This series covers all areas of research at Perimeter Institute, as well as those outside of PI's scope.
Category theory is a general language for describing things and processes - called "objects" and "morphisms". In this language, many counterintuitive features of quantum theory turn out to be properties shared by the category of Hilbert spaces and the category of cobordisms, in which objects are choices of "space" and emorphisms are choices of "spacetime". This striking fact suggests that "n-categories with duals" are a promising language for a quantum theory of spacetime.
Nanostructured materials continue to be the focus of intense research due to their promise of innumerable practical applications as well as advancing the fundamental understanding of these intriguing materials. From physics, to chemistry, to biology, to computer science, across the engineering disciplines and into the imagination of the general event, nanotechnology has become an extremely popular buzzword that represents both hope and hype to many people.
A variety of physical phenomena involve multiple length and time scales. Some interesting examples of multiple-scale phenomena are: (a) the mechanical behavior of crystals and in particular the interplay of chemistry and mechanical stress in determining the macroscopic brittle or ductile response of solids; (b) the molecular-scale forces at interfaces and their effect in macroscopic phenomena like wetting and friction; (c) the alteration of the structure and electronic properties of macromolecular systems due to external forces, as in stretched DNA nanowires or carbon nanotubes.
I will describe some recent advances in the simulation of binary black hole spacetimes using a numerical scheme based on generalized harmonic coordinates. After a brief overview of the formalism and method, I will present results from the evolution of a couple of classes of initial data, including Cook-Pfieffer quasi-circular inspiral data sets, and binaries constructed via scalar field collapse. In the latter case, preliminary studies suggest that in certain regions of parameter space there is extreme sensitivity of the resulting orbit to the initial conditions.
Familiar textbook quantum mechanics assumes a fixed background spacetime to define states on spacelike surfaces and their unitary evolution between them. Quantum theory has been generalized as our conceptions of space and time have evolved. But quantum mechanics needs to be generalized further for quantum gravity where spacetime geometry is fluctuating and without definite value. This talk will review a fully four-dimensional, sum-over-histories, generalized quantum mechanics of cosmological spacetime geometry.
Globular proteins, which act as enzymes, are a key component of the network of life. Over many decades, much experimental data has been accumulated yet theoretical progress has been somewhat limited. We argue that the key results accumulated over the years inexorably lead to a unified framework for understanding proteins. Our framework yields predictions on the existence of a fixed menu of folds determined by geometry, the role of the amino acid sequence in selecting the native state structure from this menu and the propensity for amyloid formation.
Neutrinos are the big unknown in Particle Physics. Since their very beginning they behaved strangely. However, in the last decade experiments were able to solve some of their secrets. The talk will review the current experimental status of neutrino experiments and give an outlook on future activities.
The Laser Astrometric Test of Relativity (LATOR) is a Michelson-Morley-type experiment designed to improve current tests of the Einsteins theory of general relativity by more than four orders of magnitude. The LATOR mission uses laser interferometry between two laser sources placed on separate small spacecraft, whose lines of sight pass close by the Sun, to measure accurately the deflection of light in the solar gravity field.