Science Fiction of Everything

In this article, I will describe my perspective on the present state of fundamental theoretical physics and my guess on what will be the key elements of future theories of everything. First I will review three important approaches: string theory, loop quantum gravity and noncommutative geometry. I will explain their main ideas and strengths, but also point out what they are still missing on the road to providing a true unification of physics. Based on this, I will speculate about how a future theory of everything could look like: I expect that its basic degrees of freedom will be networks or matrices. Its principal achievements will be the unification of spacetime and fields, and the dynamical generation of spacetime. I will also argue that this scenario opens the way to many interesting conceptual possibilities: the existence of several spacetimes or realities that interact with each other; that spacetime and the laws of nature are not “God-given”, but evolved and contingent; that the very structure of reality could exhibit higher levels of organization. The thread that runs through the discussion will be renormalization : I will start by explaining nonrenormalizability and conclude with remarks on nonperturbative renormalization.