LETTERS TO THE EDITORS
Guiding Light
To the Editors:
In "Optically Trapped Fermi Gases" (May–June),
authors John Thomas and Michael Gehm describe how the electric field
gradient of a light beam causes the attraction of a neutral atom. An
everyday example of that principle is a charged comb attracting a
neutral piece of tissue paper. It's a magical feat I find akin to
picking oneself up by the bootstraps. Maybe if there were also a
repulsive gravitational force, we could pick ourselves up in the
gravitational field gradient of the Earth.
George Prans
Manhattan College
Bronx, New York