Re: [Phys-L] Fwd: [PTSOS] spacetime simulator: flexible conduit?

[John Denker <jsd@av8n.com>]

In the context of
  http://www.youtube.com/watch?v=MTY1Kje0yLg

On 07/17/2012 01:03 PM, Bernard Cleyet wrote:
> I don't understand how this is a space time simulator?  I though it
> was simply an (approximate) inverse square model (1/r, potential),
> nothing to do w/ special relativity.

(and/or general relativity)

> bc needs to go back to school?

BC is being ultra-polite.  The trampoline model represents a serious
misconception as to the structure of spacetime and the relationship
between curvature and motion.  

Here's a three-sentence proof of what I am saying:  Deform the trampoline 
upward instead of downward.  The intrinsic curvature would be the same
and the geodesics would be the same, so the prediction of real general 
relativity would be the same.  However the trampoline demo makes opposite 
predictions about the motion.

A much more apt model of motion in curved space can be found here:
  http://www.av8n.com/physics/geodesics.htm