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jeremyfiennes
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What is the mathematical formula for the time dilation (clock-slowing factor) for a clock in a gravitational field g, equivalent to the Lorentz factor γ for a clock traveling at a relative speed v?
There's no way to answer that question without more information.jeremyfiennes said:Not quite with you. I have a clock A in outer space where there is no gravity. And one, B, stationary in a gravitational field g. By what factor does B run slower than A?
It depends on the gravitational potential (usually denoted ##\phi##), not the gravitational acceleration (usually denoted ##g##). So your question has no answer as asked.jeremyfiennes said:Not quite with you. I have a clock A in outer space where there is no gravity. And one, B, stationary in a gravitational field g. By what factor does B run slower than A?
Indeed. Start with a light pulse of frequency f at one height and send it upwards, convert it to a mass, drop the mass, and convert it back into energy. The light needs to have lost the same amount of energy on the upwards leg as the mass gained on the downwards leg, or else we have an energy-creating device here. Thus gravitational redshift, which is the same as gravitational time dilation.Orodruin said:You actually do not need the general expression to derive the approximations. Just using the equivalence principle will work perfectly fine.
You can also just take the exact Rindler case, and note that by local Lorentz character of any GR manifold, that for a near stationary case in GR, it must be equivalent to first order to the Rindler case in SR.Ibix said:Indeed. Start with a light pulse of frequency f at one height and send it upwards, convert it to a mass, drop the mass, and convert it back into energy. The light needs to have lost the same amount of energy on the upwards leg as the mass gained on the downwards leg, or else we have an energy-creating device here. Thus gravitational redshift, which is the same as gravitational time dilation.
Ok. Thanks. Nice clear reply. I've got it now. Not as simple as I had thought.Janus said:There's no way to answer that question without more information.
For example, if you compare a clock sitting on the surface of the Earth to a clock sitting on the surface of a world with twice the radius and 4 times the mass, they will run at different rates (with the on on the larger world running slower) even though both clocks are at 1g.
Gravitational time dilation is a phenomenon in which time passes at different rates depending on the strength of the gravitational field. In other words, time moves slower in areas with stronger gravity.
The mathematical formula for calculating the clock-slowing factor is t0 / t = √(1 - (2GM / rc2)), where t0 is the time experienced by an observer in a weak gravitational field, t is the time experienced by an observer in a strong gravitational field, G is the gravitational constant, M is the mass of the object creating the gravitational field, r is the distance from the object, and c is the speed of light.
Objects in strong gravitational fields will experience time passing at a slower rate compared to objects in weaker gravitational fields. This means that clocks in strong gravitational fields will run slower than clocks in weaker gravitational fields.
Yes, gravitational time dilation has been observed and measured in various experiments and observations, such as with clocks on GPS satellites and in gravitational fields near black holes.
Gravitational time dilation plays a significant role in the concept of time travel. In theory, if an object were to travel at extremely high speeds or in a strong gravitational field, it could experience time passing at a different rate, potentially allowing it to travel to the future or past. However, the practicality and possibility of time travel using this concept are still widely debated and not yet fully understood.