Visualizing General Relativity with Fluid Analogy

lukesfn

I'm interested in using a fluid analogy of general relativity to more easily visual what is going on in certain situations, with out having to resort to visualizing curved 4d space time which is doesn't come to naturally.

However, I don't know relativity quite well enough to understand what the nature of the fluid would be, or even if it is possible to specify a fluid type of metric that can replicate all the effects of GR.

GR is often introduced with the ball rolling on rubber sheet analogy, which I always found more confusing then helpful, because it is meant to show how curved space causes a ball to fall into a dip, but in that analogy, the force of gravity is what pulls the ball down the slope, so it doesn't actually help explain much. It isn't just space that is curved, it is space time.

Instead I have always imagined the idea of space flowing into objects. What I would now like to understand better is, what would be the nature of flow, and where does this analogy break down.

If one was to create an animation, in 2D, of an object, with space flowing into it, how would it look? I imagine that the density of space would change as gravity increases. I would imagine that such an animation would give a much more intuitive idea of what is happening in GR, although, I could imagine some people may not like it because it is suggestive of some time of redundant dynamic ether.

A.T.

Fluid analogies:
http://arxiv.org/pdf/gr-qc/0411060v2.pdf
http://www.relativitet.se/Webarticle...sson74p905.pdf (chapter VII)

Non fluid analogies, which avoid the problems of the rolling on rubber sheet explanation :
http://www.relativitet.se/spacetime1.html
http://www.physics.ucla.edu/demoweb/...spacetime.html
http://www.adamtoons.de/physics/gravitation.swf

lukesfn

Thanks a lot, I haven't found these before, but they look quite interesting after some speed reading. Looks like a good starting point. There is some mention of a fluid having a rotation at each point which sounds quite interesting.


I think I have seen all of these links before. They are what I am trying to avoid. It's easier to imagine objects moving through a stream that is a similar shape to how we conceptualize the world a round us, rather then plotting some kind of geodesic on some strange higher dimensional space time surface it is difficult to relate to. Although, I expect that if you want to do any serious work, that is the way to go. Either way, it is good to be able to visualize things from different points of view.