Talks by Ted Jacobson

Gravitational thermodynamics of causal diamonds

Ted Jacobson University of Maryland

Black hole (more generally, horizon) thermodynamics is a window into quantum gravity. Can horizon thermodynamics---and ultimately quantum gravity---be quasi-localized? A special case is the static patch of de Sitter spacetime, known since the work of Gibbons and Hawking to admit a thermodynamic equilibrium interpretation. It turns out this interpretation requires that a negative temperature is assigned to the state. I'll discuss this example, and its generalization to all causal diamonds in maximally symmetric spacetimes.

Blandford-Znajek process without plasma

Ted Jacobson University of Maryland

In 1977, Blandford and Znajek  discovered a process by which a spinning 

black hole can transfer rotational energy to a force-free plasma, offering a possible mechanism for energy and jet emissions from quasars and other astrophysical sources.  This Blandford-Znajek (BZ) mechanism is a Penrose process, which exploits the presence of an ergosphere supporting negative energy states, and it involves currents of electrical charge sourcing the toroidal  magnetic field component of the emitted Poynting flux.  

Einstein's equation from maximal entropy of vacuum entanglement

Ted Jacobson University of Maryland
If entanglement entropy in a small geodesic ball is maximized at fixed volume in the vacuum, then it should be stationary under variation to a nearby state. I will show that this stationarity condition is equivalent to the semiclassical Einstein equation. If the matter QFT is not conformal, then the derivation requires a further assumption about QFT, whose validity is currently under investigation. [Based on http://arxiv.org/abs/1505.04753]

Fun with ideal plasmas

Ted Jacobson University of Maryland
I will sketch a few interesting phenomena involving ideal plasmas, including helicity conservation, frozen flux, the Blandford-Znajek mechanism, and self-confined Poynting jets, using the language of differential forms.