Energy, Mass and the Speed of Light

You know the equation, but here is some background information that you should also know. You never know when it might come in handy.

In 1905, Albert Einstein had his annus mirabilis (Latin for “extraordinary year”), publishing four major papers in the prestigious German “Annalen der Physik” (Annals of Physics), one of the oldest scientific journals on physics. These four papers contributed to the foundation of modern physics and changed our views on time, space, mass and energy.

The most famous of these is his third paper, now called Special Theory of Relativity (General Relativity came later between 1907 and 1915). But it was his final paper in November of that year that introduced us to what is probably the most well-known equation ever written, E=mc2. The paper, with the anticlimactic title, “Does the Inertia of a Body Depend Upon Its Energy Content?” does not actually contain that equation. What it does have is a verbal description of the same concept where he states (originally in German), “If a body gives off the energy L in the form of radiation, its mass diminishes by L/V2.“ He proved that mass will actually decrease or increase when energy is taken away or applied to it (heated water actually gains mass, although very little). Other physicists later expressed Einstein’s ideas in various mathematical formulas similar to the famous one. Finally, in 1946, Einstein published a layman’s paper in Science Illustrated titled, “E = mc2: the most urgent problem of our time”. The equation had entered the realm of popular science to stay.

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