BEGIN:VCALENDAR
VERSION:2.0
PRODID:https://murmitoyen.com/events/vanille/udem/
X-WR-TIMEZONE:America/Montreal
BEGIN:VEVENT
UID:69dcfb7ec061c
DTSTAMP:20260413T101942
DTSTART:20160318T160000
SEQUENCE:0
TRANSP:OPAQUE
DTEND:20160318T160000
URL:https://murmitoyen.com/events/vanille/udem/detail/675074-conferences-ni
 renberg-du-crm-en-analyse-geometrique-gunther-uhlmann-university-of-washin
 gton
LOCATION:Université de Montréal - Pavillon André-Aisenstadt\, 2920\, che
 min de la Tour\, Montréal\, QC\, Canada\, H3T 1N8
SUMMARY:Conférences Nirenberg du CRM en analyse géométrique: Gunther Uhl
 mann (University of Washington)
DESCRIPTION:Cette conférence s'adresse à un large auditoire. This lecture
  is aimed at a general mathematical audience.
\nCan we make objects invisi
 ble? This has been a subject of human fascination for millennia in Greek m
 ythology\, movies\, science fiction\, etc. \, including the legend of Pers
 eus versus Medusa and the more recent Star Trek and Harry Potter. In the l
 ast decade or so there have been several scientific proposals to achieve i
 nvisibility. We will introduce some of these in a non-technical fashion co
 ncentrating on the so-called 'transformation optics' that has received the
  most attention in the scientific literature.
\nJourney to the Center of t
 he Earth Le lundi 21 mars 2016 à 16h We will consider the inverse problem
  of determining the sound speed or index of refraction of a medium by meas
 uring the travel times of waves going through the medium. This problem ari
 ses in global seismology in an attempt to determine the inner structure of
  the Earth by measuring travel times of earthquakes. It has also several a
 pplications in optics and medical imaging among others.
\nThe problem can 
 be recast as a geometric problem: Can one determine a Riemannian metric of
  a Riemannian manifold with boundary by measuring the distance function be
 tween boundary points? This is the boundary rigidity problem. We will also
  consider the problem of determining the metric from the scattering relati
 on\, the so-called lens rigidity problem. The linearization of these probl
 ems involves the integration of a tensor along geodesics\, similar to the 
 X-ray transform.
\nWe will also describe some recent results\, joint with 
 Plamen Stefanov and Andras Vasy\, on the partial data case\, where you are
  making measurements on a subset of the boundary. No previous knowledge of
  Riemannian geometry will be assumed.
\nSeeing Through Space-Time Le mardi
  22 mars 2016 à 16 h
\nWe consider inverse problems for the Einstein equa
 tion with a time-depending metric on a 4-dimensional globally hyperbolic L
 orentzian manifold. We formulate the concept of active measurements for re
 lativistic models. We do this by coupling Einstein equations with equation
 s for scalar fields.
\nThe inverse problem we study is the question of whe
 ther the observations of the solutions of the coupled system in an open su
 bset of the space-time with the sources supported in this set determines t
 he properties of the metric in a larger domain. To study this problem we d
 efine the concept of light observation sets and show that knowledge of the
 se sets determines the conformal class of the metric. This corresponds to 
 passive observations from a distant area of space which is filled by light
  sources.
\nWe will start by considering inverse problems for scalar non-l
 inear hyperbolic equations to explain our method. No previous knowledge of
  Lorentzian geometry or general relativity will be assumed.
\nUne récepti
 on suit la conférence / A reception follows.
\n 
END:VEVENT
BEGIN:VTIMEZONE
TZID:America/Montreal
X-LIC-LOCATION:America/Montreal
END:VTIMEZONE
END:VCALENDAR