Re: Faster than light?

Robin Hanson (
Wed, 18 Dec 1996 12:55:56 -0800 (PST)

James Rogers writes:
>The Casimir force is a manifestation of these electrons popping up and
>disappearing momentarily in space. ... The net result is that the
>concentration of electrons in the space between the plates is significantly
>higher than the concentration on the outside of the plates, due to
>significant overlap of the electron density curves. This generates a
>repulsive force due to electron interaction between the plates that is
>larger than the repulsive force generated on the outside of the plates where
>the electron density is less.

Um, isn't the Casimir force between conducting plates *attractive*,
not repuslive? The usual explanation has you consider the zero point
energy of the photons in the space between the plates, and notes that
this (negative) energy gets larger as the plates get closer. Energy
gradient gives a force.

Robin D. Hanson