Skip to main content
19 events
when toggle format what by license comment
Feb 20, 2024 at 7:02 history edited Qmechanic
edited tags; edited tags
Feb 20, 2024 at 5:01 history edited Charles Hudgins CC BY-SA 4.0
added 4 characters in body
Oct 7, 2022 at 21:28 comment added Mahir Lokvancic Re "can't a quantum field be a superposition of states with different particle content...:" Actually, it already is, but it is only the interaction among systems (fields) that manifests itself thru quanta. Again, why the interactions are mediated via quanta (at least "hard" interactions) is basically an axiom of nature, to the best of my understanding of these matters. This is rather similar to the measurement problem in quantum mechanics -- it is simply a postulate (despite some claims from decoherence theories, etc, to the contrary).
Oct 7, 2022 at 21:28 comment added Mahir Lokvancic Re "why do we seem to always observe states with definite particle content:" I doubt this can be answered (reduced to other basic phenomena); it simply is so, something that we observe the way nature works. It could be because "continuous-exchange-of energy/momenta" universe could be unstable (as already indicated by original Planck's insight). Given this backdrop, we developed mathematical tools and structures that seem to incorporate the concept of quanta remarkably well and faithfully, so much so that you can essentially read nature from mathematics.
Oct 7, 2022 at 1:53 comment added Charles Hudgins @MahirLokvancic Both. My question boils down to: why do we seem to always observe states with definite particle content? Even when we aren't directly making observations, it seems that low energy macroscopic interactions happen as though there is definite particle content. In general, can't a quantum field be a superposition of states with different particle content? Why don't we see that playing out in low energy phenomena? Or, said differently, why isn't it a problem that we barely ever consider states with particle number superposition when describing phenomena?
Oct 6, 2022 at 10:16 comment added Mahir Lokvancic Are you phrasing the question in the context of virtual particles or real particles? (My impression about QFT is that it is the former with the implicit interpretation, whereas the latter has a straightforward interpretation with experiment; specific coefficients in the QFT equations correspond to elements of reality that we perceive as quanta.)
Oct 5, 2022 at 1:07 comment added DanielSank In some sense, "particle" means "the thing you can observe about a quantum field".
Oct 4, 2022 at 21:05 answer added Dexter Kim timeline score: 2
Oct 4, 2022 at 18:36 comment added michael nettleton Not all particles are observable in the conventional sense; indeed most are identified by their effects such as gravitational ones.
Oct 2, 2022 at 21:47 answer added John Doty timeline score: 2
S Oct 2, 2022 at 21:02 history mod moved comments to chat
S Oct 2, 2022 at 21:02 comment added Buzz Comments are not for extended discussion; this conversation has been moved to chat.
Oct 1, 2022 at 11:39 history edited Charles Hudgins CC BY-SA 4.0
added 41 characters in body
Sep 30, 2022 at 9:00 history tweeted twitter.com/StackPhysics/status/1575772466156371968
Sep 30, 2022 at 8:07 history became hot network question
Sep 30, 2022 at 5:24 answer added FlatterMann timeline score: 29
Sep 30, 2022 at 4:57 answer added anna v timeline score: 17
Sep 30, 2022 at 3:50 answer added niels nielsen timeline score: 8
Sep 30, 2022 at 0:07 history asked Charles Hudgins CC BY-SA 4.0