Wireless power takes charge

In 1891, Nikola Tesla performed an amazing demonstration: He illuminated a gas discharge tube (essentially a fluorescent bulb) with an electric field, showing that it was possible to transmit electric power without wires. Since then, advances in electronics and computing have given us portable versions of his contemporaries' inventions-Bell's telephone and Edison's phonograph. But when it comes to powering up those devices, we're still tethered in place.