Theoretical Physics - From Outer Space to Plasma

Oxford University

Learn about quantum mechanics, black holes, dark matter, plasma, particle accelerators, the Large Hadron Collider and other key Theoretical Physics topics. The Rudolf Peierls Centre for Theoretical Physics holds morning sessions consisting of three talks, pitched to explain an area of our research to an audience familiar with physics at about second-year undergraduate level.

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97 episodes
Updated May 7, 2025

Episodes97

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Mar 3, 2023 · 39 min
The spaghettification of stars by supermassive black holes: understanding one of nature’s most extreme events
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.
Mar 3, 2023 · 39 min
Extreme value statistics and the theory of rare events
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.
Mar 3, 2023 · 43 min
Inflation and the Very Early Universe
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.
Dec 1, 2022 · 45 min
Axion Searches from Black Holes to the Basement
Professor John March-Russell talks about the search possibilities for axions including many current and near future ultra-precise quantum `table top' experiments in the Beecroft basement. The QCD-axion, and its `axion-like-particle' generalisations, lead to new physical effects in an extraordinarily diverse range of settings including cosmology, astrophysical objects like stars and black holes, electromagnetic systems, atoms, molecules, and nuclei. He outlines how this leads to a correspondingly huge range of search possibilities for axions (and even axion dark matter) varying from those involving observations of solar-mass and supermassive black holes and a form of `gravitational atom’, to many current and near future ultra-precise quantum `table top' experiments in the Beecroft basement and others worldwide.
Dec 1, 2022 · 42 min
Axion Electrodynamics in Solid-State Materials
Professor Siddharth Parameswaran gives the second talk on Axions. Over the past decade, topological ideas have played an increasingly important role in a surprising setting: the problem of understanding the properties of insulating crystals. This has led to the identification of “topological insulators”, bulk insulating materials which are characterised by unusual surface phenomena, unconventional responses to applied electric and magnetic fields, or both. In particular, the motion of electrons in some three-dimensional solids can generate axion-like electrodynamics in the solid state. He explains how the ideas leading to the prediction of this “axion insulator” flow naturally from a deeper understanding of the electrodynamics of dielectric media and their link to topological ideas, and survey some of their unusual consequences for experiment.
Dec 1, 2022 · 48 min
The Axion: How Angles Become Particles
Professor Joseph Conlon introduces the general idea of axions: particles associated to fields which are valued on a circle rather than a real line. He describes the still unresolved strong CP problem of the Standard Model, for which the so-called QCD axion provides the most plausible solution. He explains the typical coupling of particle physics axions to electromagnetism and how this leads to axion-photon conversion in magnetic fields and potential search strategies for axions.
Apr 29, 2021 · 43 min
Fluid-gravity duality and hydrodynamics of black holes
Holography explains why black hole horizons have thermodynamic and hydrodynamic properties and inspires researchers to re-visit foundations and explore limits of relativistic hydrodynamics Since the work of Bekenstein, Hawking and others in the early 1970s, it was known that the laws of black hole mechanics are closely related if not identical to the laws of thermodynamics. A natural question to ask, then, is whether this analogy or the correspondence extends beyond the equilibrium state. The affirmative answer, given by various authors during the 1980s and 90s, became known as the "black hole membrane paradigm". It was shown that black hole horizons can be viewed as being endowed with fluid-like properties such as viscosity, thermal conductivity and so on, whose values remained mysterious. The development of holography 15-20 years ago clarified many of these issues and has led to the quantitative correspondence between Navier-Stokes and Einstein equations. It became possible to study the long-standing problems such as thermalization and turbulence by re-casting them in the dual gravity language. We review those developments focusing, in particular, on the issue of the "unreasonable effectiveness" of hydrodynamic description in strongly interacting quantum systems. Final remarks, Prof Julia Yeomans FRS, Head of Rudolf Peierls Centre for Theoretical Physics
Apr 29, 2021 · 37 min
Hydrodynamics of Quantum Many-Body Systems Out of Equilibrium
Can we apply hydrodynamics to systems with extensively many conservation laws Can we apply hydrodynamics to systems with extensively many conservation laws
Apr 29, 2021 · 46 min
Why Hydrodynamics?
What is hydrodynamics and why does it apply over 20 orders of magnitude in energy and length. Welcome, Prof Julia Yeomans FRS, Head of Rudolf Peierls Centre for Theoretical Physics Why Hydrodynamics? Prof Steve Simon
Jan 16, 2021 · 32 min
Strings and Fields
Will strings be the theory of everything?, presented by Prof Luis Fernando Alday.
Jan 16, 2021 · 36 min
Classical and Quantum Black Holes
Prof March-Russell explains our latest understanding of black holes, some of the most mysterious objects in the Universe.
Jan 16, 2021 · 33 min
Why is Quantum Gravity so hard?
A pressing question in our quest to understand the Universe is how to unify quantum mechanics and gravity, the very small and the very large.
Mar 22, 2020 · 37 min
Machine learning techniques in modern quantum-mechanics experiments
In this talk, Dr Elliott Bentine shall discuss how recent experiments have exploited machine-learning techniques, both to optimize the operation of these devices and to interperet the data they produce. Modern table-top experiments can engineer physical systems that are deeply into the quantum mechanical regime. These cutting-edge instruments provide new insights into fundamental physics, and a pathway to future devices that will harness the power of quantum mechanics. They typically require complex operations to prepare and control the quantum state, involving time-dependent sequences of magnetic, electric and laser fields. This presents experimental physicists with an overwhelming number of tunable parameters, which may be subject to uncertainty or fluctuations.
Mar 22, 2020 · 52 min
Machine Learning and String Theory
Professor Andre Lukas will discuss how string theorists have started to use methods from data science - particularly machine learning - to analyse the vast landscape of string data.
Mar 22, 2020 · 52 min
An Introduction to deep learning
Professor Ard Louis gives a basic introduction to deep learning for physicists and addresses a few questions such as: Is the hype around deep learning justified, or are we about to hit some fundamental limitations? In less than ten years, machine learning techniques based on deep neural networks have moved from relative obscurity to central stage in the AI industry. Large firms such as Google and Facebook are pouring billions into research and development of these new technologies. The use of deep learning in physics is also growing exponentially. Can physics help us understand why deep learning works so well? And conversely: How can deep learning provide new insight into the world around us?
Mar 22, 2020 · 6 min
Welcome by Ian Shipsey Head of the Department of Physics
Ian Shipsey give an update on the department and introduces the next three talk on 'AI in Physics'.
Nov 1, 2019 · 40 min
Cosmic acceleration revealed by Type la supernovae?
In this talk Subir Sarkar will explain how deflagration supernovae have been used to infer that the Hubble expansion rate is accelerating, and critically assess whether the acceleration is real and due to `dark energy’.
Nov 1, 2019 · 48 min
Supernova Explosions and their Role in the Universe
In this talk, Philipp Podsiadlowski will explain how this energy (sometimes) creates a visible fireball, before going on to explain the role of supernovae in the production of the heaviest elements in the periodic table.
Nov 1, 2019 · 46 min
What makes stars go bang?
In this talk, James Binney will outline the physics that leads to prodigeous release of energy in core-collapse and deflagration supernovae.
May 16, 2019 · 35 min
... from collisions to the Higgs boson
To study the Higgs boson at the LHC we also need to understand how highly energetic quarks and gluons interact, among themselves and with the Higgs. These interactions are described by quantum field theory, a beautiful mathematical framework that combines quantum mechanics with Einstein’s theory of special relativity. In recent years, our understanding of quantum field theory has progressed significantly, allowing us to develop a new generation of accurate theoretical predictions for key LHC reactions. In this talk, I will highlight some of the ideas behind this progress, and illustrate how they are being applied to investigate the Higgs sector at the LHC.