Past Department Colloquia

Thu, 2018-01-11 16:00 - 17:00
Anatoli Polkovnikov (Boston U.)

Phase transitions are usually defined through emergence of singularities of free
energy of the system with changing some external parameter like temperature.
Familiar examples include liquid-gas transitions, or transitions between
paramagnetic and ferromagnetic phases. Quantum phase transitions are very similar
except that they occur at zero temperature and are driven by quantum fluctuations.
In this talk I will introduce a concept of dynamical quantum phase transitions,

Thu, 2018-01-04 16:00 - 17:00
Lorne Whitehead (UBC)

The Color Vision chapter in Feynman's Lectures on Physics nicely describes the well-established fact that colour vision arises from spectrally selective photo-transduction in retinal cells.  However, that picture offers little insight into the primary evolutionary driver for colour vision - the accurate perception of the colours of surfaces.

Thu, 2017-12-07 16:00 - 17:00
David Kaplan (Johns Hopkins)

In this talk, I present the Higgs Boson's Compton wavelength (proportional to its inverse mass), as currently one of the few fundamental length-scales in physics, from which much of macroscopic physics is derived.  The Standard Model of particle physics predicts a direct relationship between the Higgs mass and the mass of all other fundamental particles, but it fails to predict the mass of the Higgs itself.  In fact, the Higgs mass is a conundrum in the Standard Model, as simple (and very reasonable) scaling arguments predict it to be sixteen orders of magnitude

Thu, 2017-11-30 17:30 - 18:30
Barry Barish (Caltech)

Albert Einstein predicted the existence of gravitational waves 100 years ago, but the effects are so tiny that even Einstein thought they could never be detected. After 40 years of controversy, theorists finally developed a consensus that they really do exist. Then the problem became whether experimental physicists could develop instruments sensitive enough to actually detect them?

Thu, 2017-11-23 16:00 - 17:00
James Pinfold (U Alberta)

MoEDAL is a pioneering experiment designed to search for anomalously ionizing messengers of new physics, such as magnetic monopoles or massive (pseudo-)stable charged particles, which are predicted to exist in a plethora of models beyond the Standard Model. MoEDAL started data taking in 2015 at the LHC at a centre-of-mass energy of 13 TeV.

Thu, 2017-11-16 16:00 - 17:00
CongJun Wu (UCSD)

Orbital is a degree of freedom independent of charge and spin. It plays an important role in physical properties of transition-metal-oxides including superconductivity and magnetism. The recent developments of optical lattices have opened up an opportunity to study novel features of orbital physics that are not easily accessible in solid state systems.

Thu, 2017-11-09 16:00 - 17:00
Victor Gurarie (U of Colorado)

Ultra-quantum matter is the proposed umbrella term to describe states of matter made of quantum particles with long range quantum entanglement among them. These states of matter lie outside the standard Landau classification of phases of matter by broken symmetries, where solid is distinct from liquid because its crystalline lattice breaks translational invariance. Typically ultra-quantum matter does not break any symmetries despite forming distinct phases of matter.

Thu, 2017-11-02 16:00 - 17:00
Brett Gladman (UBC)

Planetary formation functions much the way that 2-year olds eat; that is, most of it goes where it's supposed to, but a non-negligible fraction is dispersed in the vicinity, sometimes leaving at high speed.  In this colloquium I will cover (at a non-expert level) a series of topics related to the processes that occur in planetary systems as they form and evolve.  The size scales from dust to giant planets will be covered, including topics of: meteorite delivery; giant impacts that strip mantles off planets, exposing their bare cores; building the Oort cloud and

Thu, 2017-10-26 16:00 - 17:00
Levon Pogosian (SFU)

While cosmic acceleration is well-established, the nature of Dark Energy causing it remains unknown. A flat universe dominated by a cosmological constant (Lambda) and cold dark matter (CDM) has been cosmologists’ working model of choice for nearly two decades. However, the value of Lambda poses a serious theoretical challenge, exposing a gap in our understanding of the vacuum energy and the way it gravitates. Intriguingly, there appear to be tensions between different datasets within the LCDM framework that would be relieved if Dark Energy was non-constant.

Thu, 2017-10-19 16:00 - 17:00
Martin Barlow (UBC Mathematics)

A random walk on a graph G has anomalous diffusion if the mean square deviation after n steps is sublinear in n. Systems that have, or are expected to have, anomalous diffusion include some regular exact fractals, and random graphs at their critical point. I will discuss these, and in particular what we know about diffusion on critical percolation, the uniform spanning tree, and random planar triangulations.

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