As I mentioned in a past post, this week I attended a particle cosmology conference. The talk that I had circled, and which was the main reason for my attendance, was Eran Palti’s presentation on the string landscape and swampland conjectures. It did not disappoint.

The talk was very much a repeat of Palti’s lecture at the CERN Theory Colloquialism. A link to his notes can be found here.

It was interesting to listen to him speak on a number of matters, including the primary conjectures on the swampland. Moreover, attempts to derive the weak-gravity conjecture, distance conjecture, etc. from the idea of emergent fields is something I find to be intriguing. That the swampland conjectures may form a coherent framework is an idea I have been questioning in my own notes, as I think it is an important development, so it was nice to listen to Palti talk about such an interlinked coherent framework. I am excited to work through the derivations myself and also reconstruct these links in my own notes.

To that end, one paper that I certainly need to re-visit is a recent publication by Ooguri, Palti, Shiu, and Vafa titled “Distance and de Sitter Conjectures on the Swampland”. For anyone interested, you can find it on the archive.

The swampland constraints are deeply quantum gravitational in nature. As Palti emphasised, the proposal is thus that the swampland conjectures are “consequences of the emergent nature of dynamic fields in quantum gravity”. The conjectural properties of the swampland are not only shown to be related, but it is also outlined how they form an emerging coherent picture that raises interesting questions about the microscopic physics at work.

I have some posts planned for my particle physics blog that will examine all of this in more detail and will discuss some of the more important papers on the string landscape and swampland. Meanwhile, one last note of interest was Palti’s reference to Witten’s 1979 paper on an emergent gauge field toy model CP^N. This is one of several papers that I am eager to read. It was also nice to listen to Palti touch on a variety of other topics, including cosmological implications of the swampland, not least how inflation is in exponential tension with the conjectures.

Lots of things to think about.

It was by far the best talk of the day.