Isn’t a wave function essentially just a representation of all possible answers? Like a (perfectly flat) coin flip would be something like 0.5h + 0.5t = 1, where if t is 1, then h is zero, and vice versa?
A wave function does not collapse upon detection?
11–20 of 69 posts
Re: A wave function does not collapse upon detection?
#12Oversimplifying, but hopefully not too much. For simplicity, let's assume that it's the wave function of an electron, but this applies to any particle. The first problem is the question. What does " detection " means? The technical term is " measurement ", and the most important idea is that you can measure different things, for example the position of the electron, or the speed of the electron, or the energy of the…
The notion of the wave function collapse is very specific to Copenhagen interpretation of quantum mechanics that tries to reconcile classical and quantum world. But everything is quantum so there is no classical measurement device, just its wave function interacting according to fully deterministic equations with the wave function of the electron.
The catch is that appearance of classical objects is still unsolved problem in QM. There are various approaches that in theory can explain the experimental results, but in practice explaining, say, quantum split experiments from pure QM view of multiple interacting wave functions still not possible.
Re: A wave function does not collapse upon detection?
#13> But surely the wave function is smeared across both slits That's the whole point of the experiment - you can't get an interference pattern if it does not. > and the act of detecting which slit the photon could go through, if it were a particle The whole point of the double slit experiment is that there is only one photon, and which slit it goes through is irrelevant. Whether a photon is a wave-function is missing t…
Your answer is the honest answer.
We don't know.
The physical reality of wave functions is unknown.
It could be an approximation of something yet deeper.
The only thing we know is that the math works.
Re: A wave function does not collapse upon detection?
#14The confusion with the Copenhagen interpretation comes from two main sources in my opinion:
1. What can count as a measurement?
2. Quantum ‘thing’ interacting with a classical world
One of my favorite talks on this subject is by Sean Carroll and offers the ‘many worlds ‘ interpretation as an alternative, mainly for its simplicity. Recommend watching the whole thing but if you want just the “debunking”: 25:11 https://youtu.be/5hVmeOCJjOU
Re: A wave function does not collapse upon detection?
#15The confusion with the Copenhagen interpretation comes from two main sources in my opinion: 1. What can count as a measurement? 2. Quantum ‘thing’ interacting with a classical world One of my favorite talks on this subject is by Sean Carroll and offers the ‘many worlds ‘ interpretation as an alternative, mainly for its simplicity. Recommend watching the whole thing but if you want just the “debunking”: 25:11 https://…
Interpretation is a crutch, gives nothing extra, and only obfuscates things; it should be discarded.
Let's just accept that (1) we don't know the objective reality, and (2) there is something that ensures consistency of information across fairly large distances -- entanglement experiments have been done up to 1000+ km's -- maybe even across the entire universe, though the latter has never been tested.
Re: A wave function does not collapse upon detection?
#16Oversimplifying, but hopefully not too much. For simplicity, let's assume that it's the wave function of an electron, but this applies to any particle. The first problem is the question. What does " detection " means? The technical term is " measurement ", and the most important idea is that you can measure different things, for example the position of the electron, or the speed of the electron, or the energy of the…
> If you measure the exact position of an electron, the wave function collapses to a point. Note, though, that in reality you can never measure the exact position of an electron (or anything else); the best you can do is to measure that the electron is inside some finite-sized (possibly very small) region. The "exact position" measurement is an idealization that can be useful for pedagogy but can't be realized in any…
spin? things go one direction or the other in a magnetic field
Re: A wave function does not collapse upon detection?
#17> But surely the wave function is smeared across both slits That's the whole point of the experiment - you can't get an interference pattern if it does not. > and the act of detecting which slit the photon could go through, if it were a particle The whole point of the double slit experiment is that there is only one photon, and which slit it goes through is irrelevant. Whether a photon is a wave-function is missing t…
> as if particle know when they are being measured
Are there measurements that don't require an interaction? Is locality false?
Re: A wave function does not collapse upon detection?
#18Oversimplifying, but hopefully not too much. For simplicity, let's assume that it's the wave function of an electron, but this applies to any particle. The first problem is the question. What does " detection " means? The technical term is " measurement ", and the most important idea is that you can measure different things, for example the position of the electron, or the speed of the electron, or the energy of the…
The notion of the wave function collapse is very specific to Copenhagen interpretation of quantum mechanics that tries to reconcile classical and quantum world. But everything is quantum so there is no classical measurement device, just its wave function interacting according to fully deterministic equations with the wave function of the electron. The catch is that appearance of classical objects is still unsolved pr…
> The catch is that appearance of classical objects is still unsolved problem in QM.
What? Decoherence explains classical objects.
Re: A wave function does not collapse upon detection?
#19"Shut up and calculate"
Re: A wave function does not collapse upon detection?
#20Earlier quoted context omitted.
The notion of the wave function collapse is very specific to Copenhagen interpretation of quantum mechanics that tries to reconcile classical and quantum world. But everything is quantum so there is no classical measurement device, just its wave function interacting according to fully deterministic equations with the wave function of the electron. The catch is that appearance of classical objects is still unsolved pr…
> The catch is that appearance of classical objects is still unsolved problem in QM. What? Decoherence explains classical objects.
While quantum decoherence explains appearance of classical objects in simple models, predicting the results of real experiments still not possible. And given this has not changed much as far as I know for the last 20 years, I started to suspect that decoherence alone may not be enough.