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Velocity of Bosonic String

  1. May 28, 2004 #1
    I've started to study superstring now and I have a little doubt. If you consider the open string with free ends, Polchinski's book says that the ends move with the speed of light. But if the ends move this fast, as the length of the string is fixed the rest of it must have the same velocity. If it depends only on the boundary conditions, massive states of the string will have the same velocity... It should not be this way, what am I doing wrong?
  2. jcsd
  3. May 29, 2004 #2


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    What they did was to imagine the string SPINNING, so the middle was moving slower than the ends. But I think the real answer was to remove the freedom from the ends by having them fixed with Dirichlet boundary conditions to what were at first called "walls" and are now called D-branes. This was I believe the origin of the brane idea in string physics.
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