Causality and Positivity with Gravity - Claudia de Rham

Explore the intersection of causality, positivity, and gravity in this conference talk from the Kavli Institute for Theoretical Physics' "UV Meets the IR" online conference. Delve into the complexities of effective field theories (EFTs) and their relationship with quantum gravity. Examine the implications of string theory's landscape and the swampland program on low-energy physics. Investigate bottom-up S-matrix techniques and their applications in bounding EFTs. Learn about recent developments in quantum field theory, including the modern on-shell amplitudes program and bootstrap methods. Follow the speaker's analysis of non-gravitational EFTs, the addition of gravity to these theories, and the resulting positivity bounds in gravitational low-energy effective field theories. Discover insights into scalar QED with gravity, compactified bounds, and approximate positivity. Explore the EFT for gravity, the speed of gravity, and support outside the light cone. Investigate QED on curved spacetime, time delays and advances, and the regime of validity for EFTs. Conclude by examining causality in gravitational theories, the concept of no support outside the light cone, and the implications of superluminality and negativity in these frameworks.