world is matter. Substantivalists believe space is a substance, a thing itself over and above the material contents of the world; relationists believe ‘space’ is just a pretty way of talking about the relations that hold between bodies. This might seem to be an arcane, even a semantic debate, but Newton’s arguments show its significance for physics: if all that exists is matter, we don’t seem to have any way to define the rest frame that we need to do physics.
Substantivalists
Relationists
