“Force from empty space drives a machine” cites the attraction between a gold plate and a ball as proof of vacuum energy and the Casimir force, but isn’t it possible that science has jumped the gun? There may be other causes of this behavior, such as the photoelectric effect producing static electricity, chemical-bonding forces, magnetism, or vacuum welding at macroscopic distances. Physicists should tune up their skepticism and examine more prosaic explanations before accepting the notion that something can be conjured out of nothing just by splitting temporal hairs. G. Solov
San Diego, Calif.