12 Jan
2014
12 Jan
'14
4:32 a.m.
Has anyone ever proposed in the Annals of Improbable Research or a similar venue that, in addition to undergoing periodic reversals of its magnetic field, Earth is also subject to occasional short-lasting reversals of its gravitational field?
For Einstein gravity, the equivalence principle holds literally; the sign of m (or of M) doesn't reverse the dynamics. A negative-mass dinosaur will experience an upward force, which will make it fall in a downward direction, still at 1 gee. Joshua