Full Idea
The magnetic and the gravitation field can occupy all the same places without merging.
Gist of Idea
Magnetic and gravity fields can occupy the same place without merging
Source
Harré,R./Madden,E.H. (Causal Powers [1975], 9.IV)
Book Reference
Harré,R/Madden,E.H.: 'Causal Powers: A Theory of Natural Necessity' [Blackwell 1975], p.180
A Reaction
We can divide stuff into two classes, then, according to whether they usually merge if coextensive in space. Oil and water can be mixed, but eventually separate again.