For example: Is the sand other than the rocks?That is, is the sand perhaps nothing but a great number of very tiny stones? Isthe moon a great rock? If we understood rocks, would we also understand the sandand the moon? Is the wind a sloshing of the air analogous to the sloshing motionof the water in the sea? What common features do different movements have? Whatis common to different kinds of sound? How many different colors are there? Andso on. In this way we try gradually to analyze all things, to put together thingswhich at first sight look different, with the hope that we may be able to reducethe number of different things and thereby understand them better.
例如：沙子与岩石有何不同？也就是说，沙子或许无非就是大量非常小的石头？月亮是不是一块巨大的岩石？如果我们理解了岩石，我们是否也就理解了沙子和月亮？风是空气的拍打，它与海里面水的拍打，是否可类比？不同的运动，有什么共同的特点？不同的声音，有什么共同的特点？总共有多少种不同的颜色？如此等等。我们尝试以这种方式，逐渐分析所有事物，把第一眼看上去不同的事物，放在一起，寄希望我们可以减少不同事物的数量，从而对其理解更深。

A few hundred years ago, a method wasdevised to find partial answers to such questions. Observation, reason,and experiment make up what we call the scientific method. Weshall have to limit ourselves to a bare description of our basic view of whatis sometimes called fundamental physics, or fundamental ideas which havearisen from the application of the scientific method.
几百年前，发明了一种方法，可以发现这些问题的部分答案。观察、思考原因、和实验，形成了我们今天称为科学方法的东西。从科学方法的应用，产生了我们有时称为基础物理学或基础想法的东西，对这些东西，我们有个基本观点，现在，我们将把我们自己，限制在仅仅对此基本观点的描述上。

What do we mean by “understanding” something?We can imagine that this complicated array of moving things which constitutes“the world” is something like a great chess game being played by the gods, andwe are observers of the game. We do not know what the rules of the game are;all we are allowed to do is to watch the playing. Of course, if we watchlong enough, we may eventually catch on to a few of the rules. The rules ofthe game are what we mean by fundamental physics. Even if we knew everyrule, however, we might not be able to understand why a particular move is madein the game, merely because it is too complicated and our minds are limited. Ifyou play chess you must know that it is easy to learn all the rules, and yet itis often very hard to select the best move or to understand why a player movesas he does. So it is in nature, only much more so; but we may be able at leastto find all the rules. Actually, we do not have all the rules now. (Every oncein a while something like castling is going on that we still do not understand.)Aside from not knowing all of the rules, what we really can explain in terms ofthose rules is very limited, because almost all situations are so enormously complicatedthat we cannot follow the plays of the game using the rules, much less tellwhat is going to happen next. We must, therefore, limit ourselves to the morebasic question of the rules of the game. If we know the rules, we consider thatwe “understand” the world.
我们所说的“理解”某事，究竟是什么意思呢？我们可以想象，组成这个世界的巨大的事物阵列，就像一个巨大的国际象棋游戏，它由上帝来玩，我们只是这个游戏的旁观者。我们并不知道这个游戏的规则是什么，我们被允许做的，只是“观察”这个游戏。当然，如果我们观察的足够久，最终，我们可以发现一些规则。游戏的规则就是我们称为基础物理学的东西。即便我们知道每条规则，我们还是不能理解，为什么游戏中会有某个移动，这只是因为，这个游戏太复杂，而我们的心智有限。如果你学过象棋，就会知道，学会所有规则很容易，但是，做出最佳选择，或者理解一个选手为什么要那样做，还是很难。在自然中，也是如此，只是要更复杂一些；但是，我们至少有可能找到所有这些规则。实际上，我们现在还没有找到所有这些规则。（偶尔，像‘国际象棋中的王车易位’这种事情，还是会发生，但我们还是不理解。）抛开不知道所有这些规则，我们能按照这些规则所解释的事情，还是非常有限，因为几乎所有的情况，都非常复杂，以至于，我们无法使用规则，来跟随这个游戏去玩，更不用说，预测下一步会发生什么了。因此，我们应该把我们限制在：关于游戏规则的更基本的问题上。如果我们知道了规则，我们就可以认为，我们“理解”了这个世界。

How can we tell whether the rules which we“guess” at are really right if we cannot analyze the game very well? There are,roughly speaking, three ways. First, there may be situations where nature has arranged,or we arrange nature, to be simple and to have so few parts that we can predictexactly what will happen, and thus we can check how our rules work. (In one cornerof the board there may be only a few chess pieces at work, and that we can figureout exactly.)
对于这个游戏，如果我们不能分析的很好的话，那么，我们怎么才能知道，我们所猜测的这些规则，是正确的呢？简单地说，有三种方式。第一，可能有一些情况，它们是自然安排的、或是我们安排的，这些情况，可能很简单，且只有很少的组成部分，以至于，我们可以准确地预测，将会发生什么，这样，我们就可以检查我们的规则是如何工作的了。（在棋盘的一角，可能只有几个棋子在工作，这样，我们就可以准确地想出，将会发生什么了。）

A second good way to check rules is interms of less specific rules derived from them. For example, the rule on themove of a bishop on a chessboard is that it moves only on the diagonal. One candeduce, no matter how many moves may be made, that a certain bishop will alwaysbe on a red square. So, without being able to follow the details, we can alwayscheck our idea about the bishop’s motion by finding out whether it is always ona red square. Of course it will be, for a long time, until all of a sudden wefind that it is on a black square (what happened of course, is that in themeantime it was captured, another pawn crossed for queening, and it turned intoa bishop on a black square). That is the way it is in physics. For a long timewe will have a rule that works excellently in an overall way, even when we cannotfollow the details, and then some time we may discover a new rule. Fromthe point of view of basic physics, the most interesting phenomena are of coursein the new places, the places where the rules do not work—not the placeswhere they do work! That is the way in which we discover new rules.
第二种检查规则的好方法，就是依据从这些规则推出的具体性稍差的规则。例如，在棋盘上，相移动的规则，就是它只在对角线上移动。我们就可以推导，无论某个相移动多少次，它肯定总是在红方块上。于是尽管不能跟踪相移动的具体路线，我们总是可以通过发现它是否总是在红方块上，来检查我们的相的运动的想法。当然，很长时间，它都会是在红方块上，直到某时，我们会突然发现，它在一个黑的方块上（发生了什么呢？当然是它被俘了{被吃了}，同时，一个卒子走到底线，变身成为了一个黑方块上的相）。这就是物理上的方式。在很长一段时间里，我们所拥有的规则，在所有方面，都会工作的很好，即便当我们不能跟踪细节的时候也如此，然后在某时，我们会发现一条新的规则。从基础物理学的观点看，最有趣的现象当然是在新的地方，新的地方，是指规则不能工作的地方，而不是指现象不起作用的地方！这就是们发现新规则的方式。

The third way to tell whether our ideas areright is relatively crude but probably the most powerful of them all. That is,by rough approximation. While we may not be able to tell why Alekhinemoves this particular piece, perhaps we can roughly understand thathe is gathering his pieces around the king to protect it, more or less, since thatis the sensible thing to do in the circumstances. In the same way, we can oftenunderstand nature, more or less, without being able to see what every littlepiece is doing, in terms of our understanding of the game.
我们的想法是否正确，第三种告诉我们此事的方式，可能相对粗鲁一点，但也可能是这三种方式中最有力的。此方法就是通过粗略的近似。我们可能无法知道，为什么阿廖欣要移动这个棋子，但或许我们可以粗略地理解，他在国王的周围，部署这些棋子，或多或少是为了保护它，因为，在那个环境下，这样做，是一件有意义的事情。以同样的方式，我们通常也可以或多或少的理解自然，而不用能够看到：依据我们对这个游戏的理解，每一个小的棋子正在做什么。

At first the phenomena of nature were roughlydivided into classes, like heat, electricity, mechanics, magnetism, propertiesof substances, chemical phenomena, light or optics, x-rays, nuclear physics, gravitation,meson phenomena, etc. However, the aim is to see complete nature asdifferent aspects of one set of phenomena. That is the problem in basictheoretical physics, today—to find the laws behind experiment; to amalgamatethese classes. Historically, we have always been able to amalgamate them,but as time goes on new things are found. We were amalgamating very well, whenall of a sudden x-rays were found. Then we amalgamated some more, and mesons werefound. Therefore, at any stage of the game, it always looks rather messy. Agreat deal is amalgamated, but there are always many wires or threads hanging outin all directions. That is the situation today, which we shall try to describe.
首先，自然现象被粗略地分类，比如热学、电学、机械学、电磁学、材料学、化学现象、光或光学、x射线、和物理学、万有引力、介子现象等。然而，分类的目的，是把完整的自然，看作是一组现象的不同方面。这就是今天基础理论物理学的课题，找出实验背后的规律；去融合这些类。从历史上讲，我们总是能够融合它们，但随着时间的推移，又会发现新的事物。曾经我们融合的很好，突然又发现了x射线。随后，我们融合的更多，但接着又发现了介子。因此，这个游戏的任何阶段，看上去总是比较乱。很多东西都被融合了，但是，总有一些线头，挂在外面，伸向四面八方。这就是今天的情况，下面将会讲到。

Some historic examples of amalgamation are thefollowing. First, take heat and mechanics. When atoms are inmotion, the more motion, the more heat the system contains, and so heat andall temperature effects can be represented by the laws of mechanics. Anothertremendous amalgamation was the discovery of the relation between electricity,magnetism, and light, which were found to be different aspects of the same thing,which we call today the electromagnetic field. Another amalgamation isthe unification of chemical phenomena, the various properties of various substances,and the behavior of atomic particles, which is in the quantum mechanics ofchemistry.
历史上一些融合的例子如下。首先，是热学和力学。当原子处于运动中时，运动越大，则系统包含的热量就越多，于是，热量和所有温度效果，都可以通过力学规律来表现。另外一个巨大的融合，是发现了电、磁、和光之间的关系，它们的被发现是同一个事物的不同方面，它们现在被称为电磁领域。再一个融合，就是化学现象的统一，不同实质体的不同属性，及原子中的诸粒子的表现，这些统一在化学量子力学之中。

The question is, of course, is it going to bepossible to amalgamate everything, and merely discover that this worldrepresents different aspects of one thing? Nobody knows. All we know isthat as we go along, we find that we can amalgamate pieces, and then we findsome pieces that do not fit, and we keep trying to put the jigsaw puzzle together.Whether there are a finite number of pieces, and whether there is even a borderto the puzzle, is of course unknown. It will never be known until we finish thepicture, if ever. What we wish to do here is to see to what extent this amalgamationprocess has gone on, and what the situation is at present, in understanding basicphenomena in terms of the smallest set of principles. To express it in a simplemanner, what are things made of and how few elements are there?
问题当然就是：把所有的事情都融合在一起，是否可能？从而最终发现这个世界，只是表现着同一个事物的不同方面？没人知道答案。我们所知道的只是，在我们前进的时候，我们发现我们能够融合一些碎片，然后，我们又发现了一些东西，并不与前面的适合，我们的尝试去完成这个拼图游戏。这个拼图，是否是由有限的部分组成，及是否有边界，当然是不知道的。在我们完成这副画之前--如果我们能完成的话，永远也不会知道。我们希望在这里做的，就是要看看，这个融合过程已经走了多远？现在的情况如何？为的是依据最小数量的原理集，来理解基础现象。简单地说就是：万物是由什么构成的，及构成万物的最基本的元素有多少？

2–2Physics before 1920 2–2 1920年以前的物理学
It is a little difficult to begin at once withthe present view, so we shall first see how things looked in about 1920 andthen take a few things out of that picture. Before 1920, our world picture wassomething like this: The “stage” on which the universe goes is the three-dimensionalspace of geometry, as described by Euclid, and things change in a mediumcalled time. The elements on the stage are particles, for examplethe atoms, which have some properties. First, the property of inertia:if a particle is moving it keeps on going in the same direction unless forcesact upon it. The second element, then, is forces, which were then thoughtto be of two varieties: First, an enormously complicated, detailed kind of interactionforce which held the various atoms in different combinations in a complicatedway, which determined whether salt would dissolve faster or slower when we raisethe temperature. The other force that was known was a long-range interaction—a smoothand quiet attraction—which varied inversely as the square of the distance, andwas called gravitation. This law was known and was very simple. Whythings remain in motion when they are moving, or why there is a law ofgravitation was, of course, not known.
从现在这个观点，立即开始，稍微有点困难，所以，我们先看看，在1920年前后，事情是怎么回事，然后，从那幅图像里，拿出几个事情来。在1920年之前，我们关于世界的图像大致如此：宇宙运行的“舞台”，是一个三维的地理空间，正如欧几里德{Euclid}所描述，而事物的变化，是在一个被称为时间的媒介中进行的，舞台上的元素，就是粒子{particles}，例如原子，粒子有若干属性{properties}。首先，惯性{inertia}的属性，如果一个粒子在运动，那么，它就一直沿着一个方向运动，直到有力作用于它。因此，就有了第二个元素，力，在那个时候，它被认为有两个品种：第一种力，巨复杂，从细节上看，又是相互作用的，它以一种复杂的方式，把不同的原子，以不同的组合方法，抓在一起；这种方式，决定了为什么当我们提高温度的时候，盐在水中溶解的快还是慢。另外一个力，就是我们知道的长距离的交互作用，一种平稳而安静的吸引力，与距离的平方成反比，被称为万有引力。这条规律，众所周知，且非常简单。当事物运动的时候，为什么会保持运动状态，或者，为什么会有一条万有引力定律？当然，是不知道的。

A description of nature is what we are concernedwith here. From this point of view, then, a gas, and indeed all matter,is a myriad of moving particles. Thus many of the things we saw while standing atthe seashore can immediately be connected. First the pressure: this comes fromthe collisions of the atoms with the walls or whatever; the drift of the atoms,if they are all moving in one direction on the average, is wind; the randominternal motions are the heat. There are waves of excess density, wheretoo many particles have collected, and so as they rush off they push up pilesof particles farther out, and so on. This wave of excess density is sound.It is a tremendous achievement to be able to understand so much. Some of thesethings were described in the previous chapter.
对自然的描述，是我们这里所关心的一个问题。从这个观点出发，气体，事实上所有的物质，都是极大数量的移动着的粒子。这样，我们站在海边能看到的所有事物，都立即被联系了起来。首先是压力，它来自原子对墙壁之类的碰撞；原子的漂流，如果它们平均是在一个方向上移动，就是风；随机的内部运动，就是热。还有过剩密度的波浪，这样，当它们冲击的时候，就在更远的地方，把粒子堆起来。这个过剩密度的波浪，就是声音。能理解这么多，已然是巨大的成就了。其中的一些事情，我们上一章都曾讲过。

What kinds of particles are there?There were considered to be 92 at that time: 92 different kinds of atoms were ultimately discovered. They had differentnames associated with their chemical properties.
都有哪些种类的粒子呢？那时，总共有92种，即有92种不同的原子，最终被发现了。它们有不同的名字，而名字，是与它们的化学属性相关联的。

The next part of the problem was, what arethe short-range forces? Why does carbon attract one oxygen or perhaps twooxygens, but not three oxygens? What is the machinery of interaction betweenatoms? Is it gravitation? The answer is no. Gravity is entirely too weak. But imaginea force analogous to gravity, varying inversely with the square of the distance,but enormously more powerful and having one difference. In gravity everythingattracts everything else, but now imagine that there are two kinds of “things,”and that this new force (which is the electrical force, of course) has theproperty that likes repel but unlikes attract. The “thing” thatcarries this strong interaction is called charge.
这个问题的第二部分就是：什么是短距离的力？为什么碳只吸引一个或两个氧？而不是三个氧？原子之间相互作用的机制是什么？是万有引力吗？答案是否。重力完全太弱。但是，想象有一种力，它与重力可以类比，与距离的平方成反比，然而，却更强有力，并且，有一个区别。在重力中，每个事物的之间相互吸引，但是，现在想象有两类事物，这个新的力（它当然是电子力），具有一种属性，更像排斥，而不是像吸引。此带有这种强相互作用的“事物”，被称为电荷。

Then what do we have? Suppose that we havetwo unlikes that attract each other, a plus and a minus, and that they stick veryclose together. Suppose we have another charge some distance away. Would it feelany attraction? It would feel practically none, because if the first twoare equal in size, the attraction for the one and the repulsion for the other balanceout. Therefore there is very little force at any appreciable distance. On theother hand, if we get very close with the extra charge, attractionarises, because the repulsion of likes and attraction of unlikes will tend to bringunlikes closer together and push likes farther apart. Then the repulsion willbe less than the attraction. This is the reason why the atoms, which areconstituted out of plus and minus electric charges, feel very little force whenthey are separated by appreciable distance (aside from gravity). When they comeclose together, they can “see inside” each other and rearrange their charges, withthe result that they have a very strong interaction. The ultimate basis of aninteraction between the atoms is electrical. Since this force is so enormous,all the plusses and all minuses will normally come together in as intimate a combinationas they can. All things, even ourselves, are made of fine-grained, enormously stronglyinteracting plus and minus parts, all neatly balanced out. Once in a while, by accident,we may rub off a few minuses or a few plusses (usually it is easier to rub offminuses), and in those circumstances we find the force of electricity unbalanced,and we can then see the effects of these electrical attractions.
那么，我们有什么呢？假设我们有两个异性电荷，互相吸引，一个正一个负，并且非常紧密地粘在一起。假设我们在不远的距离之内，有另外一个电荷。它能感到吸引力吗？它将感觉不到，因为，如果前两个电荷大小相等的话，那么，对一个的吸引力，将与对另一个的排斥力，相互抵消。因此呢，在任何可见的距离内，将只有非常小的力。另一方面，如果我们能够非常接近另外一个电荷的话，那么，吸引就会产生，因为同性间的排斥和异性间的吸引，将倾向于把异性带的更近，而把同性推的更远。因此，排斥将比吸引弱。这就是为什么当原子被分开的时候，只能感觉到非常小的力（重力除外）；而原子，则是由正电荷与负电荷组成的。当它们走得更近的时候，它们相互之间可以“看到对方的内部”，从而重新安排它们的电荷，结果就是，它们有一个非常强的相互作用。原子间相互作用的终极基础，就是电力。由于此力，非常巨大，所有的正电荷和负电荷，通常最后都会形成一种尽可能亲密的组合。所有的事物，甚至包括我们自己，都是由精密的、巨大的、强相互作用的正负电部分所组成，且都精妙的平衡了。有时，由于偶然的原因，我们会擦掉一些负电或正电（通常负的更容易擦掉），在此情况下，我们就会发现，电不平衡了，然后，你就会看到那些电子吸引的作用了。