- #1
KurtLudwig
Gold Member
- 144
- 31
The equations for gravity vary differently depending on the distances involved: Inside a body, such as a planet, the weight varies directly with the distance from the center - as r. Outside of the planet or sun, gravity varies as the inverse square law - as 1/r^2. At distances at the edges of a galaxy and presumably further, gravity decrease less gradually - as 1/r, as calculated by an equation such as MOND.
Question 1: In the vast reaches of the universe, between galaxies, is the strength of gravity calculated by 1/r? I think that gravity decreases more slowly as 1/r.
Question 2: How is gravity calculated for interstellar gas? How can the inverse square law apply to a point mass, such as a hydrogen atom?
Question 3: Has gravity been actually measured in deep mines or bore holes? It cannot be directly proportional to r, since mass is more dense at the center of a planet or sun.
Question 1: In the vast reaches of the universe, between galaxies, is the strength of gravity calculated by 1/r? I think that gravity decreases more slowly as 1/r.
Question 2: How is gravity calculated for interstellar gas? How can the inverse square law apply to a point mass, such as a hydrogen atom?
Question 3: Has gravity been actually measured in deep mines or bore holes? It cannot be directly proportional to r, since mass is more dense at the center of a planet or sun.