The Ockham Lecture - The Merton College Physics Lecture

A lecture given by Professor Irene Tracey, Nuffield Chair of Anaesthetic Science and Head of the Nuffield Department of Clinical Neuroscience at the University of Oxford, and Warden-elect of Merton College. With over 85 billion neurons making approximately 1.5x1014 connections (synapses) and a similar quantity of non-neuronal cells all within the adult human brain, it's a feat of brilliance and beauty that our perceptions and creative thinking arise from their interplay. Our knowledge of how this occurs has grown significantly in the past few decades, and physicists have been at the forefront of this wave in understanding. In this talk, Professor Irene Tracey, Nuffield Chair of Anaesthetic Science and Head of the Nuffield Department of Clinical Neuroscience at the University of Oxford, and Warden-elect of Merton College walks you through some of the landmark discoveries and their application to the brain, highlighting Oxford’s major role in developing the modern field of neuroscience. Finally, she gives a brief overview of her own work using advanced neuroimaging to understand pain perception, pain relief and anaesthesia-induced altered states of consciousness.

Given by Professor Charles Clark, Fellow of the Physical Measurement Laboratory at the National Institute of Standards and Technology, and Fellow and Adjunct Professor at the Joint Quantum Institute, University of Maryland, USA. Wave motions in nature were known to the ancients, and their mathematical expression in physics today is essentially the same as that first provided by d'Alembert and Euler in the mid-18th century. Yet it was only in the early 1990s that physicists managed to control a basic property of light waves: their capability of swirling around their own axis of propagation. During the past decade such techniques of control have also been developed for quantum particles: atoms, electrons and neutrons. I will present a simple description of these phenomena, emphasising the most basic aspects of wave and quantum particle motion. Neutron interferometry offers a poignant perspective on wave-particle duality: at the time one neutron is detected, the next neutron has not yet even been born. Here, indeed, each neutron "then only interferes with itself." Yet, using macroscopically-machined objects, we are able to twist neutron deBroglie waves with sub-nanometer wavelengths.

Given by Professor Yuri Manin, Professor Emeritus, Max Planck Institute for Mathematics, Bonn, Germany; Professor Emeritus, Northwestern University, Evanston, USA; Principal Researcher, Steklov Mathematical Institute, Academy of Sciences, Moscow, Russia. In the 1930s, George Kingsley Zipf discovered an empirical statistical law that later proved to be remarkably universal. Consider a corpus of texts in a given language, make the list of all words that occur in them and the number of occurences. Range the words in the order of diminishing frequencies. Define the Zipf rank of the word as its number in this ordering. Then Zipf's Law says: "Frequency is inversely proportional to the rank". Zipf himself suggested that this law must follow from the principle of 'minimisation of effort' by the brain. However, the nature of this effort and its measure remained mysterious. In my lecture, I will argue that Zipf's effort needed to produce a word (say, name of the number) must be measured by the celebrated Kolmogorov complexity: the length of the shortest Turing program (input) needed to produce this word/name/combinatorial object/etc. as its output. I will describe basic properties of the complexity (some of them rather counterintuitive) and one more situation from the theory of error-correcting codes, where Kolmogorov complexity again plays the role of 'energy in the world of ideas'.

Given by Dr Aldo Faisal, Senior Lecturer in Neurotechnology, Department of Bioengineering and Department of Computing, Imperial College London, and Associated Investigator, MRC Clinical Sciences Centre. The lecture is introduced by Professor Alex Schekochihin, Professor of Theoretical Physics at Oxford University. The Merton College Physics Lecture (the Ockham, or Occam, Lecture, so named in honour of one of the greatest—if unattested—alumni of the College and of his philosophical principle of intellectual discipline) started in 2009 and is held once a term. It is organised by the physics tutors of the College to promote both intellectual curiosity and social cohesion of the Merton Physics community.

According to the 'standard' quantum theory, states evolve with certainty between measurements, but 'collapse' randomly when we measure them. But what is measurement? And why does it (appear to) enjoy a privileged position in the theory? The measurement problem has been one of the hottest topics in physics ever since quantum theory was proposed and, despite much progress, remains so today. The 1st Ockham Debate (The 12th meeting in the Ockham Lecture series) for the first time offered the different perspectives of not one but two expert speakers: Simon Saunders, Professor of the Philosophy of Physics and Fellow of Linacre College, a leading proponent of the 'many worlds' interpretation of quantum mechanics, which argues that the Universe we see it is emergent, and constantly subject to 'splitting' including during measurements; and James Binney, Professor of Physics and Fellow of Merton College, who advocates an alternative programme, suggesting that we should gain insight into measurement by better understanding the dynamics of the system's interactions with the measuring apparatus.