Register to reply 
Twins paradox and ageing 
Share this thread: 
#37
Dec2609, 05:28 PM

P: 801




#38
Dec2609, 08:22 PM

P: 1,414

SR can't answer the question of the deep physical cause(s) for differential aging. Relative position in gravitational field is also connected to differential aging. Atoms, quartz clocks, humans, etc., all material objects are bounded, standing wave structures, ie., oscillators, of lesser or greater complexity. One take on differential aging is that acceleration affects the periods of oscillators. 


#39
Dec2609, 08:34 PM

P: 1,060

Differential aging is a logical consequence of clocks following different spacetime paths. This requires acceleration on the part of one or both of the clocks but the acceleration is not the direct cause of the effect. Remember we are using ideal clocks that satisfy the clock hypothesis. Matheinste. 


#40
Dec2609, 08:49 PM

P: 801

Clocks which are unaffected by acceleration will show that the ship twin has less elapsed time. 


#41
Dec2809, 02:08 PM

P: 1,414

Thanks for the input(s). My concern is that in calculating in terms of instantaneous velocities (vis clock postulate), and visualizing in terms of paths in spacetime geometry, then maybe some important physical considerations get glossed over.
We agree that relativity theory is not designed to provide an answer to the OP's question about deeper physical cause(s) of differential aging. A more fundamental (wave?) theory is required. The physical evidence does suggest that modifications of oscillatory periods happen during intervals of acceleration. 


#42
Dec2809, 02:28 PM

P: 1,060

Matheinste. 


#43
Dec2809, 02:55 PM

P: 1,414

I'm not familiar with the experiments you're talking about. I'd be interested to see an experiment that shows that acceleration has no effect on clocks. 


#44
Dec2809, 03:21 PM

P: 1,060

Matheinste. 


#45
Dec2809, 03:38 PM

P: 127

Now we are speaking of a innate characteristic of the universe  is there something that is responsible for this? CERN is busy spending billions to find a particle that may or may not hold the secret to mass  is there a chronological particle/wave/force? 


#46
Dec2809, 03:51 PM

P: 801




#47
Dec2809, 04:41 PM

P: 1,414




#48
Dec2809, 05:07 PM

Mentor
P: 17,269

Here is a link to the abstract:
http://www.nature.com/nature/journal.../268301a0.html You can probably find it at a local library. Nature and Science are widely subscribed to. There also used to be a hyperphysics page describing it, but I couldn't connect to it today. 


#49
Dec2809, 05:09 PM

P: 1,414

So, assuming that a clock's tick rate is proportional to the speed at which the clock is moving, the question I'm interested in is: when tick rates change  during what are called acceleration intervals  then what are the mechanics of the change? 


#50
Dec2809, 05:13 PM

Emeritus
Sci Advisor
PF Gold
P: 2,361

Put a clock at the end of a centrifuge. Spin up the centrifuge so that the clock is traveling in circle at a given speed while experiencing an acceleration. Compare the clock's rate with that expected just due to its velocity and see if it varies. (is the acceleration having an additional effect on the clock rate). By varying the radius of the centrifuge and its rate of spin you can create situations where you have different accelerations but maintain the same speed for the clock or maintain the same acceleration for different speeds of the clock. Th experiment has been done with high speed centrifuges and using samples of a radioisotope for the clock. To the accuracy already stated, it has been found that the measured decay rate of the sample is only determined by the speed at which it moves and that the acceleration has no effect. 


#51
Dec2809, 05:19 PM

P: 1,414




#52
Dec2809, 05:24 PM

P: 1,414




#53
Dec2809, 10:47 PM

P: 801

For example a clock on a "moving" spaceship will run at the same rate as the watch of a comoving observer on the ship, both keeping proper time. But if that observer decides to leave the ship on a shuttle and decelerate to come to rest with earth, then the ship's clock will then run slow relative to him. Nothing happened to the clock at all. There are no "mechanics of the change" because there was no physical change of the clock. Another analogy is kinetic energy. The kinetic energy of an object is different in different reference frames. Would you ask for the "mechanics of the change" to explain how the object gained or lost kinetic energy simply because we switched reference frames? Of course not, because, like the rate of a clock in SR, kinetic energy is frame dependent. 


#54
Dec2909, 01:57 PM

P: 451




Register to reply 
Related Discussions  
The twins paradox and explanation  Special & General Relativity  22  
Twins Paradox question  Special & General Relativity  12  
Twins paradox  General Physics  6  
The twins paradox  Special & General Relativity  129 