Take an LED that produces intense, blue light. Coat it with a thin layer of special microscopic beads called quantum dots. And you have what could become the successor to the venerable light bulb. Chemists at Vanderbilt University have discovered a way to make quantum dots spontaneously produce broad-spectrum white light. In recent years LED's have begun to appear on the market that replace conventional light bulbs, but they have been quite expensive. They are more energy efficient than incandescent bulbs, last much longer and are very tough.