Webinar.1〝A cautionary case of casual causality〞

In recent years, causality has become a popular criterion to distinguish between Effective Field Theories(EFTs) arising from physical and unphysical high-energy theories. A direct way to ensure a given EFT is causal is to demand a lower bound on scattering time delays, which essentially bounds the propagation speed averaged over the entire trajectory. In flat space, this is unambiguously dictated by the Minkowski light cones, but the situation is much more subtle on curved backgrounds. The speaker will make the case that the relevant notion is the so-called infrared causality. He will then apply this notion of causality to the EFT of gravity on spherically symmetric black hole backgrounds. Careful consideration of the regime of validity shows that time delays are never resolvable(in the geometric optics sense), and therefore there is never any observable violation of infrared causality.

This talk is based on arXiv:2112.05031 in collaboration with C. de Rham, A. Margalit, and A. Tolley.

時間:2022.10.11(二) 21:00~22:20
頻道:(網上講授)Zoom ID:421-480-1692 ← cosmology
講者:Calvin Chen(Imperial College, London)



“Copernicus Webinar and Colloquium Series”: To promote scientific discussions during this pandemic, they are organizing an online seminar series, i.e. Copernicus Webinar Series, seeking the most outstanding speakers to introduce innovative ideas and important progress in the field of gravity and cosmology. This series is named after the famous Polish Astronomer, Nicolaus Copernicus, whose discovery eventually marked the dawn of modern science.




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