If the wavelength is large though, there will be more free electrons (if there are more than one). If the wavefunction of the electron extends over the whole material in question, you will make a better chance with large wavelengths.

oops! I misspoke. I have corrected my post.

So if we sent 1 photon at a time at the slits and try to detect which slit they go through it would collapse the wave function whether or not a person checks the hard drive of results to compare against the background pattern? — TiredThinker

Strictly following the axioms of QM, no. Only when an observer measures the one photon, be it directly or via memory disks, the wave function collapses. As hard to digest this might sound, a proponent of observer induced collapse can always keep this up. Strange stuff like the many worlds interpretation (to preserve unitarity of the evolution of the wave function, relocating non-unitarity merely to the branching points where the wave function splits in the states that were superimposed before a measurement, although it looks as if unitarity is maintained), and decoherence (which only seems to solve the problem of wave function collapse) are invented to solve the measurement (collapse) problem.

But even the friend of Wigner's friend who observes a person looking at Schrödingers can, can always say that it is him or her that causes collapse, no matter what the guy observing the cat directly, or the guy that observes this guy feels or thinks. Only in a theory with non-local hidden variables, the situation can be interpreted as a real, physical collapse, independent of observers. So let's hope they are discovered.

The Quantum Enigma: the true nature of reality seemingly becomes reality itself the moment it is observed and simultaneously exists as a fuzzy and probabilistic state while unobserved. So, what does this mean, actually? Well, maybe an answer is that maybe that all of the potential physical states of reality do truly exist at the inception of the universe and thereby carry those probabilistic states alongside with it despite the truth that it is predetermined already which probabilistic states are to exist based on that said initial inception and state of the universe based on whatever its initial state inherits— trajectories such as perhaps the Big Bang theory or an inflationary type of re-cyclical universe theory? Whatever classifies as the beginning of the universe, I mean. Regardless, the illusion of quantum physics wanting to be probabilistic based on our observations is just that: an illusion. The moon is of course there whenever I am or someone else is not observing it and that is an objectively true statement irrespective of subjective states of consciousness and that goes to show that consciousness must also be independent from one another because they still concur with each other what that true probabilistic state of where the moon might be located at any given time (we can conclusively measure this with one observer or with millions); I don’t rely on someone else to tell me where the moon is and they don’t rely on me to do the same. So, unless all consciousness is bound together as one sort of meta-conscious and that meta-conscious is subject to those probabilities of a non-deterministic universe, then it is safe to say that the current universe is and always will be based on some type of deterministic state which might simply mimics a probabilistic or fuzzy state of reality.

even the friend of Wigner's friend who observes a person looking at Schrödingers cat, can always say that it is him or her that causes collapse, no matter what the guy observing the cat directly, or the guy that observes this guy feels or thinks. Only in a theory with non-local hidden variables, the situation can be interpreted as a real, physical collapse, independent of observers. So let's hope they are discovered. — Cryptic

Isn't that equivalent to trying to explain away the physically central subjective role of all possible observation? I.e., the observer is not at the center of the Universe but the Universe is always centered on any possible observer? Perhaps that is why C is a constant, if O then c?

Maybe you can just look at it this way: There is a universal wave function of the universe, where everything is only probabilities. However, every single elementary particle "knows" where it is located. Thus it sees a reduced wave function, because it has an information about itself. Also measuring instruments "know" where they are. And humans also. Each particle and each group of particles sees another wave function.

What is the significance of the double slit experiment if a human observation isn't needed to collapse the wave function? Does that only show that the electrical measuring device interfered with the photons or electrons when they passed through?

Any physics experts here? — TiredThinker

Maybe the physicists are studying an elaborate optical illusion they are mistaking for actual reality.

A ‘particle’ goes through both slits because it is a field quantum, and the ‘particle’ is ever the quantum field. The ‘particle’ or ‘wavicle’ is spread out and vibrating in the quantum field; so, as it isn’t a pinpoint it’s best to just refer to it as a a field quantum.

Many wanna-be ‘particles’ don’t reach the stable quantum energy level and so they come and go rather quickly, arising and returning back into the zero-point energy that isn’t zero, at the rest energy of the field or near to, they being known as the virtual ‘particles’. They do not come from ‘Nothing’ nor do they return to ‘Nothing’; so they can only be said to pop in and out of ‘existence’ in their ‘particle’ type nature as a so-called ‘particle’.

The entire universe is temporary, presumably because everything leaks, probably because infinite precision cannot be; however the Permanent quantum vacuum with its overall quantum field ever remains to someday make another universe of temporaries.

As I have described, the universal wave function does not collapse, the observer-specific one does.

All paradoxes dissolve, if each observer has his own wave function. Of course, all are compatible with each other.

1. Panopticon

2. Closed-circuit television (CCTV)

3. Weeping Angels (Dr. Who).

Ergo,

4. There's something immoral/bad about waves.

The electron, which is negatively charged, in a sense, knows it's being watched/observed and behaves/acts accordingly. In my experience, only conscious entities do this. Are electrons, by extension everything, conscious? Panpsychism?

:joke:

From the point of view of an electron, you would have a reduced wave function, which does not mean that an electron is conscious. It is only the idea of being in the place of an electron.

One speaks also of the temperature inside the sun, although nobody will ever bring a themometer there.

It's been a while since my QM classes and I've moved on to bigger things now. Still, there are lots of resources out there by smarter people about QM and since it's not really a done deal yet, older stuff is still relevant. The thread started by asking about consciousness and observation, but wave-particle duality hits deeper than that. It could mean that time is an illusion, for example.

Max Born wowed everyone with statistics. State is probabilistic:

One does not get an answer to the question, What is the state after collision? but only to the question, How probable is a given effect of the collision? From the standpoint of our quantum mechanics, there is no quantity which causally fixes the effect of a collision in an individual event.

If God has made the world a perfect mechanism, He has at least conceded so much to our imperfect intellect that in order to predict little parts of it, we need not solve innumerable differential equations, but can use dice with fair success

Schroedinger insisted on an equation. It's got a "wavefunction" in it, whatever that is.

Einstein is having none of it:

God does not play dice.

Heisenberg:

The more I ponder about the physical part of Schroedinger's theory, the more disgusting it appears to me.

Bohm thought that it is actually all deterministic and we just don't have enough information. And there's definitely others I've missed. At the bottom of the wikipedia page for "Copenhagen interpretation" there are some comments about alternatives, which could be of interest.

That's all to say, as far as I know, we're not much closer to putting the finger on any of this. As for the measurement problem, there are some people who dispute the idea of "wavefunction collapse" at all. [1] [2]

Other people still worry about consciousness though: [3] [4]

If you're interested in the consciousness aspect, I think the "delayed choice quantum eraser" experiment could be more useful as a search term than "double slit", which has many variations. Not just a thought experiment either, there are lab experiments of it, e.g. [5]

The third ref is paywall locked, but there could be preprints floating around. I'd love to give my opinion instead of just dumping references, but I'm severely underqualified. Hopefully this can at least motivate people less lazy than myself to look at this stuff.

there are some people who dispute the idea of "wavefunction collapse" at all — the affirmation of strife

When the river freezes the flow disappears by magic.

Here's another:

https://www.chemistryworld.com/news/quantum-double-slit-experiment-done-with-molecules-for-the-first-time/4014819.article

The problem with wavefunction-collapse is that it's a mathematical collapse, leaving room for two interpretations. Or better, three. One that says the collapse happens on observation, one that says every interaction makes it collapse, and one that says there is no collapse at all (MWI, merely relocating unitarity to branching points, which obviously are non-unitary and which made Hugh Everett happily smoke three packets a day, drink a bottle in between, eat what he liked, and a daughter kill hersellf in the happy thought she would meet him in a parallel state).

The first interpretation sticks to the most to the axioms of QM. The second assigns an objective existence to a mathematical entity (the wavefunction), which is absurd. I won't mention the third option again...

What's left is assigning a physical reality of what the wavefunction describes. And only such an interpretation can make all nonsense disappear like a bad dream.

The second assigns an objective existence to a mathematical entity (the wavefunction), which is absurd. — Cartuna

:up:

assigns an objective existence to a mathematical entity (the wavefunction), which is absurd — Cartuna

Do you know of any theory in physics or other sufficiently mathematized science that doesn't do exactly that?

What's left is assigning a physical reality of what the wavefunction describes. — Cartuna

So... MWI then?

Do you know of any theory in physics or other sufficiently mathematized science that doesn't do exactly that? — SophistiCat

All of them. Math is just a way to describe physical stuff.

So... MWI then? — SophistiCat

No. My point is that the the MWI is caused by the wavefunction being seen as a mathematical entity. Giving rise to the problem of a non-unitary collapse. And according to the rules of QM this wavefunction has to evolve unitarian which it doesn't when measured. This is also mathematically done by a unitary time operator, which is of course only done by people, as there truly is no time propagating operator in nature.

As was decided in Copenhagen once. And eversince has been pushed in the minds of students, incĺuding mine. But who says that Nature is inherently probabilistic? How can this be? How can there be a mathematical distribution of chance, without a deterministic substrate, as it was decided back then? And also Einstein had this thought though he bases it on the understandable chances as seen in the throwing of a dice, after which Gòd lets a particle take position, so to speak.

If it was decided back then to start a search for a deeper theory, which de Broglie proposed more or less (by means of physical pilot waves), who knows what the theory would have looked like these days? But people were satisfied to shut up and calculate, leaving room for dozens interpretations. Among which hidden variables. Now these variables might seem just as obscure as pure, undetermined chance, but they somehow feel more satisfactory. Local hidden variables are ruled out by experiment, but the ones needed are obviously the non-local ones. But exactly what is hidden then? The mystery...

My point is that the the MWI is caused by the wavefunction being seen as a mathematical entity. — Cartuna

That's not right. The wavefunction is a mathematical entity. MWI came from taking that entity as a literal description of the universe.

If it was decided back then to start a search for a deeper theory, which de Broglie proposed more or less (by means of physical pilot waves), who knows what the theory would have looked like these days? — Cartuna

It would look like Bohmian mechanics.

That's not right. The wavefunction is a mathematical entity. MWI came from taking that entity as a literal description of the universe. — Kenosha Kid

That's exactly what I mean. But it is no literal description.

It would look like Bohmian mechanics. — Kenosha Kid

Yes. Like. The point is that it came too late. Giving birth to weird paradoxes like Schrödingers cat or Wigners friend. Or even weirder, the MWI. It gave Eels though...

That's exactly what I mean. But it is no literal description. — Cartuna

That's just a fundamental belief. For all we know it's spot on. (I don't believe so either, but I don't claim to know things that haven't yet been determined.)

Yes. Like. — Cartuna

It would look like Bohmian mechanics because it is Bohmian mechanics, developed by Bohm and Dirac.

That's just a fundamental belief. For all we know it's spot on. (I don't believe so either, but I don't claim to know things that haven't yet been determined.) — Kenosha Kid

I don't say it is not spot on. It's indeed my fundamental belief that the wavefunction as a mathematical entity is a kind of Platonic view on reality, the metaphysical world of math being the world itself. How can a particle be at several places at the same time and how can it be pure chance (whatever that means without a deterministic substrate) that determines?

How can a particle be at several places at the same time and how can it be pure chance (whatever that means without a deterministic substrate) that determines? — Cartuna

The fundamental belief here being that a particle cannot be in more than one place. Remove the belief and the question vanishes. All that remains is to falsify or verify that belief.

MWI doesn't say it's pure chance. Chance plays a role only in QM interpretations with collapse mechanisms.

The fundamental belief here being that a particle cannot be in more than one place. Remove the belief and the question vanishes. All that remains is to falsify or verify that belief. — Kenosha Kid

A partìcle can be in all places it likes. But not at the same time. Call it a fundamental belief. If you think this all weird stuff of QM vanishes. You might ask yourself if that wouldn't generate, in the case of an electron, EM radiation, the electron hopping around weirdly like a Brownian particle. But a smeared out electron is just as weird.

MWI doesn't say it's pure chance. — Kenosha Kid

But it still assigns probabilities to branching points.

A partìcle can be in all places it likes. But not at the same time. Call it a fundamental belief. — Cartuna

I did, because it is. You're not making an argument here, you're just reasserting outdated beliefs. There's nothing more here than someone insisting that evolution is untrue because God made everything.

Science is driven by observation, and observations (such as the double slit experiment) do not favour your beliefs. Bohmian mechanics doesn't solve your problem either, since Bohm was obliged to move particle properties from the particle to the pilot wave to explain experimental outcomes (such as the zero electric moment of ground state hydrogen), and because the pilot wave itself is a field, i.e. a thing that's already in multiple places at once.

What we learned from Bohm was not that particles are points, but that we should keep an open mind.

But it still assigns probabilities to branching points. — Cartuna

It assigns branch widths according to the Born rule.

I did, because it is. You're not making an argument here, you're just reasserting outdated beliefs. There's nothing more here than someone insisting that evolution is untrue because God made everything. — Kenosha Kid

Why should I make an argument? I just belief it. Juat like you belief your stuff about the wavefunction. I don't see where God and evolution enter here. My view is just unorthodox.

It assigns branch widths according to the Born rule. — Kenosha Kid

So still a probability distribution. If one state has 0.1 (squared) weight and another 0.9, what does this entail for the corresponding two parallel universes? That the connecting branches have different widths? But what does that mean for the two univeres after the branching?

Why should I make an argument? I just belief it. Juat like you belief your stuff about the wavefunction. I don't see where God and evolution enter here. — Cartuna

You don't see where God and evolution enter into the realm of fundamental beliefs that conflict with scientific evidence? Curious...