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# Colloquium

This series covers all areas of research at Perimeter Institute, as well as those outside of PI's scope.

## Seminar Series Events/Videos

Currently there are no upcoming talks in this series.

## Gravitational-wave astronomy: progress and prospects

Mercredi nov 04, 2009
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Gravitational waves provide a unique way to study the Universe. From
2005 to 2007, the Laser Interferometer Gravitational-wave Observatory

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## A physicist's approach to economics

Mercredi oct 14, 2009
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Physicists have been working for banks and hedge funds on applied problems in finance for more than two decades, and recently have doing academic research as well. This talk will survey academic research by physicists and contrast it with mainstream economics. I will argue that the difference comes not from the application of alternative techniques or new mathematics, but rather from fundamental differences in what questions are considered interesting and how one should go about solving them.

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## Beyond the Quantum

Mercredi oct 07, 2009
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According to hidden-variables theories, quantum physics is a special 'equilibrium' case of a much wider 'nonequilibrium' physics. We describe the search for that wider physics in a cosmological context. The hypothesis that the universe began in a state of quantum nonequilibrium is shown to have observable consequences. In de Broglie-Bohm theory on expanding space, relaxation to quantum equilibrium is shown to be suppressed for field modes whose quantum time evolution satisfies a certain inequality, resulting in a 'freezing' of early nonequilibrium for these particular modes.

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## Experimental Quantum Cosmology with the BICEP CMB Polarimeter

Mercredi sep 23, 2009
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The Background Imager of Cosmic Extragalactic Polarization (BICEP) experiment is the first polarimeter developed to measure the inflationary B-mode polarization of the CMB. During three seasons of observing at the South Pole, Antarctica beginning in 2006, BICEP mapped 2% of the sky chosen to be clean of polarized foreground emission, with sub-degree resolution.

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## The Search for the Perfect Language

Lundi sep 21, 2009
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I will tell how the story given in Umberto Eco's book The Search for the Perfect Language continues with modern work on logical and programming languages.(For more information, see http://www.umcs.maine.edu/~chaitin/hu.html.)

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## Spacetime can be simultaneously discrete and continuous, in the same way that information can.

Mercredi sep 16, 2009
Speaker(s):

TBA

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## The Birth of Neutron Stars and Black Holes

Lundi sep 14, 2009
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Gamma-ray bursts (GRBs) -- rare flashes of ~ MeV gamma-rays lasting from a fraction of a second to hundreds of seconds -- have long been among the most enigmatic of astrophysical transients. Observations during the past decade have led to a revolution in our understanding of these events, associating them with the birth of neutron stars and/ or black holes during either the collapse of a massive star or the merger of two compact objects (e.g., a neutron star and a black hole).

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## Beyond the Standard (cosmological ) Model

Mercredi sep 09, 2009
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The Standard model of Cosmology consists of a package of ideas that include Cold Dark Matter, Inflation, and the existence of a small Cosmological Constant. While there is no consensus about what lies beyond the Standard Model, there is a leading candidate that also includes a small package of ideas: A Landscape of connected vacua: the idea that the universe started out with a large energy density, and Coleman DeLuccia Tunneling between vacua. An additional idea that comes from string theory and black hole physics is the Holographic Principle.

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## Hamilton's diabolical singularity

Mercredi juin 03, 2009
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The transformation of a narrow beam into a hollow cone when incident along the optic axis of a biaxial crystal, predicted by Hamilton in 1832, created a sensation when observed by Lloyd soon afterwards. It was the first application of his concept of phase space, and the prototype of the conical intersections and fermionic sign changes that now pervade physics and chemistry.

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## Using Large-Scale Structure and CMB Observations to Probe the Properties of Dark Energy

Mercredi mai 27, 2009
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Cosmologists are struggling to understand why the expansion rate of our universe is now accelerating. There are two sets of explanations for this remarkable observation: dark energy fills space or general relativity fails on cosmological scales. If dark energy is the solution to the cosmic acceleration problem, then the logarithmic growth rate of structure $dlnG/dlna = \Omega^\gamma$, where $\Omega$ is the matter density independent of scale in a dark matter plus dark energy model.

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## LECTURES ON-DEMAND

### Roger Melko: Perimeter Institute and University of Waterloo

Speaker: Roger Melko