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A surprising clarificationOctober 2005 Toward the end of 2005 we're celebrating the 100th anniversary of Albert Einstein's publication of his famous equation, E = mc², which expresses the equivalence of matter (mass) and energy. In the equation, "E" stands for energy, "m" stands for mass, and "c" is the speed of light, about 300,000 km (or 186,000 miles) per second. In other words, the energy contained in a bit of matter is found by multiplying its mass by the square of the speed of light, which yields the substantial-looking number 9x10 (that's 90,000,000,000,000,000) m²/sec². An impressive result!
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It's often heard that the enormity of the speed of light gives this equation its power, and illustrates the vast amount of energy that is contained in a small amount of matter. But the speed of light, though absolute, is a relative matter. That is, it's relative to the scale we choose. We represent it as a large number (let go for now the point that there are no "large numbers") because we choose to measure its speed in meters or kilometers per second. If we chose instead to express the speed of light in terms of, say, light-seconds (an absolute measure of distance) per second, the speed of light ( E = m. But Einstein wisely chose not to do that. The well-known form has a lot more mystery and pizzazz.
In fact, the
But truly Einstein had more in mind than mystery and pizzazz when he introduced the term
But Einstein was right: |

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