Re: [Phys-l] GR and Earth Rotation

[John Denker <jsd@av8n.com>]

On 03/07/2008 08:06 PM, Al Bachman wrote:
>   ... to the effect that General Relativity shows that a
> stationary earth model is of equal validity to a rotating earth.

There's no doubt about that.  Consider the following argument:

  1) Newtonian gravitation is analogous to electrostatics.
   As the saying goes, the same equations have the same
   solutions.

  2) It is well known that electrostatics plus special
   relativity /requires/ additional terms including 
   something we call magnetism.
     http://www.av8n.com/physics/magnet-relativity.htm

   Maxwell's electrodynamics is 100% compatible with special
   relativity;  there are no "relativistic corrections" needed.

  3) It should, therefore, come as no surprise that Newtonian
   gravity + special relativity /requires/ additional terms,
   including something we call gravitomagnetism, also called
   frame dragging. 
     http://en.wikipedia.org/wiki/Frame-dragging
   A simple Gedankenexperiment that may help remove the last
   vestige of doubt about this can be found at
     http://www.av8n.com/physics/gravity-source.htm

   Einstein's GR is 100% compatible with SR. 

  4) People have been looking for direct observational
   evidence of frame dragging ... but it is not so easy.
   Gravity is many many orders of magnitude weaker than
   electrostatics, and at obtainable velocities the
   gravitomagnetic field is smaller still, so the signal
   to noise ratio of existing observations is nothing to
   write home about.  But ask again in a couple of months,
   to see what Gravity Probe B can come up with.
     http://en.wikipedia.org/wiki/Gravity_Probe_B


If you really want to know what's going on, an excellent
text is _Gravitation_ by Misner, Thorne, and Wheeler.  It 
is surprisingly readable (surprising given the intrinsic
complexity of the subject matter).