Episodes
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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.
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Episodes manquant?
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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.
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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.
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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.
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Professor Jacqueline van Gorkom delivers the 18th Hintze Lecture. How do galaxies get their gas and how do they lose it? Theories of galaxy formation predict that the growth of galaxies is regulated by the infall of hydrogen gas. This gas is the fuel for star formation. When galaxies run out of gas star formation stops. Interestingly, observationally we know much more about the stars in galaxies and how the star formation rate has evolved over time than we know about the gas. The gas is hard to observe. Currently a renaissance is taking place in observational radio astronomy, new telescopes have been developed, which can image this gas, and even better ones are being constructed. I will show what we already have learned, discuss remaining puzzles and outline what the future might bring.
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Professor Mark Newton describes some of the key events in the discovery and development of Electron Paramagnetic Resonance (EPR). Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) spectroscopy as it is also known is a method for studying systems with unpaired electrons. The basic concepts of EPR are analogous to those of nuclear magnetic resonance (NMR), but it is electron spins that are excited instead of the spins of atomic nuclei. EPR was first observed in Kazan State University by Soviet physicist Yevgeny Zavoisky in 1944 and was developed independently at the same time by Brebis Bleaney at the University of Oxford.
In the 75 years that have followed EPR has found many applications in physics, chemistry, biology, medicine, geology and archaeology. In this talk I will endeavour to describe some of the key events in the discovery and development EPR but spend most of the time focusing on applications of the technique and its many derivatives. EPR is very much an evolving technique, with detection of single electron spins now routine in some systems, such that we can optimistically look for applications ranging from studies of single molecules, to enhanced sensitivity and spatial resolution in magnetic resonance imaging.
This annual lecture commemorating Professor Brebis Bleaney (1915-2006) was endowed by Bleaney's pupil Professor Michael Baker (1930-2017). -
The 17th Hintze Lecture, given by Professor Rocky Kolb, Arthur Holly Compton Distinguished Service Professor of Astronomy and Astrophysics, The University of Chicago. In daily life we do not experience the quantum nature of the world on the scale of elementary particles, nor do we sense the expansion and evolution of the universe on cosmic scales. Humans, midway in size between quantum and cosmic scales, evolved to perceive nature not as it actually is, but merely as required to survive in our environment. How remarkable that we have developed an understanding of the quantum realm and the cosmic realm, and realized that the inner space of the quantum and the outer space of the cosmos are intimately connected. In this lecture I will highlight some of the remarkable connections between the quantum and the cosmos.
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Dr James Green, current Chief Scientist of NASA gives a talk on the how life may be distributed on Earth and in the Solar System with consideration of the age of our sun. This talk was a joint lecture held by the The Department of Physics and the Worshipful Company of Scientific Instrument Makers.
NASA's Gravity Assist podcast, hosted by Dr. James Green:
https://www.nasa.gov/mediacast/gravity-assist-explorer-1-jim-green-s-gravity-assist -
The 3rd Wetton lecture, 19th June 2018 delivered by Professor David W. Hogg, Center for Cosmology and Particle Physics, New York University In the last 20 years, the astronomical community has found thousands of planets around other stars, and we now know that many or even most stars in our Galaxy host planets. These planets have been found by making exceedingly precise measurements of stars.
Some of the planets we find are extremely strange; most known planetary systems are very different from our own Solar System. Here we will look at how these measurements are made, and how planets are found in the data. The data analysis - the search for the planets in the mountains of data - involves cutting-edge ideas from data science and machine learning. These technologies are transforming our capabilities in astronomy. -
The 16th Hintze lecture, 25th April 2018 delivered by Professor René Doyon, Director, Mont-Mégantic Observatory & Institute for Research on Exoplanets, University of Montreal, Canada It is now well established that planetary systems are very common in the Solar neighbourhood, in particular small rocky planets, similar to Earth, around low-mass stars. Thanks to new ground-and spaced-based infrared facilities soon to be deployed, it will be possible not only to find the closest habitable worlds but also to detect their atmosphere and obtain constraints on their composition. This will be a major stepping stone towards the detection of life outside the Solar system. This lecture will highlight recent exoplanet discoveries and present an overview of ongoing and future projects aiming for the detection and characterisation of nearby habitable worlds.
The detection of a biosignature, the evidence for biological activity beyond the Solar System, may be just a few decades away. -
The 2018 Astor Visiting Lecture 14th March 2018 delivered by Professor Adam Leroy, Ohio State University. The Atacama Large Millimeter/sub-millimeter Array (ALMA) is the largest, most complex ground-based telescope ever built. From its perch high in the Chilean Andes, ALMA is now unveiling the birth of planets, stars, and galaxies. I will give a taste of the revolution ushered in by ALMA. This includes resolving the disks that form new Solar systems, finding the seeds of gaseous giant planets, weighing – and maybe even directly imaging – black holes, and watching galaxies form at the edge of the universe. Then, I will show how my colleagues and I are using ALMA to understand the origins of stars in galaxies. As part of ALMA’s largest project to date, we are studying all of the stellar nurseries across the nearby universe. We see that the cold clouds of gas and dust that form stars appear to be shaped by violent, dynamic processes that vary from galaxy to galaxy. We also see that the birth of stars from these clouds is both inefficient and terribly destructive.
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Our Universe was created in 'The Big Bang' and has been expanding ever since. Professor Schmidt describes the vital statistics of the Universe, and tries to make sense of the Universe's past, present, and future.
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An introduction to the fascinating world of superconductors and the many surprising phenomena they exhibit, from zero resistance to quantum levitation. Superconductors are metals with remarkable and unexpected properties at low temperatures which defied explanation for many decades. In this talk, illustrated with practical demonstrations, Professor Andrew Boothroyd recounts the long history of superconductivity and gives simple explanations for how superconductors work and what they are useful for.
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How can we test a quantum computer? An exploration of some of the theoretical puzzles of this field and how we can investigate them with experimental physics. What is the relationship between quantum physics, computer science and complexity theory? In this talk, Dr Jelmer Renema will introduce a conceptual problem that sits at the intersection between these fields, namely: how can we show that a quantum computer can outperform an ordinary computer?
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A family-friendly demonstration of superconductors in action. Fran explores the low temperatures we need to make them work, and how we can use superconductors for levitating trains. When something superconducts, it behaves as a magnetic mirror, so will be repelled from magnetic fields. We can use this property to float a superconductor above a bed of magnets. However, for this to work, the superconductor has to be very cold. Graduate student Fran Kirschner uses liquid nitrogen to cool some superconductors (among other things) and show what they can do. Along the way, she explains some of the history and uses of these amazing materials.
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Public Lecture organised by the Aeronautical Society of Oxford in conjunction with the Department of Physics.
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The 2017 Halley Lecture 7th June 2017 delivered by Professor Rainer Weiss, MIT on behalf of the LIGO Scientific Collaboration The recent observations of gravitational waves from the merger of binary black holes open a new way to learn about the universe as well as to test General Relativity in the limit of strong gravitational interactions – the dynamics of massive bodies traveling at relativistic speeds in a highly curved space-time. The lecture will describe some of the difficult history of gravitational waves proposed 100 years ago. The concepts used in the instruments and the methods for data analysis that enable the measurement of gravitational wave strains of 10-21 and smaller will be presented. The results derived from the measured waveforms, their relation to the Einstein field equations and the astrophysical implications are discussed. The talk will end with our vision for the future of gravitational wave astronomy.
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