Our Mathematical Universe: My Quest for the Ultimate Nature of Reality

by Max Tegmark

Physicists have known for a century that solid steel is really mostly empty space, because the atomic nuclei that make up 99.95% of the mass are tiny balls that fill up merely 0.0000000000001% of the volume, and that this near-vacuum only feels solid because the electrical forces that hold these nuclei in place are very strong.

Evolution endowed us with intuition only for those aspects of physics that had survival value for our distant ancestors, such as the parabolic orbits of flying rocks (explaining our penchant for baseball). A cavewoman thinking too hard about what matter is ultimately made of might fail to notice the tiger sneaking up behind her and get cleaned right out of the gene pool. Darwin’s theory thus makes the testable prediction that whenever we use technology to glimpse reality beyond the human scale, our evolved intuition should break down.

If my life as a physicist has taught me anything at all, it’s that Plato was right: modern physics has made abundantly clear that the ultimate nature of reality isn’t what it seems. But if reality isn’t what we thought it was, then what is it? What’s the relation between the internal reality of our mind and the external reality? What’s everything ultimately made of? How does it all work? Why? Is there a meaning to it all, and if so, what? As Douglas Adams put it in his sci-fi spoof The Hitchhiker’s Guide to the Galaxy: “What’s the answer to the ultimate question of life, the universe, and everything?”