Theoretical Physics - From Outer Space to Plasma Oxford University

Archie Bott explains how a promising scheme for fusion relies on a novel feature of hot laser-plasmas: introducing a magnetic field of the correct strength alters the plasma’s fundamental properties in a highly counterintuitive yet beneficial manner. One key scientific breakthrough of 2022 was the achievement of fusion ignition; using the world’s largest laser facility, physicists created a plasma in which nuclear fusion reactions generated around 50% more energy than the laser energy required to get those reactions going. Arguably the hottest question in laser fusion-energy research right now is how to surpass this result.

Georgia Acton introduces stellarators, discusses the features that distinguish them from tokamaks, highlight the challenges we currently face, and discusses how we might overcome them. Tokamaks have been at the forefront of fusion research for the last 50 years. Despite significant improvements over this time we have yet to produce a device that is a sustainable, reliable power source capable of net energy output. In this talk Georgia hopes to convince you that stellarators are the future of fusion, capable of overcoming many of the fundamental problems of tokamaks; crucially offering a reliable and continuously operating source of fusion power that can be used to power humanity forward.

Michael Barnes introduces the basic concepts behind magnetic confinement fusion, he describes why it is so challenging and discusses possibilities for the future. One gram of hydrogen at 100 million degrees for 1 second: This is (roughly) what is needed to produce net energy from magnetic confinement fusion. Scientists have been working towards this goal for over half a century, applying strong magnetic fields to contain a hot, ionised gas long enough for a significant number of fusion reactions to occur. However, there has been a recent surge in interest and optimism surrounding fusion as a terrestrial energy source.

The spaghettification of stars by supermassive black holes: understanding one of nature’s most extreme events - Andrew Mummery On a rare occasion an unfortunate star will be perturbed onto a near-radial orbit about the supermassive black hole in its galactic centre. Upon venturing too close to the black hole the star is destroyed, in its entirety, by the black hole’s gravitational tidal force, a process known as “spaghettification”. Some of the stellar debris subsequently accretes onto the black hole, powering bright flares which are observable at cosmological distances. In this talk I will discuss recent theoretical developments which allow us to describe the observed emission from these extreme events in detail, allowing them to be used as probes of the black holes at their centre. I am a Leverhulme-Peierls Fellow in the Department of Physics and Merton College. I completed both my undergraduate degree and DPhil at Oxford, working for my DPhil in the astrophysics department under the supervision of Steven Balbus. I work on astrophysical fluid dynamics, with a particular focus on the behaviour of fluids when they are very close to black holes.

Extreme value statistics and the theory of rare events - Francesco Mori Rare extreme events tend to play a major role in a wide range of contexts, from finance to climate. Hence, understanding their statistical properties is a relevant task, which opens the way to many applications. In this talk, I will first introduce extreme value statistics and how this theory allows to identify universal features of rare events. I will then present recent results on the extreme values of stochastic processes, including Brownian motion and active particles. I moved to Oxford in October 2022 to take the position of Leverhulme-Peierls Fellow at the Department of Physics and New College. Previously, I was a PhD student at Paris-Saclay University, working with Satya Majumdar. During my PhD, I worked on extreme value statistics of stochastic processes. I am interested in out-of-equilibrium physics, extreme value theory, and large-deviation theory. In particular, I am currently applying ideas from statistical physics to study living systems.

Inflation and the Very Early Universe - Georges Obied The universe we observe seems to have come from surprisingly fine-tuned initial conditions. This observation is at the heart of two of the most important puzzles in cosmology, called the horizon and flatness problems. To explain these puzzles, cosmologists invoke a period of accelerated expansion in the early universe (called inflation). As a bonus inflation, when considered with quantum mechanics, produces fluctuations in the energy density that become the galaxies, planets and other structures we see around us. In this talk, I will explain the motivation and physics of the inflationary paradigm. I am Leverhulme-Peierls Fellow at New College. Before coming to Oxford, I completed my PhD at Harvard University under the supervision of Prof. Cumrun Vafa. My research interests lie at the interface of particle physics, string theory and cosmology. At this junction, I work on various aspects of dark energy, dark matter and early universe cosmology from a fundamental physics point of view.