Talks

: In this talk I will review the common appearance of torsion in solids as well as some new developments. Torsion typically appears in condensed matter physics associated to topological defects known as dislocations. Now we are beginning to uncover new aspects of the coupling of torsion to materials. Recently, a dissipationless viscosity has been studied in the quantum Hall effect. I will connect this viscosity to a 2+1-d torsion Chern-Simons term and discuss possible thought experiments in which this could be measured. Additionally I will discuss a new topological defect in 3+1-d, the torsional monopole, which does not require a lattice deformation to exist. If present, torsional monopoles are likely to impact the behavior of materials with strong spin-orbit coupling such as topological insulators.

The dynamics of fluids is a long standing challenge that remained as an unsolved problem for centuries. Understanding its main features, chaos and turbulence, is likely to provide an understanding of the principles and non-linear dynamics of a large class of systems far from equilibrium. We consider a conceptually new viewpoint to study these features using black hole dynamics. Since the gravitational field is characterized by a curved geometry, the gravity variables provide a geometrical framework for studying the dynamics of fluids: A geometrization of turbulence. We present new experimental predictions for relativsitic and non-relativistic turbulent flows and for heavy ion collisions.

Numerical simulations of binary black holes with spin have revealed some surprising behavior: for antialigned spins in the orbital plane, 1) one sees an up-and-down "bobbing" of the entire orbital plane at the orbital frequency and 2) the merged black hole receives an enormous kick that depends on the phase at merger. Natural questions are: What causes the bobbing? Can the kick be viewed as a post-merger continuation of the bobbing? We show that this type of bobbing is in fact ubiquitous in relativistic mechanics, occurring independently of the type of force holding two spinning bodies in orbit. The cause can be identified as a spin correction to the naive center of mass of a body; the effect is analogous to Thomas precession and is ``purely kinematical'' in the same way. Since a kick requires the release of field momentum, it is instead very dependent on the type of force holding bodies in orbit. In a mechanical analog (spinning balls connected by a string), there is bobbing but can be no kick. In an electromagnetic analog, one should be able to tune the kick independently of the bobbing. In the gravitational case the spin parameter happens to control both bobbing and kick, making separate tuning impossible and giving the appearance of causation to two essentially unrelated phenomena. Our answers are therefore: the bobbing is caused by a purely kinematical effect of spin, and the kick cannot be viewed its post-merger continuation.

The dynamics of fluids is a long standing challenge that remained as an unsolved problem for centuries. Understanding its main features, chaos and turbulence, is likely to provide an understanding of the principles and non-linear dynamics of a large class of systems far from equilibrium. We consider a conceptually new viewpoint to study these features using black hole dynamics. Since the gravitational field is characterized by a curved geometry, the gravity variables provide a geometrical framework for studying the dynamics of fluids: A geometrization of turbulence. We present new experimental predictions for relativsitic and non-relativistic turbulent flows and for heavy ion collisions.