What Physicists Mean By "Creation From Nothing"

But that’s surely not to be taken literally, right? It’s not that there are literal ball-on-a-spring objects which collectively constitute a field whose oscillations are particles, even if the behavior of these “things” are similar to that of a ball-on-a-spring. What is a field really, then? It surely must be something physical and tangible, not mere Platonic mathematical objects, because particles (and atoms and molecules) are physical and tangible. I don’t think we think about this much in QFT - at some point we just write down an equation (analogous to the plots of oscillations that you drew) and proceed with calculations.

(For this discussion, let’s put aside the caveat that QFT is not a final theory, that it could really be strings, etc. - these only push back the discussion one step back.)

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I think it’s more accurate to put it this way: QFT is defined in such a way that mathematically, when there is no oscillation there is no particle. Of course, a definition by itself means little - QFT could be completely wrong. But, we have done many experimental tests of QFT and found that it corroborates extremely well to what we observe in nature. Thus, we have good reason to believe its claims - when there is no oscillation there is no particle.

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These are all interesting questions - as you know, physicists love to reduce things and be done with it. I suppose that whether fields are real or existing depends on what your definitions of real and existing are.

This is an interesting point:

Field to me is as tangible as particles. I have never seen a particle directly, I have only seen its affect on my experiments. That’s as far as I would go to ascribe some sort of tangibility to particles, but then I would say that the same is true for fields.

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So from what I can gather, the idea that there is no particle without oscillation is derived from interpreting a mathematical equation as such, and the only way it is corroborated is by confirming the equation works. Is that correct? And could the 0 in the equation be interpreted differently, e.g., as humanly undetectable?

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I’m curious, what is “ℏ” in the equation above?

This is correct.

This is sort of correct, but just to be clear: “the equation” here refers to QFT as a whole, not necessarily the statement about no particles in particular. I don’t know if anyone has directly experimentally verified specifically the statement that there are no particles when there is no oscillation. By itself, this statement doesn’t mean much to an experimental physicist. To actually test QFT, you need to convert theoretical, mathematical statements like these into statements about quantities that are accessible in the lab. This is we test QFT by say, measuring the magnetism (or g-factor) of the electron (see explanation here). Because QFT turns out to be extraordinarily correct in most of these tests, we think that it is a robust theory and we can believe its claims more generally without having to test every single equation directly (if that is even a coherent notion to talk about).

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The Planck’s constant divided by 2π. It’s just some number.

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So how do virtual particles fit into the narrative of creation from nothing. It seems they always enter this conversation at some point or another. Are they relevant to the discussion?

Virtual particles are particles, e.g. electrons, photons, etc, that do not have the right mass. They are most useful as a mathematical technique in integrating some quantities in quantum field theory. However, under certain circumstances they can produce observable effects. They result as a consequence from the energy-time uncertainty relation that I wrote in the main post:

\Delta E \Delta t \ge \frac{\hbar}{2}

Because the energy cannot be pinned down exactly, for a small enough length of time physics allows temporary violations of the conservation of energy that allows for these virtual particles to be generated.

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Does that mean it can’t be accurately measured?

No, there is an inherent variance in the energy. This is analogous to the uncertainty relation between momentum and position.

Oh, OK. So how is it determined what is happening with disturbances between energy fields in relation to virtual particles? Seems like it would create a bit of uncertainty as to what is actually going on if there is difficulty in “pinning down” both the energy and the particle, wouldn’t it?

I am not sure what are these “disturbances between energy fields” you are referring to.

Oh, I read that virtual particles are just a result of disturbances of an energy field caused by interference from a nearby energy field or fields. Is that not correct?

Virtual particles are the result of fluctuations of the quantum vacuum due to quantum uncertainty relations, such as the energy-time uncertainty relation I wrote in previous posts.

Note that despite its name, the “uncertainty” in “uncertainty principles” does not mean that we are “uncertain” of what physical process is going on. The “uncertainty” in “uncertainty principles” refers to the fact that things like energy or momentum are better described by a probability distribution. But we know exactly how these probability distributions behave through the well-corroborated equations of quantum mechanics.

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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.