moved during the photon's travel.

Moreover, I believe that I explained the relative phenomenon that the man in the elevator sees the photon's trajectory as curving downward, yet arrive at the opposite wall at exactly the same time as the the photon in the stationary elevator as being due to the time dilation, although I am not even sure if that needs to be qualified. AFAIK the photon always moves in a straight line, it is the elevator that moves and produces the impression of a curved path to the man in the elevator, which appears to be longer than the straight path, but isn't in reality.

Last edited: May 6, 2020
18. ### phytiRegistered Senior Member

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Look again to see the graphic labeled 'B frame'. It's B's description of events, not that of P.

19. ### exchemistValued Senior Member

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Do you agree, then , that the effect is physically real, i.e. more muons arrive at the earth's surface than would be the case if they were not travelling so fast?

20. ### Write4UValued Senior Member

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This confirms your assertion that muons are subject to relativistic time dilation. But I don't see how the behavior of muons answer the question in relation to the man in the elevator, which is
Muons decay through the process :

Scheme of muon decay in electron and two neutrino
This simple exponential relation is typical of radioactive decay.

It appears that there is also an exponential function in play. I am only focusing on the thought experiment of the man in the elevator, which seems straight forward, without the bells and whistles of the behavior and decay rate of muons.

I really cannot see any relationship between a complicated example on the survival rate of muons and a single photon travelling in a straight line relative to a moving enclosure accelerating at a right angle to the path of the photon.

Last edited: May 6, 2020
21. ### Write4UValued Senior Member

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Question:
If a gunner shoots a bullet at a person @ 100 yards and the person steps aside, the bullet appears to curve away from the person's POV and misses the target, right?

But does the bullet actually curve and travel a longer distance from the gunner's POV? No, it does not, right? The gunner sees the person step aside out of the path of the bullet. That's all. Nothing to do with time dilation at near "c".

In either case the bullet reaches the target plane at right angles to it's trajectory at exactly the same time, from both the gunner's and the target's POV. It's the same bullet. In reality, it cannot possibly have two speeds at the same time.

Is there a flaw in the logic?

Last edited: May 6, 2020
22. ### Neddy BateValued Senior Member

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Write4U, I believe you like to learn from videos, so please watch this:

Get it now?

23. ### Write4UValued Senior Member

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Thank you Neddy for the link.

Nicely presented yet false, IMO.
Is "c" faster in a stationary box than in a moving box? Just a while ago he states that "c" is a constant regardless of POV.

I could not see this at all. From 3:00 he is talking pure speculation. He merely states that the light bouncing in the moving box moves at less than "c", because it has to travel a longer path, which is a contradiction to his prior statement that light always moves at "c" regardless of FoR. Moreover the light is not traveling a greater distance. The box is.

It makes no difference if you stand still or run up an escalator moving @ "c". You always get to the top in the same time, regardless if you stand still or run up the escalator.

The example of the two boxes seems false to me. If "c" is a constant from all POV, then the bouncing photons in both boxes must always be synchronous, not one photon bouncing slower than the other. That made absolutely no sense to me. Why was the photon in the moving box travelling at less than "c"? Did he ever explain this satisfactorily? Before we can talk about the emergence of time, should we not clearly define how constant the speed of "c" is.

And if we make the photon @ "c" in the moving box always bounce in perfect synchronicity with the photon in the stationary box then everything becomes much clearer. Let's begin by using the constant "c" in a constant manner.

p.s. I can think of one reason why an accelerating clock might tick at a slower rate than if stationary and that is a result of inertia of the physical properties. A stationary clock of 1 lb may quadruple in apparent weight due to the law of inertia when accelerated at a rapid rate. A clock that now has a hundred parts weighing 4 times their original weight, driven by a spring that is calibrated and designed to power all the parts in the 1 lb clock, a slow down in performance might well be encountered. But that is a physical problem and has nothing to do with emergent times of duration.

Last edited: May 7, 2020