quantum physics

Before the discovery in the 1920s of quantum mechanics—laws that explain the way the world works on the very small scale of atoms and electrons—the fact that bleach and peroxide glow when mixed would have seemed like just another chemical reaction that gives off light, like fire or fireflies. But it’s actually a glimpse into the impossible.

In the strange, subatomic world of quantum mechanics, even complete nothingness exerts a force. According to a principle known as the Casimir Effect, two plates separated by an incredibly small space will experience a force pushing them together. While the Casimir effect isn’t powerful enough to affect daily life, it has complicated efforts to build effective nanotechnology.

The device is a cylinder a bit smaller than a pinky finger, filled with helium and cooled to just above absolute zero. Inside, a young universe—or something very much like one—evolves. As the helium sloshes about, it mimics a process that may have powered our own universe a few moments after the big bang. And once the fluid settles down, the little whirlpools that remain may be akin to the defects in early spacetime that ultimately gave rise to galaxies, stars and planets.

Is all this work on string theory and multiple dimensions and extra universes still science? Thats the question physicist Sean Carroll and writer John Horgan recently debated. Carroll, of the California Institute of Technology, also blogs regularly for Cosmic Variance, and he wrote out a detailed post explaining his position. Obviously, as a cosmologist who works full-time on these seemingly preposterous ideas, he is a bit biased. Hes not the guy youd expect to stop and say it isnt real science. But his piece on the subject does effectively explain why he and, one assumes, other theoretical physicists working on these problems think this way.

For those of you who sometimes wonder why string theory can be one of the most talked about scientific ideas of our day without a whisper of evidence backing it up—admit, there are a few of you out there—there's a very interesting and not too complex article in the new issue of Physics World. The piece reviews some of the history and progress of past scientific theories, and why considering only the big ideas that can be backed by some experimental proof isn't a good thing for advancing our understanding of the universe. The simplified conclusion: At this point, string theory is the only real candidate capable of pulling together gravity and quantum physics, so we might as well stick with it.—Gregory Mone

This past Sunday the New York Times featured an excellent piece by Dennis Overbye about the film What the Bleep: Down the Rabbit Hole, a sequel to the cult hit of two years ago What the #$%* Do We Know!? Both movies feature a coterie of scientists, philosphers and visionaries who speak with mixed credibility about quantum physics and the possibility that reality could be a mental construct. Overbye clearly thinks this is a bunch of hooey (as does PopSci's own Greg Mone—see for yourself how he ripped the makers of the original film a new one in 2004 here) and his essay makes for really entertaining reading. —Megan Miller