CHANCE. 71 



ible and that the world is tending towards uniformity. 

 When two bodies of different temperatures are in 

 conjunction, the warmer gives up heat to the colder, 

 and accordingly we can predict that the temperatures 

 will become equal. But once the temperatures have 

 become equal, if we are asked about the previous state, 

 what can we answer ? We can certainly say that one 

 of the bodies was hot and the other cold, but we 

 cannot guess which of the two was formerly the 

 warmer. 



And yet in reality the temperatures never arrive 

 at perfect equality. The difference between the 

 temperatures only tends towards zero asymptotically. 

 Accordingly there comes a moment when our 

 thermometers are powerless to disclose it. But if 

 we had thermometers a thousand or a hundred 

 thousand times more sensitive, we should recognize 

 that there is still a small difference, and that one of 

 the bodies has remained a little warmer than the 

 other, and then we should be able to state that this 

 is the one which was formerly very much hotter than 

 the other. 



So we have, then, the reverse of what we found in 

 the preceding examples, great differences in the cause 

 and small differences in the effect. Flammarion once 

 imagined an observer moving away from the earth 

 at a velocity greater than that of light. For him 

 time would have its sign changed, history would be 

 reversed, and Waterloo would come before Austerlitz. 

 Well, for this observer effects and causes would be 

 inverted, unstable equilibrium would no longer be the 

 exception ; on account of the universal irreversibility, 

 everj'thing would seem to him to come out of a kind 



