Nostalgia Just Became a Law of Nature

Simon Dedeo in Nautilus:

ScreenHunter_1020 Feb. 22 18.42John Ruskin called it the pathetic fallacy: to see rainstorms as passionate, drizzles as sad, and melting streams as innocent. After all, the intuition went, nature has no human passions.

Imagine Ruskin’s surprise, then, were he to learn that the mathematics of perception, knowledge, and experience lie at the heart of modern theories of the natural world. Quite contrary to his stern intuition, quantitative relationships appear to tie hard, material laws to soft qualities of mind and belief.

The story of that discovery begins with the physicist Ludwig Boltzmann, soon after Ruskin coined his phrase at the end of the 19th century. It was then that science first strived, not for knowledge, but for its opposite: for a theory of how we might ignore the messy details of, say, a steam engine or chemical reaction, but still predict and explain how it worked.

Boltzmann provided a unifying framework for how to do this nearly singlehandedly before his death by suicide in 1906. What he saw, if dimly, is that thermodynamics is a story not about the physical world, but about what happens when our knowledge of it fails. Quite literally: A student of thermodynamics today can translate the physical setup of a steam engine or chemical reaction into a statement about inference in the face of ignorance. Once she solves that (often simpler) problem, she can translate back into statements about thermometers and pressure gauges.

The ignorance that Boltzmann relied upon was maximal: Whatever could happen, must happen, and no hidden order could remain. Even in the simple world of pistons and gases, however, that assumption can fail. Push a piston extremely slowly, and Boltzmann’s method works well. But slam it inward, and the rules change. Vortices and whirlpools appear, streams and counter-streams, the piston stutters and may even stall.

More here.