Talks

This talk will introduce the Bala-Goyal model of epistemic networks, where agents on a network learn to solve a decision problem by performing actions and sharing the results of those actions with their neighbors.  We will discuss the conditions under which agents on these networks successfully learn to perform optimal outcomes, and how network structure can influence time to convergence and accuracy.

Many theorists have employed game theory to model the emergence of stable social norms, or natural “social contracts.” One branch of this literature uses bargaining games to show why many societies have norms and rules for fairness. In cultural evolutionary models, fair bargaining emerges endogenously because it is an efficient way to divide resources. But these models miss an important element of real human societies – divisions into groups or social categories. Once such groups are added to cultural evolutionary models, fairness is no longer the expected outcome.  Instead “discriminatory norms” often emerge where one group systematically gets more when dividing resources. I show why the addition of categories to bargaining models leads to unfairness, and discuss the role of power us in this process. I also address how categories might emerge to support inequity, and the possibility of modeling social change. Altogether this work emphasizes that if one wishes to understand the naturalistic emergence of social contracts, one must account for the presence of categorical divisions, and unfairness, as well as for norms of fairness.

Bacteriophages are the most abundant organisms on the planet and play key roles as shapers of ecosystems and drivers of bacterial evolution. Temperate phages can choose between (i) lysis: exploiting their bacterial hosts to produce multiple offspring phage and releasing them by lysing the host cell, and (ii) lysogeny: establishing a mutually beneficial relationship with the host by integrating their chromosome into the host cell’s genome. I will describe how we combine dynamical systems and game theory to model the  competition of phage mutants that have different lysogeny propensities. We find that there is a narrow range of optimal propensity values that phages can evolve, and this predicted range covers the values observed for various phage species. Our results also offer an explanation for why temperate phages tend to utilize bistable switches that can incorporate the number of infecting phage into the lysis-lysogeny decision. If there is time, I will describe other work that examines the range of network structures that can produce such functionality.

Multiplayer Evolutionary Games (MEGs) extend classical evolutionary game theory by incorporating interactions among multiple participants rather than just two. This lecture introduces MEGs and their foundational connection to population genetics and their evolutionary dynamics. Theoretical principles such as fitness, selection, and mutation are explored, illustrating how MEGs capture non-linear interaction effects. The importance of higher-order interactions is emphasized, demonstrating how MEGs naturally extend traditional evolutionary models to more complex, real-world scenarios.

In this talk I will discuss the energy probability density function of an evaporating near-extremal charged black hole. At sufficiently low energies, such black holes experience large quantum metric fluctuations in the $AdS_{2}$ throat which are governed by a Schwarzian action. These fluctuations modify Hawking evaporation rates, and therefore also affect how the black hole state evolves over time. In previous work on Schwarzian-corrected Hawking radiation, the black hole was taken to be in the microcanonical or canonical ensemble [arXiv:2411.03447]. However, we find that an initially fixed-energy or fixed-temperature state does not remain so in the regime where Schwarzian corrections are important. We consider three decay channels: the emission of massless scalars, photons, and entangled pairs of photons in angular momentum singlet states. In each of the three cases, we find that in the very low energy, quantum dominated regime, the probability distribution of the black hole energy level occupation tends toward a particular attractor function that effectively depends on only one combination of time and energy. This function is independent of the initial state and gives new predictions for the energy fluxes and Hawking emission spectra of near-extremal charged black holes.