Deeper course for Theorists
The Swampland — an outsider’s perspective
Benjamin Knorr (University Heidelberg)
Abstract
The taming of quantum gravity — that is, finding a unified description of both quantum and gravitational effects that works in all physical scenarios — has fascinated physicists for many decades, so far without final resolution. At the centre lie some deep questions about our universe, e.g., what is really inside black holes, and how did the big bang actually play out? The problem is that we cannot directly answer these questions experimentally, which leaves a lot of room for speculation.
One interesting idea to make some systematic progress in narrowing down the search for potential theories of quantum gravity is that of the swampland programme. There, we ask a more general question: given a non-gravitational theory, can you consistently couple gravity to it at all scales? In string theory, the answer is “almost always no”, but other approaches to quantum gravity might find different answers.
In this course, you will get an overview of the swampland programme from someone who is not a string theorist. We will first cover what the issue is with quantum gravity. Then we discuss the swampland in some general terms. Finally, I will present one specific approach to quantum gravity — asymptotic safety — and discuss what it has to say about the swampland.
