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SUMMARY:What is the momentum of a photon propagating in a medium? - Prof. 
 Steve Barnett\, University of Strathclyde
DTSTART:20090618T131500Z
DTEND:20090618T141500Z
UID:TALK18767@talks.cam.ac.uk
CONTACT:Dr Jonathan Keeling
DESCRIPTION:  We are used to identifying the momentum of a photon as _ħk_
  or _h/λ_. This fundamental idea underlies much of\nquantum physics and\,
  indeed\, was used by de Broglie in his derivation of de Broglie waves. Bu
 t what happens to this\nmomentum when the photon enters a (transparent) me
 dium? A very simple (even unanswerable?) derivation based\non Newton’s f
 irst law of motion leads to Abraham’s result that the momentum is _reduc
 ed by_ the refractive index.\nUnfortunately\, an equally simple derivation
  points unambiguously to Minkowski’s result that that the momentum is\n_
 increased_ by the refractive index. Even in 2009\, after more than a centu
 ry of debate\, experimental papers are being\npublished in high-profile jo
 urnals supporting one or other of these momenta. So what is going on? In a
  sense both\nmomenta are correct ...\n
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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