What Physicists Mean By "Creation From Nothing"

No particle(wave) is fully a particle(wave) but both, neither, or a superposition of particle-like features and wave-like features. Because of the Uncertainty principle, ΔEΔt≥ℏ2 you can’t get to all particle-like features or all wave-like features.

Let’s ask a similar question, which might help answer your question:

Suppose I look at a spot on my desk where there could be a coffee cup. However, I see no coffee cup, and there is no other evidence I can discern that would indicate the presence of a coffee cup.

Would it be correct to conclude from this that there is no coffee cup on that spot on the desk?

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Here is the article I read: Virtual Particles: What are they? – Of Particular Significance

Maybe I’m not expressing it properly, but it seems he’s saying that it’s electron fields, electromagnetic fields, positron fields, etc., that get disturbed by coming into proximity or contact with the same or other types of fields and the disturbances are what cause the “virtual particles” to appear.

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Okay, this gives better context. These fields are the same types of fields that I mentioned in the main post, i.e. they are analogous to the many ball-on-a-spring system. They are not, as you say,

The “disturbance” that Prof. Strassler talks about are what I call “oscillations”, and the reason that the presence of other fields can cause this disturbance are the uncertainty principles. Note that these are all words that physicists do not typically use to talk to each other, but more a translation of the math that we used to communicate with other physicists.

I am not quite sure what you are trying to say here. To most physicists, a particle is always a wave function. What lay people call a “particle”, i.e. a very localized object, is just a wave function that is very peaked in space.

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I am saying that the wave-particle duality is another way of describing the Heisenberg Uncertainty principle.

I’m not clear on what you mean here. It’s not clear to me what the connection is between the uncertainty principles, and the reason for the presence of other fields causing disturbance. Wouldn’t it be the electrical charges in the other fields that are the reason for the disturbance?

The presence of the other fields cannot generate virtual photons if you don’t allow for the temporary violations of energy conservation that is due to the energy-time uncertainty principles.

A caveat: in what physicists call the non-perturbative regime (at very high energies), this picture fails and what you get are just these disturbances, not particles.

Okay, let me make a comment on your edited post:

This depends on what you mean by “particles” and “waves”. In quantum mechanics, all particles are wave-functions. What people usually call “particle”, i.e. something that is highly localized in space is just a wavefunction that is highly confined in space.

If you mean particle in the sense of something highly localized in space, then this is allowed by the Heisenberg Uncertainty Principle (the one on position and momentum). Indeed, this is exactly what happens when you make an observation to determine the particle’s position and collapse the wave function.

If you do not mean this, then I need a clarification on what you mean by “particles” and “waves”.

The problem is in our definition of the words particle and waves. A particle being a solid thing that has a length, width, height, and mass. And a wave being a sine wave of infinite duration with a frequency, wavelength, and velocity. Both definitions are not allowed in QM.

Whose definitions?

These are not my definitions, or the typical physicists’.

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Strassler:

It turns out that since electrons carry electric charge, their very presence disturbs the electromagnetic field around them, and so electrons spend some of their time as a combination of two disturbances, one in in the electron field and one in the electromagnetic field . The disturbance in the electron field is not an electron particle, and the disturbance in the photon field is not a photon particle. However, the combination of the two is just such as to be a nice ripple, with a well-defined energy and momentum, and with an electron’s mass.

If I’m following this correctly, it seems to be saying that there’s a time when the electron is kind of in “limbo” where it’s got one foot in one field and one in the other. When that combining of the two happens the effect is what for a moment appears like a particle. Once that moment of combination is over, the mysterious particle seems to have “disappeared.”

Is this appearance of the “mystery” particle what is meant by the notion of a temporary violation of energy conservation?

First of, Prof. Strassler (who gave some lectures in a class I took back when I was a graduate student) is giving a picture that is valid in the non-perturbative regime that I mentioned in my last post. This regime is the very high energy regime. What he calls “virtual particles” are not really particles - they are excitations in the photon/electron/what-have-you field. The virtual particles that I mentioned are things that actually look like particles - which are approximations of Prof. Strassler’s more general excitations in the low energy (perturbative regime). We are referring to slightly different things. Perhaps this accounts for some of your confusion.

In general, virtual particles disobey the conservation of energy. This is only allowed for a brief period of time that one can compute using the uncertainty principle. Without the uncertainty principle, you are not allowed to make these virtual particles, as they disobey the conservation of energy.

Perhaps this paragraph from Gordon Kane (source) makes more sense to you:

Quantum mechanics allows, and indeed requires, temporary violations of conservation of energy, so one particle can become a pair of heavier particles (the so-called virtual particles), which quickly rejoin into the original particle as if they had never been there.

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Oh, OK. What do you mean by “actually look like particles?” Is that in reference to the increase in weight which isn’t present in the non-perturbative regime?

A particular excitation (oscillation) of the fields.

Oh. So the oscillation of the virtual particle in the perturbative regime looks like the oscillation of a particle, the difference being the former is only for a moment while the latter is a sustained signal?

Correct!

Both of them in general last only for a moment. The amount of time is given by the \Delta t in the energy-time uncertainty relation.

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One down, and how many to go…? :slight_smile:

OK. Intuitively one would expect an actual particle oscillation to last more than a moment since, well, a particle is a particle. So for an actual particle does its oscillation only last briefly because it keeps moving back and forth between different fields, and therefore the signal is lost at points in those in between moments?

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In general, virtual particles do not have the right mass, they are not the same as a regular particle.

At this point, I think we are hitting the limit of intuition and analogies. In the end, words such as “disturbances” and “oscillations” can only go so far, and (I think) actually becomes more difficult to understand than just learning the mathematics behind it. If you are curious about deeper details of the topic, I think you should pick up a physics book. I recommend “Quantum Field Theory for the Gifted Amateur”.

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I have that book! It is really good, though I wish it spent just a little bit more time discussing what QFT looks like on different interpretations of quantum mechanics.

I also recently came across this thesis in the philosophy of physics, the fourth chapter of which explains quite well how QFT relates to non-relativistic quantum mechanics.

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