(2024) | Drawings, chalk on paper

A microstate of a system is a description of the position and momenta of all its particles; of space and time.

A measure of the number of possible microstates was defined by physicist and philosopher Ludwig Boltzmann (1844-1906) as entropy. Entropy is the key concept of the second law of thermodynamics, which is not only about heat and energy, but has to do with our concept of time as well.

All our laws of physics are reversible, and so is the second law of thermodynamics in theory. However, why this doesn’t seem to be the case in practice (heat and time only appear to flow in one direction) we don’t know. Entropy is central to the debate, as is probability: some things are more likely to happen than others.

William James Sidis (1898-1944) was an exceptionally gifted American (supposedly being the person with the highest IQ ever measured — which says more about his life than his intellect). Like many great thinkers he had a poetic view on science.

Fascinated by the origins of life and working on a theory of reversibility he published a book in 1920 named The Animate and the Inanimate, in which he makes a sharp and wonderful observation, which he carefully analyses:

When we film a ball bouncing of a flight of stairs and we play the film backwards the ball appears to be alive.

Sidis poses a fantastic question: events in the reverse universe appear as though they were living phenomena. What if life — living — is the reversal of the second law of thermodynamics?