Search Talks

Weak gravitational lensing is a powerful probe of modifications of General Relativity on cosmological scales, since such modifications can affect both how matter produces gravitational potential wells and how photons move within these wells. I will discuss alternative theories of gravitation and how we may constrain such theories using weak lensing observables, including those that could be obtained with the balloon-borne High Altitude Lensing Observatory (HALO). I will also discuss the "parametrized-post-Friedmannian" approach for obtaining model-independent constraints, in which new parameters are introduced to characterize the departure from General Relativity on large scales.

We utilize the tools of the gauge/gravity correspondence in order to investigate electroweak symmetry breaking (EWSB). For quite some time now, a walking technicolor sector has been viewed by phenomenologists as a very promising alternative to the Higgs boson. Unfortunately however, no precise computations have been possible since in the technicolor gauge theory EWSB is due to strong-coupling dynamics. Using recent developments in the gauge/gravity duality, we construct a gravity dual of a walking technicolor model and aim to compute the Peskin-Takeuchi S-parameter, which is an observable that can distinguish between a Higgs and a technicolor sector.

Our understanding of the physical world at the most fundamental level is based on two theories: quantum theory and general relativity. They are impressively successful when each is considered on its own, but in situations where both play a role, we are reduced to puzzles and absurdity. To the great frustration of researchers, candidate theories of quantum gravity produce more puzzles than answers. We shall tour of some of the problems, focusing on the role of spacetime and causality. We will consider the possibility that spacetime did not always exist but is instead emergent and explore how one can create a spacetime from a world with no notion of "here" and "there".

The mysteries of quantum theory run deep. Despite 80 years of research, there is still no consensus on its interpretation. This talk will explore some of the important issues in the foundations of quantum theory, from the idea that we have only a limited knowledge of a deeper reality, like the prisoner in Plato’s cave who sees only the shadows of objects and never the objects themselves, to John Bell’s famous discovery of the difference between quantum correlations and Dr. Bertlmann’s socks, namely, that whereas the mismatched colours of the doctor’s socks can be attributed to a decision at the sock drawer that morning, certain quantum correlations cannot be explained by a common cause, at least not without doing violence to some cherished principles of physics, such as the fact that causes cannot travel faster than the speed of light.