Please note that the list below only shows forthcoming events, which may not include regular events that have not yet been entered for the forthcoming term. Please see the past events page for a list of all seminar series that the department has on offer.
The AO-model describes crystalline solids in the presence of defects like dislocation lines. We demonstrate that the model supports low-energy structures like grains and determine for simple geometries the grain boundary energy density. At small misorientation angles we recover the well-known Read-Shockley law. Due to the atomistic nature of the model it is possible to consider the the Boltzmann-Gibbs distribution at non-zero temperature. Using ideas by Froehlich and Spencer we prove rigorously the presence of long-range order if the temperature is sufficiently small.
- Partial Differential Equations Seminar
Oxford Mathematics Public Lectures- The Roger Penrose Lecture
Carlo Rovelli - Spin networks: the quantum structure of spacetime from Penrose's intuition to Loop Quantum Gravity
Monday 2 December 2019
In developing the mathematical description of quantum spacetime, Loop Quantum Gravity stumbled upon a curious mathematical structure: graphs labelled by spins. This turned out to be precisely the structure of quantum space suggested by Roger Penrose two decades earlier, just on the basis of his intuition. Today these graphs with spin, called "spin networks" have become a common tool to explore the quantum properties of gravity. In this talk Carlo will tell this beautiful story and illustrate the current role of spin networks in the efforts to understand quantum gravity.
Carlo Rovelli is a Professor in the Centre de Physique Théorique de Luminy of Aix-Marseille Université where he works mainly in the field of quantum gravity and is a founder of loop quantum gravity theory. His popular-science book 'Seven Brief Lesson on Physics' has been translated into 41 languages and has sold over a million copies worldwide.
5.30pm-6.30pm, Mathematical Institute, Oxford
Please email firstname.lastname@example.org to register.
The Oxford Mathematics Public Lectures are generously supported by XTX Markets.
- Oxford Mathematics Public Lecture
Charles Babbage (1791–1871) was Lucasian Professor of mathematics in Cambridge from 1828–1839. He displayed a fertile curiosity that led him to study many contemporary processes and problems in a way which emphasised an analytic, data driven view of life.
In popular culture Babbage has been celebrated as an anachronistic Victorian engineer. In reality, Babbage is best understood as a figure rooted in the enlightenment, who had substantially completed his core investigations into 'mechanisation of thought' by the mid 1830s: he is thus an anachronistic Georgian: the construction of his first difference engine design is contemporary with the earliest public railways in Britain.
A fundamental question that must strike anybody who examines Babbage's precocious designs is: how could one individual working alone have synthesised a workable computer design, designing an object whose complexity of behaviour so far exceeded that of contemporary machines that it would not be matched for over a hundred years?
We shall explore the extent to which the answer lies in the techniques Babbage developed to reason about complex systems. His Notation which shows the geometry, timing, causal chains and the abstract components of his machines, has a direct parallel in the Hardware Description Languages developed since 1975 to aid the design of large scale electronics. In this presentation, we shall provide a basic tutorial on Babbage's notation showing how his concepts of 'pieces' and 'working points' effectively build a graph in which both parts and their interactions are represented by nodes, with edges between part-nodes and interaction-nodes denoting ownership, and edges between interaction-nodes denoting the transmission of forces between individual assemblies within a machine. We shall give examples from Babbage's Difference Engine 2 for which a complete set of notations was drawn in 1849, and compare them to a design of similar complexity specified in 1987 using the Inmos HDL.
- History of Mathematics
A mechanism is described to symmetrize the ultraspherical spectral method for self-adjoint problems. The resulting discretizations are symmetric and banded. An algorithm is presented for an adaptive spectral decomposition of self-adjoint operators. Several applications are explored to demonstrate the properties of the symmetrizer and the adaptive spectral decomposition.
- Numerical Analysis Group Internal Seminar