@ACuriousMind I legitimately forgot about that rule, although it's likely because I still don't understand the rationale. To what end are we avoiding talking about certain users?
I get the whole "he's not here to defend himself" thing, but do you think he honestly cares about our opinions if he keeps getting himself banned?
@SirCumference It doesn't matter whether this specific user actually cares. The rule is in place 1. to protect those who might care. 2. to generally prevent chat from piling onto banned users, whether they actually "deserve" it or not.
@MoreAnonymous What would be the benefit of knowing two links to and the same thing?
This argument works nicely in wave mechanics as well (no need for Heisenberg time evolultion, you seem to dislike): " A state that only exists for a short time cannot have a definite energy. To have a definite energy, the frequency of the state must be defined accurately, and this requires the state to hang around for many cycles, the reciprocal of the required accuracy."
@Rudi_Birnbaum I have no idea how this conversation got there but I think Anonymous is talking about relative phase measurements as in physics.stackexchange.com/q/322013/50583
To me it seems everything is explained in the WP link I gave. Everything else, about these "non-unitary" things to me seems to be based on a incomplete understanding of the involved technicalites.
@MoreAnonymous Usually, they would have left a comment if they were interested in starting a discussion about the question with you. You can of course try pinging them, but do not ping them more than once if they do not respond. Many users vote to close several questions in a day and they cannot be expected to have time to debate their decision for all of them.
3rd way: lets not talk about the measurement ... (maybe even call it non-unitary) 4th way: the measurement can be modelled as a unitary system once apparatus is taken into account
@ACuriousMind would any of you be willing to help me rephrase this? (I mean if so it would be gr8 as I think I only get $1$ chance(/edit) to effectively re-open this question) ... I would be very grateful if yes ... Please let me ASAP ... I'd be willing to participate in some chat at a convenient time for any of you?
I'm planning on multiple tagging people in the above comment
@MoreAnonymous 1. I, personally, have no interest in talking about the content of that question any further. 2. If you intend to send this to the people who closed your question, some further advice:
a) Don't use textspeak ("gr8"), write full, coherent sentences. You expect these people to expend effort for you in their voluntary time here, show some effort in return. b) Avoid things like "Let me [know?] ASAP". There is absolutely no urgency to anything that happens on this site, and people will just view this as being pushy.
Okay heres another difference .. 3 says apparatus is something that lets us do a measurement ... 4 says apparatus is just another system (yes I do use the word quasi-classical)
But 4 is of the opinion u can do it with quantum as well .. its just very difficult
@MoreAnonymous It basically boils down to two points: Are you willing to accept an explanation within the framework of any_ONE_ of the QM formulations that made it into textbooks. If yes you go with the WP link. If no and you insist on technicalities or subtilities that are moreover object of current research, in that case you must improve you question significantly, and I am afraid that means deepening your understanding of QM prior to the formulation of the question.
Otherwise this might only lead from one to the next confusion.
@Rudi_Birnbaum I'm an open minded (and even dodgy) person :P ... I go with that ... that which lets me expand on usage of current tools ...
as for "technicalities or subtilities that are moreover object of current research" ... I do provide links including lecture notes
And I think Landau wrote his book ages ago
Intuitively I think it's plausible but Im not sure ... Hence the question
@Rudi_Birnbaum I am trying to learn about this subject as soon as possible I wasnt even aware that with different interpretations u can get different mileage outta the same derivation ... This now seems plausible is welll woooow
physical cases the this "quasi-classical measuring apparatus and the Copenhagen interpretation" seem to work for that the original objection stops (way 3)?
@Rudi_Birnbaum by mileage I mean if we assume way 4 then does the applicability of the derivation to the number of physical systems increase as compared to using way 3?
Is this better/
?
If the number of systems increase then thats my metric of mileage
@Rudi_Birnbaum okay (to be fair the question was intended to be broader ... but maybe making it narrower will help ... Also my family doesnt like to talk about physics with me ... Esp on freewill )
So let's say I'm interested in a specific case of the energy time uncertainty principle:
Why can't the time between $2$ measurements be $0$
So there this great derivation on the internet (joshphysics) answer.
Now, I ponder about it and figure this derivation doesnt apply to that case! Because there is no notion of a measurment in his derivation (way 3)
However, after asking around there is one way to make it apply to that case ... it seems like magic but it seems to say there is no measurement at all (way 4: The measurement is a unitary process when the apparatus is taken into account)
@Rudi_Birnbaum Grandma style no math equation either
*physical situation which I can't talk about? = any physical situation I can't apply the time energy uncertainty principle to (esp with way 4)
"Why can't the time between $2$ measurements be $0$" that sounds like a much more feasible question for (p)se. Maybe with time being $\varepsilon>0$ it could even make sense.
I think what I've got in mind is that a frequent -application- of the time-uncertainty relation is to situations where two measurements are made and $\Delta t$ is the time between them. (whether that is a -sound- application is what I'm wondering)
@Rudi_Birnbaum Feel free to clarify I am tired so I tend to skip sentences and make mistakes
@Rudi_Birnbaum Let's just talk about this observable being the energy of the system
Sorry took me time to figure out the quesiton
This is what I was talking about:
Also Landau states: "From section 44 of Landau, the ΔE in the time-uncertainty relation is the difference "between two exactly measured values of the energy E+ε at two different instants, and not the uncertainty in the value of the energy at a given instant" (for a system of two parts with energies E and measuring apparatus energy ε)"
So basically (I think) Landau is saying if you measure the energy $E_1$ at $t_1$ and then the energy $E_2$ at $t_2$ .. Then using $/delta x = x_2 - x_1$ you can get an energy time uncertanity princple
There now Landau with his way 4 manages to say what he said I suspect with way 3 with that derivation it would be impossible
*derivation or interpretation
@Rudi_Birnbaum This might be in alignment with way 3 (?)
@Rudi_Birnbaum Im guessing what you want to say is:
The uncertainty principle for energy and time is not a canonical uncertainty relation because it is not based/produced by canonical hamiltonian variables, instead it expresses dispersion and lifetime of a state. There is a confusion of a cartesian space-time x,t (used as parameters) and canonical position and momenta (q,p) which are functions of these parameters (however simple in some cases, like q=x)
@NovaliumCompany U remind me of a uni housemate who others didnt like ... He talked way too much about politics and intellectual stuff ... Something happened with him in school and he lacked social interactions and thus social skills ...
But to me he was a really nice genuine person ... If I had to tell him something I'd say try talking about something others are interested in too
@NovaliumCompany its okay when they have some kind opinion which doesn't conform to mainstream and they don't answer questions which contradict them and they convince u in chat about their ideas ... For which u go through hell ... If only I found that paper earlier
There is a fair chance that OP chose the title How does a linear operator act on a bra? with no double entendre in mind, but of course it instantly became clickbait in the HNQ!
@MoreAnonymous That question is all over the place, very had to make any sense of it, and still days later - nowhere did you explain why unitarity for the Schrodinger/Heisenberg equations fails... There is no derivation of these equations for non-unitary processes... Even worse everything you're saying would apply to all aspects of QM not just time-energy... Way 1 (the velocity comment) makes zero sense, way 2 on continuity is as unexplained as the unitarity issue...
Way 3 also makes no sense the way it's written. So far it still seems to be the case that the buzzwords 'non-unitarity' and 'continuity' randomly mean everything fails but it's never explicitly shown how these buzzwords actually show up to wreck everything. I literally have no idea how you concluded "bolbteppa is and was wrong!"
