E = mc2. It"s the world"s most famous equation, but whatdoes it really mean? "Energy equals mass times the speed of light squared."On the most basic level, the equation says that energy & mass (matter) areinterchangeable; they are different forms of the same thing. Under the rightconditions, energy can become mass, & vice versa. We humans don"t see themthat way—how can a beam of light & a walnut, say, be different forms ofthe same thing?—but Nature does.
Bạn đang xem: Einstein's big idea
So why would you have lớn multiply the mass of that walnut by the speed oflight to determine how much energy is bound up inside it? The reason isthat whenever you convert part of a walnut or any other piece of matter khổng lồ pureenergy, the resulting energy is by definition moving at the speed of light.Pure energy is electromagnetic radiation—whether light or X-rays orwhatever—and electromagnetic radiation travels at a constant tốc độ of300,000 km/sec (186,000 miles/sec).
Why, then, vì chưng you have to square the speed of light? It has to vày withthe nature of energy. When something is moving four times as fast as somethingelse, it doesn"t have four times the energy but rather 16 times theenergy—in other words, that figure is squared. So the tốc độ of lightsquared is the conversion factor that decides just how much energy lies withina walnut or any other chunk of matter. Và because the tốc độ of light squaredis a huge number—90,000,000,000 (km/sec)2—the amount ofenergy bound up into even the smallest mass is truly mind-boggling.
Here"s an example.
Xem thêm: Hình Nền Máy Tính Mùa Xuân Đẹp Nhất, Mẫu Hình Nền Mùa Xuân
If you could turn every one of the atoms in a paperclip into pure energy—leaving no mass whatsoever—the paper clipwould yield 18 kilotons of TNT. That"s roughly the kích thước of the bomb thatdestroyed Hiroshima in 1945. On Earth, however, there is no practical way toconvert a paper clip or any other object entirely to energy. It would requiretemperatures and pressures greater than those at the chip core of our sun.