> For gravity, I'm okay with calling spacetime the medium I thought spacetime was supposed to be identical with the gravitational field. It can't be gravity's

> For gravity, I'm okay with calling spacetime the medium I thought spacetime was supposed to be identical with the gravitational field. It can't be gravity's "medium" if that medium is itself gravity. I find this extremely hard to think about; gravity both generates spacetime, and warps it. It's really hard to escape from the earthman's experience of space as a sort of instantaneous volume; we don't really experience time at all, except in the sense that we have a sense of certain events as being not the present (i.e. the past). We know that time exists in some sense; but all we experience of spacetime is the space bit.