# What's the connection between gravity and relativity?

1. Apr 18, 2013

### bcrelling

I understand there is a connection, as there is time dilation due to gravity and also time dilation due to velocity. The formula for gravitational time dilation also looks very similar for the Lorentz factor used to calculate relativistic time dilation.

Is it because light is(in a sense) impeded by a gravitational field(a higher density region of space) and so observers within in it must slow down to observe the speed of light maintaining a constant velocity?

2. Apr 18, 2013

### Simon Bridge

The connection is called General Relativity - it comes from requiring that the laws of physics are the same to all inertial observers and noticing that you cannot tell a gravitational frame from an accelerating one.

You can look it up online.

3. Apr 18, 2013

### harrylin

"Higher density region" sounds like a physical model of space; but as far as I know no good physical model is known. However, in 1920 Einstein said about general relativity that The existence of the gravitational field is inseparably bound up with the existence of space and empty space'' in its physical relation is neither homogeneous nor isotropic, compelling us to describe its state by ten functions (the gravitation potentials g).