诺奖得主Wilczek：“花瓶”物理学

撰文 | Frank Wilczek

翻译 | 胡风、梁丁当

来源：蔻享学术

中文版

自 1950 年以来，基础性物理研究对技术的贡献几乎为零。这是因为物理学家太过沉溺于对美的追求吗？

如果一项研究的思想与实践脱节，但想法特别漂亮，那么物理学家应该为这样的研究感到内疚吗？又应该如何评价这类工作？在现实生活中，科学家常常会遇到这样的问题。一方面是尽情展开想象的翅膀所带来的愉悦与可能的荣耀；另一方面是朝着既定目标稳步前进而得到的实际回报。在两者之间，我们必须进行权衡。

在基础性物理研究的前沿领域，这两者的冲突尤其突出。基础性物理研究旨在解析那些无法用既有定律解释的物理现象，它们只能通过发现新的定律来理解。一直到20世纪初，基础性物理研究本身也是最重要的应用物理学之一。通过揭示原子和光的量子秘密，物理学为化学、材料科学和工程学奠定了基础。

1929年，物理学家保罗·狄拉克 (Paul Dirac) 宣称：“对于大部分的物理与整个化学，它们的数学理论所依照的基本物理定律，我们都已知晓。”我们对这些基本定律的验证已经远远超过了实际应用所要求的精准度，以至于我们放宽了对“实际应用”的定义。印证这项成功的是一个颇具讽刺意味的事实 ：20世纪50年代之后，基础性物理研究领域的发现对技术几乎没有任何贡献。

在基础性物理研究中仍然存在一些重要而“不实际”的问题，比如宇宙的大部分质量源于一种所谓的“暗物质”——一种不是电子、光子、夸克、胶子或中微子的物质。尽管研究人员费尽了心力去探索暗物质这类问题，研究的进展依然缓慢。那么，一个雄心勃勃的理论物理学家又能做什么呢？

千百年来数学家一直面对着一个类似的问题 ：到底是选择纯粹性的研究还是应用性的工作？在G · H · 哈迪 (G.H. Hardy) 于1940年出版的《数学家的道歉》(A Mathematician's Apology) 一书中，他为纯粹的研究提供了一个硬核的理由 ：“可是一个普通的应用数学家的立脚点，在某种程度上，是不是有点可怜？‘想象的’宇宙要远比这个笨拙构建的‘真实’宇宙美丽得多。”

而 另 一 方 面， 约 翰 · 冯 · 诺 依 曼 (John von Neumann) 在 他1947年 的 文 章《 数 学 家 》(The Mathematician) 中谴责了这种纯粹性 ：“当一门数学学科远离了它的经验来源时……它将面临严重的危险。它变得越来越美学化，到了这个地步，我觉得唯一的补救办法就是回到原点，即重新或多或少地结合一些实际的想法。”

我认为冯 · 诺依曼在这个争论中占了上风。在他的职业生涯中，他利用数学天赋成为了博弈论和计算机科学的先驱，从而在纯科学与实用技术方面都留下了巨大的科学遗产。

简单来说，一些科学家更注重于理想的美，另一些则更看重经验真理。我自己的方法是 ：遵循哥白尼、伽利略和开普勒的伟大传统，把美作为真理的向导。这种研究方法在纯粹的基础性物理研究中已经变得比较困难与缓慢了，因为我们已经了解了太多。但这种知识积累所带来的“诅咒”也有好的一面，它让我们有信心在想象与现实之间建立起一座桥梁。

所以，不！我不会因为有一个漂亮的主意而感到内疚。但我不能，也不愿忘记我心中的英雄理查德·费曼 (Richard Feynman) 含蓄的警示 ：“不管你的理论有多美，也不管你有多聪明，如果它与实验不符，那就是错的。”

英文版

ILLUSTRATION: TOMASZ WALENTA

Since the 1950s, fundamental physical research has made little contribution to technology. Arephysicists too focused on beauty?

Should physicists feel guilty about working on ideas with no real-world consequences, just because they’re intellectually beautiful? How should such work be evaluated? These questions arise often in the life of research scientists. We have to weigh the pleasure and potential glory of imaginative flights against the more solid rewards of steady progress towards clear goals.

This dilemma has become acute at the frontier of fundamental physics. Until the early 20th century, fundamental physics—that is, the study of phenomena that can’t be explained by existing laws but require the discovery of new ones—was also the most important applied physics. By unveiling the quantum secrets of atoms and light, physics was laying the foundations for chemistry, materials science and engineering.

In 1929, the physicist Paul Dirac announced that “the underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are… completely known.” Those basic laws have now been tested with far greater accuracy than is required for practical applications—even allowing for a generous interpretation of “practical.” An ironic demonstration of this triumph is that since the 1950s discoveries in fundamental physics have contributed little if anything to technology.

There are still some big “impractical” problems in fundamental physics, such as the fact that most of the mass in the universe is made of something that is not electrons, photons, quarks, gluons or neutrinos—the so-called “dark matter.” But experimenters and observers must sweat blood to probe those problems, and progress has been slow. So, what’s an ambitious theoretical physicist to do?

Mathematicians have faced a similar choice between pure and applied work for millennia. In his 1940 book “A Mathematician’s Apology,” G.H. Hardy made a hard-core case for purity: “But is not the position of an ordinary applied mathematician in some ways a little pathetic?…‘Imaginary’ universes are so much more beautiful than this stupidly constructed ‘real’ one.”

On the other hand, John von Neumann rebuked purity in his 1947 essay “The Mathematician”: “As a mathematical discipline travels far from its empirical source…it is beset with very grave dangers. It becomes more and more purely aestheticizing,… whenever this stage is reached, the only remedy seems to me to be the rejuvenating return to the source: the re-injection of more or less directly empirical ideas.”

I think von Neumann has the better of this argument. In his own career, he used his mathematical talents to pioneer fields like game theory and computer science, leaving a titanic legacy, practical as well as intellectual.

To put it over-simply, some scientists focus on ideal beauty, others on empirical truth. My own approach, following a great tradition going back to Copernicus, Galileo and Kepler, has been to use beauty as a guide to truth. That approach has become difficult and slow in pure fundamental physics, basically because we know so much already. But that “curse” of knowledge empowers us to build bridges connecting imagination to reality with confidence.So no, I don’t feel guilty about working out pretty ideas. But I can’t and don’t want to shake off my hero Richard Feynman’s implicit challenge: “It doesn’t matter how beautiful your theory is, it doesn’t matter how smart you are. If it doesn’t agree with experiment, it’s wrong.”

Frank Wilczek

弗兰克·维尔切克是麻省理工学院物理学教授、量子色动力学的奠基人之一。因发现了量子色动力学的渐近自由现象，他在2004年获得了诺贝尔物理学奖。

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