BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Covariant phase space with boundaries - Daniel Harlow (MIT)
DTSTART:20200604T130000Z
DTEND:20200604T140000Z
UID:TALK143722@talks.cam.ac.uk
CONTACT:Pietro Benetti Genolini
DESCRIPTION:The Hamiltonian formulation of mechanics has several decisive 
 advantages: it gives a clear accounting of the physical degrees of freedom
 \, the initial-value problem is naturally formulated\, and the relationshi
 p to quantum mechanics is clear. On the other hand\, as usually formulated
  it destroys manifest spacetime covariance and applies only to equations o
 f motion with at most two derivatives. Both of these problems are avoided 
 in the covariant phase space formalism\, developed most notably by Wald an
 d collaborators in the early 1990s. Their formalism however suffers from a
 mbiguities related to total derivatives and boundary terms\, which so far 
 have been dealt with on an ad hoc case-by-case basis. This is especially u
 nfortunate for gravitational theories\, for which any nontrivial Hamiltoni
 an will necessarily be a boundary term and thus boundary effects are of ce
 ntral importance. In this talk I will describe work with Jie-qiang Wu wher
 e we improve the covariant phase space formalism to systematically include
  boundary effects: the result is that for any Lagrangian field theory base
 d on a local action with a finite number of derivatives\, there is now a s
 ystematic\, practical\, and fully-covariant way to construct the phase spa
 ce and Hamiltonian\, as well as any other conserved charges. Moreover the 
 approach is quite convenient in practice\, for example it allows perhaps t
 he most compact derivation so far of the ADM Hamiltonian.
LOCATION:Online (Zoom)
END:VEVENT
END:VCALENDAR