Search Talks

I will describe recent results obtained for N=4 superconformal field
theories in four dimensions by means of the conformal bootstrap.

This talk will be related to the content of arXiv:1304.1803, as well as
some additional work in progress.

The direct detection of gravitational waves promises to open up a new spectrum that is otherwise mostly closed to electromagnetically based astronomical observations. Detecting gravitational waves from binary black holes and neutron stars, as well as estimating their parameters, requires a sufficiently accurate prediction for the expected waveform signal. Unfortunately, the state of the art for the pillars of gravitational wave theory -- numerical relativity, the post-Newtonian approximation, and linear black hole perturbation theory -- have yet to cover accurately the entire parameter space even when taken together. In this talk, I present a new direction for systematically describing compact binaries that is valid over a potentially very large portion of the parameter space.

The approach uses high-order black hole perturbation theory in the mass ratio together with ideas and techniques borrowed from effective field theory for incorporating the physics of extended masses like spin and tidal effects. I discuss recent advances, future prospects, and potential impacts in this direction.

We show explicitly how the exact renormalization group
equation of interacting vector models in the large N limit can be
mapped into certain higher-spin equations of motion. The equations of
motion are generalized to incorporate a multiparticle extension of the
higher-spin algebra, which reflects the "multitrace" nature of the
interactions in the dual field theory from the holographic point of view.

Spins play a major role in the strong-field dynamics of
black-hole binaries and their gravitational-wave emission. By detecting spin
effects in the waveforms, existing and future gravitational-wave detectors
therefore provide a natural way to test gravity in strong-field, highly
dynamical regimes.

In the first part of my talk, I will show that the
inclusion of the spins in the gravitational templates for future space-based
detectors will permit testing scenarios for the formation and cosmological
evolution of supermassive black holes, and possibly shed light on models of
galaxy formation. In the second part, I will show that the effective-one-body
(EOB) model provides an efficient way to account for spin effects in both the
dynamics and waveforms, by combining information from post-Newtonian theory,
the self-force formalism, and numerical-relativity simulations.

While quantum mechanics is an immensely powerful and precise theory which seems to describe everything in the world, its insistence on only predicting what happens when we make "measurements" has left scientists and philosophers alike puzzled - as David Mermin summarized one of Einstein's concerns, "Is the moon there when nobody looks?" Dr. Steinberg will talk about some of the new ideas revolutionizing our view of quantum measurement, in particular the surprising advantages of measuring things "weakly" and suggest that new hints may be emerging about how we should think about Einstein's moon.

While quantum measurement remains the central philosophical conundrum of quantum mechanics, it has recently grown into a respectable (read: experimental!) discipline as well.  New perspectives on measurement have grown  out of new technological possibilities, but also out of
attempts to design systems for quantum information processing, which promise to be exponentially more powerful than any possible classical computer.  I will try to give a flavour about some of these perspectives, focussing largely on a particular paradigm known as "weak measurement."
Weak measurement is a natural extension of a pragmatic view of what it means to measure something about a quantum system, yet leads to some rather surprising results.  I will describe a few examples of our recent experiments using weak measurement to probe fundamental issues in  uantum mechanics such as what the minimum disturbance due to a quantum measurement is.  I will also argue that there are regimes in which weak measurement offers a practical advantage for sensitive measurements.  

The ground-based gravitational-wave telescopes LIGO and Virgo approach the era of first detections.  Gravitational-wave observations will provide a unique probe for exploring strong-field general relativity and compact-binary astrophysics.  In this talk, I describe recent predictions regarding the distributions of black-hole and neutron-star binary mergers, and progress on solving the inverse problem of turning gravitational-wave observations into astrophysical information. I highlight some exciting recent investigations into the use of gravitational waves as tests of general relativity.

The fuzzball proposal makes a conjecture about the nature of black hole
microstates. Now, more than a decade old and including several different
philosophies and perspectives, it is especially relevant after the recent
firewall argument and ensuing debate. Over three lectures, I plan to start
with a very general discussion of the general ideas and motivations, then
review the theoretical evidence from string theory, and finally close by
discussing open questions, including the fate of a freely falling observer
as he/she passes through the black hole horizon.

The fuzzball proposal makes a conjecture about the nature of black hole
microstates. Now, more than a decade old and including several different
philosophies and perspectives, it is especially relevant after the recent
firewall argument and ensuing debate. Over three lectures, I plan to start
with a very general discussion of the general ideas and motivations, then
review the theoretical evidence from string theory, and finally close by
discussing open questions, including the fate of a freely falling observer
as he/she passes through the black hole horizon.