Having studied GR as far as Einstein's tensor equation and a bit beyond, I'm just doing a bit of a double-take wondering what we mean when we talk about spacetime. Frequently it is referred to as if it is a thing that exists, like mass and energy. For example, we say that spacetime is curved as if it is a thing in the universe that is curved. If hypothesising about multiverses we might talk about there being numerous distinct spacetimes as if they were all different things. On reflection though, I have gravitated towards the following view: 1.- spacetime is just a mathematical model that's useful for predicting the interaction of mass-energy 2.- it has no independent existence of its own and without mass or energy there would be no meaningful concept of spacetime 3.- when we talk about spacetime being curved we are just talking about properties of the theoretical 4-dimensional manifold we use to determine what path light rays will follow, particles will fall etc. Does this view make any sense?