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> 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
by bowsamic 2y ago
> 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
- Galatians4_16 2y agoGödel's incompleteness Theorem, applied to QM, in three paragraphs.
- eigenket 2y agoNeither 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 2y agoGuess 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 2y agoPhysics isn’t based on mathematics and logical systems, it’s based on measurements that the mathematics are chosen to fit
- cb321 2y agoThere 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_Theory_Possible.html?id=rcrf0P8DSe0C 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 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).
- bowsamic 2y agoOf course there are attempts and opinions but I'm pointing out that there is absolutely no consensus
- elashri 2y agoThey 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.
- griffzhowl 2y agoThanks for the reference! Looks like an intriguing book from a glance at the contents pages
- dguest 2y agoAnother 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.