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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?
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?