Physicists Look at a Superconductor, See a Cappuccino

Like a lot of physics ideas based in quantum mechanics, the magnetic fields produced by superconductors are difficult to picture in your mind. But if you want an illustration, scientists from the U.S. Department of Energy say, look in your coffee cup. Superconductivity means that a metal offers no resistance to electricity, having expelled its magnetic field. Only some metals, like lead and aluminum, have this property, and only at extremely cold temperatures—lead must drop below a critical temperature of about 7 degrees Kelvin. But when scientists at the DOE's Ames Laboratory at Iowa State University looked at the arrangement of superconducting lead's magnetic domains—the groups of atoms with a preferred magnetic direction—they saw a pattern: The picture looked an awful lot like bubbles in the frothed milk on top of a cup of cappuccino. The researchers call them "suprafroths," and though the nature of superconductors is still not well understood, the scientists say that suprafroths are a fundamental property. The magnetic domains can pop or disappear just like the froth of detergent bubbles in your sink—they even do so at the same statistical rate as an ordinary froth. And despite the fact that suprafroths exist only at bitterly cold temperatures, the scientists say they could be a model for studying the complex systems of ordinary froths, like the milk on your latte. So the next time you skip out on work to go to Starbucks, just tell your boss you're doing it as a service to science.