Full Idea
General Relativity describes space-time in a way that allows it to exist with determinate properties not reducible to the properties and relations of its material contents. Hence nearly all physicists and philosophers writing on GR are substantivalists.
Gist of Idea
General Relativity allows substantivalism about space-time - that it has independent properties
Source
Carl Hoefer (The Metaphysics of Space-Time Substantivalism [1996], p.5), quoted by Barbara Vetter - Potentiality 7.3
Book Reference
Vetter,Barbara: 'Potentiality: from Dispositions to Modality' [OUP 2015], p.262
A Reaction
I'm encouraged by this, as I instinctly favour substantivalism. Imagine removing all the objects from space-time, one by one. What happens as you approach the end of the task? Once they are removed, can they be replaced?