On Oct 12, 1:42*am, Thomas Prufer wrote:

Ah, ok, you're thinking the Earth vanishes, and the planets and stuff are still
around. I was thinking of a hollow shell of gas in a theoretical void -- the
same void used for electrons next an infinite plane with a charge... In such a
void, I'd think it would pull itself into a cloud without a hole in the middle,
slowly.

I'm pretty sure the cloud would not coalesce. Each molecule of the
cloud has a velocity. And that velocity will be greater than the
escape velocity for a body with the gravitational field of that cloud
itself. This is why the moon has no atmosphere - and it has far more
gravitational pull than the cloud we're describing would.

An engineer friend saw a perpetual motion machine once...

Are you sure? : )