I What is the Concept of Velocity and Acceleration in General Relativity?

AngPhysics
Messages
2
Reaction score
0
I am hoping someone can clarify some confusion I have. It is my understanding that there is no such thing as absolute velocity or acceleration in GR. If one observer is moving near the speed of light and the other is stationary each observer will see the other as in motion. But if they each throw a ball away from themselves the observer in motion, from my understanding, has a much larger gravitational potential than the observer at rest so their would be a feature that distinguishes between their "velocities".
 
Physics news on Phys.org
AngPhysics said:
It is my understanding that there is no such thing as absolute velocity or acceleration in GR.
While there is no absolute velocity, there is the concept of proper acceleration. This is the acceleration experienced by an observer following a particular world line and is invariant.

The same is true in SR.

AngPhysics said:
from my understanding, has a much larger gravitational potential
Your understanding is wrong. The concept of relativistic mass does not apply to gravitation and how GR couples the metric to matter content. The correct statement is significantly more complicated. I suggest reading my insight article on relativistic mass, which is an obsolete concept not used by most physicists today.
 
  • Like
Likes AngPhysics
Thank you for the direction!
 
OK, so this has bugged me for a while about the equivalence principle and the black hole information paradox. If black holes "evaporate" via Hawking radiation, then they cannot exist forever. So, from my external perspective, watching the person fall in, they slow down, freeze, and redshift to "nothing," but never cross the event horizon. Does the equivalence principle say my perspective is valid? If it does, is it possible that that person really never crossed the event horizon? The...
In this video I can see a person walking around lines of curvature on a sphere with an arrow strapped to his waist. His task is to keep the arrow pointed in the same direction How does he do this ? Does he use a reference point like the stars? (that only move very slowly) If that is how he keeps the arrow pointing in the same direction, is that equivalent to saying that he orients the arrow wrt the 3d space that the sphere is embedded in? So ,although one refers to intrinsic curvature...
So, to calculate a proper time of a worldline in SR using an inertial frame is quite easy. But I struggled a bit using a "rotating frame metric" and now I'm not sure whether I'll do it right. Couls someone point me in the right direction? "What have you tried?" Well, trying to help truly absolute layppl with some variation of a "Circular Twin Paradox" not using an inertial frame of reference for whatevere reason. I thought it would be a bit of a challenge so I made a derivation or...
Back
Top