諾獎得主Wilczek:「花瓶」物理學

撰文 | Frank Wilczek

翻譯 | 胡風、梁叮噹

來源:蔻享學術

中文版

自 1950 年以來,基礎性物理研究對技術的貢獻幾乎為零。這是因為物理學家太過沉溺於對美的追求嗎?

如果一項研究的思想與實踐脫節,但想法特別漂亮,那麼物理學家應該為這樣的研究感到內疚嗎?又應該如何評價這類工作?在現實生活中,科學家常常會遇到這樣的問題。一方面是盡情展開想像的翅膀所帶來的愉悅與可能的榮耀;另一方面是朝著既定目標穩步前進而得到的實際回報。在兩者之間,我們必須進行權衡。

在基礎性物理研究的前沿領域,這兩者的衝突尤其突出。基礎性物理研究旨在解析那些無法用既有定律解釋的物理現象,它們只能通過發現新的定律來理解。一直到20世紀初,基礎性物理研究本身也是最重要的應用物理學之一。通過揭示原子和光的量子秘密,物理學為化學、材料科學和工程學奠定了基礎。

1929年,物理學家保羅·狄拉克 (Paul Dirac) 宣稱:「對於大部分的物理與整個化學,它們的數學理論所依照的基本物理定律,我們都已知曉。」我們對這些基本定律的驗證已經遠遠超過了實際應用所要求的精準度,以至於我們放寬了對「實際應用」的定義。印證這項成功的是一個頗具諷刺意味的事實
:20世紀50年代之後,基礎性物理研究領域的發現對技術幾乎沒有任何貢獻。

在基礎性物理研究中仍然存在一些重要而「不實際」的問題,比如宇宙的大部分質量源於一種所謂的「暗物質」——一種不是電子、光子、誇克、膠子或中微子的物質。儘管研究人員費盡了心力去探索暗物質這類問題,研究的進展依然緩慢。那麼,一個雄心勃勃的理論物理學家又能做什麼呢?

千百年來數學家一直面對著一個類似的問題 :到底是選擇純粹性的研究還是應用性的工作?在G · H · 哈迪 (G.H. Hardy) 於1940年出版的《數學家的道歉》(A Mathematician’s Apology) 一書中,他為純粹的研究提供了一個硬核的理由
:「可是一個普通的應用數學家的立腳點,在某種程度上,是不是有點可憐?『想像的』宇宙要遠比這個笨拙構建的『真實』宇宙美麗得多。」

而 另 一 方 面, 約 翰 · 馮 · 諾 依 曼 (John von Neumann) 在 他1947年 的 文 章《 數 學 家 》(The Mathematician) 中譴責了這種純粹性 :「當一門數學學科遠離了它的經驗來源時……它將面臨嚴重的危險。它變得越來越美學化,到了這個地步,我覺得唯一的補救辦法就是回到原點,即重新或多或少地結合一些實際的想法。」

我認為馮 · 諾依曼在這個爭論中占了上風。在他的職業生涯中,他利用數學天賦成為了博弈論和計算機科學的先驅,從而在純科學與實用技術方面都留下了巨大的科學遺產。

簡單來說,一些科學家更注重於理想的美,另一些則更看重經驗真理。我自己的方法是 :遵循哥白尼、伽利略和開普勒的偉大傳統,把美作為真理的嚮導。這種研究方法在純粹的基礎性物理研究中已經變得比較困難與緩慢了,因為我們已經瞭解了太多。但這種知識積累所帶來的「詛咒」也有好的一面,它讓我們有信心在想像與現實之間建立起一座橋樑。

所以,不!我不會因為有一個漂亮的主意而感到內疚。但我不能,也不願忘記我心中的英雄理察·費曼 (Richard Feynman) 含蓄的警示 :「不管你的理論有多美,也不管你有多聰明,如果它與實驗不符,那就是錯的。」

英文版

諾獎得主Wilczek:「花瓶」物理學

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.」

諾獎得主Wilczek:「花瓶」物理學

Frank Wilczek

弗蘭克·維爾切克是麻省理工學院物理學教授、量子色動力學的奠基人之一。因發現了量子色動力學的漸近自由現象,他在2004年獲得了諾貝爾物理學獎。

本文經授權轉載自微信公眾號「蔻享學術」。

來源:kknews諾獎得主Wilczek:「花瓶」物理學