納什的離世 讓你重新思考選擇

Most academics spend their lifetime craving to leave one lasting contribution to their field. By the age of 30, John Nash, who died at 86 in a weekend road accident along with his wife Alicia, had made discoveries that would revolutionise two disciplines and secure him both the Nobel Prize in economics and its equivalent for mathematics, the Abel Prize.

多數學者的畢生願望，就是在他們所在的領域留下一份有持久價值的貢獻。約翰•納什(John Nash) 30歲以前的學術發現徹底改變了兩個學科，並讓他贏得了諾貝爾經濟學獎(Nobel Prize in Economics)以及數學領域一項與諾貝爾獎比肩的大獎——阿貝爾獎(Abel Prize)。上週末，納什與妻子阿莉西亞(Alicia)一同遭遇車禍去世，享年86歲。

His doctoral thesis at Princeton, a slender 32-page document completed when he was just 21, placed game theory, the study of strategic interactions pioneered by mathematician John von Neumann, at the heart of economics.

年僅21歲時，納什就在普林斯頓大學(Princeton University)完成了他的博士論文。這篇薄薄的、只有28頁的博士論文，使博弈論成爲經濟學的核心理論。博弈論最早由數學家約翰•馮諾伊曼(John von Neumann)提出，研究對象是策略間的互動。

After Nash, economists stopped thinking exclusively about unrealistic models of perfectly competitive markets and began focusing on cases in which each agent has to consider the actions of rivals.

在納什之後，經濟學家不再一門心思考慮不切實際的完全競爭市場模型，而是開始關注那些每個主體都需考慮對手行動的案例。

The concept of the “Nash equilibrium”, which he invented, changed the way we look at the choice by companies to advertise or by governments to stock a nuclear arsenal. While both decisions can appear wasteful, individuals still take them in response to what they think their opponents will do.

他創造的“納什均衡”(Nash equilibrium)概念，改變了我們對企業做廣告或政府儲備核武的看法。雖然這兩項決定看上去可能都會造成浪費，但個體依然選擇這麼做，爲的是應對他們腦海中對手將採取的行動。

“John Nash’s definition of the Nash equilibrium was for the social sciences what the discovery of the DNA structure by James Watson and Francis Crick was for biology,” said Roger Myerson, a fellow Nobel laureate in economics. “It was one of the most important contributions in the history of economic thought.”

“約翰•納什的‘納什均衡’理論對於社會科學的意義，堪比詹姆斯•沃森(James Watson)和弗朗西斯•克里克(Francis Crick)發現的脫氧核糖核酸(DNA)結構對於生物學的意義，”同爲諾貝爾經濟學獎得主的羅傑•邁爾森(Roger Myerson)說。“它是經濟思想史上最重要的貢獻之一。”

Born on June 13 1928 in Bluefield, West Virginia, after receiving his doctorate Nash joined the Massachusetts Institute of Technology, where he proceeded to solve problems in the field of partial differential equations that had confounded mathematicians for years.

納什1928年6月13日生於美國西弗吉尼亞州布盧菲爾特(Bluefield)，獲得博士學位後，他加入麻省理工學院(MIT)，繼續解決困擾數學家多年的偏微分方程領域的問題。

“I recall a seminar where he proved one of his outstanding results,” said Joseph Kohn, a maths professor at Princeton who knew Nash for more than 60 years. “Even the most distinguished professors of the department could not believe what they saw.”

“我記得在一次研討會上，他證明了他的一項卓越研究成果，”與納什相識60多年的普林斯頓大學數學系教授約瑟夫•科恩(Joseph Kohn)表示，“就連這個系中最傑出的教授，也被他們所看到的東西驚呆了。”

At MIT Nash met Alicia, from El Salvador, who would soon become his wife. She would also be the rock of his existence when, in 1959, Nash was stricken by schizophrenia, which would plague him for more than 20 years. As paranoia and delusional episodes intensified, he underwent repeated spells of hospital stays. He had to stop working and engaged in seemingly random actions, including a trip to Europe where he tried to relinquish his US citizenship.

在麻省理工學院，納什遇見了來自薩爾瓦多的阿莉西亞，後者很快成爲了納什的妻子，並在隨後的歲月裏成爲他生命的堅實依靠。1959年，納什患上了精神分裂症，在隨後20多年時間裏飽受該病困擾。隨着偏執和妄想症狀加重，納什多次住院治療。他不得不停止工作，行爲處事也看似都是隨性而爲，包括去了趟歐洲——在那次旅行中他試圖放棄美國國籍。

His wife divorced him in 1963 but then chose to let him live in her house near Princeton as a lodger (they remarried). Nash became a familiar figure across the Princeton campus, wandering around and leaving mysterious formulas on classroom blackboards.

1963年，阿莉西亞同納什離婚，但她還是決定讓納什以房客的身份住在她位於普林斯頓附近的房子裏（他們兩人後來複婚）。人們經常能在普林斯頓大學校園裏看到納什的身影，他到處閒逛，在教室黑板上留下神祕的公式。

The genius turned into the “Phantom of Fine Hall”, as he became known.

這位天才變成了“數學系大樓的幽靈”(Phantom of Fine Hall)，逐漸爲衆人所知。

Just like when a mathematical intuition mysteriously materialises, Nash’s brain suddenly began to heal. “I seem to be thinking rationally again in the style that is characteristic of scientists,” he wrote in an autobiographical account for the Nobel Foundation when he won the award alongside John Harsanyi and Reinhard Selten in 1994.

就像一個數學直覺不可思議地變成現實一樣，納什的大腦突然間開始康復。當他與約翰•豪爾沙尼(John Harsanyi)和賴因哈德•澤爾騰(Reinhard Selten)一道獲得1994年諾貝爾經濟學獎時，他在提交給諾貝爾基金會(Nobel Foundation)的自傳性陳述中寫道：“我似乎能夠再次以科學家特有的風格進行理性思考了。”

Just as startlingly, academic recognition was followed by Hollywood glory. A biography by author Sylvia Nasar provided the basis for the plot of A Beautiful Mind, a blockbuster featuring Russell Crowe as Nash, which scooped four Academy Awards.

同樣令人稱奇的是，在得到學術認可之後，納什又被罩上了好萊塢光環。西爾維婭•納薩爾(Sylvia Nasar)撰寫的納什傳記，爲好萊塢大片《美麗心靈》(A Beautiful Mind)提供了情節素材。該片一舉奪得四項奧斯卡大獎(Academy Awards)，羅素•克勞(Russell Crowe)在片中出演納什。

“He was initially sceptical about the movie,” says Eric Maskin, another Nobel laureate and a friend of the Nashes. “But he then realised that even though the movie was mostly fiction, it brought issues which he cared about such as game theory and schizophrenia into the public domain.”

“起初，他對該片持懷疑態度，”納什夫婦的朋友、另一位諾貝爾獎得主埃裏克•馬斯金(Eric Maskin)說，“但後來他意識到，雖然該片大部分是虛構的，但它將他所關心的問題，如博弈論和精神分裂症，帶入了公共領域。”

The prodigy who had earlier abounded in intellectual arrogance learnt to deal graciously with his newfound fame. Prof Maskin remembers how a decade ago, Nash was about to give a highly technical talk to a packed auditorium. “Aren’t you pleased with all this public?” he was asked. “They did not come here to see me,” Nash said. “They came here to see Russell Crowe.” Ferdinando Giugliano

這位早年“恃才傲物”的天才學會了客氣地對待自己新得到的聲譽。馬斯金教授還記得10年前納什在一個擠滿聽衆的禮堂做一場極具理論性的演講前的情形。當被問到“看到眼前的這些公衆，難道你不高興嗎？”時，納什答道：“他們不是來看我的，他們是來看羅素•克勞的。”