Theoretical Physics - From Outer Space to Plasma-logo

Theoretical Physics - From Outer Space to Plasma

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Members of the Rudolf Peierls Centre for Theoretical Physics host a morning of Theoretical Physics roughly three times a year on a Saturday morning. The mornings consist of three talks pitched to explain an area of our research to an audience familiar with physics at about the second-year undergraduate level and are open to all Oxford Alumni. Topics include Quantum Mechanics, Black Holes, Dark Matter, Plasma, Particle Accelerators and The Large Hadron Collider.

Members of the Rudolf Peierls Centre for Theoretical Physics host a morning of Theoretical Physics roughly three times a year on a Saturday morning. The mornings consist of three talks pitched to explain an area of our research to an audience familiar with physics at about the second-year undergraduate level and are open to all Oxford Alumni. Topics include Quantum Mechanics, Black Holes, Dark Matter, Plasma, Particle Accelerators and The Large Hadron Collider.
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Location:

United States

Description:

Members of the Rudolf Peierls Centre for Theoretical Physics host a morning of Theoretical Physics roughly three times a year on a Saturday morning. The mornings consist of three talks pitched to explain an area of our research to an audience familiar with physics at about the second-year undergraduate level and are open to all Oxford Alumni. Topics include Quantum Mechanics, Black Holes, Dark Matter, Plasma, Particle Accelerators and The Large Hadron Collider.

Language:

English


Episodes

Why the world is simple - Prof Ard Louis

2/15/2019
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The coding theorem from algorithmic information theory (AIT) - which should be much more widely taught in Physics! - suggests that many processes in nature may be highly biased towards simple outputs. Here simple means highly compressible, or more formally, outputs with relatively lower Kolmogorov complexity. I will explore applications to biological evolution, where the coding theorem implies an exponential bias towards outcomes with higher symmetry, and to deep learning neural networks,...

Duration:00:38:47

Topology in Biology - Prof Julia Yeomans FRS

2/15/2019
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Active systems, from cells and bacteria to flocks of birds, harvest chemical energy which they use to move and to control the complex processes needed for life. A goal of biophysicists is to construct new physical theories to understand these living systems, which operate far from equilibrium. Topological defects are key to the behaviour of certain dense active systems and, surprisingly, there is increasing evidence that they may play a role in the biological functioning of bacterial and...

Duration:00:38:38

Welcome from the Head of the Physics Department

2/15/2019
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Ian Shipsey delivers the welcome speech for the Saturday Mornings of Theoretical Physics.

Duration:00:13:41

Entropy from Entanglement

12/3/2018
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Siddharth Parameswaran, Associate Professor, Physics Department. The usual picture of entropy in statistical mechanics is that it quantifies our degree of ignorance about a system. Recent advances in cooling and trapping atoms allow the preparation of quantum systems with many interacting particles isolated from any external environment. Textbook discussions of entropy — that invoke the presence of a “large” environment that brings the system to thermal equilibrium at a fixed temperature ---...

Duration:00:42:12

Entropy: two short stories

12/3/2018
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John Chalker, Head of Theoretical Physics, gives a talk on entropy. Thermodynamics and statistical mechanics give us two alternative ways of thinking about entropy: in terms of heat flow, or in terms of the number of micro-states available to a system. John Chalker will describe a physical setting to illustrate each of these. By applying thermodynamics in a realm far beyond its origins, we can use the notion of an ideal heat engine to find the temperature of a black hole. And by applying...

Duration:00:39:53

Entropy: Gaining Knowledge by Admitting Ignorance

12/3/2018
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Alexander Schekochihin, Professor of Theoretical Physics, gives a talk on entropy. When dealing with physical systems that contain many degrees of freedom, a researcher's most consequential realisation is of the enormous amount of detailed information about them that she does not have, and has no hope of obtaining. It turns out that this vast ignorance is not a curse but a blessing: by admitting ignorance and constructing a systematic way of making fair predictions about the system that rely...

Duration:00:52:31

Networked Quantum Information Technologies

7/6/2018
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This talk reviews the developments in quantum information processing.

Duration:00:21:09

Quantum logic with trapped-ion qubits

7/6/2018
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This talk reviews testing and developing ideas in quantum computing using laser-manipulated trapped ions.

Duration:00:25:16

The ultimate limits of privacy and randomness...for the paranoid ones

7/6/2018
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This talk explains how qubits are used to represent numbers in a way that permits 'quantum-mechanical parallel' computing. We show how this can used to achieve fast factorisation of large numbers, and hence the breaking of current codes. We end by explaining how entangled pairs of particles can be used to provide an alternative and entirely secure cryptographic system.

Duration:00:54:51

“Open” Quantum Systems

7/6/2018
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This talk reviews how to deal with quantum systems that are coupled to the outside world, as in reality all systems are. We first introduce density operators and explain how quantum states give rise to them. We then turn to measures of entanglement that can be computed from a density operator, and show that entanglement grows with time. Finally, we show how the interaction with the environment gives rise to the phenomenon of decoherence.

Duration:00:47:29

Quantum Systems from Group up

7/6/2018
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This talk reviews the modern formulation of the basic ideas of quantum mechanics. We start by explaining what quantum amplitudes are, how they lead to the idea of a quantum state and how these states evolve in time. We then discuss what happens when a measurement is made before describing correlated ('entangled') systems. Applying these ideas to two-state systems ('qubits') we point out that the complexity of computing the evolution of an N qubit system grows like exp(N)

Duration:00:40:13

Galaxy Dynamics: The chemical evolution side

1/25/2018
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Dr Ralph Schoenrich will talk about the chemical evolution side Spiral density waves patterns re-distribute stars throughout the entire system, making it impossible to know a star's origin from just its kinematics. However, stars are more than just points in phase space: every star is labelled with the elemental abundances of the gas cloud from which it was formed. Over the last few years a number of observational campaigns have started to measure these labels for millions of stars in our...

Duration:00:39:04

Galaxy Dynamics: The dynamics of galaxy discs

1/25/2018
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Dr John Magorrian will talk about the dynamics of galaxy discs In galaxy discs it is energetically favourable for angular momentum to move outwards and mass to move inwards. This transportation is effected by spiral arms, but what causes them? Simple linear response calculations demonstrate that even the smallest perturbation is amplified manyfold, while the differential rotation of the disc means that the response is stretched out into a spiral-like pattern. John Magorrian will introduce...

Duration:00:44:24

Galaxy Dynamics: Stellar systems: a new state of matter

1/25/2018
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Prof James Binney FRS will talk about stellar systems: a new state of matter The long range of gravity means that many concepts from undergraduate statistical mechanics do not apply: energy is not extensive; there is no microcanonical or canonical ensemble. Stars and dark matter particles have long mean free paths, which means that to a very good approximation their motion is determined by the mean-field gravitational potential. James Binney will identify a hierarchy of timescales,...

Duration:00:51:19

Superfluids in Flatland: Topology, Defects, and the 2016 Nobel Prize

11/3/2017
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In this talk, Siddharth Parameswaran discusses how a topological approach to 2D systems reveal that they can indeed become superfluid, and lead to surprising and beautiful universal results whose implications continue to resonate today. Superfluids spontaneously break a continuous symmetry linked to the conservation of particle number in a many-body system. Standard lore holds that such symmetries must remain unbroken at any temperature above absolute zero in a two-dimensional material, such...

Duration:00:43:13

Quantum mechanics on the human scale

11/3/2017
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Stephen Blundell reviews a theory of superconductivity that was developed in Oxford in the 1930’s by Fritz London. The idea is that under certain conditions quantum coherent effects can become manifest on a large scale. In an effect such as superconductivity, this idea can be put to use in such applications as magnetic resonance imaging, in which a living human patient is inserted inside a quantum coherent wave function. He will explain how coherent effects can be measured in real...

Duration:00:35:48

From Identical Particles to Frictionless Flow

11/3/2017
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John Chalker discusses how the laws of quantum mechanics lead us from the microscopic world to macroscopic phenomena. The notion that atoms of a given isotope are indistinguishable has profound consequences in the quantum world. For liquids made of identical bosons, indistinguishability forces the particles into a quantum condensate at low temperature, where they all dance in perfect synchrony. Treated gently, such a condensate has no viscosity: once it is set in motion --say around a...

Duration:00:46:03

Exploring the very early universe with gravitational waves

5/10/2017
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John March-Russell gives a talk about gravitational wave signals of stringy physics, a ‘soundscape’ connected to the landscape of string vacua.

Duration:00:46:56

The birth of gravitational wave astronomy

5/10/2017
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Subir Sarkar reviews the detection of the ‘chirrup’ signal from a pair of merging massive black holes by the Laser Interferometer Gravitational-Wave Observatory, as well as subsequent experimental developments.

Duration:00:42:46

From action at a distance to gravitational waves

5/10/2017
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James Binney gives a talk about the mathematics that describe Gravitational waves.

Duration:00:46:40