最美的十大物理实验

Science's 10 Most Beautiful Experiments 科学史上最美的十个实验

科学史上最美的十个实验之序言 在科学家眼里，美，应该怎样阐释？ —用最简单的实验和设备获得最根本、最直接、最精确的科学结论，这就是美！ Whether they are blasting apart subatomic particles in accelerators, sequencing the genome or analyzing the wobble of a distant star, the experiments that grab the world's attention often cost millions of dollars to execute and produce torrents of data to be processed over months by supercomputers. Some research groups have grown to the size of small companies.

But ultimately science comes down to the individual mind grappling with something mysterious. When Robert P. Crease, a member of the philosophy department at the State University of New York at Stony Brook and the historian at Brookhaven National Laboratory, asked physicists to nominate the most beautiful experiment of all time, the 10 winners were largely solo performances, involving at most a few assistants. Most of the experiments took place on tabletops and none required more computational power than that of a slide rule or calculator. What they have in common is that they epitomize the elusive quality scientists call beauty. This is beauty in the classical sense: the logical simplicity of the apparatus, like the logical simplicity of the analysis, seems as inevitable and pure as the lines of a Greek monument. Confusion and ambiguity are momentarily swept aside, and something new about nature becomes clear.

无论在加速器中裂解亚原子粒子，还是测序基因序列，或分析一颗遥远恒星的摆动，这些让世界瞩目的实验常常动辄耗资百万美元，产生出洪水般汹涌的数据，并需要超高速计算机处理几个月。一些实验小组因此成长为一个个的小公司。 罗伯特·克瑞丝是美国纽约大学石溪分校哲学系的教员、布鲁克海文国家实验室的历史学家，他最近在美国的物理学家中作了一次调查，要求他们提名历史上最美丽的科学实验。《物理学世界》刊登了排名前10位的最美丽实验，其中的大多数都是我们耳熟能详的经典之作。令人惊奇的是这十大实验中的绝大多数是科学家独立完成，最多有一两个助手。所有的实验都是在实验桌上进行的，没有用到什么大型计算工具比如电脑一类，最多不过是把直尺或者是计算器。 所有这些实验共同之处是他们都仅仅“抓”住了物理学家眼中“最美丽”的科学之魂，这种美丽是一种经典概念：最简单的仪器和设备，发现了最根本、最单纯的科学概念，就像是一座座历史丰碑一样，人们长久的困惑和含糊顷刻间一扫而空，对自然界的认识更加清晰。 Science's 10 Most Beautiful Experiments 科学史上最美的十个实验

科学史上最美的十个实验之一 Double-slit electron diffraction 双缝电子衍射 Neither Newton nor Young was quite right about the nature of light. Though it is not simply made of particles, neither can it be described purely as a wave. In the first five years of the 20th century, Max Planck and then Albert Einstein showed, respectively, that light is emitted and absorbed in packets — called photons. But other experiments continued to verify that light is also wavelike. It took quantum theory, developed over the next few decades, to reconcile how both ideas could be true: photons and other subatomic particles — electrons, protons, and so forth — exhibit two complementary qualities; they are, as one physicist put it, "wavicles." To explain the idea, to others and themselves, physicists often used a thought experiment, in which Young's double-slit demonstration is repeated with a beam of electrons instead of light. Obeying the laws of quantum mechanics, the stream of particles would split in two, and the smaller streams would interfere with each other, leaving the same kind of light- and dark-striped pattern as was cast by light. Particles would act like waves.

牛顿和托马斯·杨对光的性质研究得出的结论都不完全正确。光既不是简单的由微粒构成，也不是一种单纯的波。20世纪初，麦克斯·普朗克和阿尔伯特·爱因斯坦分别指出一种叫光子的东西发出光和吸收光。但是其它实验还是证明光是一种波状物。经过几十年发展的量子学说最终总结了两个矛盾的真理：光子和亚原子微粒（如电子、光子等等）是同时具有两种性质的微粒，物理上称它们：波粒二象性。 将托马斯·杨的双缝演示改造一下可以很好地说明这一点。科学家们用电子流代替光束

来解释这个实验。根据量子力学，电粒子流被分为两股，被分得更小的粒子流产生波的效应，它们相互影响，以至产生像托马斯·杨的双缝演示中出现的加强光和阴影。这说明微粒也有波的效应。 Science's 10 Most Beautiful Experiments 科学史上最美的十个实验

科学史上最美的十个实验之二 Galileo's experiment on falling objects

伽利略的自由落体实验 In the late 1500's, everyone knew that heavy objects fall faster than lighter ones. After all, Aristotle had said so. That an ancient Greek scholar still held such sway was a sign of how far science had declined during the dark ages. Galileo Galilei, who held a chair in mathematics at the University of Pisa, was impudent enough to question the common knowledge. The story has become part of the folklore of science: he is reputed to have dropped two different weights from the town's Leaning Tower showing that they landed at the same time. His challenges to Aristotle may have cost Galileo his job, but he had demonstrated the importance of taking nature, not human authority, as the final arbiter in matters of science. 在16世纪末，人人都认为重量大的物体比重量小的物体下落得快，因为伟大的亚里士多德已经这么说了。 伽利略，当时在比萨大学数学系任职，他大胆地向公众的观点挑战。著名的比萨斜塔实验已经成为科学中的一个故事：他从斜塔上同时扔下一轻一重的物体，让大家看到两个物体同时落地。伽利略挑战亚里士多德的代价也许是他失去了工作，但他展示的是自然界的本质，而不是人类的权威，科学作出了最后的裁决。