On the Origin of Gravitational Force

Equivalence principle is the basement of general relativity theory. It points out that the gravitational force is equivalent to the inertial force. However, the general relativity theory does not give the reason. In this paper, we assume the space is a kind of elastic media. The energy can take pressure on the space. It will make the space curved. The curved space-time produces gravitational force. This paper gives the mathematical calculation based on elasticity theory to show that this assumption is true. It also gives the accurate relationship between mass and gravitational force. The relationship is in line with the conclusion of general relativity.