And

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????? ?????????? ???????? And Maxwell
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Speed of light in a medium

• I run slower in water than I do on a track.
  Similarly, matter impedes the movement of light,
  and light does not necessarily travel at c(3 X
  108 m/s) inside a medium, like glass, water,
  air, etc. c is the speed of light in a vacuum.
• frequency is constant
• nc/v, called the index of refraction. ngt1 always.

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Cerenkov radiation is to light as a sonic boom is
to sound This is a picture from inside a nuclear
reactor (which is on). Nuclear fission produces
high energy charged particles which move faster
than light IN WATER (nothing goes faster than
light in a vacuum).
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Invisibility cloak

• ok, so ngt1but if I have a composite material, a
  metamaterial, which is made of normal
  physics-obeying matter then maybe I could build a
  negative refractive index (U.Tokyo, berkeley, UCL
  london, duke,etc)