Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 29/06/2016 02:50:01

Title: How does space time work in 3D?
Post by: thedoc on 29/06/2016 02:50:01

John Moen asked the Naked Scientists:
   Hello Naked Scientists,

I have a question about the nature of space-time. We are told to imagine the distortion of space-time by the gravity of heavy objects as like an infinite rubber sheet distorted by the weight of a heavy ball. This seems to be a two-dimensional representation of space-time. What happened to the third (and other postulated) dimension of space? How does it (they) fit into this model of gravity?

Best regards

John
What do you think?

Title: Re: How does space time work in 3D?
Post by: jeffreyH on 29/06/2016 04:47:03

The rubber sheet visualisation of geometric distortions is a simplification of the gravitational effects of mass on spacetime. What in effect it is trying to represent is a gradient. If we record at different positions in space around a large mass how length contracts we can then plot this against the gravitational field strength at each point. If we do the same for time then we can in fact produce a graph of length contraction against time dilation. The resulting curve has a changing gradient or steepness along its length. This is a more mathematical representation of spacetime curvature. However visualisations can often portray complex subjects in a more comprehensible way and generate much more interest.