Order and chaos are concepts used in everything from theoretical physics to psychology. But are order and disorder built into the fabric of reality itself, or are they just concepts that humans use to make sense of the world? In this interview with physicist Avshalom Elitzur, he argues the physics behind the 2nd law of thermodynamics is indisputable, and explores the implications this has for the future, and possible end, of humanity.

This article is presented in association with Closer To Truth, a partner for HowTheLightGetsIn Festival 2024.

What is entropy and why is it essential to our understanding of the universe?

Entropy is something very peculiar. Let's remember that all physical quantities are conserved: In any closed system, energy is conserved, matter is conserved, momentum is conserved. That means that these values do not vanish and are not created anew.

There is, however, one value which is not conserved, and this is entropy.

Now the question is, what is entropy? There are several definitions or measures.

1. The simplest, and most intuitive, is disorder. Some scientists do not like this definition because they say it's subjective. Other scientists propose some other definitions. I think that disorder is a fairly good definition. But to be more precise, let us give two more definitions: