Redshift Factor in a Symptotic Stationary Flat Space

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SUMMARY

The discussion centers on a problem from Wald's book regarding an asymptotic stationary flat space involving two observers, A and B, connected by a rope. Observer A is positioned at a finite radius while observer B is at infinity, experiencing a redshift factor that affects the force transmitted through the rope. The participants emphasize the importance of energy conservation and momentum conservation in understanding the differing forces experienced by A and B due to the redshift. The tension in the rope is analyzed in the context of photon streams impacting each observer, highlighting the complexities of relativistic effects in stationary frames.

PREREQUISITES
  • Understanding of general relativity concepts, particularly asymptotic flatness.
  • Familiarity with energy conservation and momentum conservation principles in physics.
  • Knowledge of redshift effects in gravitational fields.
  • Basic grasp of the implications of stationary observers in relativistic contexts.
NEXT STEPS
  • Study the implications of redshift in general relativity, focusing on gravitational redshift.
  • Explore the concept of asymptotic flatness in spacetime geometries.
  • Learn about the conservation of momentum in relativistic systems.
  • Investigate the role of photon streams in exerting forces on stationary objects.
USEFUL FOR

Physicists, students of general relativity, and anyone interested in the dynamics of forces in relativistic frameworks will benefit from this discussion.

johnstrass
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I am reading Wald's book. There is a problem confused me: page 158, problem 4,(b). An symptotic statoinary flat space, two stationary observer connected with a rope. One observer A is at finite r and the other B is at infinity. Observer B is really stationary by other forces and holding the rope in order for A to be stationary. Use the energy conservation argument to proof the force asserted through the rope on B differ from the force on A from the rope by a redshift factor. How to think in the problem? Thanks.
 
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Haven't looked in the book yet, but..

By conservation of momentum, you would expect the rope to be tensioned, but not accelerate, if some "observer" C is applying equal and opposite streams of photons against (solar parachutes attached to) each end of the rope. But A & B would differ in the flux of momentum they measure impinging at their respective end.
 

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