Recharging your laptop computer, your cell phone and a variety of other gadgets may one day be as convenient as surfing the web wirelessly.Like many of us, Marin Soljacic, an assistant professor in MIT's Department of Physics and Research Laboratory of Electronics, often forgets to recharge his cell phone, and when it is about to die it emits an unpleasant noise. Needless to say, this always happens in the middle of the night," he said. "So, one night, at 3 a.m., it occurred to me: Wouldn't it be great if this thing charged itself?" He began to wonder if any of the physics principles he knew of could turn into new ways of transmitting energy.After all, scientists and engineers have known for nearly two centuries that transferring electric power does not require wires to be in physical contact.