Relax And Think Like A Rat

Don't feel guilty about the breaks you've been sneaking at work—they could be helping you learn. Neuroscientists at MIT find that rats take a similar pause after exploring an unfamiliar maze. During that break, the animals' brains repeatedly review a backward version of the route they just took, most likely cementing memories of the steps needed to reach the goal.

David Foster and his team zero in on this process by placing tiny wires into the rats' brains and then eavesdropping on individual cells. The neurons that light up during the experiments lie in a region known to form short-term memories. But as those cells play the memory again and again—10 times faster than the original experience—the rest of the brain has lots of opportunities to absorb the information and to place it into long-term storage. "This implies that it's not just during an experience that learning occurs," Foster says. "If we're right, the period after the experience is just as important, maybe more important."

The results may explain previous studies showing that people and animals learn best when given breaks between tasks—and provide a persuasive new justification for office daydreaming.

A Better Energizer

If you've ever had a cell phone suddenly die on you, you know that batteries are the weak link in mobile electronics. That's why MIT electrical engineer Joel Schindall thinks the time is ripe for capacitors. "They are better than batteries in almost every way, except in the amount of energy they store," he says. Schindall and his research group have licked that limitation.

Unlike batteries, which produce voltage from a chemical reaction, capacitors store electricity between a pair of metal plates. The larger the area of the plates, and the smaller the space between them, the more energy a capacitor can hold. Schindall's group had a radical idea: Cover the plates with millions of microscopic filaments known as carbon nanotubes. The tiny tubes vastly expand the surface area, creating a perfect sponge for electricity. "Now we can expect to store an amount of energy that is comparable to what batteries store," he says.

A capacitor-powered cell phone could be charged in minutes or seconds instead of hours. And since capacitors can be reused indefinitely, environmental waste from discarded batteries would become a thing of the past. Schindall says battery-free bliss may be less than five years away.