書評
偉大的天才是怎樣犯錯的
2013年08月05日
1915年阿爾伯特·愛因斯坦(Albert Einstein)在給一個物理學家同行的信中，描述了科學家是怎樣犯錯的：
「1. 魔鬼用錯誤的假設牽着他的鼻子走。（這一點值得我們同情）。」
- 檢視大圖
Luca D'Urbino
「2. 他的論證錯誤而草率（這一點應該挨打）。」
根據愛因斯坦的原則，他本人既值得同情，也該挨打。「這兩種錯誤愛因斯坦本人當然都犯過，」天體物理學家馬里奧·利維奧(Mario Livio)在他具有啟發意義的新書《聰明的錯誤》(Brilliant Blunders)中寫道。
我們讀到的科學故事大多都是成功的：科學家們剛剛發現了最古老的人類化石；他們是怎麼做到的？成
功當然是科學故事的一部分，但是輝格黨(Whig)歷史的這個版本蒙蔽了我們，讓我們無法看到人們實際上是如何做科學研究的。科學是一團糟。它是由科學家
工作的那個時代和地點決定的。科學家決定做某項實驗或者解釋某個現象是有很多原因的。「愛因斯坦最初的論文中有超過20%含有某種錯誤，」利維奧寫道，
「有好幾次，雖然他在研究過程中犯了一些錯誤，但最終的結論仍然是正確的。這往往是偉大理論家的品質特點：他們聽從直覺而非形式主義的指引。」
但是很多人以為，偉大的科學家就是從不犯錯的科學家。所以經常看到雜誌封面用大標題醒目地宣布：愛因斯錯了，或者問道：愛因斯坦錯了嗎？
利維奧的書是糾正這種曲解的一劑良藥。他提到了五位偉大的
科學家——愛因斯坦、查爾斯·達爾文(Charles Darwin)、開爾文勛爵(Lord Kelvin)、萊納斯·鮑林(Linus
Pauling)和弗雷德·霍伊爾(Fred
Hoyle)——他們每個人都有過重大發現，也犯過嚴重錯誤。所有這五個人都曾押錯過賭注，甚至是在其他觀點很流行的時候。由於利維奧強烈的好奇心，他把
《聰明的錯誤》一書變成了對科學道路本身的深思。
1859年查爾斯·達爾文提出進化論的時候，他給整個現代
生物學建立了基礎。他的理論最關鍵的證據是動物和植物遺傳其祖先的特點。有些特點通過自然選擇被保留了下來，而另一些特點消失了，從而導致最終的重大變
化。但是達爾文不知道遺傳是怎樣進行的。他花很多時間想出的一些思路在如今看來有些愚蠢。「達爾文接受的教育是當時普遍盛行的理論，認為父母雙方的特點會
混合在孩子身上，」利維奧寫道，「就像顏料的混合一樣。」按照這個邏輯，每個祖先的基因特點在下一代身上會減少一半。
這種觀點不僅是錯誤的，而且摧毀了達爾文進化論的根基。如果我們的遺傳特徵只是粒子混合的結果，那這些特徵就不可能通過自然選擇在幾代之後得以改變。雖然達爾文可能也嘗試過，但是他想不出一個更好的解釋。
不過就在達爾文出版《物種起源》(On the
Origin of Species)的那個時期，捷克修道士格雷戈爾·孟德爾(Gregor
Mendel)正在創立遺傳學。通過在自己的花園裡雜交種植豌豆，他對遺傳的實際過程有了模糊的認識。達爾文顯然從未注意到孟德爾的研究，他本人也沒有得
出孟德爾的結論。
如今，生物學家能從分子水平追蹤進化過程，因為他們知道基
因是由什麼構成的。20世紀50年代初，弗朗西斯·克里克(Francis Crick)和詹姆斯·沃森(James
Watson)發現了DNA的雙螺旋結構。他們研究得很快，因為他們知道諾貝爾獎得主、生物化學家萊納斯·鮑林也在努力解開這個謎團。鮑林在快要成功的時
候犯了一個大錯，而當時沃森和克里克正好取得了突破。他陷入了一個錯誤的假設，認為DNA是由3條相互纏繞的螺旋構成的，更糟糕的是，他在化學研究中犯了
一個低級錯誤——他的核酸分子實際上不是酸。
1953年在克里克和沃森公布他們的發現不久，鮑林就去劍
橋拜訪了他們，檢驗了他們的DNA模型。他承認他們是對的，自己是錯的，不久之後就公開發表了同樣的聲明。不過，利維奧提到的犯過重大錯誤的科學家們並不
是都這樣大度。偉大的物理學家開爾文勛爵直到1907年去世還堅持認為地球只有數千萬年的歷史。
開爾文認為生命是被設計出來的，他研究地球年齡的其中一個目的是反駁達爾文的自然選擇理論。假如達爾文的理論是正確的，那地球應該很老了，但是當時地質學家們沒有辦法準確測量地球的年齡。開爾文聰明地預見到也許能從岩石的溫度中找到答案。
開爾文正確地推斷出地球最初是一團熔岩。他認為，只需要一
個簡單的數學運算就能算出地球花了多長時間冷卻到現在的溫度。開爾文進行了這樣的運算，得出的結論是地球相當年輕，只有差不多1億年的歷史（現在我們知道
這個數字大約是45.67億年）。他用同樣的方法算出了太陽的年齡。開爾文認為，假設太陽真的是在幾十億年前就形成了的話，那它早就燃燒殆盡了。
開爾文犯錯的原因有兩個。他以前的一個學生曾指出，開爾文
認為地球內部是固定的，熱量在所有的地方以同樣的速度向外散發。實際上，地球內部像沸騰的水一樣翻騰。另一個原因是量子物理學。放射現象在幫助地球保溫，
核聚變讓太陽燃燒了45.67億年。開爾文的批評者提醒他注意這兩個相反的論點，但是他似乎對這些論點很不屑，沒有理會。
核聚變不僅給恆星提供能量，還能產生新元素，比如碳和鐵。
英國天體物理學家弗雷德·霍伊爾(Fred
Hoyle)在20世紀四五十年代發現了這個重要現象。不幸的是，霍伊爾更為人所知的也許是他宣揚的一個關於宇宙起源的錯誤理論：他堅信宇宙處於不斷創造
的狀態。隨着大爆炸理論證據的增加，他越來越被看做一個令人尷尬的怪人。
利維奧選擇愛因斯坦做他的犯錯五重奏的第五個成員。愛因斯
坦一直不明白為什麼宇宙沒有自己塌陷。他認為，空無一物的空間含有一種向外推的神秘力量，阻止了宇宙向內塌陷。在他發表了這個觀點（後來被稱為宇宙常數）
之後，他後悔了。他說這個常數不是從他的等式中自然出現的；他像是用一塊廉價的膠合板修補屋頂的大洞。
愛因斯坦最終否定了宇宙常數，結果犯下了大錯。20世紀90年代物理學家們發現了暗能量，它與愛因斯坦提到的神秘力量非常類似。
利維奧把歷史學家的謹慎用到了自己聰明的描述中，避免了英
雄讚歌式的陳詞濫調。他不太善於解釋為什麼這些偉大的科學家會犯錯，過於頻繁地引用流行心理學的觀點，以說明為什麼人們即使在看到相反的證據之後仍然固執
地堅持錯誤的觀點。研究壞科學的心理學是個迷人的話題，但是它需要更寬闊的視野，看看整個科學領域是怎樣運轉的。五個科學家——不管他們多麼偉大——挑不
起這個重擔。
Carl Zimmer為《紐約時報》撰寫「Matter」專欄，曾出版《病毒星球》(A Planet of Viruses)等書。本文最初發表於2013年6月9日。
翻譯：王艷
The Genius of Getting It Wrong
August 05, 2013
In a letter to a fellow physicist in 1915, Albert Einstein described how a scientist gets things wrong:
“1. The devil leads him by the nose with a false hypothesis. (For this he deserves our pity.)
“2. His arguments are erroneous and sloppy. (For this he deserves a beating.)”
According to his own rules,
Einstein should have been pitied and beaten alike. “Einstein himself
certainly committed errors of both types,” the astrophysicist Mario
Livio writes in his enlightening new book, “Brilliant Blunders.”
Much of what we read about science is some version of a success story: Scientists just discovered the oldest human fossil; how did they do it?
Success is certainly part of the story, but this version of Whig
history blinds us to how people actually do science. Science is a mess.
It’s shaped by the time and place in which scientists work. Scientists
choose to do a certain experiment or interpret an observation for many
reasons. “More than 20 percent of Einstein’s original papers contain
mistakes of some sort,” Livio writes. “In several cases, even though he
made mistakes along the way, the final result is still correct. This is
often the hallmark of great theorists: They are guided by intuition more
than by formalism.”
For many people, however,
being a great scientist means being above error. That’s why it is so
common to see a magazine cover headline declaring, in screaming type,
Einstein was wrong, or its weasel-word variant, was Einstein wrong?
Livio’s book is a valuable
antidote to this skewed picture. He profiles five great scientists —
Einstein, Charles Darwin, Lord Kelvin, Linus Pauling and Fred Hoyle —
each of whom made major discoveries and major mistakes. All five put
their chips down on the wrong number, even as others prevailed. Thanks
to his deep curiosity, Livio turns “Brilliant Blunders” into a
thoughtful meditation on the course of science itself.
When Charles Darwin
presented his theory of evolution in 1859, he built a foundation for all
of modern biology. Crucial to his theory was the fact that animals and
plants inherited traits from their ancestors. Natural selection favored
some traits over others, giving rise to long-term change. But Darwin
didn’t know how heredity worked. He devoted a lot of time to developing
ideas that, in hindsight, seem daft. “Darwin had been educated according
to the then widely held belief that the characteristics of the two
parents become physically blended in their offspring,” Livio writes, “as
in the mixing of paints.” By this logic, each ancestor’s genetic
contribution would be halved in each generation.
This idea wasn’t just
wrong. It undermined Darwin’s own theory of evolution. If our traits are
just a result of blended particles, it shouldn’t be possible for
natural selection to change traits over the generations. But try as he
might, Darwin couldn’t figure out a better explanation.
Yet right around the time
that Darwin published “On the Origin of Species,” the Czech monk Gregor
Mendel was discovering genetics. Crossing pea plants in his garden, he
got a glimpse at how heredity actually does work. Darwin apparently
never became aware of Mendel’s work, nor did he discover Mendel’s
results for himself.
Today biologists can track
evolution at the molecular level because they know what genes are made
of. In the early 1950s, Francis Crick and James Watson worked out the
double-helix structure of DNA. They worked quickly, because they knew
that the Nobel Prize-winning biochemist Linus Pauling was trying to
solve the puzzle as well. Pauling came very close, but stumbled just as
Watson and Crick were making their breakthrough. He got stuck on the
idea that DNA forms three intertwined spirals, rather than two, and
worse, he made an elementary error in the chemistry — his nucleic acid
molecule was actually not an acid.
Shortly after Crick and
Watson published their discoveries in 1953, Pauling paid them a visit at
Cambridge and examined their model of DNA. He acknowledged that they
were right and he was wrong, and soon afterward he made the same
declaration in public. That kind of graciousness is not universal among
Livio’s blunderers, though. The great physicist Lord Kelvin held firm,
until his death in 1907, to his conviction that the Earth was only
millions of years old.
Kelvin believed that life
had been designed, and he investigated the age of the Earth in part to
rebut Darwin’s theory of natural selection. If Darwin’s theories were
right, then the Earth must be very old, but geologists had no way to
precisely measure the planet’s age. Kelvin had the brilliant insight
that the temperature of rocks might hold the answer.
The Earth, Kelvin rightly
reasoned, had started out as a ball of molten rock. It took a
straightforward mathematical exercise to calculate how long it had taken
for the Earth to cool to its current temperature. And when Kelvin did
the math, he concluded that the Earth was fairly young, roughly 100
million years (we now know it to be about 4.567 billion years old). He
carried out similar calculations to work out the comparable age of the
Sun. If the Sun had indeed formed billions of years ago, Kelvin believed
it would have burned out long ago.
Kelvin was wrong for two
reasons. As a former student of his pointed out, Kelvin assumed that the
Earth’s interior was fixed and transports heat at the same rate
everywhere. In fact, it roils like boiling water, transporting heat to
the surface. The other reason for Kelvin’s error was quantum physics.
Radioactivity helps keep the Earth warm, and nuclear fusion has allowed
the Sun to burn for 4.567 billion years. Kelvin’s critics brought both
these counterarguments to his attention, but he seems to have viewed
them with contemptuous indifference.
Nuclear fusion doesn’t just
power stars, it also creates new elements like carbon and iron. The
British astrophysicist Fred Hoyle made this tremendous discovery in the
1940s and ’50s. Unfortunately, Hoyle might be better known for promoting
a flawed theory about the origin of the universe: He was convinced that
the universe was in a continual state of creation. As evidence for the
Big Bang mounted, he became an increasingly embarrassing crank.
Livio chooses Einstein as
the fifth member of his blundering quintet. Einstein was puzzled as to
why the universe didn’t cave in on itself. Empty space, he suggested,
contained a mysterious energy pushing outward, resisting the universe’s
inward collapse. After he published this idea — what came to be known as
the cosmological constant — he regretted it. He said it didn’t emerge
naturally from his equations; he’d tacked it on like a cheap piece of
plywood over a hole in a roof.
Einstein eventually
denounced the cosmological constant. And that, it turns out, was his big
mistake. In the 1990s, physicists discovered dark energy, something
very similar to that mythical force.
Livio brings the care of a
historian to his nimble narratives, avoiding heroic clichés. He’s less
adept at explaining why these great scientists made their mistakes, too
often trotting out pop psychology to demonstrate why people stubbornly
cling to ideas even when they see evidence to the contrary. The
psychology of bad science is a fascinating topic, but it requires a
broader look at how the entire scientific community operates. Five
scientists — no matter how great — cannot shoulder that load.
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