Friday, 17 June 2016

Darwin and particle physics

Darwin had little or nothing to do with particle physics but some of his conclusions inspired at least one physicist.  From Reciprocity Blog, Has Evolution been proven?
It's a little-known fact that the earliest objections to Darwin's work didn't come from the religious, it came from a different quarter entirely, and a surprising one at that: Physicists.

The big problem was that, since Newton, it was thought that the universe was just like a big clockwork machine. Pierre-Simon Laplace famously stated that, with Newton's work, all we needed to know was the position and velocity of every particle in the universe and we could predict with perfect accuracy any past or future state.
This is now known as Laplacian determinism. All the physicists of Darwin's day were Laplacian determinists. They couldn't countenance the idea that there were random elements at play in the universe. But what do we actually mean by random here?

Random, in the way that I employ it, and in the way that it arises in evolutionary theory, means 'statistically independent'. It does not mean, as some suppose 'uncaused'. It simply means that, of a range of possible outcomes, any one outcome is statistically as probable as any other outcome.
To give a concrete example of something random, we can look at the decay of a single atom. The moment of decay of, say, an atom of caesium, is entirely random. It can happen any time from the moment the atom first arises to the heat-death of the universe. There's absolutely no way to predict when it will decay. Each of those moments, and thus the time of decay, is statistically independent.
So, Darwin had introduced the random and the probabilistic, and the physicists weren't too happy about it. Ludwig Boltzmann, father of thermodynamics, cites Darwin as one of his major influences in the formulation of statistical mechanics, and describes him, having laid the groundwork that would ultimately result in quantum mechanics, as the greatest physicist of the 19th century.
By the way, the blogger feels that evolution has been proven, at least in a 'beyond a reasonable doubt' way.