Virtual particles aren't particles (2011) | Hacker News Reader

Virtual particles aren't particles (2011)

profmattstrassler.com

73 pointskrohling15 comments

The "virtual" particles are intended to avoid the "action at a distance" issue with fields. The virtual particles are place-holders for calculations.

They came about from looking at the philosophical problem of "What is a field"? A field between two interacting electrons changes the electrons trajectory.

OK... but what does it mean for the electrons to "interact"? Saying "there's a field" is just a circular argument.

The better response is "they exchange a photon". OK, but is the photon real? No... it's just a place-holder to make calculations easier.

Do two electrons actually exchange virtual photons? No one really knows... All we can say is that the theoretical calculations match the experimental ones. What that means is a question for philosophers. :)

Is it a question for philosophers, though? Or is it just a current limitation of our model that we don't understand? They are obviously "communicating" somehow. The mechanism is simply unknown.

It's one of those dark, dirty corners of physics theory that doesn't have a great conceptual explanation (like wave function collapse). The math works but we honestly don't have a great understanding of "what's really happening".

The question of meaning is a question for philosophers. Physicists deal with what they can model / explain.

> They are obviously "communicating" somehow. The mechanism is simply unknown.

The mechanism is the "virtual particles". Whether those particles have physical existence is a question physicists avoid.

The best answer is that the model (i.e. the explanation for reality) matches reality.

Does this mean that the model accurately and correctly describes the underlying mechanism for communication? The best answer to that is "Yes, so far as we can tell".

Virtual particles are an artefact of the calculation method usually used, perturbation theory, and the Feynmann diagrams that produces. They needn't exist with other methods.

Why is physics is not an artifact of the calculation method used?

This is an amazing article that's made a lot of things much clearer for me. To stop thinking of particles as "things" and start thinking of them as certain configurations of a field. Perhaps it makes sense to think of them as configurations that the mathematics ensures are somehow stable.

And then virtual particles and other interactions make a lot more sense. They are just other configurations.

My new understanding might not be correct but this article has certainly opened my eyes and suddenly a lot of previous things make a lot more sense!

Nice summary. It's really interesting stuff isn't it?

Strassler has a lot of articles of this kind on his site, highly recommended. Check the articles menu on his homepage. There's a nice series on dark matter.

There's also this page with various links: http://profmattstrassler.com/about/about-this-site-and-how-t...

Something that I found rather interesting but still don't quite understand is the effect of the Uncertainty Principle in a vacuum. Apparently the Uncertainty Principle affects not only particles, but fields as well (which in my mind is possibly due to the mass/energy equivalence?). This manifests as disturbances, which is what causes these virtual particles to "appear" in a vacuum.

thanks. Human language seems to be an impediment to understanding here due to previous definitions of terms. Sometimes, it is better to create a completely new term than overload an old already-understood term.

Didn't read the article, but aren't the "holes" as encountered in semiconductor physics also virtual particles? Or is this a new concept?

That is something different, holes are quasiparticles [1], phenomena that show characteristics of and can be mathematically described like particles but are not particles but for example collections of particles or the absence of a particles in case of a holes. They really show particle like behaviour while virtual particles don't.

[1] https://en.wikipedia.org/wiki/Quasiparticle

Wouldn't "emergent particle" be a better term? The fact that it is a side effect of multiple particles doesn't make its effects less tangible. It feels like object orientation is clouding our perception.

Programming analogy:

There are several ways to implement the laws of physics. Virtual particles are an implementation detail, you can factor them out of the code, but it makes it a bit more readable.

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