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Do virtual particles violate Conservation of Energy?

  1. May 31, 2004 #1
    We are all familiar with the Law of Conservation of Energy:

    Energy cannot be created nor destroyed

    In other words, the total energy in a closed system is constant.

    But if the above "axioms" are correct, how does it cope with the existence of virtual particles? In quantum physics, events are described by probability,which means the advent of an event can only be described as "likely" or "unlikely" to happen, but not "impossible". The chance that virtual particles been detected is miniscule, but it does happen, they are created due to the large uncerntainty of energy fluctuation in a very short time interval.

    What it struck me is the existence of these enigmatic particles but what is more amusing is that it has negative energy and mass, and it just pops out of nowhere in vacuum and disappears in the next moment. Surely this phenomena violates the Law of Conservation of Energy - "Energy cannot be created nor destroyed", but on the other hand, it might not have for the law of Conservation of Energy also states the total energy in a closed system is constant. Since virtual particles pertain negative energy and mass in vacuum, at the instant a virtual particle appears, another "real" particle would also appear in another place in the system to balance the amount of energy in the system.
  2. jcsd
  3. May 31, 2004 #2


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    Do you have a reference on the negative mass part of what you said? I had not heard that.
  4. Jun 1, 2004 #3

    Virtual particles are created in pairs, particle and antiparticle such that conservation laws are not violated. Also even so there is energy necessary to create them (the two seperated particles have more potential particles when created than when they recombine and annihilate) and this energy is stipulated to come from the uncertainty principle, giving it meaning not just as a limitation on our measurement, but a real physical meaning that particles do not have a definite energy but that the energy is physically uncertain.
  5. Jun 1, 2004 #4


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    the *definition* of virtual particles directly implies they violate the equation relating energy and momentum, ie they violate at least one of these. Here uncertainty principle enters the game: the violation can stand only during a very small time, about h/E. Because of this, they are called virtual.
  6. Jun 1, 2004 #5
    So for a very short time there can be an increase of energy/mass. Does this also work in the opposite direction? Can an already existing particle such as an electron or proton blink out of existence for a short period of time?
    Last edited: Jun 1, 2004
  7. Jun 1, 2004 #6
    No it cannot, because proton is not the antiparticle of electron. A positron is the real antiparticle of electron.

    I'm not sure if this argument is valid. When you say virtual particles are created in pairs, does that imply simultaneity? But in the real world there is no simultaneity. So, can two observers in two different frame of references see a different order of events?

    The above also rises the question whether the Law of Conservation of Energy is symmetrical at quantum scale?
  8. Jun 1, 2004 #7


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    Quoting from here:

  9. Jun 2, 2004 #8


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    The problem, you can violate energy for a brief lapse of time, or momenta in a short extension of space. But you can not violate charge conservation, so a electron can nor blink out of existence, it only can transform in other particle for such short interval. For instance it could become a virtual W- plus a virtual neutrino, and then both coalescing to make the original electron.

    Another example: a quark of charge +2/3 inside a proton becomes a quark -1/3 plus a virtual W-. Then the W-, instead of fusing again with the quark, disintegrates in electron plus antineutrino. This is called, surprise, "beta radiation".
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