Kevin Wampler <wam### [at] uwashingtonedu> wrote:
> If the levitating triangle was this: 
> http://en.wikipedia.org/wiki/Ionocraft then the guy was delusional or 
> flat out lying when he said that science can't explain it.  The upshot 
> is that the voltage induces a slight air current through the triangle, 
> and since the triangle is very lightweight this is sufficient to lift 
> it. I believe it's not currently practical for "real-life" use because 
> the voltage source would weigh significantly more than the lift it 
> generates (which is why the demos you see are powered by an external 
> voltage source).

  Btw, one common feature to all (actual) physical phenomena that seem
to levitate objects is that they actually don't. Ok, it depends on how
you define "levitation", but usually it means something that somehow
nullifies gravity. (If "levitation" meant simply "does not touch the
ground for a long period of time", then planes, helicopters and hot
air balloons all "levitate" without problems.)

  Gravity is not being affected in any way in any of these phenomena.
The "levitating" object is still being pulled down by gravity, and hence
it's applying a force to the ground. The only difference between these
phenomena and just an object that is in direct contact with the ground is
that there's an invisible force mediating between the object and the ground
(usually a magnetic field or a flow of air).

  I don't really understand why some people get so excited about these
"levitation" experiments. They are no different from airplanes and
helicopters. All of them hover in the air without toucing the ground.
The mechanism is just a bit different depending on the phenomenon.

  What makes the "levitation" of a superconductor over a magnet (or the
other way around) so cool is that it's not something you experience in
everyday life (for obvious reasons). You could try to levitate a magnet
over another magnet, but it will just quickly fall off. The Meissner
effect makes the superconductor stay in place, which is unintuitive and
not common-day experience.

-- 
                                                          - Warp

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