UCL Maths Gravity Seminar and Journal Club
Organizer: Tomáš Hale
Upcoming events
2 November 2026, Room 309 Gordon House
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Past events
26 October 2026, Room 416 Mathematics Department
Christian Boehmer (UCL)
Coupling fluids to gravity 1
I will discuss how to derive the energy-momentum tensor of a perfect fluid through a variational principle. While this is well-understood, it is rarely discussed in much detail. After discussing the basic ingredients needed to make this work, I will show why this becomes essential when discussing theories of gravity that include a non-minimal coupling between the fluid and the geometry.
19 October 2026, Room 416 Mathematics Department
Eissa Alnasrallah (UCL)
Natural modification of quantum uncertainty, modified gravity, and cosmology
A common approach in physics and mathematics is to extend and modify theories and frameworks by considering what is often described as a "natural'' extension or modification by including higher-order terms or by introducing other non-linearities. We show that such an approach must be taken with care as physical models can be connected in indirect ways. What looks like a natural approach in one setting will likely not be natural in another. We use the flat Friedmann-Lemaitre-Robertson-Walker equations of cosmology to connect the generalized uncertainty principle to modified theories of gravity. A simple additional term in one setting leads to enormous complications in the other.
We identify Born-Infeld models as the only ones which appear natural in both settings.
12 October 2026, Room 416 Mathematics Department
Tomáš Hale (UCL)
Excising Cauchy Horizons with Nonlinear Electrodynamics
Charged and/or rotating black holes in general relativity feature Cauchy horizons, which indicate a breakdown of predictability in the theory. In this talk, nonlinear electrodynamics will be used as an example of a modified matter model, which, in the strong field regime, diverges from low-energy behaviour of standard Maxwell electrodynamics, and admits exact charged and rotating black hole solutions without Cauchy horizons, thus adhering to strong cosmic censorship. Such solutions may be viewed as an approximation of some asymptotic stationary state of a realistic collapse scenario which doesn’t modify the gravitational theory; in a sense ‘saving GR’ from the perils of Cauchy horizons and mass-inflation.
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