Since 2002 Perimeter Institute has been recording seminars, conference talks, and public outreach events using video cameras installed in our lecture theatres. Perimeter now has 7 formal presentation spaces for its many scientific conferences, seminars, workshops and educational outreach activities, all with advanced audio-visual technical capabilities. Recordings of events in these areas are all available On-Demand from this Video Library and on Perimeter Institute Recorded Seminar Archive (PIRSA). PIRSA is a permanent, free, searchable, and citable archive of recorded seminars from relevant bodies in physics. This resource has been partially modelled after Cornell University's arXiv.org.
In the first part of the talk, a brief introduction to general relativity and quantum theory is given. Their independent successes are discussed, as well as the desire and difficulty in merging them, to obtain a unique language to describe the universe.
Then I focus on Loop quantum gravity, a particular approach towards this objective, in which a discrete microscopic structure of spacetime is envisaged.
An ingredient in recent discussions of curvature singularity avoidance in quantum gravity is the "inverse scale factor" operator and its generalizations. I describe a general lattice origin of this idea, and show how it applies to the Coulomb singularity in quantum mechanics, and more generally to lattice formulations of quantum gravity. The example also demonstrates that a lattice discretized Schrodinger or Wheeler-DeWitt equation is computationally equivalent to the so called "polymer"
quantization derived from loop quantum gravity.
The world at the size of individual atoms obeys very different laws of physics from those we are used to in the everyday world around us. Quantum mechanics rules, allowing atoms to be, in some sense, in more than one place at a time. Researchers all over the world are working to build \"quantum computers\" whose memories manipulate an inherently new type of information, \"quantum information.\"
The world at the size of individual atoms obeys very different laws of physics from those we are used to in the everyday world around us. Quantum mechanics rules, allowing atoms to be, in some sense, in more than one place at a time.
One simple way to think about physics is in terms of information. We gain information about physical systems by observing them, and with luck this data allows us to predict what they will do next. Quantum mechanics doesn\'t just change the rules about how physical objects behave - it changes the rules about how information behaves. In this talk we explore what quantum information is, and how strangely it differs from our intuitions.
For more than 70 years, astronomers have had the uneasy suspicion that there was more to the universe than met the eye - much, much more. In the past five years, this suspicion has become a certainty. We now know for sure that normal matter and normal radiation account for only 4% of the density of the universe. One of the two biggest components, dark matter, may be finally be identified by new experiments coming on line next year. I\'ll summarise the long quest to identify dark matter and our prospects for finally achieving this goal in the next two years.