Since 2002 Perimeter Institute has been recording seminars, conference talks, public outreach events such as talks from top scientists 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 and 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.
Accessibly by anyone with internet, Perimeter aims to share the power and wonder of science with this free library.
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.
It is a standard axiom of quantum mechanics that the Hamiltonian H must be Hermitian because Hermiticity guarantees that the energy spectrum is real and that time evolution is unitary. In this talk we examine an alternative formulation of quantum mechanics in which the conventional requirement of Hermiticity is replaced by the more general and physical condition of space- time reflection (PT) symmetry. We show that if the PT symmetry of H is unbroken, Then the spectrum of H is real. Examples of PT-symmetric non-Hermitian Hamiltonians are $H=p^2+ix^3$ and $H=p^2-x^4$.
This is an introduction to background independent quantum theories of
gravity, with a focus on loop quantum gravity and related approaches.
Basic texts:
-Quantum Gravity, by Carlo Rovelli, Cambridge University Press 2005 -Quantum gravityy with a positive cosmological constant, Lee Smolin,
hep-th/0209079
-Invitation to loop quantum gravity, Lee Smolin, hep-th/0408048 -Gauge fields, knots and gravity, JC Baez, JP Muniain
Prerequisites:
This is an introduction to background independent quantum theories of
gravity, with a focus on loop quantum gravity and related approaches.
Basic texts:
-Quantum Gravity, by Carlo Rovelli, Cambridge University Press 2005 -Quantum gravityy with a positive cosmological constant, Lee Smolin,
hep-th/0209079
-Invitation to loop quantum gravity, Lee Smolin, hep-th/0408048 -Gauge fields, knots and gravity, JC Baez, JP Muniain
Prerequisites:
While modern theories lavishly invoke several spatial dimensions within models that seek to unify relativity theory and quantum mechanics, none seems to consider the possibility that a yet-unfamiliar aspect of time may do the work. I introduce the notion of Becoming and then consider its consequences for physical theory. Becoming portrays a possible aspect of time that is "curled" very much like the extra spatial dimensions in superstring theories.
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.
I discuss the backreaction of inhomogeneities on the expansion of the universe. The average behaviour of an inhomogeneous spacetime is not given by the Friedmann-Robertseon-Walker equations. The new terms in the exact equations hold the possibility of explaining the observed acceleration without a cosmological constant or new physics. In particular, the coincidence problem may be solved by a connection with structure formation.
We express the total equation of state parameter of a spatially flat Friedman-Robertson-Walker universe in terms of derivatives of the red-shift dependent spin-weighted angular moments of the two-point correlation function of the three dimensional cosmic shear. In the talk I will explain all the technical terms in the first sentence, I will explain how such an expression is obtained and highlight its relevance for determining the expansion history of the universe.
Check back for details on the next lecture in Perimeter's Public Lectures Series