Gravity in General Relativity and Earth's Surface

Jerry Friedman
Messages
13
Reaction score
1
Is there something in General Relativity whose value is 9.8 m/s2 at the surface of the Earth?
 
Physics news on Phys.org
Yes. The proper acceleration of the surface.
 
  • Like
Likes Jerry Friedman
Jerry Friedman said:
Is there something in General Relativity whose value is 9.8 m/s2 at the surface of the Earth?

The acceleration of the stationary observer in the spherically symmetric vacuum according to GR is ##a=\frac{m}{r^2\sqrt{1-2m/r}}## (up to a sign).

If ##r>>m## this is very close to Newtons value.
 
  • Like
Likes Jerry Friedman
Thank you, Orodruin and Mentz114. I may be back with another question.
 
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...
ASSUMPTIONS 1. Two identical clocks A and B in the same inertial frame are stationary relative to each other a fixed distance L apart. Time passes at the same rate for both. 2. Both clocks are able to send/receive light signals and to write/read the send/receive times into signals. 3. The speed of light is anisotropic. METHOD 1. At time t[A1] and time t[B1], clock A sends a light signal to clock B. The clock B time is unknown to A. 2. Clock B receives the signal from A at time t[B2] and...

Similar threads

Back
Top