[extropy-chat] unidirectional thrust

[spike]

> > ... I assume the equal
> > and opposite force goes into the magnet which is bolted to the floor and
> > hence doesn't move because the entire earth takes up the impact...
> > switches it on. Or am I missing something elementary here?
> >
> > Damien Broderick [still not a physicist]
> 
> The earth moves back the other way.  Not very much of
> course, being as it is 6E24 kg, but it reacts the same
> way any mass would.  Momentum is conserved.
> 
> spike

On second thought, I could be wrong.

Thought experiment: take a 1 kg ball and toss
it upward 6 meters into the air.  When the ball reaches
its apex, the Earth has traveled about 1e-24 meters
in the opposite direction.

But one might argue that since this distance is
more than 6 orders of magnitude less than a 
Planck radius (1.6e-18 meters) that there is only 
one chance in 1.6 million that the earth moved
at all.  

Some physics wonk might jump in here.

spike