In present article, the 'space' is considered as a physical entity, and the gravity is discussed as a consequence of equal and opposite interaction between 'mass' and the 'space' around every mass. In order to explain the cause of gravity, a very new concept of root force is introduced as a fundamental nature of 'mass' and the 'space' both. The unit of root force is (?m?kg/s) or square root of newton. It is learnt that may be, it is a root force which gives mass to every particle and make existence possible. The exact nature of root force is beyond current understanding of physics. Another new concept of super-vacuum (absolute emptiness) is also introduced in this paper. This concept is essential to understand the importance of the 'space'. It is concluded that 'mass' and 'space' shares equal and opposite interaction, which causes gravitation. And magnitude of root force causes time dilation.