2.2 Laplace’s demon
As they stood, Newton’s laws were suitable only for objects that could be treated as ‘point particles’ (meaning that their mass is concentrated in one spot, known as the centre of mass) and wider applicability was sought. This was achieved by the next generation of mathematicians, most notably by the great Swiss mathematician Leonhard Euler, who provided more generalised equations which could be applied in more complex settings where objects are not necessarily rigid.
Such was the success of this next generation in applying Newton’s laws of motion, that it seemed mathematics could be harnessed to describe the motion of everything in the universe: past, present and future. This view, that the universe is completely knowable, is known as determinism. It was summed up by the French mathematician Pierre-Simon Laplace in 1814:
We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all the forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movement of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes.
Laplace’s all-comprehending intelligence is now famously known as ‘Laplace’s demon’. It is called a ‘demon’ because it is supposed to be a secular entity and not a divine intelligence. Although it is not known who first used and popularised the term, the notion became well known in the 19th century, feeding into the belief that ultimately no motion could defy prediction.
However, as you are about to see, by the end of the 19th century this belief was to be completely shattered. This will have serious repercussions for the quest to predict the outcome of rolling a die. But first you are going to look at a famous problem that particularly interested Laplace.