## The Speed of Time.

 Quote by conner.ubert How fast does time travel when it is not interrupted by curves in space-time? In other words what is the fastest time can travel? By how fast does it travel, to elaborate, I mean what is the fastest possible transition from one moment in the past to another moment in the future? Is it the speed of light or maybe faster? Or is time the fastest thing in the universe and light can only travel as fast as time will allow? I hope this makes sense.
Hi, conner. We say that someone moving away from us at near light speed appears to move slower through time than we do. In this sense we say that time has a relative speed. Furthermore, we say that a clock in orbit around the Earth moves faster than a clock on the earth, so again we are saying that time has a relative speed. I believe you are talking about these relative speeds of time and asking how fast time can travel in the absense of (1) all relative motion and (2) all gravitational slowing.

Would an answer based on Earth time as a stationary speed of time (that's all relative anyway), and corrected for the effect of Earth's gravity (and maybe the gravitational effects of the Sun and Moon, etc.?) give you the answer you need? I don't know how much time dilation is caused by one gee of gravity so I can't even give you the simple answer, but I think someone can.

Samm

 Quote by conner.ubert How fast does time travel when it is not interrupted by curves in space-time? In other words what is the fastest time can travel?
Some members have correctly mentioned that time does not travel.

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.

 Quote by manojr Some members have correctly mentioned that time does not travel. 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.
Perfect.

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 Quote by conner.ubert How fast does time travel when it is not interrupted by curves in space-time? In other words what is the fastest time can travel? By how fast does it travel, to elaborate, I mean what is the fastest possible transition from one moment in the past to another moment in the future?... ...
 Quote by manojr Some members have correctly mentioned that time does not travel. 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.
The speed of time (in the sense of a ratio between two rates of time-passage) was the topic of a technical paper recently, and a talk by Matteo Smerlak, a postdoc at Perimeter Institute in Canada. I think it's still an area of active research interest---not everything is resolved about it. Just my non-expert opinion.

Around 1930 Tolman (a relativist at Oxford) discovered that the gravitational field has a temperature---this is called the Tolman effect, or the Tolman-Ehrenfest 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 time-passage i.e. the speed of one time compared with the other.

http://arxiv.org/abs/1005.2985
Thermal time and the Tolman-Ehrenfest 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 general-relativistic thermodynamics. Here we study this notion in the restricted context of stationary spacetimes. We show that the Tolman-Ehrenfest 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 Tolman-Ehrenfest 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
 Recognitions: Gold Member 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.
 Recognitions: Gold Member Time passes one second locally when local light has traveled 299,792,458 meters locally.

 Quote by manojr Some members have correctly mentioned that time does not travel. 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.
Suppose you are in a deep gravitational well, doesn't a clock higher up appear to tick faster?

 Quote by cosmik debris Suppose you are in a deep gravitational well, doesn't a clock higher up appear to tick faster?
This question seems to beg another: What is the MAXIMUM possible speed-up of a clock, assuming it is a vast distance from the gravity well (Earth) and assuming it has no relative velocity relative to Earth? I suppose that the mass if the clock itself needs to be considered, lets say it's one Kg.

 Quote by cosmik debris Suppose you are in a deep gravitational well, doesn't a clock higher up appear to tick faster?
Yes, clocks up in satellites do tick faster.

 Quote by Oldfart This question seems to beg another: What is the MAXIMUM possible speed-up of a clock, assuming it is a vast distance from the gravity well (Earth) and assuming it has no relative velocity relative to Earth? I suppose that the mass if the clock itself needs to be considered, lets say it's one Kg.
From wikipedia (Gravitational time_dilation Outside a non rotating sphere):
the fast-ticking 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

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 Quote by conner.ubert How fast does time travel when it is not interrupted by curves in space-time? In other words what is the fastest time can travel? By how fast does it travel, to elaborate, I mean what is the fastest possible transition from one moment in the past to another moment in the future? Is it the speed of light or maybe faster? Or is time the fastest thing in the universe and light can only travel as fast as time will allow? I hope this makes sense.
I agree with Hootenanny here in post #8 where, on 14 September 2011, he said the question can be restated to "Can time be quantized?"

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 > hep-th > arXiv:hep-th/0308190
High Energy Physics - Theory
Title:Time Quantization and q-Deformations
Authors:Claudio Albanese, Stephan Lawi

arXiv.org > quant-ph > arXiv:quant-ph/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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