Effective field theory is the classic paradigm to describe the dynamics of low-energy degrees of freedom below a cutoff in many areas of physics. However, according to the so-called Swampland idea, theories which involve gravity are expected to behave rather differently in some respects: Not every effective field theory, even though consistent as a quantum field theory, can arise as the low-energy approximation of a fundamental quantum theory which includes the dynamics of gravity. Finding criteria for an effective field theory to lie in the `Swampland' of theories which cannot be completed into a consistent quantum gravity is therefore an equally ambitious and important goal in fundamental physics. In this colloquium we will exemplify some of these oftentimes surprising Swampland criteria which have been proposed in the recent literature and illustrate how an interplay of heuristic and necessarily conjectural arguments and their rigorous test in top-down approaches to quantum gravity such as string theory is providing novel insights into the possible structure of quantum gravity.
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Meeting ID: 813 4698 2513