74 THE RUNNING-DOWN OF THE UNIVERSE 



The uniform march of a regiment is not the only form 

 of organised motion; the organised evolutions of a 

 stage chorus have their natural analogue in sound waves. 

 A common measure can now be applied to all forms 

 of organisation. Any loss of organisation is equitably 

 measured by the chance against its recovery by an acci- 

 dental coincidence. The chance is absurd regarded as 

 a contingency, but it is precise as a measure. 



The practical measure of the random element which 

 can increase in the universe but can never decrease is 

 called entropy. Measuring by entropy is the same as 

 measuring by the chance explained in the last paragraph, 

 only the unmanageably large numbers are transformed 

 (by a simple formula) into a more convenient scale of 

 reckoning. Entropy continually increases. We can, 

 by isolating parts of the world and postulating rather 

 idealised conditions in our problems, arrest the increase, 

 but we cannot turn it into a decrease. That would 

 involve something much worse than a violation of an 

 ordinary law of Nature, namely, an improbable coinci- 

 dence. The law that entropy always increases — the 

 second law of thermodynamics — holds, I think, the 

 supreme position among the laws of Nature. If someone 

 points out to you that your pet theory of the universe 

 is in disagreement with Maxwell's equations — then so 

 much the worse for Maxwell's equations. If it is found 

 to be contradicted by observation — well, these experi- 

 mentalists do bungle things sometimes. But if your 

 theory is found to be against the second law of thermo- 

 dynamics I can give you no hope; there is nothing for 

 it but to collapse in deepest humiliation. This exaltation 

 of the second law is not unreasonable. There are other 

 laws which we have strong reason to believe in, and we 

 feel that a hypothesis which violates them is highly 



