Though the Casimir force-a mysterious, phantom force exerted by nothing at all-seems like science fiction, it exists. It is a tiny force and very difficult to measure, but in 1995 the physicist Steven Lamoreaux measured the Casimir effect directly. By putting two gold-covered plates on a sensitive twist-measuring device, he determined how much force it took to counteract the Casimir force between them. The answer-about the weight of one slice of an ant that's been chopped into 30,000 pieces-agreed with Casimir's theory. Lamoreaux had measured the force exerted by empty space.