Hello, I came across the following explanation of E-mc^2 on pbs.org: "So why would you have to multiply the mass of that walnut by the speed of light to determine how much energy is bound up inside it? The reason is that whenever you convert part of a walnut or any other piece of matter to pure energy, the resulting energy is by definition moving at the speed of light. Pure energy is electromagnetic radiation—whether light or X-rays or whatever—and electromagnetic radiation travels at a constant speed of roughly 670,000,000 miles per hour." Link: http://www.pbs.org/wgbh/nova/einstein/legacy.html" [Broken] I've never heard this explanation before and it seems suspicious to me. It's as if the author is implying that the Newtonian equation for kinetic energy, E=mv^2/2, applies to something that is moving at the speed of light, and substitutes c for v, but doesn't divide by 2. So does the given explanation constitute one of the correct ways of looking at the meaning of E=mc^2, or is it only partially correct, or incorrect entirely?