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A Can strings increase length without changing their energy?

  1. Jan 9, 2017 #1
    For a string in string theory,
    Energy = string tension * length
    So I'm wondering if it can increase its length with increasing its energy.
     
  2. jcsd
  3. Jan 10, 2017 #2

    jambaugh

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    Short Answer: Yes, Solve and you get Tension = 0.

    But since string theory is not yet a physical theory there is not yet a physical "can it happen that-a-way" answer. Whether the premises of the theory allow it will depend on what premises have been adopted (beyond my knowledge here) but I suspect zero tension strings would be considered "un-physical".
     
  4. Jan 10, 2017 #3

    haushofer

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    No, I don''t think so. In this respect strings and branes differ. Brane surface/volumes/... can develop spikes without changing its energy.

    I don't understand jambaugh's Answer.
     
  5. Jan 10, 2017 #4

    mfb

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    I would be surprised if a classical approach works here.
     
  6. Jan 10, 2017 #5

    jambaugh

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    To clarify my answer. In the example of special relativity, a physical theory, the answer to "can an object travel faster than c" is a definitive "no". It is physically impossible. In the example of say, "geometry" which is a mathematical theory not a physical one, if you ask "can two lines intersect at more than one point?" then the answer is "it depends on which geometry you consider". String/brane theories are still in the "mathematical theory" category though they are aimed at constructing a physical theory at some point. They rather represent classes or possible physical theories.
     
  7. Jan 12, 2017 at 9:57 AM #6

    haushofer

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    I don''t understand. I regard this as a mathematical question which should be answered by looking at the Nambu-Goto action. String theory would be ill-defined if the answer to the OP would be "yes", because nothing would prevent the string from becoming arbitrarily long. How would you obtain a discrete particle spectrum then, for instance ?
     
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