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Do Virtual Particles Cause The Wave Function To Collapse?

  1. May 24, 2015 #1
    I was just wondering, when particles interact with a force (which would be all the time) , does it cause the wave function to collapse? If so does that mean particles interact with forces in small time periods, since we know particles exist as a probability function? I just assumed that fields of force do not cause the particle's wave function to collapse, so when a particle moves through a field, what is actually moving, the particle or is it a shift in the probability distribution?
  2. jcsd
  3. May 24, 2015 #2


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    As has been beaten to death on this forum, virtual particles are a mathematical fiction used in some calculations. They do not have corporeal existence.
  4. May 24, 2015 #3

    Simon Bridge

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    ... to add to that - wavefunctions also do not have corporeal existence.
    But I suspect that Ryan-Duddy is mixing up several different descriptions of quantum mechanics.
    This is not surprising because pop-sci shows do the same all the time. Lets see what can be done about it...

    "collapse" in this context is not a physical phenomena - it just means there is a clear "before" state and a clear "after" state, and we can do our maths on these without knowing, in detail, how one turns into the other.

    All measurement processes involve forces - forces are often described as being mediated by virtual particles. In this sense, virtual particles can be said to contribute to the "collapse". Probably lots of them. It's not really a useful observation because it's just another way of saying "stuff happened and we dunno what". Consider how complicated a car crash is while it's going on - though the initial and final states of the cars can be simple. There is not just one thing happening to the cars that gets them from one state to the other, and it is often pointless to untangle the mess of interactions. We just say that the initial state turned (i.e. "collapsed") into the final state in such a way that total momentum was conserved.

    Particles and probability functions are different things - so: no - particles do not exist as probability functions. Some properties of particles, such as their position, can be described in terms of probability density functions. It is more usual to use a probability amplitude function (called a wave-functon). However, descriptions involving virtual particles for forces it is more usual to use QED of QFT and state vectors.
    Particles do not interact with force fields - they interact with each other.
    When you use a model where forces are mediated by virtual particles - the actual force-fields kinda go away.
    Particles interact with each other in varying time frames depending on the interaction - what counts as a small time frame depends on what you are comparing it to. In Feynman diagrams, the particles come together at a point - suggesting zero time - but the interaction is the whole diagram.

    Recall that these particles have no corporeal existence - they are a step in a calculation, a trick used to make the math easier.
    The "wave function collapse" is by definition "a shift in the probability density".
    The collapse is caused by a measurement.
    All methods of measurement involve force fields ... look at the stern-gerlach apparatus for eg.
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