Hi folks, A system of two masses, stationary with respect two each other, is the starting point. For convenience I'll specify one mass as being much larger than the other. The only force acting between them is their mutual gravitational attraction. At time zero they are an arbitrary distance apart. Some time later they are further apart. Possible or not? It's actually quite possible. Hint: the smaller mass splits into two during the manoeuvre. Springs, or similar mechanical devices, are allowed. Just a bit of fun. ;) Bob.