万物简史 第170期:爱因斯坦的宇宙(13)

You may not feel outstandingly robust, but if you are an average-sized adult you will contain within your modest frame no less than 7 x 10 18 joules of potential energyenough to explode with the force of thirty very large hydrogen bombs, assuming you

万物简史 第169期:爱因斯坦的宇宙(12)

His famous equation, E =mc 2 , did not appear with the paper, but came in a brief supplement that followed a few months later. As you will recall from school days, E in the equation stands for energy, m for mass, and c 2 for the speed of light square

万物简史 第199期:威力巨大的原子(13)

Neutrons and protons occupy the atom's nucleus. The nucleus of an atom is tinyonly one millionth of a billionth of the full volume of the atombut fantastically dense, since it contains virtually all the atom's mass. As Cropper has put it, if an atom

万物简史 第200期:威力巨大的原子(14)

Neutrons and protons occupy the atom's nucleus. The nucleus of an atom is tinyonly one millionth of a billionth of the full volume of the atombut fantastically dense, since it contains virtually all the atom's mass. As Cropper has put it, if an atom

万物简史 第201期:威力巨大的原子(15)

As physicists began to delve into this subatomic realm, they realized that it wasn't merely different from anything we knew, but different from anything ever imagined. Because atomic behavior is so unlike ordinary experience, Richard Feynman once obs

万物简史 第202期:威力巨大的原子(16)

It was while puzzling over this problem that Bohr was struck by a solution and dashed off his famous paper. Called On the Constitutions of Atoms and Molecules, the paper explained how electrons could keep from falling into the nucleus by suggesting t

万物简史 第203期:威力巨大的原子(17)

Meanwhile the tireless Rutherford, now back at Cambridge as J. J. Thomson's successor as head of the Cavendish Laboratory, came up with a model that explained why the nuclei didn't blow up. He saw that they must be offset by some type of neutralizing

万物简史 第204期:威力巨大的原子(18)

As it was, the Europeans had their hands full trying to understand the strange behavior of the electron. The principal problem they faced was that the electron sometimes behaved like a particle and sometimes like a wave. This impossible duality drove

万物简史 第205期:威力巨大的原子(19)

Finally, in 1926, Heisenberg came up with a celebrated compromise, producing a new discipline that came to be known as quantum mechanics. At the heart of it was Heisenberg's Uncertainty Principle, which states that the electron is a particle but a pa

万物简史 第207期:威力巨大的原子(21)

It seemed as if there was no end of strangeness. For the first time, as James Trefil has put it, scientists had encountered an area of the universe that our brains just arent wired to understand. Or as Feynman expressed it, things on a small scale be

万物简史 第208期:威力巨大的原子(22)

Remarkably, the phenomenon was proved in 1997 when physicists at the University of Geneva sent photons seven miles in opposite directions and demonstrated that interfering with one provoked an instantaneous response in the other. 令人惊叹的是，这

万物简史 第209期:威力巨大的原子(23)

Quantum theory is very worthy of regard, he observed politely, but he really didnt like it. God doesnt play dice, he said. Or at least that is how it is nearly always rendered. The actual quote was: It seems hard to sneak a look at Gods cards. But th

万物简史 第210期:威力巨大的原子(24)

To explain what kept atoms together, other forces were needed, and in the 1930s two were discovered: the strong nuclear force and weak nuclear force. The strong force binds atoms together; its what allows protons to bed down together in the nucleus.

万物简史 第211期:威力巨大的原子(25)

Einstein disliked that, too. He devoted the rest of his life to searching for a way to tie up these loose ends by finding a grand unified theory, and always failed. From time to time he thought he had it, but it always unraveled on him in the end. As

万物简史 第212期:把铅撵出去(1)

10 Getting The Lead Out 第十章 把铅撵出去 In the late 1940s, a graduate student at the University of Chicago named Clair Patterson (who was, first name notwithstanding, an Iowa farm boy by origin) was using a new method of lead isotope measur

万物简史 第213期:把铅撵出去(2)

Lead is a neurotoxin. Get too much of it and you can irreparably damage the brain and central nervous system. Among the many symptoms associated with overexposure are blindness, insomnia, kidney failure, hearing loss, cancer, palsies, and convulsions

万物简史 第206期:威力巨大的原子(20)

What this means in practice is that you can never predict where an electron will be at any given moment. You can only list its probability of being there. In a sense, as Dennis Overbye has put it, an electron doesnt exist until it is observed. Or, pu

万物简史 第221期:把铅撵出去(10)

But there were many technical difficulties to overcome. Holmes also neededor at least would very much have appreciatedsophisticated gadgetry of a sort that could make very fine measurements from tiny samples, and as we have seen it was all he could d

万物简史 第214期:把铅撵出去(3)

As Sharon Bertsch McGrayne notes in her absorbing history of industrial chemistry, Prometheans in the Lab, when employees at one plant developed irreversible delusions, a spokesman blandly informed reporters: These men probably went insane because th

万物简史 第215期:把铅撵出去(4)

Buoyed by the success of leaded gasoline, Midgley now turned to another technological problem of the age. Refrigerators in the 1920s were often appallingly risky because they used dangerous gases that sometimes leaked. One leak from a refrigerator at