There are lots of ways to create visible light, but not all methods are created equal. While light created by sound is a cool phenomenon, it happens on such a tiny scale that we probably won’t be powering flashlights with sound waves any time soon. And light created from intense pressure on a material results in some pretty strange effects — anyone heard of earthquake light? — though it could be hard to harness those effects in a useful way.
Most commonly, our daily lives are lit by incandescent light, but heat as a light source is terribly inefficient. That’s why at Brookhaven we’re exploring the properties of electroluminescence and pushing LEDs to near-perfect efficiency.