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Why does observation collapse the wave function of a particle? Are you telling me particles are aware of humans?
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>observation
This single misnomer has been the biggest source of physics pseudery in the 21st century.-
physics scrotes are all to blame for this, they couldn’t develop nomenclature like chemchads.
yeah call it spin, braket, blackbody, dark matter, force, strange, bottom, energy, heat and jerk. the public is definitely not going to confuse these for the definitions they used before and use daily.-
Rofl chemscrotes:
>Oxygen: meaning "sharp/acidifying"
>It’s actually hydrogen that causes acidity in solution-
you are confusing acidity with oxidation/redox. to be fair oxidation is a bit of misnomer since the first oxidation reactions were rusting of iron with oxygen so all reactions where total number of electrons decreases is called oxidation. also oxidation isn’t a household word like energy and work are
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There is no real wavefunction collapse. You (the measuring device) just get entangled to the system you’re measuring.
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Basically this. Its like trying to Smell your own nose, or see your own Eyeball. You cannot do it because you require your eyeball to be able to see. You are entangled with the Eyeball
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quantum mechanics proves particles are aware.
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>Are you telling me particles are aware of humans?
not only are particles aware, but they are omniscient. they can know weather a particle they were entangled with during the big bang is spin up or down any number of galaxies away. -
The universe is a product of your mind, and you suffer from social anxiety.
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Stop manipulating people who don’t understand quantum physics into believing obviously scrotebrained hippy bullshit.
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>t. quantum-truth-denying seether
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>Thinks calling someone else a "seether" is a valid substitute for actually understanding the science.
ngmi-
Sadly, that’s like 50% of the "arguments" on LULZ.
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Consider the collapse of the wavefunction for a single particle in the double slit experiment.
There is a certain amount of information encoded in the particle waveform, but by observing which slit it passes through a lot of that information is passed from the waveform itself to the measurement system, thus there is not enough information left in the waveform to do anything other than go through one of the slits like a point-like particle. On the other hand, when not measured, the information has nowhere to go, and thus it must be encoded by the angle the particle exits the slits, with certain bands being more likely-
*some good comments.
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Observation doesn’t mean “a living being looked at it,” it means anything by which information could be determined about its state.
If you have a particle floating around in a box how are you going to determine, for example, where in the box it is? You’d have to bounce something off of it like photons (light) or other particles and infer its location from that. And it’s that interaction that causes a wavefunction collapse.
There is no “hands off” way to observe the properties of particles.-
The weird thing is why that entangled particle outside of the box also has its wave function collapse
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That’s definitely a weird aspect of quantum mechanics. Einstein himself was never satisfied with that “spooky action at a distance.”
The one thing that lets me tentatively accept it is that it is impossible to actually transmit any information across arbitrary distances using this property. Measuring an entangled particle before or after it has been collapsed by its partner gives indistinguishable results without corroboration from whoever has the partners.
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Anons, help a libarts scrote out: What does ‘information’ mean in the quantum context? I only understand it in the Shannon sense with regards to a channel carrying capacity which is dictated by the ‘maximal entropy’ possible in that channel.
This is how I always understood it. It’s sort of like if I ask my friend "hey, we still on for Saturday night?" the mere act of asking could change their answer "Oh shit, I forgot, yeah of course! Good thing you reminded me I was about to organize a different thing."
>inb4 someone says "sounds like a shit friend" instead of just accepting it as a naive analogy for my understanding of what’s happening-
"Information" in the quantum sense is not terribly different, it’s just that things are done in "quantum bits" instead of bits. This means that the storage states can be superpositions of 1 and 0 instead of just one or the other and they can be entangled with other qubits.
One important takeaway from quantum information theory is that a communication over a quantum channel by wave function collapse (teleported, as it were) cannot be decoded without a corresponding signal over a classical channel to convey what the sender got from their measurements. Information is thus still limited by the speed of light.>we don’t know.
Case closed, but it sure took a long time for us to get there, huh?
Ctrl-F4.Sure, but it’s not incompatible with CI which is where I hopped in.
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you lost poor brainlet me at "can be entangled with other qubits", kek so please excuse me if what I ask next is infuriating either in it’s ignorance or just plain being wrong…
Superimposition is the state of not being a 1 or a 0 right? I remember some Suskind lecture where he giving the example of if you put a single particle in a magnetic field to influence the ‘spin’ that the particle would give off a photon and the power of that photon would tell you what the spin of the particle was before you exerted a magnetic field on it to ‘observe it’. So lets say a ‘left’ spin could be 1, and a ‘right’ spin could be 0? Am I on the right track?
Now, in that example, the photon is part of measuring it through a ‘classical channel’ right?
Anyway, I still don’t understand how they can get ‘entangled’ with other qubits…-
>Anyway, I still don’t understand how they can get ‘entangled’ with other qubits…
Ultimately, you get entanglement because of the existence of superpositions. In turn, you get superpositions because the observables in Quantum mechanics are matrices instead of numbers and hence don’t necessarily commute i.e. if the observables are the matrices A and B, then AB is not necessarily equal to BA (the Heisenberg uncertainty principle for example states that the position and momentum observables don’t commute). As a consequence of this non-commutativity, when you have a state where the value of one observable is sharp, i.e. if you have a state which is an eigenvector of one of the observables, it need not be an eigenvector of some other observable – instead, it will be a linear combination of eigenvectors, which is what a superposition is.-
>if the observables are the matrices A and B, then AB is not necessarily equal to BA (the Heisenberg uncertainty principle for example states that the position and momentum observables don’t commute)
That bit actually helps a lot! Remembering they are matrices!The classical channel thing comes into play with communication by entangled particles. Say person A and person B each take one particle of an entangled pair. A can take a qubit and combine it with their particle to influence B’s particle as well, but the "sent" qubit can only be determined by B after A tells them what they measured on their particle.
>but you can get more complex systems.
Let’s just stick with the simple example for now, but good to know that there can be more complicated systems that can be in superimposed states
>The "how" of entangling is complicated, but it usually comes down to getting two particles produced from one event/interaction
I’m having a hard time understanding this, but it does make it a little more clearer.
> A can take a qubit and combine it with their particle to influence B’s particle as well, but the "sent" qubit can only be determined by B after A tells them what they measured on their particle.
I’m worried, because this sounds rather understandable because it resembles just any causality: person B can only know the state after person A sends the bit. And I fear I’ve missed out on something if it seems so simple
Thanks anons for your responses, they’re actually enlightening.-
>I’m worried, because this sounds rather understandable because it resembles just any causality
If it sounds mundane… it kinda is. With entanglement and the sender’s measurements, the receiver can produce the sent quantum states. The no-communication theorem holds that a quantum measurement/"collapse" alone cannot transfer information, as that would violate causality.
It’s a neat experiment though.In a mostly unrelated topic I found while looking up this stuff to make sure I wasn’t spouting bullshit, there’s been experiments that have been able to produce rudimentary photos of objects using photons that never encountered the object, but were entangled with photons that did.
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Superposition is a state of being some combination of basis states. "0" and "1" states of spin are the simplest to deal with (and what most quantum computing is woke af around) but you can get more complex systems. You’re on the right track with your example, yeah.
The "how" of entangling is complicated, but it usually comes down to getting two particles produced from one event/interaction (and then NOT TOUCHING THEM or they’ll collapse (decoherence)). I’m not actually sure how they even use them in quantum computing, I just know that they do.The classical channel thing comes into play with communication by entangled particles. Say person A and person B each take one particle of an entangled pair. A can take a qubit and combine it with their particle to influence B’s particle as well, but the "sent" qubit can only be determined by B after A tells them what they measured on their particle.
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>Sure, but it’s not incompatible with CI which is where I hopped in.
Then why did Einstein use it as a critique of CI?-
Because he felt it was insufficient.
While CI pretty much says "look we get results we don’t care HOW this works under the hood," Einstein wasn’t satisfied with that. Especially since the non-local character of the phenomenon flew in the face of how he believed reality should operate.
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At the quantum level, observation IS interaction. It is literally impossible to measure any results at that scale without "destroying" the state you were trying to measure.
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>It is conjectured by many that the particle is aware and this is not too unreasonable.
not just aware, tho. the particle is omniscient. particles know other states of all other particles at all times in the universe instantly.
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Photons are timeless, they are instantaneous ray traces in the environment. When the photon is created it knows if you observed it because its already ray traced its path through space and imparted momentum on your observation medium
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thats actually an interesting result in classical physics. I think it’s called Fermats principle or law or whatever. The principle is a ray of light through a heterogeneous medium takes the pat that minimizes time. so a ray of light somehow knows the distributions of different materials everywhere around it.
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I think another way to look at it is length contraction.
As any observer approaches the speed of light relative to another object, the length of that object as seen by the observer approaches 0.
So for light, which can travel at c, all distances are 0 for it. It arrives at its destination the moment it leaves.-
The why does it still take time for light to travel. Like it still takes years for us to see the light from a nearby star. Why wouldn’t we see it instantly?
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The time to travel as "observed" by the light itself, and as seen by observers in other reference frames, are two very different things.
From our point of view, it is the light itself that is contracted to a length of zero. A point. Kinda like a photon.-
>zero
+- the quantum uncertainty (position spectrum)
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I am surprised that there are actually good comments on anything bio/chem related ppl are usually scrotebrained.
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people always choose simple sentimentalist anthropocentric supernatural explanations instead of rigorous materialistic ones. look at what people used to think about the sun, gravity, earth, etc.
same thing with QM, there is probably an underlying mechanisms behind the weird observations that we don’t know yet but people like quantum mysticism scrotes and the like will always tell you it’s magic and justify irrational beliefs by god of the gaps (e.g. soul exists because of QM)-
>there is probably an underlying mechanisms behind the weird observations that we don’t know yet
I mean, no shit?
A significant motivating force behind QM (and similarly nuclear science, on a more macro level) is that we don’t know how the “true” underpinnings of these things work, so we instead build our understanding around statistical observations of what we CAN see.
We can’t peer deep enough into an unstable atom to see when it will decay, but by observing large populations of them we can still get ranges/averages that we can actually use.
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>people always choose simple sentimentalist anthropocentric supernatural explanations instead of rigorous materialistic ones. look at what people used to think about the sun, gravity, earth, etc.
same thing with QM, there is probably an underlying mechanisms behind the weird observations that we don’t know yet but people like quantum mysticism scrotes and the like will always tell you it’s magic and justify irrational beliefs by god of the gaps (e.g. soul exists because of QM)-
>same thing with QM, there is probably an underlying mechanisms behind the weird observations that we don’t know yet but people like quantum mysticism scrotes and the like will always tell you it’s magic and justify irrational beliefs by god of the gaps (e.g. soul exists because of QM)
Bell-
Does not do anything to disprove non-local hidden variables.
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what about this?
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pseud
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>Are you telling me particles are aware of humans?
Haven’t read the thread yet, but I hope somebody else has already said this:"Observation" in QM has nothing to do with a person looking at something. It’s about a wave or particle interacting with something else.
Muh double-slit experiment:
Huh, that’s weird, if I pass photons through a double slit WITHOUT interacting with anything first, I get one result, but if they DO interact with something else first, I get a different result!
Woooowwww, totes spooky!-
>"Observation" in QM has nothing to do with a person looking at something. It’s about a wave or particle interacting with something else.
While true the fact that particle B can know that particle A was interacted with at a speed faster then light and possibly instantaneous is quite spoopy.-
I might be totally off-base with this but I imagine it as one “stretched” quantum system describing two particles rather than two distinct particles.
So when it’s observed, the whole system assumes a fixed state. -
>quite spoopy.
You DO understand that quantum entanglement’s "spoopy action at a distance" is a straw-man argument intended to critique the Copenhagen Interpretation, right?
Just like Schrodinger’s cat?-
Quantum entanglement has been tested and confirmed. Actual brainlet.
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>Quantum entanglement has been tested and confirmed.
"spoopy action at a distance" remains a mystery.
And I’m not wrong about the straw-man aspect.
https://en.wikipedia.org/wiki/Quantum_entanglement
>Einstein and others considered such behavior impossible, as it violated
>the local realism view of causality (Einstein referring to it as "spooky action
>at a distance")[4] and argued that the accepted formulation of quantum
>mechanics must therefore be incomplete.Let me know when the "accepted formulation of quantum mechanics" is complete.
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>"spoopy action at a distance" remains a mystery.
No shit halfwit, that doesn’t mean it isn’t a thing.
>And I’m not wrong about the straw-man aspect
Yes you are actually, do you know what a strawman is? Einstein didn’t make up spooky action at a distance. Other scientists did, and he argued that the action is impossible. Which he later got BTFO’d on.
>i’m going to sit around online calling scientifically tested events bulshit until we know everything there is to know about everything.
Truly a waste of oxygen. Please feel free to have a nice day as soon as possible.-
>halfwit, that doesn’t mean it isn’t a thing.
I never said it wasn’t, try to keep up, especially before insulting others.>Please feel free to have a nice day as soon as possible.
Wow. What a guy. I’m sure your mother doesn’t lie awake at night, recriminating herself because she _didn’t_ strangle you to death in your crib when she had the chance.
Say "hi" to her for me.-
>You DO understand that quantum entanglement’s "spoopy action at a distance" is a straw-man argument intended to critique the Copenhagen Interpretation
Stupid scrotebrain-
I can’t work the 4chins well enough to quote the post I’m replying to, but surely *YOU’RE* the dum-dum.
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Nope, I am the one agreeing with the evidence gathered from repeated scientific experiments. You guys denying them because it doesn’t fit your world view are the "dum-dums".
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>Which he later got BTFO’d on.
Quantum interpretations are (by definition) untestable.
The Copenhagen Interpretation alleges particles don’t have spin until that property is called into existence by measurement.
That might be true, but how can you tell?
If you don’t measure a particle’s spin, how can you be sure it doesn’t have one?
We definitely know two "matched" photons have complementary spin.
But if Heisenberg and Bohr were right, how do you explain this phenomenon?
This remains a mystery to this day, but instead of pretending physics has uncovered some kind of "evidence" for the supernatural, let’s assume the Copenhagen Interpretation is imperfect.-
Again, we have scientific experiments validating that both spoopy action at a distance is a thing, and that it happens faster then light. You morons should leave this board, this is for science discussion not denial.
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>we have scientific experiments validating that both spoopy action at a distance is a thing
No, you freaking don’t.
You have evidence that two "matched" photons have complementary spin, an observation wholly incompatible with the Copenhagen Interpretation. Unless you believe in essentially supernatural forces, "spooky" is bullshit, and demonstrates a flaw in the Copenhagen Interpretation.-
>an observation wholly incompatible with the Copenhagen Interpretation.
Not that guy, but how is it incompatible? As far as I know CI doesn’t say anything about it. -
>Not that guy, but how is it incompatible?
The CI says properties, such as spin, don’t actually exist until the property is called into existence by being measured.
A pair of entangled photons are created, and yet (supposedly) neither has spin until one of them encounters (let’s say) a magnetic field, thus revealing/causing(?) its spin to exist.
Since we know they have complementary (opposite) spins, we now have advance knowledge of what they other particle’s spin must be, even if that spin won’t actually manifest until it also runs into a magnetic field, thus revealing/manifesting a spin we can predict by having observed the other particle.
This is actually weirder than "spooky action at a distance" because it’s also "spooky action" over time.
What if one photon travels ten meters before reaching a spin detector, while the other is headed for deep space, and won’t have it’s spin revealed/manifested for years, maybe? -
There is no action for there to be a spooky action. It is just a preservation of CORRELATION. This is completely consistent with the copenhagen interpretation.
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>There is no action for there to be a spooky action
yes there is. the electron sees what happened to it’s entangled pair, then made a conscious decision to become the opposite spin. it did all this faster than the speed of light too.
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>he electron sees what happened to it’s entangled pair
Completely freaking wrong lmao. The copenhagen interpretation says nothing about what the electron does or whatever bullshit. It says that the person who makes the measurement on one electron can ‘know the state of the electron’, by which they mean that IF this person also measures the other electron, he would get a result consistent with the first measurement. This is just a preservation of correlation as a I said earlier. The spooky part about copenhagen is not spooky action or some other nonsense, it’s the fact that reality itself is not that well-defined. -
*’know the state of the other electron’
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>This is just a preservation of correlation as a I said earlier.
pseud. -
??? That is the prevalent explanation of the ‘non-locality’ of entanglement. That it is just the preservation of correlations. If you think I’m wrong, explain why.
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>??? That is the prevalent explanation of the ‘non-locality’ of entanglement.
no. its not. i read Nature. One electron sees what happened to the other and changes its state accordingly over any distance at infinite speed. -
Ok, I think you’re trolling but anyway, there is no real ‘state’ in the copenhagen interpretation it is just a way of quantifying an observer’s information of the system. So there is no superluminal collapse either because the ‘collapse’ is just what happens when the observer updates their information.
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>there is no superluminal collapse
read Nature. -
Read a textbook on quantum mechanics first.
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>Read a textbook on quantum mechanics first.
listen, your interpretation is contrary to Copenhagen, Einstein, and Nature. You can insist all you want, but your interpretation is pseud bullshit. -
i think you know very well that he’s trolling but some deep insecurity is preventing you from committing to a position that you know is perfectly safe, because the mere logical possibility of being wrong about anon poses enough threat to give you reservation. this is a sickness
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Take your meds lmao
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please respond
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please respond
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>there is no real ‘state’ in the copenhagen interpretation it is just a way of quantifying an observer’s information of the system
Alright.
>So there is no superluminal collapse either because the ‘collapse’ is just what happens when the observer updates their information.
Not quite. Getting the information necessitates interaction with the system, and that interaction does affect the other end. Call it collapse, update, or donut, it happens all the same.
See Bell’s Inequality for proof that the information cannot simply be embedded in the particle. -
"Getting the information necessitates interaction with the system, and that interaction does affect the other end."
ok i’m not him but it sounds like you’re saying it’s impossible to read the output of a light sensor without interacting with a laser beam? aren’t you supposed to design the experiment so that doesn’t happen? like the laser should be in a dark room with no humans breathing on it -
The light sensor itself has interacted with the laser beam, or it couldn’t determine anything about the beam.
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i see so you can never see how light behaves when there’s nothing to absorb it unless you have some ESP eye of god
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More or less. You can make very accurate predictions, but you can’t know every property of a system all at the same time.
On the macroscopic scale we see things at in day to day life the effects of observation are vanishingly small, but on the quantum level the effects are dramatic and unavoidable. -
this makes me worry like there’s an unresolved problem with my way of thinking because i don’t see the world around me (with sense organs that require interaction) in the same way i see things in my internal model of the world (with my imagination). this asymmetry bothers me
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>this makes me worry like there’s an unresolved problem with my way of thinking
this is precisely the intended effect, most of quantum physics is gatekeeping and copenhagen interpretation garbage like the OP is literally misinformation.Yes they literally just made you go though a whole roundabout to say that no we can’t observe light without it hitting something. The best part is that its all a ruse because this has NOTHING to do with the actual uses of QM. look its pictures of electron orbitals, surely this should be impossible right!?! freaking quacks the majority of them, they dont care about science they care about the gay mysticism with muh observation causes wave-function collapse
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>Getting the information necessitates interaction with the system, and that interaction does affect the other end.
It does not ‘affect’ anything distant because that would violate relativity. Whatever you measure is just guaranteed to be correlated with what the person who measures the distant particle observes. You can see this by considering a third observer who observes the entire system consisting of the two distanct observers and the particles which they perform the experiments on. -
*distant observers
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>There is no action for there to be a spooky action.
Seems likely.>It is just a preservation of CORRELATION.
Ok, I’ll buy that. But how is the correlation preserved _before_ ether’s spin is manifest and there (supposedly) aren’t any local hidden variables?Not saying you’re wrong, we’re just getting beyond my understanding.
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How the correlation is created in the first place depends on how the entangled photons are produced if that’s what you’re asking
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>The CI says properties, such as spin, don’t actually exist until the property is called into existence by being measured.
I don’t quite get that out of the (most common) properties of the Copenhagen Interpretation.
It says (among other things) that the wave function gives probabilities for the outcome of measurements on a system, and measuring any property means that any complementary properties cannot be known at the same time. I don’t think that’s what you’re referring to but it’s my closest guess. Can you point to a specific statement somewhere where you’re getting this from? -
>Can you point to a specific statement somewhere where you’re getting this from?
Mostly just picking up pop-sci as I go along.
I’m pretty sure I’ve heard that CI prohibits "local hidden variables".
Also, if your explanation is common knowledge, then why the "spooky" interpretation so commonly voiced? -
>CI prohibits "local hidden variables".
QM itself prevents local hidden variables. That is a mathematical theorem, it’s not dependent on the interpretation. -
>QM itself prevents local hidden variables.
OK, then how do the entangled photons "keep track" of the (apparently predestined?) spin?Again, not disagreeing, just genuinely ignorant.
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>the entangled photons "keep track" of the (apparently predestined?) spin?
It would only ‘keep track’ if the entanglement isn’t destroyed by some other process. For that to happen, these photons would have to be very isolated from the environment so as to prevent any decoherence. But really, you can’t make statements like ‘the electron keeps track’ etc. in the copenhagen interpretation. In CI, the wavefunction is just a way the observer keeps track of information, it’s not something real. -
>it’s not something real.
OK, then why do they have complementary spin?
I’m not hearing an answer to this basic question, and I guess I’m really not expecting one.
I kind of assume there’s no ready reconciliation between a lack of local hidden variables and the consistently complementary spins, which (I guess) is why people keep calling it "spooky".
Unless, of course, you _are_ arguing for action at a distance? -
>OK, then why do they have complementary spin?
For you to know that they have complementary spin, you need to measure both the spins in the first place. If the observer knows that the photons are entangled in the first place, then his initial knowledge of the unmeasured system would be represented by a wave function of the form [math] frac{|1 rangle |0 rangle + |0 rangle |1 rangle}{sqrt{2}} [/math] (assume that both the spins are in the x-direction). Once the obsever measures the spins of both the electrons in the x-direction, the only results he can get are either 0,1 or 1,0 – that is just the definition of what it means to be entangled. If instead of measuring both the particles, suppose the observer only measures one particle and gets the result 0. Then even without measuring the other particle, he could conclude that IF he did measure the other particle, he would get a 1. That’s all there is to it. In the copenhagen interpretation, you simply don’t talk about what is ‘really going on’ or things like that because if you do, you be lead to make wrong conclusions (conclusions inconsistent with experimental evidence). That is what things like the double-slit experiment are meant to show. -
In all honesty we don’t know. CI doesn’t claim to answer that, but it isn’t falsified by its existence either. It cares about what we can measure, the results.
What we do know is that there is some character to quantum systems that cannot be explained by classical/"local" approaches.>Unless, of course, you _are_ arguing for action at a distance?
Not him but it’s not exactly something we can claim doesn’t exist.
"Action" may be pushing it though. -
>we don’t know.
Case closed, but it sure took a long time for us to get there, huh?
Ctrl-F4. -
As far as I know "spooky" was just Einstein’s wording for the phenomenon, as he was not a fan of it. And the nomenclature stuck.
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particles be dropping pocket spaghetti since dawn of time
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Measuring is taking something in, like light entering the retina. That or light just bounces of a wall, so yes measurements give light a new ride.
Hence different info on measure or not.
In this case measurement aperatus.Seems freaking obvious really.
Just that now you so small you see the tiniest changes of the lights journey. Etc.
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>Why does observation collapse the wave function of a particle? Are you telling me particles are aware of humans?
because particles dont really exist, they are just detection events. only the wave exists.Waves can have energy put into or taken out of them only in discrete quantities. When you ‘see’ a particle what you are seeing is that wave emit energy. Inside the wave all the energy of all the particles is homoginous. A single particle makes a wave existing in all places along that waves path, untill it is detected, the detection event then makes ‘the particle exist in the observed location’.
This is the truth the quantum memers dont want you to know.
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You’re brain takes time to process stuff so things seem shorter. Like if a horse did the double slit experiment and can’t measure things the electrons would probably still be chaotic too.
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Honestly, the only people who complain about the copenhagen interpretation are those who have understood incorrectly due to some bad explanation of it – symptoms of this misunderstanding include thinking that wavefunctions are real things and collapse is some physical process. What the copenhagen interpretation does imply is that the idea of a classical reality where things definitely happen and have precise values is only an approximation/emergent concept. Once you accept that, it’s all completely logical and sensible.
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"…the idea of a classical reality where things definitely happen and have precise values is only an approximation/emergent concept"
an approximation of what? this seems like a huge caveat-
I call it an approximation because ultimately, when you say that things happen, what that means in quantum mechanical terms is that you performed some experiment on some object and as a result, you were entangled with that object. Now because you are a macroscopic object, decoherence implies that it’s safe for some other observer who is modeling your time evolution to assume (even without performing any measurement on you) that you obtained some specific result (but not exactly which result) once you performed the experiment – technically, this means that this observer can now model the result of your experiment as a mixed state instead of a pure state, and a mixed state is basically just a classical probability distribution. This assumption which allows the other observer to say that things happen even without them directly measuring it (this is the basis of the classical view of reality), while typically valid, is an approximation because decoherence is not perfect, so the transition from a pure state to a mixed state is also only approximately valid. So essentially, this approximate picture of a classical reality arises through entanglement (which are just quantum correlations) and decoherence.
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i’m having difficulty following you, please slow down. i’m guessing you’re probably not a realist about things and i wonder if this is warranted by the copenhagen interpretation.
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Well, I don’t particularly subscribe to any philosophy regarding qm, but I would say that in the copenhagen interpretation (by which I mean mainly that the wavefunction is not accepted to be a real thing), things like particles and so on exist and interact with each other but assigning truth values to statements like ‘A measured the property X of object B and found the value x’ are ultimately done out of convenience.
> i wonder if this is warranted by the copenhagen interpretation.
I think this is the view Bohr more or less had. Einstein and Schrodinger disagreed with him however and Heisenberg had his own views which were not entirely consistent with the ones Bohr held, so copenhagen interpretation could mean lots of (sometimes inconsistent) things. You can read some article like https://plato.stanford.edu/entries/qm-copenhagen/#IntQua
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I should add there is also a view where you can assume that there really is a thing such as a wavefunction which is not just a way of representing the information available to the observer. But this would, imo, clearly imply that you would also have to adopt some sort of many-worlds view. This would be a more realist (as opposed to instrumentalist) view of quantum mechanics and is probably a consistent view to hold but it requires some extra work to define in what sense exactly these many-worlds are real.
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I never studied QM beyond introductory course and this thread made me very insecure. Is everything I’ve learned from Griffiths a lie?
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>I never studied QM beyond introductory course and this thread made me very insecure. Is everything I’ve learned from Griffiths a lie?
no. electrons are omnipresent and omniscient. Whats so hard to understand about that?
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