chapter 14

 The Heuristic Value of the Theory of Relativity

 

Our train of thought in the foregoing pages can be epitomised in the following manner. Experience has led to the conviction that, on the one hand, the principle of relativity holds true and that on the other hand the velocity¹ of transmission of light in vacuo has to be considered equal to a constant c. By uniting these two postulates² we obtained the law of transformation³ for the rectangular co-ordinates x comma y comma z and the time t of the events which constitute the processes of nature. In this connection we did not obtain the Galilei transformation, but, differing from classical mechanics, the Lorentz transformation.

 

The law of transmission of light, the acceptance of which is justified⁴ by our actual knowledge, played an important part in this process of thought. Once in possession of the Lorentz transformation, however, we can combine this with the principle of relativity, and sum up the theory thus:

 

Every general law of nature must be so constituted that it is transformed into a law of exactly the same form when, instead of the space-time variables x comma y comma z comma t of the original coordinate⁵ system K, we introduce new space-time variables  x prime comma y prime comma z prime comma t prime of a co-ordinate system K′. In this connection the relation between the ordinary and the accented magnitudes is given by the Lorentz transformation. Or in brief: General laws of nature are co-variant with respect to Lorentz transformations⁶.

 

This is a definite mathematical condition that the theory of relativity demands of a natural law, and in virtue⁷ of this, the theory becomes a valuable heuristic aid in the search for general laws of nature. If a general law of nature were to be found which did not satisfy this condition, then at least one of the two fundamental assumptions of the theory would have been disproved. Let us now examine what general results the latter theory has hitherto evinced.

 

1 velocity   

n.速度，速率

参考例句：

• Einstein's theory links energy with mass and velocity of light.爱因斯坦的理论把能量同质量和光速联系起来。
• The velocity of light is about 300000 kilometres per second.光速约为每秒300000公里。

2 postulates   

v.假定，假设( postulate的第三人称单数 )

参考例句：

• They proclaimed to be eternal postulates of reason and justice. 他们宣称这些原则是理性和正义的永恒的要求。 来自辞典例句
• The school building programme postulates an increase in educational investment. 修建校舍的计画是在增加教育经费的前提下拟定的。 来自辞典例句

3 transformation   

n.变化；改造；转变

参考例句：

• Going to college brought about a dramatic transformation in her outlook.上大学使她的观念发生了巨大的变化。
• He was struggling to make the transformation from single man to responsible husband.他正在努力使自己由单身汉变为可靠的丈夫。

4 justified   

a.正当的，有理的

参考例句：

• She felt fully justified in asking for her money back. 她认为有充分的理由要求退款。
• The prisoner has certainly justified his claims by his actions. 那个囚犯确实已用自己的行动表明他的要求是正当的。

5 coordinate   

adj.同等的，协调的；n.同等者；vt.协作，协调

参考例句：

• You must coordinate what you said with what you did.你必须使你的言行一致。
• Maybe we can coordinate the relation of them.或许我们可以调和他们之间的关系。

6 transformations   

n.变化( transformation的名词复数 )；转换；转换；变换

参考例句：

• Energy transformations go on constantly, all about us. 在我们周围，能量始终在不停地转换着。 来自辞典例句
• On the average, such transformations balance out. 平均起来，这种转化可以互相抵消。 来自辞典例句

7 virtue   

n.德行，美德；贞操；优点；功效，效力

参考例句：

• He was considered to be a paragon of virtue.他被认为是品德尽善尽美的典范。
• You need to decorate your mind with virtue.你应该用德行美化心灵。