Talks

Twenty-first century finance is built on complex mathematical tools developed by “quants,” a different breed of investor with expertise in fields such as physics, mathematics, and computer science. These models have been the basis for both new trading strategies and new financial products, leading to untold wealth. In some cases, however, these models have done more damage than good, making markets less stable and introducing new systemic risk. In this talk, Dr. James Weatherall will tell the story of how in the aftermath of World War II, some innovative physicists and mathematicians saw surprising connections between physics, gambling, and finance, and put those connections to use to become the first quants. Dr. Weatherall will introduce some of the ideas behind modern quantitative trading and show how the history of mathematical reasoning in finance reveals that these models can be extremely useful-but only if we understand their limitations.

Cold dark matter provides a remarkably good description of cosmology and astrophysics. However, observations connected with small scales might be in tension with this framework. In particular, structure formation simulations suggest that the density profiles of dwarf spheroidal galaxies should exhibit cusps, in contrast to observations. I will show that Fermi repulsion can explain the observed cored density profiles in dwarf galaxies for sub-keV fermionic dark matter.  While in conventional dark matter scenarios, such sub-keV thermal dark matter would be excluded by free streaming bounds, I will argue that these constraints are ameliorated in models with dark matter at lower temperature than conventional thermal scenarios. Finally, I will outline a class in which the dark matter typically has a lower temperature than the thermal expectation, dubbed Flooded Dark Matter, and discuss aspects of model building.

Astrophysical black hole candidates, although long thought to have a horizon, could be horizonless ultra-compact objects. This intriguing possibility is motivated by the black hole information paradox and a plausible fundamental connection with quantum gravity. In this talk I will consider the asymptotically free quadratic gravity as the UV completion of general relativity. Using a classical theory that captures its main features, we find that sufficiently dense matter produces a novel horizonless solution, the 2-2-hole. It closely matches the exterior Schwarzschild solution down to about a Planck proper length of the would-be horizon. I will describe interesting features of the 2-2-hole and various physical implications. As a generic static solution, the 2-2-hole may be the nearly black endpoint of gravitational collapse.