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SUMMARY:Curl forces and beyond - Professor Sir Michael Berry\, University 
 of Bristol)
DTSTART:20170202T141500Z
DTEND:20170202T151500Z
UID:TALK68395@talks.cam.ac.uk
CONTACT:Edgar Engel
DESCRIPTION:Forces depending on position but which are not derivable from 
 a potential\, that is\, forces with non-zero curl\, give rise to dynamics 
 that is not Hamiltonian or Lagrangian\, while also being non-dissipative. 
 Noether’s theorem does not apply\, so the link between symmetries and co
 nservation laws is broken. The physical existence of curl forces has been 
 controversial and the subject of intense debate among engineers. But an ex
 ample is familiar in optics: force on a dielectric particle in an optical 
 field. Motion under curl forces near optical vortices can be understood in
  detail\, revealing a new and interesting kind of chaos. And the full seri
 es of ‘superadiabatic’ correction forces can be derived\, leading to a
 n exact slow manifold in which fast (internal) and slow (external) motion 
 of the particle is separated. There are related quantum effects.
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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