There's a wiki page on observers with respect to quantum mechanics. Humans aren't required.

It is irrefutable that only a consciousness brings the wave function to collapse. The consciousness connects here with the electronic eye and brings also its wave function to the collapse. With several consciousnesses, each has its own wave function (-> Wigner's friend), which are consistent with each other and correspond to the respective information state.

I can't be bothered. @Kenosha Kid have fun.

Just think classic: Wigner's friend is standing in front of the box with the cat. Its condition is only a probability for him. When he opens it, this probability collapses into certainty. For Wigner outside the room it is still only a probability.

Wigner and Wigner's friend have also classically a different view. For Wigner's friend the cat is either alive or dead, for Wigner it is in a "probability cloud".

Physicist Sean Carroll explains observers in QM.

It is irrefutable that only a consciousness brings the wave function to collapse. — SolarWind

Even if it's irrefutable, that doesn't mean it's true.

It is irrefutable that only a consciousness brings the wave function to collapse. — SolarWind

How's about we bring a Raven into it? What does he/she say?

It is irrefutable that only a consciousness brings the wave function to collapse. — SolarWind

It is even more irrefutable that wave function collapse does not require consciousness. It seems that others are pointing this out. Wigner himself abandoned this interpretation when it was shown to logically lead to solipsism. Solipsism is another irrefutable thing.

Almost all quantum experiments take place without a human observer, except to gather the data afterwards.

What counts as an observer? — TiredThinker

Metaphysically, it is one system interacting with another, in any way.
Epistemologically, it seems to be a function of awareness, be it human or otherwise.

Can they use an electronic eye to see and record where the photon actually goes

You can't watch a photon. If you measure its path, any interference disappears.

and half the time delete the results before a human becomes aware of it

Human awareness does not play a metaphysical role (except in the Wigner interpretation). A result can be kept in superposition, but I know of no way to 'delete' a measured result.

I want to know if the electronic eye is interfering with the experiment and collapsing the wave function, or if it is awareness by a conscious human being.

The E-eye is not necessary either. Any interaction (the photon hitting the far wall in a room with no people or sensory devices) is enough to collapse the wave function, in interpretations with wave function collapse.

Even if it's irrefutable, that doesn't mean it's true. — T Clark

SO true!

Can they use an electronic eye to see and record where the photon actually goes, and half the time delete the results before a human becomes aware of it and half the time let it known to a human? I want to know if the electronic eye is interfering with the experiment and collapsing the wave function, or if it is awareness by a conscious human being. — TiredThinker

It's possible to mark which slit a photon goes through and then later erase that mark. With a stream of marked and then unmarked photons, an interference pattern will be formed as per the original double-slit experiment. See the quantum eraser experiment. However, apart from that kind of carefully controlled experiment, once information leaks out into the environment (say, to an electronic eye) there is no practical way of erasing it and no interference pattern would form. That's the case even if no human ever learns which slits the photons went through.

I want to know if the electronic eye is interfering with the experiment and collapsing the wave function, or if it is awareness by a conscious human being. — TiredThinker

I doubt matter underlying the wave function ever fully collapses, as if an absolute demarcation between coherence and decoherence exists, but rather morphs into different shapes and formations depending on context, and can be composed of multiple states simultaneously, wavelike, particlelike, entangled, superpositioned, etc. all at once. Trillions of interacting atoms become comparatively particlelike (localized), but still participate in weird relativistic or nonlocal dynamics, for instance infused with EM radiation and further field phenomena that stretch or transgress the boundaries of classical physics. Much of this hasn't been adequately theorized so far, why quantum physics is so fascinating, truly a pioneering science.

I haven't read about this electronic eye deal, but is it somehow designed to avoid causing decoherence?

I doubt matter underlying the wave function ever fully collapses, as if an absolute demarcation between coherence and decoherence exists, but rather morphs into different shapes and formations depending . . . — Enrique

Are you speaking of a matter wave or a probability wave in QM? Kenosha Kid is probably out making millions with his guitar rather than really important work like clarifying physics on this forum. :sad:

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

Are you speaking of a matter wave or a probability wave in QM? — jgill

The probability wave is the wave function, the quantized matter wave is the substance that the wave function probabilistically models.

I was wondering how many versions of this experiment have been run? — TiredThinker

It was performed ages ago using crystals to diffract the electrons, and more recently in a way more similar to how the experiment is actually described.

Can they use an electronic eye to see and record where the photon actually goes, and half the time delete the results before a human becomes aware of it and half the time let it known to a human? — TiredThinker

Putting a light source close to the slits destroys the interference effect: the more powerful the light source, the less interference occurs. Basically the more powerful the light source, the more likely the electron will interact with one or more photons en route to the screen. So whether you look at the electronic eye's recordings or not, the photons would kill the quantum behaviour that the experiment interrogates.

I'll try, but...

Kenosha Kid is probably out making millions with his guitar rather than really important work like clarifying physics on this forum. :sad: — jgill

I wish!

It is irrefutable that only a consciousness brings the wave function to collapse. — SolarWind

This first sentence is the only thing that made sense to me, and it's not right. It's certainly refutable that consciousness collapses the wavefunction. I'd say the greatest consensus is now around non-collapse interpretations of QM (e.g. MWI). Even among collapse adherents, I don't think it's common or even sensible to make collapse dependent on consciousness. I've never met a quantum theorist who believed this, but they do, or did, exist. Personally I think that's a symptom of humans insisting on the specialness of humans though.

I think the rest of your comment assumes your own particularly esoteric beliefs.

I doubt matter underlying the wave function ever fully collapses — Enrique

Not sure what this means either. The material properties of, say, an electron (mass, charge, lepton number, etc.) certainly do transcend whatever's going on with the wavefunction if that's what you mean. Or maybe you mean the particle field. A particle is a quantised excitement of that particle field according to QFT, that is: whatever the excitation, it is constrained to have certain properties, that aforementioned material properties that are fixed, independent of the actual wavefunction.

The material properties of, say, an electron (mass, charge, lepton number, etc.) certainly do transcend whatever's going on with the wavefunction if that's what you mean. — Kenosha Kid

As I understand it, the "collapse of the wave function" essentially models matter insofar as large quantities of interacting particles give rise to contexts of decoherence, resulting in definite statistical distributions relating initial and final states, beyond which the probabilities are effectively negligible.

What I was saying is that these probability distributions the wave function models when it collapses into a definite state are relative to a specific perspective on large wavicle quantities, where these wavicles tend to act like particles. The picture of matter as in an absolutely decoherent, "collapsed" state works for many practical purposes, but quantum nonlocality shows that this is an illusion, a degree of coherence always remains.

Perhaps you can explain to us how this "coherence" or quantum entanglement amongst wavicles is modeled. Local hidden variables were ruled out by experiment, so where is theory currently at in accounting for nonlocality?

pseudo science...

you can take an academic course or watch a lecture on the topic. There are free on youtube.
In order to make any observation you need to crash bosons and fermions...not the most typical observation out there.

As I understand it, the "collapse of the wave function" essentially models matter insofar as large quantities of interacting particles give rise to contexts of decoherence, resulting in definite statistical distributions relating initial and final states, beyond which the probabilities are effectively negligible. — Enrique

Well the classical limit ensures that, for the most part, material properties of large many-particle systems themselves are well defined. This doesn't mean that the particles within them have collapsed. Conducting electrons in metals, for instance, could be spread throughout the entire metal, but the metal itself still has well-defined material properties. On the other hand, as I said above, a single photon is sufficient to collapse an electron wavefunction. So it's not like there's a one-to-one correspondence between system size and collapse.

Perhaps you can explain to us how this "coherence" or quantum entanglement amongst wavicles is modeled. Local hidden variables were ruled out by experiment, so where is theory currently at in accounting for nonlocality? — Enrique

Properly by the many-particle wavefunction (the solution to the many-particle Schroedinger equation). However that is difficult to interrogate. Usually by other approximate methods then, such as quasiparticle methods in which those correlations and the "wavicle" are treated as one independent thing, or by density- or density-matrix methods where they are replicated by exchange and correlation forces. These forces are intrinsically nonlocal, but not really there, rather they're just approximations to whatever is going on in the real wavefunction. Check out modular space-time too, in which locality is pretty much redefined to not be spatial.

Is it possible that a star has a wave function that is distributed over the whole galaxy? I don't see any mathematical problem there.

Either it is possible, then also huge objects can be non-collapsed or the mathematics of the Schrödinger equation is wrong.

Yes I was asking if the human mind is special in relation to the physical world. When I first heard about the double slit experiment it gave me hope that our thoughts are more than just random electrical signals in a brain, which has always seemed too unreliable from a psychological point of view.

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?

One should consider the Bohmian mechanics. But after the measurement empty wave functions arise. But since one already knows where the particle is, this no longer corresponds to Born's rule.

A consciousness can "think away" the empty wave functions.

When I first heard about the double slit experiment it gave me hope that our thoughts are more than just random electrical signals in a brain, which has always seemed too unreliable from a psychological point of view. — TiredThinker

I don't think any physicist or neurologist or psychologist believe that our thoughts are random electrical signals (if that's any reassurance). In fact, "random" and "signal" contradict one another.

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

Aye. The particle would collapse upon scattering with the photon and the pattern that would build up would be a classical double Gaussian rather than the stripes characteristic of interference.

The particle would collapse upon scattering with the photon and the pattern that would build up would be a classical double Gaussian rather than the stripes characteristic of interference. — Kenosha Kid

One always has interactions with radio waves or neutrinos. How then can there ever be interference patterns?

And what is a neutrino famous for? Not interacting with matter. :smile:

Which frequencies of light a material can absorb depend on the properties of that material. In the simplest case, an atom, this is determined by the energy levels of that atom. Some of those energy levels are filled, some are empty. Which depends on the state of the atom, but generally the gap between two energy levels diminishes with increasing energy, until you hit the ionisation energy of the atom.

As such, unless an atom is in a highly excited state, you green generally need higher energy EM radiation to interact with it. Most atoms are going to be transparent to radio waves simply because, whatever energy levels the electrons are at, jumping to the next one up will require more energy.

Collections of atoms such as molecules and crystals have lower energy band gaps. Water vapour appears white, for instance, because it can absorb and therefore re-emit radiation at pretty much any frequency in and around the visible range. Metals will absorb any radiation no problem because the density of available energy levels is so high.

Most atoms are going to be transparent to radio waves simply because, whatever energy levels the electrons are at, jumping to the next one up will require more energy. — Kenosha Kid

It is not about atoms. Why can't a single free electron interact with radio waves or infrared radiation in the apparatus?

modular space-time — Kenosha Kid

Cool.
"This concept embodies the standard tenets of quantum theory and implements in a precise way a notion of relative locality. The usual string backgrounds (non-compact space-time along with some toroidally compactified spatial directions) are obtained from modular space-time"
and
"the principle of relative locality, a proposed generalization of the principle of relativity in which different observers see different notions of spacetimes."

It can, it's called scattering. Basically the shorter the wavelength, the [EDIT] higher the probability of scattering.

It is not about atoms. Why can't a single free electron interact with radio waves or infrared radiation in the apparatus?
2h — SolarWind

I can interact. Why shouldn't it?