# Carroll Symmetry and Cosmology

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Seminar hosted by QG unit.

Speaker: Jelle Hartong, The University of Edinburgh

Title: Carroll Symmetry and Cosmology

In 1965 Lévy-Leblond studied the contraction of the Poincaré group in which the speed of light c is sent to zero. This is called the Carroll limit and it is a bit of an unconventional limit to study. However, gradually, it is becoming clear that this limit is relevant for physics. We are accustomed to taking non-relativistic approximations and expand around c=\infty. Much less is known about the `opposite' question: is expanding a relativistic theory around c=0 a useful approximation and what can we do with it? In this talk I will give an overview of the basic properties of systems with Carroll symmetry. I will show that there are two types of particles: those that do not move and those that cannot stand still. We will also take a look at Carroll fluids and field theories as well as Carroll geometry and its occurrences in GR: e.g. every null hypersurface such as a black hole horizon is a Carrollian spacetime. Finally, I will discuss dark energy and inflationary cosmology from a Carrollian perspective.

Topic: 【Zoom Seminar】 Guest Speaker: Jelle Hartong

Time: Oct 20, 2021 03:30 PM Osaka, Sapporo, Tokyo

Join Zoom Meeting

https://oist.zoom.us/j/92202075469?pwd=ZjVsbHRHS1hqSjBqc0hpZ0U2TmR3Zz09

Meeting ID: 922 0207 5469

Passcode: 990472

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