Is the Universe Entirely Mathematical? Feat. Max Tegmark

Mathematics is a powerful tool in physics, describing everything from the shapes of planetary orbits to the properties of atoms. Math was used to predict the existence of the planet Neptune, radio waves, and the Higgs boson. Some think it means nothing profound, or that math is simply something we've made up to be useful. Others think it means that there is something fundamentally mathematical about nature. And the most extreme possibility is that our universe is completely mathematical, in the sense that it has no properties except mathematical properties. But at first glance, our universe doesn't seem very mathematical at all. A sheep has properties such as cuteness and fluffiness, not mathematical properties. Yet we know that this sheep and everything else in our universe is ultimately made of elementary particles, such as electrons and quarks. And what properties does an electron have? Smell? Color? Texture? No, only properties like minus one, one half, and one. We physicists call these properties electric charge, spin, and lepton number, but the electron doesn't care what we call them. The fundamental properties that an electron has are just numbers, mathematical properties. And as far as we know, all elementary particles, the building blocks of everything around, are purely mathematical objects in the sense that they don't have any properties except for mathematical properties. The same goes for the space that these particles are in. For example, it has the property three, the number of dimensions. If space is mathematical and everything in space is also mathematical, then the idea that everything is mathematical doesn't sound as crazy anymore. Quantum mechanics and string theory introduce even more mathematical structures with nerdy names like Hilbert space, linear operators, and Calabi-Yau manifolds, and we physicists still haven't found any properties of nature that we can prove are non-mathematical, which is why some of us, including me, think that perhaps there just isn't anything else out there other than math. And that thought makes me one positively awestruck mathematical object. Again, thanks to Audible for helping me continue to make these videos, and for giving you a free audiobook at audible.com.