Colloquium

There is an analogy between the propagation of fields in the vicinity of astrophysical black holes and the that of small excitations in fluids and superfluids. This analogy allows one to test, challenge and verify, in tabletop experiments, the elusive processes of black hole mass and angular momentum loss.

I will first present a brief overview on analogue black hole experiments, and then discuss in more detail some of my earlier and more recent experimental and theoretical results on the subject.

The discovery of the Higgs boson at the Large Hadron Collider marks the culmination of a decades-long hunt for the last ingredient of the Standard Model. At the same time, this discovery has started a new era in the search for more fundamental physics. In this talk, I will discuss what we have learned from the Higgs discovery about the mechanism of electroweak symmetry breaking and the implications for the existence of additional Higgs bosons. I will then highlight the future prospects of the Higgs boson in shedding light on New Physics and in particular on the nature of Dark Matter.

Galileons are higher-derivative effective field theories with curious properties which have attracted much recent interest among cosmologists.  I will review their origins, their properties, their generalizations, and some recent developments.

Thanks to the spectacular observational advances since the 1990s, a `standard model' of the early universe has now emerged. However, since it is based on quantum field theory in curved space-times, it is not applicable in the Planck era. Using techniques from loop quantum gravity, the theory can be extended over the 12 orders of magnitude in density and curvature from the onset of inflation all the way back to the Planck regime, providing us with a possible completion of the standard model.

Contrary to a wide-spread belief, the resulting pre-inflationary dynamics can have observational consequences for the longest wave length modes of cosmological perturbations. Thus, there is now an an interesting interplay between fundamental theory and observations. The talk will provide a broad overview of these results addressed to non-experts.

Web-links:

Viewpoint: A glance at the earliest universe; APS Physics Spotlighting Exceptional Research: http://physics.aps.org/articles/v5/142

U tube video

http://www.youtube.com/watch?v=IFcQuEw0oY8&feature=c4-overview&list=UUtOgK

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In holographic duality a gravitational spacetime emerges as an equivalent description of a lower-dimensional conformal field theory (CFT) living on the asymptotic boundary. Traditionally, the dimension not present in the CFT is interpreted in terms of its Renormalisation Group flow. In this talk I exploit the relation between boundary entanglement entropies and bulk minimal surfaces to define a quantitative framework for the holographic Renormalisation Group, in which quantum information theory plays a fundamental role. I will provide operational, quantitative, information-theoretic characterizations of several geometric concepts in asymptotically AdS3 spacetimes, including the radial direction and lengths of bulk curves.

Perhaps the biggest conceptual benefit of the information-theoretic framework for holographic Renormalisation Group is a quantitative correspondence between holography and the Multi-Scale Entanglement Renormalisation Ansatz (MERA). I also discuss prospects for understanding the near-horizon structure of black holes.

After 50 years of dreaming about it, space-based microlensing observations are now underway.  A 2014 100-hr Spitzer Pilot Program generated "microlens parallaxes" for dozens of lenses, opening the prospect of measuring the Galactic distribution of planets.  This program will be expanded 8-fold in 2015.  Analogous observations by Kepler will measure the mass function of free-floating planets.

WFIRST microlensing observations will, as advertised, "complete the planetary census" but they will do an immense amount of astrophysics as well.  I discuss how microlensing's take off builds on rapid, ongoing, ground-based developments.

The interplay of quantum mechanics and inter-particle interactions leads to enormously rich tapestry of quantum phases of matter. In this talk I will illustrate the unique synthesis offered by quantum entanglement on the landscape of quantum phases. I will especially discuss phases which do not show any kind of ordering even at the absolute zero temperature, two prime examples being spin liquids and quantum Hall phases. These phases are fascinating because they can exhibit extraordinary properties such as emergent fermions in a system composed only of bosons, or systems where the elementary excitations are neither fermions, nor bosons (“anyons”). I will discuss how quantum entanglement not only plays a crucial role in characterizing and diagnosing such quantum disordered phases, but in fact it also sheds light on their stability.

We investigate through non-equilibrium molecular dynamic simulations the flow of anomalous
fluids inside rigid nanotubes. Our results reveal an anomalous increase of the overall mass flux
for nanotubes with sufficiently smaller radii. This is explained in terms of a transition from a
single-file type of flow to the movement of an ordered-like fluid as the nanotube radius increases.
The occurrence of a global minimum in the mass flux at this transition reflects the competition
between the two characteristic length scales of the core-softened potential. Moreover, by increasing
further the radius, another substantial change in the flow behavior, which becomes more evident at
low temperatures, leads to a local minimum in the overall mass flux. Microscopically, this second
transition is originated by the formation of a double-layer of flowing particles in the confined
nanotube space. These nano-fluidic features give insights about the behavior of confined isotropic
anomalous fluids.

The remnant accretion disk formed in binaries involving neutron stars and/or black holes is a source of non-relativistic ejecta. This 'disk wind' is launched on a thermal and/or viscous timescale, and can provide an amount of material comparable to that in the dynamical ejecta. I will present recent work aimed at characterizing

the properties of these winds through time-dependent radiation-hydrodynamic simulations that include the relevant physics needed to follow the ejecta composition. I will focus on the effect of black hole spin and/or hypermassive neutron star lifetime on the disk wind, and on the interaction of the wind with the dynamical ejecta. I will also discuss the implications of these results for the optical/IR signal from these events, and for the origin of r-process elements in the Galaxy.

In this talk I will describe recent work with Almheiri and Dong, where we proposed a connection between the emergence of bulk locality in AdS/CFT and the theory of quantum error correction. Bulk notions such as Bogoliubov transformations, location in the radial direction, and the holographic entropy bound all have natural CFT interpretations in the language of quantum error correction.  Time permitting, I will also discuss work in progress with Pastawski, Preskill, and Yoshida on a new class of stabilizer codes that explicitly realize many of the properties we argued the AdS/CFT error correcting code should have.  

Shape Dynamics is a theory of gravity which replaces relativity of simultaneity for spatial conformal invariance, maintaining the same degree of symmetry of General Relativity while avoiding some of its shortcomings.

In SD several kinds of singularities of GR become unphysical gauge artefacts, and the presence of a preferred notion of simultaneity fits better into the structure of quantum theory. In this talk I will outline the present status of research in SD on black holes and gravitational collapse, on the emergence of spacetime and on the first-order formulation of the theory.

The AdS/CFT correspondence from string theory provides a quantum theory of gravity in which spacetime and gravitational physics emerge from an ordinary non-gravitational system with many degrees of freedom. In this talk, I will explain how quantum entanglement between these degrees of freedom is crucial for the emergence of a classical spacetime, and describe progress in understanding how spacetime dynamics (gravitation) arises from the physics of quantum entanglement."