Does the Gravity field inherent in the space structure of the Universe need a mass to exist?

Answer 1

Gravity is not inherent to the structure of space, it is brought about because of the interaction between space-time and mass.
Think of it like this, you and your friends stretch a sheet out into a flat plane. This flat plane could be thought of as space. Now throw a ball onto the sheet. The ball will cause the sheet to warp around it. This dent can be thought of as gravity. Now if you were to put a lighter ball on this sheet, it would roll toward the first ball. This would bee the same as gravitational attraction. Now if you were to throw a bowling ball onto the sheet and rip a hole in it, that is the same as a black hole.

Hope this helps.

Answer 2

Gravitation can exist independent of mass as the Weyl tensor. In General Relativity the source of the Ricci tensor is the energy-momentum of the local matter distribution. The Weyl tensor in General Relativity provides curvature to spacetime when the Ricci tensor is zero.

Answer 3

of course. gravitiy is the natrual force between masses as the electro force between electrons and protons