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Do tachyons exist or not?if so causality will be failed

  1. Sep 11, 2004 #1
    do tachyons exist or not?if so causality will be failed!!!

    is there any particle that can travel faster than photon and still preserve the einstein's postulates?
    if they exist how can we explain the space like seperated events that voilate the causality.
    :surprised
     
  2. jcsd
  3. Sep 11, 2004 #2

    HallsofIvy

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    There is certainly no known particle that moves faster than light. Yes, if such a particle existed AND could interact with tardyons, then causality could be violated.
    Some people argue that if tachyons existed and could NOT interact with tardyons, then we would never know of there existance and so, as far as we are concerned they don't exist!
     
  4. Sep 11, 2004 #3
    Tachyons do not exist because the have unphysical properties like negative mass and so on...

    In QFT there is a nice way "to get rid of them", namely the continuous breakdown of symmetry (in the vacuum-state like the U(1)-symmetry). Through the Higgs-mechanism which "gives" elementary particles their mass, these tachyons can acquire positive mass-values.

    For clarity : In the Standard Model all elementary particles are masless because mass mixes up the two different chiralities (left-handed and right handed). It is proven that particles of left handed chirality behave "different" when it comes to the four interactions then those with right-handed chirality.

    I must say that the last text is not perferctly ok but it gives you a pretty clear image of what is meant by the statement that elemantary particles are massless. If you wanne know more, please just let me know. I will be more the happy to elaborate.

    regards
    marlon
     
  5. Sep 12, 2004 #4

    pervect

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    Nobody's ever seen a tachyon, so there's no evidence that they exist. Besides possible effects on causality (I gather the issue is more complicated than it first appears, see for instance )

    http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/tachyons.html

    there are some other problems with tachyons, like the tendency to create an unstable vacuum in quantum field theory, and the creation of rocket drives with efficiences greater than 100%. So they probably don't exist.
     
  6. Sep 12, 2004 #5
    If you want to travel faster than light, your mass must be imaginary ... could you imagine that?
     
  7. Sep 12, 2004 #6
    A guy called Kostelecky formulated in 1985 the hypothesis that neutrinos are really particles moving faster than light. In this theory, neutrinos are called tachyonic neutrinos. But tachyons in SR have imaginary mass and neutrinos have a little positive mass, so the hypothesis seems incorrect
    Anyway, in SR, doesn't matter if the particle is a neutrino, a photino or whatever: if its velocity is superior to c there's violation of causality
     
  8. Sep 14, 2004 #7
  9. Sep 15, 2004 #8

    selfAdjoint

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    Only in "deformed" Lorentz dynamics.
     
  10. Sep 15, 2004 #9
    Self adjoint,

    IN regards to Barton Zwiebeck.

    The topic of this post is about Tachyon's. Does Barton's view show this developement and origination?

    We have had our talks before about Tachyon Condensation in String Theory. Do you recall? I was interested in how this is percieved, and how you might have thought Barton Zweibeck contributed?

    Regards
     
    Last edited: Sep 15, 2004
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