Max Tegmark is a cosmologist and physics professor at MIT. At least, that’s what he is in this universe. I mean multiverse. Or what I should say is, he’s a physics professor in the Level I multiverse. He might also be a professor in the Level II multiverse, and maybe even on Level III, but the Level IV multiverse is made up of purely mathematical structures, so it’s hard to say what he’s up to over there. Got it? Maybe I should let him explain it.

Just a few years ago, the idea of multiple universes was seen as a crackpot idea, not even on the margins of respectability. As Tegmark relays in his new book Our Mathematical Universe: My Quest for the Ultimate Nature of Reality, he was discouraged from devoting his academic attention to it. But now, thanks in large part to Tegmark and his pursuit of controversial ideas, the concept of multiple universes (or a multiverse) is considered likely by many experts in the field.

Our Mathematical Universe is a hybrid book of memoir and theory. Tegmark explains with charismatic enthusiasm why it matters that there’s a version of reality made up entirely of math. (Or, to look at it another way: our universe is not described by math, but composed of it.) He also tells us that as a student at Berkeley, he changed his name from Shapiro to his mother’s maiden name of Tegmark in order to stand out more. Shapiro was exotic in his native Sweden, but in the U.S., he explains, he might as well have been an Andersson in Sweden. Tegmark’s book showcases the ideas and the personality that drives them.

The idea that the universe is comprised entirely of math is a deceptively simple one. It seems fairly intuitive at first, but once you spend a little time with it, your mind starts to feel like it’s bending. Tegmark’s clear, engaging prose style can take you down these exciting and unexpected pathways of thought without making you feel lost.

He also explains why it matters. If everything is indeed math, then everything can be figured out with a pencil, as he’s fond of saying. Even consciousness itself is a mathematical structure. This doesn’t make us robots, but opens up a wild range of possibilities that can be computed and deduced -- there is no dead end to thought. If we were to actually start figuring this stuff out, we could potentially understand the mind state of seemingly vegetative hospital patients, or put an actual number on how much an animal raised on a certain kind of farm suffers. Things that have always seemed unknowable will suddenly become calculations.

As Tegmark is quick to point out, this is not a totally new idea. Galileo said that our universe is a book written in the language of mathematics. But in Our Mathematical Universe, we meet a revolutionary cosmology physicist who is hell bent on figuring out if that theory is true, how to prove it, how to use it, and what it means for the world as we know it.