🚀 go-pugleaf

John Baez poses:
: Imagine an extremely (although not infinitely) rigid crystal.  It takes
: a huge amount of energy to deform the crystal lattice ever so slightly.
: Thus if this crystal is placed in the earth's gravitational field at sea
: level, the curvature of space due to the gravity prevents the
: lattice from being perfectly regular, at the cost of a large amount of
: energy.  The crystal would have much less energy if it were far away
: from the earth where the curvature of space is less.  If we make the
: crystal rigid enough it will actually be energetically favorable for the
: crystal to float upwards - since the decrease in its internal energy
: will more than compensate for the increase in gravitational potential
: energy.
: 
: Now, I *know* that this material would have to be insanely rigid for
: this effect to be noticeable at all -- far more rigid than any actual
: stuff.  However, we're talking questions of principle here.  Is there 
: any reason *in principle* why a sufficiently rigid material wouldn't
: levitate to get out of the earth's gravitational field - that's what I'm
: asking.  

I usually get this stuff wrong, but here's my answer.
The rod will flex infinitessimally, offsetting its internal energy gain
by the reduction in gravitational potential energy. This is a local energy
minimum, and that's where it'll be trapped. The space stuff is a red
herring, since there is no mechanism to get it there.
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| lord snooty @the giant |  Would You Like Space Potatoes With That?       |
| poisoned electric head |              andrew_-_palfreyman@cup.portal.com |
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