[bowsamic]

> I've never seen a satisfactory definition of what a particle is as defined by modern field theory.

Quantum physics PhD here. It's because, we don't know. We don't have an ontology for quantum mechanics. We don't know what any of the mathematical model "actually is"

It's the same for basically all modern physics. We lack an ontology for it, so no we can't tell you "what it really is". Literally no one knows

But yes, the mathematical model is: a unit of excitation of the quantum field. What that actually is, is totally unknown

[cb321]

There are reasonable & reasoned attempts to make sense of all this, such as Sunny Auyang's "How is Quantum Field Theory Possible?" (https://books.google.com/books/about/How_is_Quantum_Field_Th... )

I think such attempts are not widely disseminated / taught to young physicists because older / more experienced ones believe that quantum gravity will re-write the situation anyway. { QG itself seems necessary since in General Relativity you "solve for the metric aka solve for time" self-consistently with mass-energy and that very same "time" is the background for QFT (which is what "makes" mass-energy). So, we don't really understand this model element we call "time" - so elemental to all our ideas of dynamics - without QG. Of course, the most direct quantum gravitational phenomena are, at present, at a subtle experimental scale due to the size of 'G'. This need not remain the case -- once we know what to look for - e.g., https://en.wikipedia.org/wiki/Fraunhofer_lines were beginning to reveal atomic quantum physics in 1802 almost a full century before Planck's black body work and barely after Benjamin Franklin-ian electrostatics and long before Maxwellian electrodynamics. }

I'm mostly just trying to strike a less hopeless note for jiggawatts and provide some reading material which might be accessible (if, as noted, is probably necessarily preliminary - EDIT and some might say this of all "Science" at all times, of course).

[elashri]

They are not taught because of two things. First it just philosophical opinions and the second is that it does not matter when you are actually working with quantum mechanics/ quantum field theory. So it is usually outside the realm of your standard course/s that have a lot to cover anyway.

[bowsamic]

Of course there are attempts and opinions but I'm pointing out that there is absolutely no consensus

[griffzhowl]

Thanks for the reference! Looks like an intriguing book from a glance at the contents pages

[dguest]

Another take on this: what do you expect the cutting edge of science to look like? Of course it's going to be "these things work, we're not quite sure why", once you know why they work it's no longer the cutting edge.

[Galatians4_16]

Gödel's incompleteness Theorem, applied to QM, in three paragraphs.

[eigenket]

Neither of Gödel's two incompleteness theorems apply to quantum mechanics.

The two theorems apply to logical systems which prove facts about the natural numbers. While this is an incredibly broad class of things, it doesn't include physical theories like quantum mechanics.

[Galatians4_16]

Guess I Dunning Kruegered, when I thought physics is based on mathematics and logical systems, to which a theory (itself having been proven) aught apply.

[bowsamic]

Physics isn’t based on mathematics and logical systems, it’s based on measurements that the mathematics are chosen to fit