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Virtual particles

  1. Nov 29, 2005 #1


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  2. jcsd
  3. Nov 29, 2005 #2


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    Can someone help me? I need the answer urgently. Is it real or just nonesense.
    Thanks in advance.
  4. Nov 29, 2005 #3
    The second it mutters the phrase "let's say it travelled faster than light and travelled backwards in time" you should realize his hypothetical is instantly nonsense.
  5. Nov 29, 2005 #4


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    but, isnt it true that particles can travel fster than light in plancks time(which cannot be measured)?
    : )she claims that she is talking about a short phase where every theory can be violated.
    Last edited: Nov 29, 2005
  6. Nov 29, 2005 #5
    You cannot travel faster than the speed of light. period. You can't travel at the speed of light unless you have zero rest mass, to which end you can only travel at the speed of light and no slower. Otherwise it would violate relativity, which we know to be in outstanding agreement with experiments.
  7. Nov 29, 2005 #6
    As far as I know, the appearance of virtual particles is allowed because of the Heisenburgh uncertainty principle where energy in relation to time just so happens to be the same units as momentum in relation to position. So energy can appear for a short moment so long as it is in a short enough timeline because it is not actually detectable.

    I don't think that the planck time allows for particles to travel faster than light though. Hmm, have to look it up.
  8. Nov 30, 2005 #7
    As regarding the post that was linked to:
    The statement about the electron turning into a positron is meaningless. A particle cannot simply turn into its antiparticle. It does not happen on its own. If it did- there would be a lot of talk about it in the physics world. This is in addition to the whole objection of Special Relativity being violated. The thought experiment is BS, like almost all of them are. This is why the world does real experiments to back up any theory.

  9. Nov 30, 2005 #8


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    If you just listen to yourself, you'll realize why you're not making any sense. If "Plank time" can't be measured, how in the world would you know that particle travelled faster than light within that time? We haven't even yet discussed the lack of experimental consequences of such a thing.

    What this implies is that the whole gooblygook that you are citing is based on a series of unverified speculations based on physics that was "learned" probably form a pop-science book. Such a thing has very seldom produced anything valid.

  10. Nov 30, 2005 #9
    When people say speed of light what wavelength do they use to measure this?
    Am i wrong in thinking that red light is slower than blue?

    are there then higher resolution particles that would then be faster?

    don't neutrinos travel through all matter are they say any faster than a green photon?

    questions from a novice
    many thanks
  11. Nov 30, 2005 #10


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    thanks so much for the replies
    i think every colour of light will travel in same speed. and, if neutrino can travel faster than green, that will imply that matter is travelling faster than light, fighting one on one with special relativity.
    well, answer from ultranovice, u wont want to trust me.

    ^well, am i right in this?
  12. Nov 30, 2005 #11

    Physics Monkey

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    Yes, all wavelengths of light travel at the same speed. Until fairly recently, neutrinos were thought to be massless which would require them to travel at the speed of light. Since neutrinos are now known to have mass, we know they must travel slower than light per special relativity. So neutrinos travel slower than green light which moves at the speed of light.
  13. Nov 30, 2005 #12
    Neutrinos are neutral leptons so they don't interact via the strong nuclear force or the electromagnetic force. They only interact throught the weak nuclear force and gravity now that we found they have a very, very small mass. So for traveling through material, we will disregard gravitational interactions, the cross section for the neutrino (just think of it as the probability of the neutrino to interact with something) to interact with some amount of matter is much smaller than the cross section of a photon to interact with the same matter. Traveling through matter faster than light is not unheard of. Contrary to what you may think this does not contradict Special Relativity. This is still assuming that neutrinos actually do travel faster than light in a certain medium (I am not sure that they do).

    to quote marlon in this thread:
    Last edited: Nov 30, 2005
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