### Speaker

Kelly Stelle

### Description

What relations are there between the various ways of wrangling with quantum gravity? String theory is now much more than just a theory of strings -- branes and braneworlds abound. Some kind of effective theory for the familiar world needs to emerge. Are there ways that one could glimpse underlying structure from aspects of an effective theory? That happens for pions -- is there anything like that for gravity? Effective theories also involve higher derivatives, and those can summon up spirits (i.e. ghosts) from the vasty deep. Do asymptotic freedom or asymptotic safety give ways to exorcise them? And what might the effective theory tell us about the earliest times?

### External references

- 23100021
- 29c8b909-eb93-4333-a26a-28356d6d55a8
- 5ecd2088-1f1b-4743-8d89-50cb11d185ef