Main Question or Discussion Point
The swampland conjecture https://arxiv.org/abs/hep-th/0509212 is currently a very hot topic. Can someone explain, in simple terms, what exactly the swampland idea is? In particular, the conjecture states that the string landscape is surrounded by an even larger swampland of consistent-looking semiclassical effective field theories, which are actually inconsistent. What exactly does it mean that an effective theory is inconsistent?