A Conservative Revolutionary (II)1一个保守的革命者（下）

弗里曼·戴森 译/肖明波

Not included in either of the two books is a paper written by Frank two years ago with the title “My father and I”. This is a tribute to his father， who was a professor of mathematics and died in 1973. It is a wonderfully sensitive account of his relationship to his father and of the pain that each of them suffered as a result of their separation. His father stayed in China through the hard years while Frank grew to greatness in America. Luckily， Frank was able to visit China twice before his father died and to sit by his bedside during his last illness.

The memoir “My father and I” ends on a happier note. It ends with a glorious moment of reunion. Frank describes how he stood at midnight on July 1， 1997， at the Hong Kong Convention and Exhibition Center， to watch the Union Jack being lowered and the flag of the People’s Republic being slowly raised， while the band played “Arise， you who would not be enslaved”. Frank writes， “Had father observed this historical ceremony marking the renaissance of the Chinese people， he would have been even more moved than I. ...The intellectuals of his generation had to personally experience the humiliating exploitations in the Foreign Concessions... and countless other rampant foreign oppressions.... How they had looked forward to the day when a prosperous China could stand up， when the British Empire had to lower the Union Jack and withdraw troops， when they can see for themselves the Chinese flag proudly announce to the world： This is Chinese Territory！ That day， July the first， 1997， is the day their generation had dreamed of throughout their lives”.

We can all rejoice that Frank was standing there to give his blessing and his father’s blessing to the reunion. For me， that pride and that feeling of fulfillment that Frank expresses have a special resonance. I too belong to a great and ancient civilization. My home-town in England was also the home-town of Alfred the scholar king， who made our town into a great center of learning eleven hundred years ago， while the Tang dynasty was establishing the system of government by scholars that endured for a thousand years in China. Our king Alfred was translating scholarly texts from Latin into English， soon after the Tang poet Tu Fu wrote the poem that Frank quotes at the beginning of his selected papers： “A piece of literature is meant for the millennium. But its ups and downs are known already in the author’s heart”.

Like Frank， I too left my homeland and became an American citizen. I still remember the humiliation of that day in Trenton2 when I took the oath of allegiance to the United States， and the ignoramus who performed the ceremony congratulated me for having escaped from the land of slavery to the land of freedom. With great difficulty I restrained myself from shouting out loud that my ancestors freed our slaves long before his ancestors freed theirs. I share Frank’s ambivalent feelings toward the United States， this country that has treated us both with so much generosity and has treated our ancient civilizations with so little understanding. And I share Frank’s pride in the peaceful lowering of the Union Jack and raising of the Chinese flag that he witnessed in Hong Kong， the place where our two ancient civilizations briefly came together and gave birth to something new.

Five years ago， I had the honor of speaking at the ceremony in Philadelphia， when the Franklin Medal was awarded to Frank Yang by the American Philosophical Society. We were assembled in the historic meeting-room of the society， with the portraits of Benjamin Franklin， the founder of the society， and Thomas Jefferson， one of its most active members， looking down at us. It was self-evident that Franklin and Jefferson approved of the award. We know that Frank Yang feels a special admiration for Franklin， since he gave the name of Franklin to his elder son. I would like to end this little talk with the same words that I used to praise Frank on that happy occasion.

Professor Yang is， after Einstein and Dirac， the preeminent stylist of twentieth-century physics. From his early days as a student in China to his later years as the sage of Stony Brook， he has always been guided in his thinking by a love of exact analysis and formal mathematical beauty. This love led him to his most profound and original contribution to physics， the discovery with Robert Mills of non-Abelian gauge fields. With the passage of time， his discovery of non-Abelian gauge fields is gradually emerging as a greater and more important event than the spectacular discovery of parity non-conservation which earned him the Nobel Prize. The discovery of parity non-conservation， the discovery that left-handed and right-handed gloves do not behave in all respects symmetrically， was a brilliant act of demolition， a breaking-down of intellectual barriers that had stood in the way of progress. In contrast， the discovery of non-Abelian gauge fields was a laying of foundations for new intellectual structures that have taken thirty years to build. The nature of matter as described in modern theories and confirmed by modern experiments is a soup of non-Abelian gauge fields， held together by the mathematical symmetries that Yang first conjectured forty-five years ago.

In science， as in urban renewal and international politics， it is easier to demolish old structures than to build enduring new ones. Revolutionary leaders may be divided into two kinds， those like Robespierre and Lenin who demolished more than they built， and those like Benjamin Franklin and George Washington who built more than they demolished. There is no doubt that Yang belongs to the second kind of revolutionary. He is a conservative revolutionary. Like his fellow-revolutionaries Franklin and Washington， he cherishes the past and demolishes as little as possible. He cherishes with equal reverence the great intellectual traditions of Western science and the great cultural traditions of his ancestors in China.

Yang likes to quote the words of Einstein， “The creative principle lies in mathematics. In a certain sense， therefore， I hold it true that pure thought can grasp reality， as the ancients dreamed”. On another occasion Yang said， “That taste and style have so much to do with one’s contribution in physics may sound strange at first， since physics is supposed to deal objectively with the physical universe. But the physical universe has structure， and one’s perceptions of this structure， one’s partiality to some of its characteristics and aversion to others， are precisely the elements that make up one’s taste. Thus it is not surprising that taste and style are so important in scientific research， as they are in literature， art and music”. Yang’s taste for mathematical beauty shines through3 all his work. It turns his least important calculations into miniature works of art， and turns his deeper speculations into masterpieces. It enables him， as it enabled Einstein and Dirac， to see a little further than other people into the mysterious workings of nature.

两本书都没有收录的一篇文章，是弗兰克两年前写的《父亲和我》。这是他献给自己父亲——这位已在1973年去世的数学教授的一份厚礼。它对他们父子的关系以及分离给两人带来的痛苦作了精彩细腻的描述。在那段艰难岁月里，他父亲一直留在中国，而弗兰克却在美国成名成家了。幸运的是，弗兰克得以在父亲去世前两度访问中国，并在他临终前陪在他的病床边。

《父亲和我》这篇回忆录有一个较喜庆的结尾。它以一个美好的团圆时刻结束了全文。弗兰克描述了他在1997年7月1日零点时分，是如何站在香港会展中心，观看英国国旗降下、中国国旗缓缓升起，听着乐队奏起“起来，不愿做奴隶的人们”。弗兰克写道：“要是父亲能目睹这个象征中华民族复兴的历史性仪式，他一定会比我还要激动。……他們那一辈知识分子亲身经历了在租界中令人屈辱的欺凌……还有外族其他数不清的残暴压迫……他们多么盼望看到富强的祖国站起来的那一天，看到大英帝国降下国旗、撤出军队，看到中国的国旗向世界骄傲地宣示：这是中国的领土！这一天——1997年7月1日，正是他们终生梦寐以求的一天。”

我们都很高兴，弗兰克当时站在那里，送出了自己以及他父亲对香港回归的祝福。弗兰克所表达的自豪和满足感，特别能引起我的共鸣，因为我也属于一个伟大而古老的文明。我在英国的故乡，是学者艾尔弗雷德大帝的故乡。他在1100年前将我的故乡变成了一个伟大的学术中心，而与他同时代的唐朝，则在中国建立了持续千年的文官治理体制。我们的艾尔弗雷德大帝将拉丁文典籍译成了英文，而此前不久，唐朝诗人杜甫写出了“文章千古事，得失寸心知”——弗兰克在他那本论文选集的前面就引用了这句诗。

和弗兰克一样，我也离开故土，成了一名美国公民。我仍记得我宣誓效忠美国那天，在特伦顿受到的羞辱：那位主持仪式的无知者祝贺我脱离奴役之乡，加入自由之邦。我拼命克制才没有冲他大声喊出：我的祖辈远在他的祖辈解放他们的奴隶之前，就解放了我们的奴隶！我和弗兰克一样，对美国怀有矛盾的感情——这个国家对我们两人都是如此慷慨，可是对我们古老的文明又了解得如此之少。我能体会弗兰克在香港亲眼目睹英国国旗和平降下、中国国旗冉冉升起时发自内心的自豪。香港是我们这两种古老文明经过短暂的交汇，催生出崭新事物的地方。

五年前，美国哲学学会在费城举行颁奖仪式，授予弗兰克·杨富兰克林奖章，我有幸在仪式上致辞。我们聚集在该学会那具有历史意义的会议厅中，厅堂上方悬挂着学会创始人本杰明·富兰克林和最活跃的一名会员托马斯·杰斐逊画像。毋庸多言，富兰克林和杰斐逊都会赞同将这个奖授予弗兰克的。我们知道弗兰克·杨特别钦佩富兰克林，他甚至给自己的长子取名为富兰克林。我想借用我在那个欢乐场合称颂弗兰克的话，来结束今天这个简短的演讲。

杨教授是继爱因斯坦和狄拉克之后有如设计师一般的杰出物理学家。从他早年在中国当学生时开始，直到后来成为纽约州立大学石溪分校的哲人，引导他的思考的，一直是他对精确分析和数学形式美的热爱。这种热爱使他做出了对物理学影响最深远的和最有创见的贡献——跟罗伯特·米尔斯一道发现的非阿贝尔规范场。随着时间的推移，他所发现的非阿贝尔规范场，已渐渐成为比宇称不守恒这个惊人的发现更重大的贡献，虽然是后者使他获得了诺贝尔奖。对宇称不守恒的发现，即对左右手手套并非在各个方面都表现出对称性的发现，是一项了不起的破除行动，它清除了前进道路上的思维障碍。与此相反，非阿贝尔规范场的发现则为后来经过30年才建立起来的新思维结构奠定了基础。由当代理论描述并为当代实验所证实的物质的本质，是多个非阿贝尔规范场的一种混叠，将它们合在一起的是数学对称性，杨在45年前率先作出了这一猜想。

科学研究也像在城市重建和国际政治中一样，破过时的旧总比立持久的新更容易。革命领袖可以分为两类：一类是罗伯斯庇尔和列宁那种，破坏的比创建的多;另一类是本杰明·富兰克林和乔治·华盛顿那种，创建的比破坏的多。毫无疑问，杨是属于后一类的革命者。他是一位保守的革命者。跟富兰克林和华盛顿一样，他珍惜过去，尽可能少去破坏它。对西方科学的伟大学术传统和中国祖先的伟大文化传统，他怀着同样崇敬的心情予以珍惜。

杨喜欢引用爱因斯坦这段话：“创造的源泉在于数学。因此，在某种意义上，我相信，像古人梦想的那样，纯粹通过思考可以把握事物的真相。”在另一个场合，杨教授说过：“一个人的品位和风格竟与他对物理学的贡献有如此密切的关系，乍听起来也许会令人感到奇怪，因为物理学被认为是一门客观地研究物质世界的学问。然而，物质世界具有结构，而一个人对这些结构的洞察，对这些结构中某些特点的好恶，正是构成其自有风格的要素。因此，品位和风格之于科学研究，就像它们对文学、艺术和音乐一样重要，这是不足为奇的。”杨在数学美方面的品位体现在他所有的工作中。它使他最不重要的计算变成了袖珍的艺术品，又使得他深层次的猜想成为杰作。这种品位还使他能够对大自然的神秘运作看得比别人更深远一点，曾经爱因斯坦和狄拉克也是如此。