Time and Gravity

[TheBaker]

I'm trying to explain simply the relationship between gravity and time dilation for a project I'm doing, and I wanted to check whether the following analogy provides a correct representation of the link.

 

If we imagine spacetime as a rubber sheet, it looks like this (from the side on):

 

A ---------------------- B

 

If there's an object with mass though, spacetime becomes distorted to look like this (kind of, it's rather a poor drawing):

 

A --------_/------------- B

 

Would it be correct to say that time is dilated because it has further to travel along the surface of spacetime in the second example? The distance between A and B is longer in the second example because a mass has distorted the spacetime between them.

[Farsight]

No, sorry. Time doesn't travel. There's no "surface" to spacetime. OK you can fix this by talking about light travelling through spacetime, but even then you've got some confusion between cause and effect: time isn't dilated because light has got further to travel through spacetime. Time is dilated. That, in essence, is what the gravity is.