[extropy-chat] Casimir Torque Project

[Hal Finney]

Maybe I can convince you that this won't work by a more detailed analysis.

> http://www.wingedcat.com/ct/casimirtorque.txt
> http://www.wingedcat.com/ct/casimirtorque.gif

As I understand it, this device consists of a disk that has a metal
square in the center and a metal ring around the outside.  Between the
disk and the ring are specially shaped black body structures which block
the Casimir force.  The whole thing is one piece and rigid.  Your design
is intended to produce a net unbalanced torque force, such that if this
device were suspended in a vacuum in empty space, it would spontaneously
begin spinning, superficially at least violating conservation of angular
momentum and conservation of energy principles.  Is that right?

The problem that I see with your design is elementary.  You try to
arrange the black body shields so that the unblocked places on the rim
are attracted towards the center square with a net torque.  But you have
forgotten Newton's third law!  Every action has an equal and opposite
reaction.  This means that if the rim is attracted to the center square,
then the center square is equally attracted back to the rim.  And the
torque due to the center square is exactly the opposite of the torque
due to the rim.  These will cancel each other out and it won't spin.

Consider a large model of your device, which instead of using the Casimir
force, uses rubber bands.  Stretch rubber bands between each unblocked
point on the rim and each unblocked point on the central square.
Your analysis still goes through!  Each point on the rim has more
clockwise torque than counterclockwise.  Yet this rubber-band device
will obviously not start spontaneously spinning, merrily generating
energy and angular momentum that we can run the world off of.  Again,
the reason is because the rubber bands pull as hard counterclockwise on
the central square as they pull clockwise on the outer rim.

Nothing in your design relies on any properties of the Casimir force
other than that it is attractive and can be blocked.  Clearly no such
device can violate the laws of physics.

Hal