What is the principle of gravity?

Answer 1

According to Albert Einstein and relativity gravity is caused by massive objects (planets, stars etc) displacing space itself, like (to use Einstein's metaphor) putting a Bowling ball on a mattress. It displaces and distorts the mattress so if you were to roll a ball along side the bowling ball it would be pulled toward it.

Answer

Gravity according to Newton is the potential energy between two bodies proportional to the masses of the bodies and inverse to the separation to the bodies.

E= -GmM/R

Einstein's view that gravity displacing space is mistaken. Einstein's deflection is answered by Newton, tan(g) = y/R= 1/2g t2/R = 1/2gR/c2 =8.1667E-6 , where g is the Earth's gravity g=9.88 and R is the distance to the sun 150G m.

My own Theory is that The Gravitational Energy

E= -GmM/R + mcv

is the correct formulation. Newton and Einstein 's model is missing the vector energy mcv, the motion energy of the mass m. This is the basis of the "dark energy". It is the source of the centrifugal acceleration away from the gravitational center. It also shows that the Universe is finite and in Equilibrium. The redshift is the indicator of the equality of the centripetal force mv2/R and the centrifugal force mcv/R cos(v), where cos(v) is the cosine of radial angle of the velocity. For example the redshift of the earth is v/c = 30k/c = 1/10000 the angle is arc cos 1/10000 = 89 degrees 59 minutes and 39.37 seconds, very close to 90 degrees.

mv^2/R=mcv/R cos(v) gives v/c= cos(v) = z the redshift. The redshift is a manifestation of Gravitational Equilibrium, a stable Universe, not an expanding Universe.