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[转载] GOODBYE FANTASY 专访：Sean M. Carroll
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Sean Carroll先生是加州理工大学的高级物理研究员，主要兴趣在于理论物理。他也是教 科书《Spacetime and Geometry》的作者。《再见幻想》杂志这次对他进行采访，主要探讨物理和科学话题。 ---- ■ 你为什么决定学物理？ □ 我很早就对物理有兴趣了－－大约10岁。不过我不记得是否某件事激发了我的兴趣 。我只是开始阅读有关夸克、黑洞和大爆炸的书籍。有谁不对这些感兴趣吗？我立刻就被 吸引了，并再也没有回头。 ■ 你为什么决定写《时空与几何：广义相对论导论》？你是如何排列主题，以便让读 者顺利阅读？ □ 在１99６年，我正在作博士后，在麻省理工教广义相对论的研究生课程。我非常投 入，每节课前都把详细的课堂笔记打出来。总有学生向我索要笔记，所以最后我把它们传 到了网上(http://preposterousuniverse.com/grnotes/)。出版社的人注意到了这个，就 开始来骚扰我，让我把笔记扩充为一本内容完整的书。最终我一心软就同意了。这本书的 写作从来就没经过伟大的计划（教科书编写需要很多的努力，而利益却难以估计），然而 我很高兴我把它完成了。 ■ 你觉得一个让小孩子学习科学，并保持好奇心的优秀环境应该是怎样的？ □ 我不确定我知道答案。我想重要的是把众多不同观点展现给小孩--除了科学和数学 ，还有历史、文学和广义上的学习。一旦他们开始读书，务必认真对待他们的提问，以便 鼓励他们独立思考他们阅读和听闻到的。 我对我的那本教材的定位是，为一门一学期的广义相对论导论课程提供足够但是适度 的教学内容。由于不同的学生有不同的知识水平和兴趣，我尽量把最基本的知识内容写在 正文中，而把更高级的数学内容放在一系列的附录中。我希望这样学生就可以按照他们所 适合的速度使用本书。 ■ 当你选择研究领域的时候，考虑哪些因素？ □ 这需要对很多因素做复杂的权衡。你当然希望研究有趣的问题，它们可能告诉你一 些宇宙的秘密。但是，你同样希望选择能进行下去的工作！所以，诀窍是选择足够困难因 而有趣的领域，但又不至于难到无从下手。 ■ 你可以对“广义相对论”和“量子理论”做个比较吗，我指的是从它们如何解决问 题以及它们为何吸引你的方面来说？ □ 这是非常难的。广义相对论简单、高雅并且自成体系；量子力学相对来说并没有被 很好的定义，造成一些深刻而持久的概念性问题，但是却丰富很多。广义相对论由于它的 美感而吸引人，而量子力学由于其深刻和精明而惹人喜爱。但它们都是理解宇宙如何工作 的关键。 ■ 当考虑普朗克尺度的宇宙时，你更喜欢“量子引力”还是“超弦理论”？为什么？ □ 严格的说，“量子引力”和“超弦理论”并不冲突；后者只不过是前者的一个可能 的模型而已。量子力学和引力理论必将通过某种方式相互调和；弦论是这种调和的一种可 能方式。另外的方式包括“圈量子引力”，“动力学刨分”，“欧几里得路径积分”等等 。 我想说，从目前的状况看，弦论毫无疑问是达到这种目的的最有希望的办法。它已经 成功的解答了一些确切问题，甚至还引申出一些出乎意料的新结果。另一方面，我们事实 上还不能很好的理解这个理论，而只在一些特别的情形下可以策略性地使用它。 所以目前我对于弦论给出的任何预言都很感兴趣，虽然我也接受其它可能性。 ■ 你对于一个“漂亮的理论”的判据是什么？有没有什么原因使得物理世界总是能够 很精确的用数学来解释？ □ 物理世界能精确的用数学解释这件事情，要么再显然不过，要么是个奇迹，这只取 决于你如何来看待它。数学是逻辑的延伸，所以从某种意义上，我们的宇宙按照逻辑运行 并不是什么值得诧异的事情。从另一方面说，让人感到惊诧的是，深奥而非直觉的数学不 断被应用于物理学研究中。 漂亮的理论有一些共同的性质：它们简单而强大，并且一旦被意识到，就被认为几乎 不可避免。但是美感因观测者而异；两个人看待同一个理论，在其中发现的美也不同。 ■ 当你进行物理研究时，美学会影响你吗？特别是当你试图对爱因斯坦场方程作一些 修改时？ □ 会影响，但是美学的位置终究低于处于物理。爱因斯坦方程非常漂亮，但是它们成 为基本原理的可能性很低；很可能它们只是某个完全不同理论的低能近似。当我们找到那 个不同的理论时，它可能乍一看并不那么漂亮，但是它拥有那种通过深入研究才能察觉的 内在美。 所以美学可以给我们提供一种有益的引导，但是它并不是一切。 ■ 你觉得物理比其它科学学科更难吗？如果一个人并不是非常聪明但是非常努力，她 /他有可能在这个领域有所成就吗？ □ 几乎根据定义，物理学就并不比任何其它学科难。和所有其它学科一样，这个领域 中简单的问题已经被解决了，而那些难的留了下来；所以我们只能着手难易适中的问题。 我不知道“聪明”这个概念是否应该被用在这里。物理研究需要许多完全不同的能力 ——抽象推理能力、创造力、熟练的运算能力、物理直觉、逻辑推理。你当然需要其中的 一些——但是除此以外你还需要加倍努力！——如果你想成为一个成功的物理学家的话。 但是，做物理有很多不同的方式，而人们已经从完全不同的道路取得了物理成就；同样的 ，很多人能在IQ测试中取得很好的成就，但她/他们在物理界却最终一事无成。但是，在其 它因素相同的情况下，你在所有这些技能上越出色，你将来就做得越好。 ■ 当你进行物理教学时，你是否发觉一些内容很难传授给学生？你是否有一些学生， 她/他们热爱物理学，但却发现其对于她/他们来说太难了？ □ 很多内容都很难向学生解释，更不用说甚至连我自己都很难理解它们！物理研究对 于人类认知来说处于前沿，因而它本质上就是很难的。 没错，很多人喜欢做物理，但是她/他们的才能却更体现在其它领域。重要的是，在你 感兴趣的和你能做出贡献的领域中寻找交集。 ■ 对于一个兴趣在理论物理方向的人来说，除了做大学教授以外，在这个世界上是否 还有其它合适的位置？因为很多人并不感兴趣或者并不能胜任教学工作，但是她/他们同样 希望进行物理研究。 □ 我不得不承认，机会不是很多。大多数理论物理研究者在大学工作；还有一些在国 家实验室，比如费米实验室或者洛斯阿拉莫斯；很少的一部分人在专门的研究机构工作， 比如Perimeter Institute；另外一些人在工业界资助的研究中心工作。不过我鼓励那些希 望做研究的人练习教学并努力把它做好。 ■ 成为一个科学家/物理学家是否影响了你的个性，或者你对于一些非科学问题的观 点？ □ 老实说我不知道，虽然或许是的。回答这类问题的困难在于，你很辨别因果关系— —是成为一个科学家使我开始这样思考，还是这样的思考方式影响了我的决定，使我成为 科学家？我确信的是，作为科学家所得到的严谨和定量推理训练，对于思考所有的事情来 说都非常有益。 ■ 我注意到你所教授的一门课所用的教材《无神论的时刻》(Moments in Atheism)， 和我在有关西方文化的课程中所用的教材类似。你觉得无神论和西方文化的发展相互有关 联吗？你对无神论的未来有什么推测？ □ 很有趣的是，无神论的历史和人类智慧的历史之间有着密切联系，至少在西方是这 样。我们在认知物理世界方面的重大发展，常常影响到人们对于超自然事物的思考。 这并不是说西方文明的历史始终如一的指向无神论，也不是说无神论会在将来取得最 终胜利。但我猜想这可以实现，只要超自然的解释最终失去了影响力——但是这恐怕需要 相当长的一段时间，并且这个过程会波澜曲折。 ■ 你认为普通大众可以从“纯科学”即那些目前还没有任何应用的科学中有所受益吗 ？ □ 当然！纯科学是我们理解这个世界如何工作的方式。所有人都可以从中“受益”， 因为理解这个世界是我们之所以称之为人类的一个要素。 ---- |
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2007年6月11日由dk完成邮件采访，翻译工作主要由H.O.L.M完成，dk进行后期翻译修改和 编辑。由于翻译能力业余，有能力的读者建议阅读原文。这个采访的文本遵守创造共用协 定（署名-非商业用途-保持一致），你可以在此框架内对其进行传播。这个采访是~在蜕变 中湮灭~网站对科学家长期采访项目中的一个。 ======== 英文版本 ======== Sean Carroll is a Senior Research Associate in Physics at California Institute of Technology. His research is mostly theoretical physics. He also wrote a textbook Spacetime and Geometry. The following interview by Goodbye Fantasy m agazine mainly focus on physics and science in general. ---- ■ Why did you decide to study physics? □ I became interested in physics very early -- when I was about 10 years old. I can't remember whether there was some specific event that triggered my interest, though. I just started reading books about quarks and black holes an d the Big Bang. Who wouldn't be interested in that stuff? I quickly became hoo ked, and never looked back. ■ What made you decide to write Spacetime and Geometry: An Introduction t o General Relativity? How did you arrange topics in a way that people can prog ress through the topics successfully? □ In 1996, as a postdoc, I taught the graduate GR course at MIT. I put a lot of work into it, typing a very detailed set of lecture notes before each c lass. People kept asking me for copies of the notes, so eventually I put them on the web (http://preposterousuniverse.com/grnotes/). Publishers noticed, and they started pestering me to expand the lecture notes into a full-fledged boo k. Eventually, in a moment of weakness, I agreed. It was never part of a maste r plan [textbook writing is a lot of work, and the benefits are somewhat intan gible], but I'm happy that I did it. ■ What do you consider a good environment for young children to learn sci ence and keep their curiosity? □ Not sure I know the answer to that one. I think it's important to expos e children to many different ideas -- science and math, but also history and l iterature and learning more generally. And once they start reading, it's impor tant to take their questions seriously; to encourage them to think independent ly about what they read and hear. My philosophy in writing the book was to aim to provide enough material to cover most reasonable one-semester introductory courses in GR, and not much m ore. Since different students have different levels of preparation and interes t, I tried to put the basics of the subject into the main text, and included m ore advanced mathematical material in a set of appendices. Hopefully people ca n go through the text at their own pace. ■ What factors do you consider when choosing research areas? □ It's a combination of a lot of things. Of course you want to do researc h on problems that are interesting, and will possibly teach you something abou t the universe. But you also want to work on something where you can make prog ress! So the trick is to pick a problem that's hard enough to be interesting, but no so hard that you can't do anything. ■ Can you make a comparison between general relativity and quantum theory , by how they solve problems about the universe and how they attract you? □ They are very different. GR is simple and elegant and self-contained; q uantum mechanics is less well defined, raises deep and persistent conceptual q uestions, but is enormously rich. GR is attractive due to its beauty, quantum mechanics is attractive due to its depth and subtlety. But both are crucial in understanding how the universe works. ■ In the study of the universe in the Planck epoch, do you prefer quantum gravity or superstring theory? Why? □ Strictly speaking, "quantum gravity" is not opposed to "string theory"; the latter is simply one possible model of the former. Quantum mechanics and gravity are going to have to be reconciled one way or another; string theory i s one possible way to do so. Other ways are loop quantum gravity, dynamical tr iangulations, Euclidean path integrals, and so on. I would say that, as of right now, string theory is certainly the most pro mising of any of these approaches. It has succeeded in answering certain defin ite questions, and led to some surprising new results. On the other hand, we c ertainly do not understand the theory very well, only in some special regimes. So right now I'm definitely interested in what string theory has to say, a lthough I'm keeping an open mind. ■ What are your criteria for a "beautiful theory"? Is there any reason wh y the physical world is often explained accurately by mathematics? □ The fact that the physical world is explained accurately by mathematics is either perfectly obvious, or a profound mystery, depending on how you look at it. Math is an extension of logic, so in some sense it's not surprising to find the universe behaving logically. On the other hand, the extent to which intricate and non-obvious mathematics keeps finding applications in physics is truly amazing. Theories that are beautiful share some basic features: they are simple, p owerful, and seem almost inevitable once they are understood. But beauty is in the eye of the beholder; two people can look at the same theory and find very different amounts of beauty in it. ■ Does aesthetics influence you when you do physics, especially when you want to do some modification in Einstein field equations? □ It does, but aesthetics is ultimately subordinate to physics. Einstein' s equations are very beautiful, but they are unlikely to be fundamental; it's quite possible that they arise as the low-energy approximation to something co mpletely different. When we find that different thing, it might look less beau tiful at first, but possess an inner beauty that is only revealed upon deeper inspection. So aesthetics can provide a useful guide, but they're not the whole story. ■ Do you think physics is harder than other sciences? Is it possible for one to succeed in this field by working hard, even if he/she is not very intel ligent? □ Physics isn't harder than any other science, almost by definition. Like any other area, the easy problems have already been solved, and the really ha rd ones have not; so we're working away at those problems that are right in be tween. I'm not sure that the idea of "intelligence" is very useful here. There ar e a number of very different skills that can be useful in doing physics -- abs tract reasoning, creativity, numerical facility, physical intuition, logical t hinking. You definitely need some of those -- in addition to hard work! -- to succeed as a physicist. But there are many different styles to doing physics, and people have been successful in very different ways; likewise, there have b een people who are very good at IQ tests who haven't managed to contribute any thing to physics. But, all things being equal, the better you are at all of th ose skills, the better off you will be. ■ When teaching physics, have you found any topic hard to explain to your students? Have you had any student who loves physics but finds it too hard? □ There are many topics which are hard to explain to students, not to men tion hard to explain to myself! Physics research is carried out at the edge o f our understanding, and will be difficult by definition. Yes, there are plenty of people who love doing physics, but whose natural talents lie in some other direction. It's important to find the intersection o f what you love to do and what you are able to contribute to the world. ■ What positions are available for people interested in theoretical physi cs besides becoming a university professor? Some people are not interested in / good at teaching, but they still want to do research. □ I have to admit, there aren't many. Most people doing theoretical physi cs research are located at universities; some are at national laboratories lik e Fermilab or Los Alamos; a very few are at specialized research institutions, like the Perimeter Institute; and a few more are at industry-funded think tan ks. But I would encourage people who want to do research to practice their tea ching and become better at it. ■ Does being a scientist/physicist affect your personality and/or your op inions on non-scientific issues? □ I'm honestly not sure, although probably yes. The difficulty with that kind of question is that it's hard to tell what is the cause and what is the e ffect -- does being a scientist make me think a certain way, or does thinking a certain way influence my decision to become a scientist? I do think that the training in careful and quantitative reasoning that one receives as a scienti st can be extremely helpful in thinking about all sorts of things. ■ I noticed that the books used in one course you taught, Moments in Athe ism, are similar to books used in my western civilization courses. Do you thin k there is a relation between the development of atheism and that of western c ulture? Do you have any prediction about atheism in the future? □ It is very interesting to see how the history of atheism is closely int ertwined with intellectual history more generally, at least in the Western wor ld. Important developments in our understanding of the physical world often ex erted an important influence on how people thought about the supernatural. That is not to say that the history of Western civilization has described a uniform trend toward atheism, nor that atheism will eventually triumph in th e future. I suspect that it will, as supernatural explanations lose their forc e -- but it might take a very long time, with many ups and downs along the way . ■ Do you think the general public can benefit from "pure sciences" i.e., sciences that have no application now? □ Absolutely! Pure science is our way of understanding how the world wor ks. Anyone can "benefit" from that, because understanding our world is part of what makes us human. |
2楼2007-12-24 19:40:11