温伯格《解释世界》前言

我是物理学家，不是历史学家，但是这些年来我对科学史越来越着迷。科学史精彩纷呈，向我们叙述着人类历史上动人心扉的故事。像我这样的科学家对科学史又有别样的痴迷。掌握科学史有助于指引今天的科学研究，对有些科学家而言，学习科学史对他们目前的科研工作起到了推动作用。我们期望我们的研究工作将来能够在自然科学宏大历史篇章中占有一席之地，即使非常微小。 我过去的作品已经涉及到历史题材，不过主要是现代物理和天文史，跨度大致从19世纪后期到近期。虽然在我们这个时代我们已经掌握了大量新的知识，但物理学的目的和标准并没有发生根本性变化。假如1900年的物理学家来学习今天的宇宙学标准模型或基本粒子物理，他们一定会倍感惊奇，但是这种通过采用数学方程描述以及可实验验证的客观原理来解释各种现象的方法看起来一定非常熟悉。 后来我决定对早期科学史进行更深入的挖掘，那时科学研究的目的和标准还没有成型。做为一位大学教师，当我想掌握什么内容时，自然而然会自愿去教授这方面的课程。过去十年中我在得克萨斯大学不时为没有特别科学，数学和历史背景的本科生教授物理和天文史。本书就是基于那些课程的教学讲稿。 但是本书不是对科学史的简单叙述，它加入了一个现代前沿科学家对过去科学的看法。我利用这个机会来阐述我对物理科学本质，以及它与宗教，技术，哲学，数学和审美学盘根错节关系的理解。 近似科学方法由来已久。大自然不时会在我们面前呈现各种各样谜团：火，雷雨，瘟疫，天体运动，闪电，潮汐等等。通过对各种现象长期地观察人们归纳出：火发烫，打雷预示下雨，新月和满月时潮汐最高等等。这些基本成为人类的部分常识。但是在各地都有些人不只满足于收集现象，他们更想解释世界。 这并不容易。我们的先贤不但没有我们现在这样对世界有全面的认识，更重要的的是他们不具备任何我们现在发现问题以及解决问题的方法。在我准备我的教学讲稿时我不止一次感受到过往几个世纪科学工作与现在有多大的不同。正如被多次引用的作家哈特利小说中所言：昔日犹如异国，其人行事迥异。在本书中我希望我不只为读者介绍科学史上发生了什么，而且能让读者感受到一丝科学工作的艰辛。 所以本书不只是介绍我们如何逐步认识纷繁复杂的世界，任何科学史都以此为主。我在本书中的着重点有所不同，我会侧重介绍我们是如何逐步学会怎样认识世界的。 我并不是没有意识到本书书名中“解释”一词会引起科学哲学家的疑问。他们早就指出很难清晰区分解释和描述的不同。但是本书关注科学史而不是科学哲学。我承认采用解释一词可能不太准确，这里的意思类似于日常生活中我们试图解释为什么某匹马赢得了比赛，为什么某架飞机发生坠毁一样。 副书名用了“发现”一词也有待商榷。我曾经想过用“现代科学的发明”做为副标题。毕竟没有人类的实践是不可能产生科学的。我最后选择“发现”而不是“发明”是为了说明科学之所以是现在这样并不是因为一系列历史上偶然的发明创造，而是因为自然本身就是这样。虽然现代科学并不完美，但历经不断调整和完善，已然非常有效。我们可以通过现代科学对世界有更可靠的认识。从这个意义上说，科学的确是一门等待人们去发现的技术。 这样人们可以谈及科学的发现，正如历史学家谈及农业的发现一样。虽然农业种类繁多，不尽完美，但由于农业实践在生物学的指引下不断完善，已然极其实用—我们依靠农业生产粮食。 采用这个副书名也是为了让我远离那些个别仅存的社会解构主义者，那些试图解释不光科学发现过程，甚至包括科学成果本身也是特定文化产物的社会学家，哲学家以及历史学家。 在科学的多种分支中，本书着重介绍物理学和天文学。物理学，尤其是物理学在天文学中的应用，奠定了现代科学的基础。当然认为像生物学这种基本理论很大程度取决于历史偶然性的科学可以或应该仿照物理学的观点有一定局限性，然而从某种程度上来说生物学和化学在19世纪和20世纪的发展确实延续着17世纪物理学的发展模式。 科学现在已然国际化，也许具备我们文明中最国际化的一面。但是现代科学的发现是发生在俗称的西方。现代科学从科学革命时期发生于欧洲的研究中学会科学方法，而后者又是从中世纪欧洲和阿拉伯国家的成就演变而来，最终源至于希腊早期科学。西方从世界各地吸取了很多科学知识 – 包括埃及几何，巴比伦天文数据，巴比伦和印度算术方法，中国的磁罗盘等等。但就我所知，现代科学方法本身并不是引进的。所以本书强调的西方（包括中世纪伊斯兰）如同曾经被奥斯瓦德-施本格勒和阿诺德-汤因比哀叹的西方一样：对发生在西方以外的科学我将甚少介绍，对于被哥伦布发现之前美洲大陆发生的有趣但与外界隔绝的科学进展我将完全不会介绍。 讲述这个故事我会面临现代历史学家小心回避的危险境地，即用现代标准评价过去。本书对历史大有不敬，我不会回避用现代视角批判过去的方法和理论。我甚至可以从揭示一些史学家过去不曾指出的科学大师的错误中找到乐趣。 一个常年致力于研究过去科学大师贡献的史学家可能会夸大他们心目中英雄的成就，我发现对柏拉图，亚里士多德，阿维森纳，格罗斯泰特以及笛卡尔的研究尤其明显。这里我并不是要指责过去一些自然哲学家有多愚蠢，而是想通过展示这些智力超群的大师与我们现在的科学概念差距有多远来试图说明现代科学的发现多么来之不易。这也是一种警示，科学还没有最后成型。在本书中我会指出科学方法虽然取得了如此巨大进步，但我们今天可能正在重复过去的一些错误。 有些科学史学家制定了一个准则，在研究过去科学时不去参考现代科学知识。我则相反会尽量用现在知识去理清过去的科学。比如我们无法知道古希腊天文学家阿波罗尼奥斯和喜帕恰斯如何从他们有限的数据中得出行星在循环本轮轨道上围绕地球运行的理论，因为他们应用的大部分数据已然失传。但是我们清楚知道古代地球和行星跟现在一样在近圆形轨道上围绕太阳运动，通过应用这个知识我们就可以理解古代天文学家手头掌握的数据是如何指引他们提出本轮理论的。不管怎样，现代人在阅读古代天文学时怎么可能忘掉我们现在已经完全掌握了的太阳系运行规律。 读者如果想详细了解古代科学家的工作如何切合实际，可以参见本书后部的“技术手册”。理解本书主要内容并没有必要一定去阅读这部分，但有些读者可能会从中学会一些物理学和天文学的瑰丽知识，就像我在准备这部分资料时所经历的一样。 科学现在与其初期相比已然完全不同。科学结果是客观的。灵感和审美判断在科学理论发展进程中固然重要，但这些理论的证实最终依赖对这些理论的预测结果做出正确的实验验证。虽然数学被应用于物理理论的公式表达以及推导出理论结果，但科学不是数学的一个分支。科学理论不能从纯粹数学思考中推演出来。科学和技术互惠，但是在最本质上科学并不完全是为了实用。科学对上帝或来世是否存在不置一词，科学的目的是对自然现象做出纯粹的解释。科学是个累积过程。每个新理论都会吸纳早期的成功理论，将其作为近似特例，而且对为什么这些近似特例有效，在什么条件下有效做出解释。 对于古代或中世纪科学家而言这些完全不是明确的，所有这些认识都是历经艰辛从发生在16世纪和17世纪的科学革命中学来的。现代科学从来不是一开始就被做为追求的目标。那么我们是如何实现科学革命并将其超越达到我们现在的高度的呢？在我们探索现代科学发现之路时我们必须去回答这些问题。

I am a physicist, not a historian, but over the years I have become increasingly fascinated by the history of science. It is an extraordinary story, one of the most interesting in human history. It is also a story in which scientists like myself have a personal stake. Today’s research can be aided and illuminated by a knowledge of its past, and for some scientists knowledge of the history of science helps to motivate present work. We hope that our research may turn out to be a part, however small, of the grand historical tradition of natural science. Where my own past writing has touched on history, it has been mostly the modern history of physics and astronomy, roughly from the late nineteenth century to the present. Although in this era we have learned many new things, the goals and standards of physical science have not materially changed. If physicists of 1900 were somehow taught today’s Standard Model of cosmology or of elementary particle physics, they would have found much to amaze them, but the idea of seeking mathematically formulated and experimentally validated impersonal principles that explain a wide variety of phenomena would have seemed quite familiar. A while ago I decided that I needed to dig deeper, to learn more about an earlier era in the history of science, when the goals and standards of science had not yet taken their present shape. As is natural for an academic, when I want to learn about something, I volunteer to teach a course on the subject. Over the past decade at the University of Texas, I have from time to time taught undergraduate courses on the history of physics and astronomy to students who had no special background in science, mathematics, or history. This book grew out of the lecture notes for those courses. But as the book has developed, perhaps I have been able to offer something that goes a little beyond a simple narrative: it is the perspective of a modern working scientist on the science of the past. I have taken this opportunity to explain my views about the nature of physical science, and about its continued tangled relations with religion, technology, philosophy, mathematics, and aesthetics. Before history there was science, of a sort. At any moment nature presents us with a variety of puzzling phenomena: fire, thunderstorms, plagues, planetary motion, light, tides, and so on. Observation of the world led to useful generalizations: fires are hot; thunder presages rain; tides are highest when the Moon is full or new, and so on. These became part of the common sense of mankind. But here and there, some people wanted more than just a collection of facts. They wanted to explain the world. It was not easy. It is not only that our predecessors did not know what we know about the world— more important, they did not have anything like our ideas of what there was to know about the world, and how to learn it. Again and again in preparing the lectures for my course I have been impressed with how different the work of science in past centuries was from the science of my own times. As the much quoted lines of a novel of L. P. Hartley put it, “The past is a foreign country; they do things differently there.” I hope that in this book I have been able to give the reader not only an idea of what happened in the history of the exact sciences, but also a sense of how hard it has all been. So this book is not solely about how we came to learn various things about the world. That is naturally a concern of any history of science. My focus in this book is a little different—it is how we came to learn how to learn about the world. I am not unaware that the word “explain” in the title of this book raises problems for philosophers of science. They have pointed out the difficulty in drawing a precise distinction between explanation and description. (I will have a little to say about this in Chapter 8.) But this is a work on the history rather than the philosophy of science. By explanation I mean something admittedly imprecise, the same as is meant in ordinary life when we try to explain why a horse has won a race or why an airplane has crashed. The word “discovery” in the subtitle is also problematic. I had thought of using The Invention of Modern Science as a subtitle. After all, science could hardly exist without human beings to practice it. I chose “Discovery” instead of “Invention” to suggest that science is the way it is not so much because of various adventitious historic acts of invention, but because of the way nature is. With all its imperfections, modern science is a technique that is sufficiently well tuned to nature so that it works—it is a practice that allows us to learn reliable things about the world. In this sense, it is a technique that was waiting for people to discover it. Thus one can talk about the discovery of science in the way that a historian can talk about the discovery of agriculture. With all its variety and imperfections, agriculture is the way it is because its practices are sufficiently well tuned to the realities of biology so that it works—it allows us to grow food. I also wanted with this subtitle to distance myself from the few remaining social constructivists: those sociologists, philosophers, and historians who try to explain not only the process but even the results of science as products of a particular cultural milieu. Among the branches of science, this book will emphasize physics and astronomy. It was in physics, especially as applied to astronomy, that science first took a modern form. Of course there are limits to the extent to which sciences like biology, whose principles depend so much on historical accidents, can or should be modeled on physics. Nevertheless, there is a sense in which the development of scientific biology as well as chemistry in the nineteenth and twentieth centuries followed the model of the revolution in physics of the seventeenth century. Science is now international, perhaps the most international aspect of our civilization, but the discovery of modern science happened in what may loosely be called the West. Modern science learned its methods from research done in Europe during the scientific revolution, which in turn evolved from work done in Europe and in Arab countries during the Middle Ages, and ultimately from the precocious science of the Greeks. The West borrowed much scientific knowledge from elsewhere—geometry from Egypt, astronomical data from Babylon, the techniques of arithmetic from Babylon and India, the magnetic compass from China, and so on—but as far as I know, it did not import the methods of modern science. So this book will emphasize the West (including medieval Islam) in just the way that was deplored by Oswald Spengler and Arnold Toynbee: I will have little to say about science outside the West, and nothing at all to say about the interesting but entirely isolated progress made in pre- Columbian America. In telling this story, I will be coming close to the dangerous ground that is most carefully avoided by contemporary historians, of judging the past by the standards of the present. This is an irreverent history; I am not unwilling to criticize the methods and theories of the past from a modern viewpoint. I have even taken some pleasure in uncovering a few errors made by scientific heroes that I have not seen mentioned by historians. A historian who devotes years to study the works of some great man of the past may come to exaggerate what his hero has accomplished. I have seen this in particular in works on Plato, Aristotle, Avicenna, Grosseteste, and Descartes. But it is not my purpose here to accuse some past natural philosophers of stupidity. Rather, by showing how far these very intelligent individuals were from our present conception of science, I want to show how difficult was the discovery of modern science, how far from obvious are its practices and standards. This also serves as a warning, that science may not yet be in its final form. At several points in this book I suggest that, as great as is the progress that has been made in the methods of science, we may today be repeating some of the errors of the past. Some historians of science make a shibboleth of not referring to present scientific knowledge in studying the science of the past. I will instead make a point of using present knowledge to clarify past science. For instance, though it might be an interesting intellectual exercise to try to understand how the Hellenistic astronomers Apollonius and Hipparchus developed the theory that the planets go around the Earth on looping epicyclic orbits by using only the data that had been available to them, this is impossible, for much of the data they used is lost. But we do know that in ancient times the Earth and planets went around the Sun on nearly circular orbits, just as they do today, and by using this knowledge we will be able to understand how the data available to ancient astronomers could have suggested to them their theory of epicycles. In any case, how can anyone today, reading about ancient astronomy, forget our present knowledge of what actually goes around what in the solar system? For readers who want to understand in greater detail how the work of past scientists fits in with what actually exists in nature, there are “technical notes” at the back of the book. It is not necessary to read these notes to follow the book’s main text, but some readers may learn a few odd bits of physics and astronomy from them, as I did in preparing them. Science is not now what it was at its start. Its results are impersonal. Inspiration and aesthetic judgment are important in the development of scientific theories, but the verification of these theories relies finally on impartial experimental tests of their predictions. Though mathematics is used in the formulation of physical theories and in working out their consequences, science is not a branch of mathematics, and scientific theories cannot be deduced by purely mathematical reasoning. Science and technology benefit each other, but at its most fundamental level science is not undertaken for any practical reason. Though science has nothing to say one way or the other about the existence of God or an afterlife, its goal is to find explanations of natural phenomena that are purely naturalistic. Science is cumulative; each new theory incorporates successful earlier theories as approximations, and even explains why these approximations work, when they do work. None of this was obvious to the scientists of the ancient world or the Middle Ages, and all of it was learned only with great difficulty in the scientific revolution of the sixteenth and seventeenth centuries. Nothing like modern science was a goal from the beginning. How then did we get to the scientific revolution, and beyond it to where we are now? That is what we must try to learn as we explore the discovery of modern science.