Delve into history with Dr Rob Johnson, Director of The Changing Character of War Centre at Oxford, as he explores a pivotal question.

A lecture by Prof Stephen Blundell, Professor of Physics – Condensed Matter - (Department of Physics and Mansfield College).

Explore the history of atomic bomb development with Dr. Georg Viehhauser, Particle Physics Research Lecturer at St John's College, Oxford.

Particle Physics Christmas Lecture, hosted by Prof. Daniela Bortoletto, Head of Particle Physics and senior members of the department with guest speaker, Professor Francis Halzen. Professor Francis Halzen is Wisconsin IceCube Particle Astrophysics Center and Department of Physics, University of Wisconsin - Madison. Prof Halzen is a theoretician studying problems at the interface of particle physics, astrophysics and cosmology. In 1987 he began working on the AMANDA experiment, a prototype neutrino telescope buried under the South Pole. It provided a proof-of-concept for IceCube, a kilometer-scale detector completed in 2010 which in 2013 discovered an extraterrestrial flux of high energy neutrinos. More recently in 2018 the first cosmic source of such neutrinos was tentatively identified. IceCube has also made precision measurements of neutrino oscillations, searched for dark matter and even contributed to our understanding of glaciology. Prof Halzen will discuss these achievements as well as plans for a much bigger detector that will firmly establish neutrino astronomy as a new window on the universe. The IceCube project has transformed a cubic kilometre of natural Antarctic ice into a neutrino detector. The instrument detects more than 100,000 neutrinos per year in the GeV to 10,000 TeV energy range. Among those, we have isolated a flux of high-energy neutrinos of cosmic origin. We will explore the use of IceCube data for neutrino physics and astrophysics emphasizing the significance of the discovery of cosmic neutrinos. We identified their first source: alerted by IceCube on September 22, 2017, several astronomical telescopes pinpointed a flaring galaxy powered by an active supermassive black hole, as the source of a cosmic neutrino with an energy of 310 TeV. Most importantly, the large cosmic neutrino flux observed implies that the Universe’s energy density in high-energy neutrinos is close to that in gamma rays, suggesting that the sources are connected and that a multitude of astronomical objects await discovery.

Professor Heino Falcke of Radboud University, Nijmegen delivers the 19th Hintze Lecture - reviewing the latest results of the Event Horizon Telescope, its scientific implications and future expansions of the array One of the most bizarre, but perhaps also most fundamental predictions of Einstein’s theory of general relativity are black holes. They are extreme concentrations of matter with a gravitational attraction so strong, that not even light can escape. The inside of black holes is shielded from observations by an event horizon, a virtual one-way membrane through which matter, light and information can enter but never leave. This loss of information, however, contradicts some basic tenets of quantum physics. Does such an event horizon really exist? What are its effects on the ambient light and surrounding matter? How does a black hole really look? Can one see it? Indeed, recently we have made the first image of a black hole and detected its dark shadow in the radio galaxy M87 with the global Event Horizon Telescope experiment. Detailed supercomputer simulations faithfully reproduce these observations. Simulations and observations together provide strong support for the notion that we are literally looking into the abyss of the event horizon of a supermassive black hole. The talk will review the latest results of the Event Horizon Telescope, its scientific implications and future expansions of the array.

Professor Stephen Blundell explores the many universes of quantum materials for the 2019 Quantum Materials Public Lecture. Physicists try to find the laws that govern the Universe, discover new particles and explain phenomena. But what if the rules that govern the Universe were different? What would happen then? This question is not just an academic one. Every new material discovered is behaves like a new Universe, with different laws and sometimes new particles. This talk explains how this idea works in practice and how the different universes discovered in so-called quantum materials are changing the way we think about the physical world.

Professor Barry C Barish gives a talk on the quest for the detection of gravitational waves. The quest for gravitational waves, following their prediction by Einstein in 1916 to their detection 100 years later will be traced. The subsequent opening of exciting new science, from rigorous tests of general relativity to using gravitational waves to explore the universe will be discussed. Prof Barish is a Ronald and Maxine Linde Professor of Physics, Emeritus at CalTech University in the USA, and has received a Nobel Prize in Physics 2017 “for decisive contributions to the LIGO detector and the observation of gravitational waves”.

Bill Diamond, President & CEO The SETI Institute gives an an update on the search for life in the Universe. Hosted by Ian Shipsey, Head of Physics.

What is the Dark Matter which makes 85% of the matter in the Universe? We have been asking this question for many decades and used a variety of experimental approaches to address it, with detectors on Earth and in space. Yet, the nature of Dark Matter remains a mystery. An answer to this fundamental question will likely come from ongoing and future searches with accelerators, indirect and direct detection. Detection of a Dark Matter signal in an ultra-low background terrestrial detector will provide the most direct evidence of its existence and will represent a ground-breaking discovery in physics and cosmology. Among the variety of dark matter detectors, liquid xenon time projection chambers have shown to be the most sensitive, thanks to a combination of very large target mass, ultra-low background and excellent signal-to-noise discrimination. Experiments based on this technology have led the field for the past decade. I will focus on the XENON project and its prospects to continue to be at the forefront of dark matter direct detection in the coming decade. Professor Elena Aprile is Professor of Physics at Columbia University in New York City. After obtaining her undergraduate degree in Physics in Naples, Italy, she earned her PhD at the University of Geneva, Switzerland. She started her research on noble liquid imaging detectors under the mentorship of Professor Carlo Rubbia, first as a student at CERN and later as postdoc at Harvard University. At Columbia, she pioneered the development of a Compton telescope for gamma-ray astrophysics based on a liquid xenon time projection chamber. She later turned her attention to the dark matter question proposing the XENON project for its direct detection using liquid xenon as target and detector medium. She founded the XENON Dark Matter Collaboration in 2002 and has served as its scientific spokesperson ever since; her international team includes more than 170 scientists and students representing 24 nationalities and 22 institutions. Aprile has been principal investigator on more than 20 research grants worth nearly $30 million over the last three decades and holds a patent for a vacuum ultraviolet light source. She has served on numerous panels and committees, for NASA, NSF, DOE, Fermilab, CNRS, ERC, etc. She is a Fellow of the American Physical Society since 2000. In 2017, she received an honorary degree from the University of Stockholm. She is the recipient of the 2019 AAS Lancelot Berkeley Prize.

The 2019 Halley lecture n February 2016, the Laser Interferometer Gravitational Wave Observatory (LIGO) announced the discovery of the merger of two black holes, each of which weighed around 30 times the mass of the Sun. Shortly thereafter, it was speculated that these black holes might make up the dark matter that has long been known to exist in galaxies (like our own Milky Way). I will review this possibility and explain why the hypothesis may or may not work.