A Formula That Changed the World

In September 1905, Einstein published another paper, considered to be a mathematical footnote to his special theory of relativity. It contained the formula now synonymous with his work, E=mc². This equation says that the amount of energy released when an atom is split equals the loss of its mass times the speed of light squared.

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E Energy

= equals

m mass

c² times speed of light squared

c² means c times c, or 186,282 miles per second times 186,282 miles per second

Because c² is a fantastically large number (34,701,000,000 mi²/sec²), a small amount of mass can be converted into an enormous amount of energy. When an atom of uranium is split, it quickly forms two smaller atoms but also loses about 0.1 percent of its mass; that tiny amount converts into a vast release of energy

Energy released

Just one pound [450 g] of any substance completely converted into energy equals:

◼ 11 billion kilowatt hours

◼ the power needed to drive a car around the earth 180,000 times

◼ the power required to propel the largest oil tanker around the world 400 times

◼ the electric power needs of the United States for one day

The reverse is also true. It takes a tremendous amount of energy to “materialize” just one atom