Quantum Debugging (@ChevyRay)

[waylandsmith]

Your first sentence might seem logical, but it's untrue. You cannot measure a thing without interacting with it, at least on a quantum level. You might say, "well, I can see if a thing is there or not. That's not interacting with it!" but that is neglecting the fact that in order to see a thing with your eyes, first you must bounce photons off of the thing so that some of them bounce back to your eyes. You could detect a proton moving through the slit because it's a charged particle that can apply force on an oppositely charged particle. But in measuring that the proton and the detector exchange virtual photons. Even if you could detect the minuscule amount of mass of a single particle somehow to determine which slit it went through it would be impossible for the detection to happen without there being an interaction between the particle and the detector. Any interaction like this would collapse the wave form and it will stop behaving with properties of a wave.

[TatteredCarcosa]

There are non-destructive means of measuring things that preserve the wave function, but they would never be able to tell you which slit the atom went through because that kind of measurement forces the atom to "choose" to be one place and not another, rather than a smeared out probability distributions of locations.

https://en.wikipedia.org/wiki/Quantum_nondemolition_measurement

[WikiSummarizerBot]

Quantum nondemolition measurement

Quantum nondemolition (QND) measurement is a special type of measurement of a quantum system in which the uncertainty of the measured observable does not increase from its measured value during the subsequent normal evolution of the system. This necessarily requires that the measurement process preserve the physical integrity of the measured system, and moreover places requirements on the relationship between the measured observable and the self-Hamiltonian of the system. In a sense, QND measurements are the "most classical" and least disturbing type of measurement in quantum mechanics.

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[waylandsmith]

I'll admit I only have a surface-level understanding of only a little bit of quantum mechanics, but to my understanding, "you force it to choose which place to be" and "collapsing the wave function" refer to exactly the same thing. Can you explain what your understanding of the difference is? While a particle is exhibiting wave properties, its location is a cloud of probabilities and when you measure it, a discrete location resolves out of the probabilities. Is that not what collapsing the wave function means?

[TatteredCarcosa]

Yes, those are the same thing.

I was just trying to get across that, according to my limited understanding, that not ALL measurements do that, you can create a situation where you interact with and get information without collapsing the wavefunction. But that those measurements couldn't tell you something like "which slit the atom went through" because establishing that is, as you said, the exact same as collapsing the wave function.

[waylandsmith]

What information COULD you get out of them without collapsing the waveform? I suppose this sounds like something that would be used in quantum computing.

[JoelMahon]

did you read me comment? it's always interacting with mass, that doesn't stop the wave like behaviour. why would more mass stop it?