Time Dilation

[searchingfortruth]

The greater the gravitational field the slower time, the less gravity the faster the time. If a certain area in space could be cleared of all gravitational effects, how would that effect time?

[swansont]

The greater the gravitational field the slower time, the less gravity the faster the time.

 

No, this is not correct. Time dilation is affected by the gravitational potential, which is not the same as the strength of the field.

 

If a certain area in space could be cleared of all gravitational effects, how would that effect time?

 

Assuming theis means the gravitational potential is zero, time would pass faster there than for any region with a nonzero gravitational potential, which will be slowed by [math]\frac{\Phi}{c^2}[/math]

[searchingfortruth]

Do you know the calculations for figuring out the differences between time with no gravitational potential and say earth?

[swansont]

Do you know the calculations for figuring out the differences between time with no gravitational potential and say earth?

 

The gravitational potential for a body is -GM/r. For the earth this is ~60MJ/kg, giving a fractional frequency shift of about 6.7 x 10^-10. This, of course, ignores the effects of all other bodies.

[morgsboi]

If there is a black hole in the centre of our galaxy, what effect would that have to our time on Earth?

[IM Egdall]

If there is a black hole in the centre of our galaxy, what effect would that have to our time on Earth?

 

There is a black hole at the center of our galaxy. But it is so far away that its effects on Earth are negligible.

[Spyman]

There is a black hole at the center of our galaxy. But it is so far away that its effects on Earth are negligible.

Are you sure? Maybe I did something wrong but I got it to roughly 2 microseconds slower each day.

[imatfaal]

I make it 50 parts in a trillion - and I haven't checked to see if that is the same (and frankly I don't have a lot of faith in those figures). But surely the main reason we ignore it is that it is everywhere and thus is unimportant. Who cares if a hypothetical observer at an arbitrarily large distance such that his clock is fast-ticking sees us as time-dilated and slow. It is important in cosmology, iff you are being super-accurate, but in all other spheres of activity it is totally meaningless as all realistic frames are at the same grav potential and at the same dilation. It is far more important to know relative velocities and the differential grav potential with respect to the earth and the sun etc. it is negligible not because it is small, but because it is present in almost every observation

Edited February 10, 2012 by imatfaal