Do the 31 realms physically exist or is it a state of mind?

I know its an imponderable or unconjecturable to us putthujjanas, but do any of the 31 realms have corporeal existence or are they states of mind (mind-made) or a mixture of both? For example, does tusita heaven physically exist, or is it purely a state of mind? If tusita does exist physically then how can one get there? Is the earthly plane and the laws of physics also mind-made?