This series covers all areas of research at Perimeter Institute, as well as those outside of PI's scope.
Winds are driven by the gradients of solar heating. Vertical gradients cause thermal convection on the scale of the troposphere depth (less than 10 km). Horizontal gradients excite motions on a planetary (10000 km) and smaller scales. Weather is mostly determined by the flows at intermediate scale (hundreds of kilometers). Where these flows get their energy from? The puzzle is that three-dimensional small-scale motions cannot transfer energy to larger scales while large-scale planar motions cannot transfer energy to smaller scales.
What are the bounds of the AdS/CFT correspondence? Which quantities in conformal field theory have simple descriptions in terms of classical anti-de Sitter spacetime geometry? These foundational questions in holography may be meaningfully addressed via the study of CFT correlation functions, which map to amplitudes in AdS. I will show that a basic building block in any CFT -- the conformal block -- is equivalent to an elegant geometric object in AdS, which moreover greatly streamlines and clarifies calculations of AdS amplitudes.
The coalescence of black hole-black hole (BHBH), black hole-neutron star (BHNS) and neutron star-neutron star (NSNS) systems are among the most promising sources of gravitational waves (GWs) detectable by Advanced LIGO/Virgo and NANOGrav. In addition, distinct observable electromagnetic radiation may accompany these GWs. Such "multi-messenger" sources can be powerful probes of fundamental physics such as the state of matter under extreme conditions, cosmology, as well as our theories of gravity.
Bott periodicity (1956) is a classical and old result in mathematics.
Its easiest incarnation of which concerns Clifford algebras. It says
that, up to Morita equivalence, the real Clifford algebras Cl_1(R),
Cl_2(R), Cl_3(R), etc. repeat with period 8. A similar result holds
for complex Clifford algebras, where the period is now 2. The modern
way of phrasing Bott periodicity in is terms of K-theory: I will
explain how one computes K-theory, and we will see the 8-fold Bott
Almost fifteen years after LIGO started listening to the cosmos, and 100 years after Einstein discovered general relativity, gravitational waves have been detected by ground-based interferometers, opening a new window on the universe. In this talk I will address some of the most exciting areas of research advanced LIGO will allow us to explore in the coming years. Detection and characterization of gravitational wave transients will be discussed, as well as their impact on astrophysics.
In recent decades probing for the subtle indications of new physics in
experimental data has become increasingly difficult. The datasets have gotten
much bigger, the experiments more complex, and the signals ever smaller. Success
stories, like LIGO and Kepler, require a sophisticated combination of statistics
and computation, coupled with an appreciation of both the experimental realities
and the theoretical framework governing the data.
I will begin by giving an overview of the current state of exoplanet
science, a field that has advanced tremendously in just the last few
years. While specialized instrumentation and observational facilities
have provided the data driving this advance, the development and
application of statistical techniques to interpret this data have been
of critical importance. These same tools are also at the core of all
data-driven science, and are thus applicable to many other fields of
Gravitational waves, as predicted by Einstein one hundred years ago, have been detected by the advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) in September last year. This finding marks the beginning of gravitational-wave astronomy. From now on, we are able to probe our universe using both long-range forces in nature.
In any quantum field theory, the energy flux at a point of spacetime can be negative. This would produce a repulsive gravitational field causing nearby light rays to defocus. This in turn threatens to produce a variety of exotic phenomena including traversable wormholes, warp drives, time machines, and evasion of singularity theorems. I will describe a new "quantum focusing conjecture" that prevents such pathologies. In the flat spacetime limit it reduces to a novel lower bound on the energy density, which can be proven for several classes of field theories.