What is reality?

I am intrigued by the question: What is reality? This is an old question, of course, going back at least to the Allegory of the Cave in Plato's Republic.

One interesting aspect of this question is that while reality is not created by humans, much of reality can be accurately described by mathematics—which is created by humans. An example is quantum mechanics, without which we wouldn't have such things as blogs (because we wouldn't have computers or fiber optic communications lines or much else of modern technology).

There isn't any a priori reason to expect mathematics to describe any portion of reality. And yet it does. It is a beautiful and wonderful feature of our world. Einstein said: "Equations are more important to me [than politics], because politics is for the present, but an equation is something for eternity."

There are some who take this idea further, and postulate that our entire world is a computer simulation. Click here for links to one recent discussion of this idea. Jaron Lanier comments here.

Whenever I think about reality, I remember a science fiction book, now out of print, that I read as a teenager: Simulacron-3, by Daniel Galouye. This book was published in 1964, before the age of digital computers, and so the computers in this book are analog instead of digital, but the concept is the same.

If part or all of reality is mathematical or computational, does that take the fun out of it? Does it make our world deterministic and predictable? Not at all! Only in recent decades have we begun to understand this. The mathematics of nonlinear dynamical systems, popularly called chaos theory, shows that unpredictable random behavior can result from extremely simple mathematical systems. An excellent book on this topic is "Chaos," by James Gleick.

This post provides a brief introduction and some background. In the next post, I will comment on something new that recently caught my eye.