Mike Hord wrote:

> When I was younger, I used to think floating cities (i.e., Cloud City in
> "The Empire Strikes Back") were an impossibility because of the massive
> amount of energy needed to hold them up.  Then one day I realized that
> if the losses in the system were small enough (high Q), you could run
> the thing for decades on a watch battery, as long as you don't plan on
> raising or lowering it. 
> 
> Because mechanical energy is force integrated over distance, if one or
> the other of those components is zero, the net energy change is zero,
> too. 

The only thing missing here is a concept how to create the necessary force
without a structure and without using the energy from the watch battery...
:)

So far, all known (to me, at least) methods to create force without using
structural means require movement. And therefore energy.

Gerhard

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