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A wave function does not collapse upon detection?

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Re: A wave function does not collapse upon detection?

#61

Post by cottager2 »

tsimionescu wrote: post #57
CuriouslyC wrote: post #50

Earlier quoted context omitted.

The many worlds interpretation works better with quantized probability. Imagine a huge computer running a monte carlo simulation with a probabilistic current state, and a set of transition states (the wave function). With quantized probability and a universe with finite "memory" the amplitude of the wave function basically maps to the amount of system memory being utilized for a portion of the simulated state space.

Well, quantized probability doesn't really make sense, there are extraordinarily improbable events happening every second. It's easy to create an event that has less probability than many things that have never been observed (flip 10,000 coins - whatever result you get has probability 1/2^10k). You could perhaps create a version of QM with a quantized amplitude for the wave function in some basis. It's also important…

Why is quantized probability nonsensical? Isn’t it equivalent to asserting the universe is not a continuum?

Re: A wave function does not collapse upon detection?

#62

Post by rstuart4133 »

raphlinus wrote: post #41

This is the video that finally made it click for me[1]. Despite the somewhat click-baity title ("What Popularizers of QM Don't Want You to Know") it actually goes into quite a bit of detail of what is and isn't a measurement, in the sense of interactions in a quantum mechanical system that strongly resemble classical behavior (it can be said that the quantum mechanical world is a simulator that can run classical mech…

Thanks.

It's perhaps not surprising an approaching quantum "paradoxes" as classical "computer" trying to analyse the quantum computer it is running on appeals to computer programmers. It sure appeals to me.

Re: A wave function does not collapse upon detection?

#63

Post by aeternum »

russellbeattie wrote: post #53
wrycoder wrote: post #37

Earlier quoted context omitted.

You are asking that the screen be moved back to the slits - less than a slit-slit distance away. The wave aspect of the EM field remains downstream of the slits. The photon aspect is only exhibited at the screen. There may be no such images, because it’s not interesting to observe two bright spots. There has to be enough path length difference to allow the phase difference causing the interference. Think about the cl…

> There may be no such images, because it’s not interesting to observe two bright spots. *Seriously?* There are an unlimited amount of uninteresting pictures on the internet, but no one has bothered to take a picture of a fundamental claim of quantum mechanics because it's so trivial as to be boring? Really??

You can do the experiment yourself with a laser pointer and two slits.

Re: A wave function does not collapse upon detection?

#64

Post by blix »

Koshkin wrote: post #49
pishpash wrote: post #18

Earlier quoted context omitted.

> The catch is that appearance of classical objects is still unsolved problem in QM. What? Decoherence explains classical objects.

Classical objects are not explained in Quantum Mechanics, they are a fundamental part of the theory itself. (Measurement is an interaction with an apparatus which is a classical object.)

The notion of a 'Classical Object' in this particular framework of QM is an assumption, not a prediction.

Since all objects are composed of quantum particles, all objects are quantum objects. So a complete theory of QM needs to be able to explain, not assume, why some objects behave classically.

Re: A wave function does not collapse upon detection?

#65

Post by tsimionescu »

cottager2 wrote: post #61
tsimionescu wrote: post #57

Earlier quoted context omitted.

Well, quantized probability doesn't really make sense, there are extraordinarily improbable events happening every second. It's easy to create an event that has less probability than many things that have never been observed (flip 10,000 coins - whatever result you get has probability 1/2^10k). You could perhaps create a version of QM with a quantized amplitude for the wave function in some basis. It's also important…

Why is quantized probability nonsensical? Isn’t it equivalent to asserting the universe is not a continuum?

By quantized probability, I assume you mean something like "there is a minimal probability p for any possible event; if the probability we compute for some event is q If this is the right definition, then it's easy to disprove: for any p you chose, I can construct a series of events that each have probability q Edit to add: to be clear, even if the universe itself were quantized, all measurable physical quantities, probability still wouldn't need to be quantized, as it's not a physical quantity, it's just a mathematical abstraction. Still, even in QM, not all physical quantities are quantized. For example, space (position) is not quantized in QM, and neither is time. They are both continuous quantities in all of the equations normally used. Planck time and Planck distance are only the shortest possible distances to measure precisely, given the Heisenberg uncertainty principle, but that doesn't require them to actually be quantized. In contrast, the quantization of mass, energy, spin etc are actually necessary for the theory to work, they are not just measurement artifacts.

Re: A wave function does not collapse upon detection?

#66

Post by CuriouslyC »

tsimionescu wrote: post #65
cottager2 wrote: post #61

Earlier quoted context omitted.

Why is quantized probability nonsensical? Isn’t it equivalent to asserting the universe is not a continuum?

By quantized probability, I assume you mean something like "there is a minimal probability p for any possible event; if the probability we compute for some event is q If this is the right definition, then it's easy to disprove: for any p you chose, I can construct a series of events that each have probability q Edit to add: to be clear, even if the universe itself were quantized, all measurable physical quantities, p…

Why do you think this is a result of an unquantized wavefunction rather than due to the mathematical edifice we use to model it? It's not clear to me that things like the product rule for probabilities would still hold if you're not transforming and normalizing amplitudes.

Re: A wave function does not collapse upon detection?

#67

Post by russellbeattie »

aeternum wrote: post #63
russellbeattie wrote: post #53

Earlier quoted context omitted.

> There may be no such images, because it’s not interesting to observe two bright spots. *Seriously?* There are an unlimited amount of uninteresting pictures on the internet, but no one has bothered to take a picture of a fundamental claim of quantum mechanics because it's so trivial as to be boring? Really??

You can do the experiment yourself with a laser pointer and two slits.

LOL. See paragraph #2 of my original post. Thank you so much.

Re: A wave function does not collapse upon detection?

#68

Post by aeternum »

russellbeattie wrote: post #67
aeternum wrote: post #63

Earlier quoted context omitted.

You can do the experiment yourself with a laser pointer and two slits.

LOL. See paragraph #2 of my original post. Thank you so much.

If you try it yourself and continue moving the 'screen' closer towards the two slits, the wave pattern will eventually disappear and you will have the two 'piles' of photons you refer to.

There's nothing like testing it yourself in 'real life' if you remain unconvinced.

Re: A wave function does not collapse upon detection?

#69

Post by russellbeattie »

aeternum wrote: post #68
russellbeattie wrote: post #67

Earlier quoted context omitted.

LOL. See paragraph #2 of my original post. Thank you so much.

If you try it yourself and continue moving the 'screen' closer towards the two slits, the wave pattern will eventually disappear and you will have the two 'piles' of photons you refer to. There's nothing like testing it yourself in 'real life' if you remain unconvinced.

Ohh. If this is true, I won't just apologize, I'll send you flowers.

Looking into it now.

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