Hi Bear with my possible ignorant. I am puzzled over this dilemma. If General Relativity states that gravity is the curvature of spacetime, that is, no spacetime no gravity, and the cause of curvature is matter (mass), it means that if no matter, there is no gravity. I understand that scientists say the Superforce existed in Planck epoch (zero to 10e-43s after the Big Bang) at which point matter did not exist even if spacetime existed. If there was no matter (mass), there was no curvature. If no curvature, there was no gravity. So, why is it assumed that gravity existed in Planck epoch? I might be totally off. I appreciate any help to understand this.