Gravitational time dilation

One of the affects of General Relativity is gravitational time dilation. This is the slowing of time by a gravitational field.

Gravitational Time Dilation Formula
The formula for gravitational time dilation is:

Where:
 * t' = Time inside the gravitational field.
 * t = Time outside the gravitational field.
 * m = The mass causing the gravitational field.
 * r = The distance from the center of the gravitational field.
 * c = The speed of massless particles (a.k.a. the speed of light in a vacuum).
 * G = The gravitational constant = 6.6742 X 10-11 N m2 kg-2

Because the gravitational constant is so small, it takes a large mass with a small radius to produce significant time dilation. However by using atomic clocks it is possible to detect the effect on Earth.



The Significance of Atomic Clocks
There are identical atomic clocks at both the Royal Observatory in Greenwich England and the National Bureau of standards in Boulder Colorado. The one in Greenwich England ticks 5 microseconds / year slower than the one in Boulder Colorado which is predicted by General Relativity given their one mile difference in altitude. The clocks are accurate to 1 microsecond / year so the difference cannot be a result of error. According to General Relativity, both clocks are right in their respective frames of reference.

Dr. Russell Humphreys' White Hole Cosmology shows that, given the right starting conditions, the Earth could have been significantly time-dilated relative to the rest of the universe, thus allowing star light from deep space to reach Earth.

Related References

 * Gravitational Red Shift by HyperPhysics Concepts