
#19
Jun2512, 05:05 AM

P: 62

Does following make sense, can some expert comment please? Clocks run more slowly in deeper gravitational wells (gravitational time dilation), and moving clocks tick more slowly than an observer's stationary clock. In both cases, we see the effect of time ticking slowly. Never do we see clocks ticking faster. So, answer to your question is, time can travel (tick) only as fast as it travels in your reference frame. It may tick slower, but never faster. 



#21
Jan2213, 10:38 AM

Astronomy
Sci Advisor
PF Gold
P: 22,792

Around 1930 Tolman (a relativist at Oxford) discovered that the gravitational field has a temperaturethis is called the Tolman effect, or the TolmanEhrenfest effect. In 2011 Smerlak and Rovelli published a paper in Classical and Quantum Gravity showing that this Tolman temperature was the ratio of two rates of timepassage i.e. the speed of one time compared with the other. http://arxiv.org/abs/1005.2985 Thermal time and the TolmanEhrenfest effect: temperature as the "speed of time" Carlo Rovelli, Matteo Smerlak The notion of thermal time has been introduced as a possible basis for a fully generalrelativistic thermodynamics. Here we study this notion in the restricted context of stationary spacetimes. We show that the TolmanEhrenfest effect (in a stationary gravitational field, temperature is not constant in space at thermal equilibrium) can be derived very simply by applying the equivalence principle to a key property of thermal time: at equilibrium, temperature is the rate of thermal time with respect to proper time  the 'speed of (thermal) time'. Unlike other published derivations of the TolmanEhrenfest relation, this one is free from any further dynamical assumption, thereby illustrating the physical import of the notion of thermal time. 4 pages Class.Quant.Grav.28,2011 Here is a Vimeo (online video) of a portion of Smerlak's talk about this in March 2011: http://vimeo.com/33363491 



#22
Jan2213, 12:02 PM

PF Gold
P: 244

Time and speed of light are related. Both are slowing down in a gravity field at the same rate. GPS satelites are compensated for the less gravity in space. Their clock are tuned slightly slower than the clock on earth. When the satelite is orbiting, its clock speeds up due to less gravity and finally syncs correctly with the clock on the ground. If not, the GPS in your car would display an error of several meters over a relative short distance of travel.




#23
Jan2213, 01:34 PM

P: 5,634

Time passes one second locally when local light has traveled 299,792,458 meters locally.




#24
Jan2213, 03:01 PM

P: 284





#25
Jan2213, 09:33 PM

P: 191





#26
Jan2313, 12:15 AM

P: 62

the fastticking observer is using Schwarzschild coordinates, a coordinate system where a clock at infinite distance from the massive sphere would tick at one second per second of coordinate time, while closer clocks would tick at less than that rate". "clock on the surface of the Earth (assuming it does not rotate) will accumulate around 0.0219 seconds less than a distant observer over a period of one year." To compare with solar system, I did some calculation, assuming sun as point mass, it's Schwarzschild Radius of 3000 meters, the ratio of coordinate time to proper time at various distances from sun are as following: At Schwarzschild Radius: Undefined (clock runs infinitely slow) At 1 meter from Schwarzschild Radius: 0.018596951 At earth (1 AU): 1.000141631 At outer edge of solar system (at around 1000 AU): 1.000001416 Far away from solar system (at around 1000000 AU): 1 



#27
Jan2313, 05:10 AM

PF Gold
P: 1,852

My answer is yes, time can be quantized. One may google "chronon" to find a description of this shortest duration of time, plus these two additional sources for reference: arXiv.org > hepth > arXiv:hepth/0308190 High Energy Physics  Theory Title:Time Quantization and qDeformations Authors:Claudio Albanese, Stephan Lawi arXiv.org > quantph > arXiv:quantph/9706059 Quantum Physics Title:Introduction of a Quantum of Time ("chronon"), and its Consequences for Quantum Mechanics Authors:Ruy A. H. Farias, Erasmo Recami Cheers, Bobbywhy 


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