Can something come of nothing? Philosophers debated that question for millennia before physics came up with the answer—and that answer is yes. For quantum theory has shown that a vacuum (ie, nothing) only appears to be empty space. Actually, it is full of virtual particles of matter and their anti-matter equivalents, which, in obedience to Werner Heisenberg's uncertainty principle, flit in and out of existence so fast that they cannot usually be seen.
This makes the Casimir effect possible, something that now, according to the Economist.com, may have a practical use.