B What percent of everyday-life electrons are collapsed?

[VECT]

So if particles such as the electrons when "measured" forsake their probabilistic wave form and manifest into a definite particle form, does that mean for all intent and purpose the electrons of every objects we observe are already collapsed?

If that's the case how did the labs get pre-collapse electrons for their test? Can collapsed particles be turned back to their pre-collapsed waveform?

And if every day objects do not have already collapsed electrons, how are we observing stable molecules? Do collapsed electrons vs pre-collapsed electrons have any bearings/differences on chemical/physical structures of macro objects?

 

[EPR]

Quantum theory is not a very good description of the observed reality. There are many interpretations of how the world works but few will make sense wrt to the observed world. So the short answer - it's unknown. It's unknown and debatable whether collapse even takes place as such.

Take a look at the interpretations after you've learned the fundamentals and pick your favourite.

 

[Nugatory]

So if particles such as the electrons when "measured" forsake their probabilistic wave form and manifest into a definite particle form,

That’s not what happens. The particle is always described by a wave function; a measurement changes the wave function but doesn’t make it go away.

“Wave-particle duality”, the idea of electrons switching from waves to particles when measured was abandoned many decades ago when the modern theory of quantum mechanics was developed. Unfortunately it still lives on in the popular press, mostly because it’s easier to explain without math, so you’ll see it a lot.

Giancarlo Ghirardi’s book “Sneaking a look at God’s cards” is a good layman-friendly introduction to the real thing.

 

[VECT]

That’s not what happens. The particle is always described by a wave function; a measurement changes the wave function but doesn’t make it go away.

“Wave-particle duality”, the idea of electrons switching from waves to particles when measured was abandoned many decades ago when the modern theory of quantum mechanics was developed. Unfortunately it still lives on in the popular press, mostly because it’s easier to explain without math, so you’ll see it a lot.

Giancarlo Ghirardi’s book “Sneaking a look at God’s cards” is a good layman-friendly introduction to the real thing.

https://books.google.ca/books?id=PEpfZ3Ul8u8C&printsec=copyright&redir_esc=y#v=onepage&q&f=false

Sorry but that book does not look layman-friendly at all.

Also the point you made seem to be just semantics.

"Something" happens when a measurement is made. The wave function gets changed so that it's 0% in all other places and 100% in one place. If it's not correct to call this collapsing into a particle then call it whatever.

But going back to what I was asking, have the electrons of stuff we observe everyday already under-gone this change? And does this change have any bearings on the macro structure of an object?

Pardon my bluntness here but non-physicists such as myself am just interested in straight answers (if there is one) and we don't know if there isn't.

 

[hutchphd]

"Getting measured" is not an intrinsic property of the electron. It describes a set of interactions that necessarily involve the rest of the world. After measurement the electron is still an electron described by a (probably altered) quantum description (wavefunction if you like) and time evolution . It is not like electronic puberty or a Bar Mitvah.

 

[atyy]

"Something" happens when a measurement is made. The wave function gets changed so that it's 0% in all other places and 100% in one place. If it's not correct to call this collapsing into a particle then call it whatever.

Not all measurements collapse the wave function from 0% in one place to 100% in another place. Only a subset of accurate position measurements do so. The measurements in everyday life are not this sort of accurate measurement. For example, it is not possible to measure position and momentum accurately simultaneously, However, in everyday life we do measure position and momentum simultaneously but inaccurately. These inaccurate measurements lead to a different sort of collapse.

 

[atyy]

If that's the case how did the labs get pre-collapse electrons for their test? Can collapsed particles be turned back to their pre-collapsed waveform?

A lab may deliberately make a certain type of measurement to collapse a system in a certain way. Measurement is a type of preparation procedure.

After a system is collapsed, it evolves by the same rules as it was just before collapse. In the case of a measurement that collapses a particle to a definite position, after the collapse the wave function can evolve by spreading out so that it again has an indefinite position.

 

[atyy]

And if every day objects do not have already collapsed electrons, how are we observing stable molecules? Do collapsed electrons vs pre-collapsed electrons have any bearings/differences on chemical/physical structures of macro objects?

Everyday measurements don't affect the chemical/physical structures of macro objects. Of course this depends on what one meas by everyday, but we do have mathematical models for many everyday measurements that can be carried out in the lab, and that correspond to everyday properties of materials such as conductivity.

 

[VECT]

Okay, that actually explains a lot for me, thank you.

And just a last question out curiosity.

Say that you have a glass of water in front of you, and you have the power to manipulate the waveform/wavefunction of every electron of every atom in that water to the exact degree of what you want, what would that do on a macro scale? Can you theoretically change that glass of water to wine?

 

[DaveC426913]

https://books.google.ca/books?id=PEpfZ3Ul8u8C&printsec=copyright&redir_esc=y#v=onepage&q&f=false

Sorry but that book does not look layman-friendly at all.

Indeed. The only e-version is for Kindle. Nothing for Kobo.

Pity, it would have been emboughtened in two minutes flat.

 

[atyy]

Say that you have a glass of water in front of you, and you have the power to manipulate the waveform/wavefunction of every electron of every atom in that water to the exact degree of what you want, what would that do on a macro scale? Can you theoretically change that glass of water to wine?

No you can't, because wine and water differ in their nuclei of their atoms also, not only the electrons of their atoms. So one would need greater magical powers than this.

 

[VECT]

No you can't, because wine and water differ in their nuclei of their atoms also, not only the electrons of their atoms. So one would need greater magical powers than this.

Right, but isn't nuclei particles also just waveforms governed by the wavefunction :)

Anyhow, appreciate very much the responses.

 

[atyy]

Right, but isn't nuclei particles also just waveforms governed by the wavefunction :)

Roughly yes. In a quantum theory, one specifies
1) the quantum state (in many cases this is also called the wave function)
2) the Hamiltonian (which governs how the state changes with time)
3) the observables (which govern what measurements can be made)

So if you have arbitrary control over all of these, you can make any system you want.

 

[DrChinese]

1. But going back to what I was asking, have the electrons of stuff we observe everyday already under-gone this change? And does this change have any bearings on the macro structure of an object?

2. Pardon my bluntness here but non-physicists such as myself am just interested in straight answers (if there is one) and we don't know if there isn't.

1. A bound electron in an atom normally will not have a definite position or momentum at any time. If you observe it, you might well free it from the atom.

2. There are no "straight answers" to many questions about Quantum Mechanics. The reason is: QM features very accurate (and useful) complex mathematical descriptions that do not translate well into normal language (such as English). Trying to describe the position or momentum of a bound electron is an example. Ditto with trying to explain electron spin (what is spinning?). And most bound electrons can be considered as entangled with other electrons, thereby losing their individual identity and instead acting as part of a quantum system.

So please understand that no one here is trying to evade your questions by giving you a run around.

Also: You asked about turning water into wine. The issue is that there are conservation rules: total quantum numbers (including mass-energy) do not change under any known physical processes. As already mentioned by others, the nuclei of molecules of wine ingredients are different than those of water molecules.

 

[PeterDonis]

isn't nuclei particles also just waveforms governed by the wavefunction

"Waveforms governed by the wave function" is not the same as "you can do whatever you want".

In a quantum theory, one specifies
1) the quantum state (in many cases this is also called the wave function)
2) the Hamiltonian (which governs how the state changes with time)
3) the observables (which govern what measurements can be made)

You left out a very important one: 4) the Hilbert space (which describes the available degrees of freedom). States that are described by "water" might not even share a Hilbert space with states that are described by "wine".

if you have arbitrary control over all of these

Which you never do.

 

[PeterDonis]

"Something" happens when a measurement is made.

Yes: what happens is that the system being "measured" (electron, glass of water, whatever) interacts with another system, called the "measuring device". This correlates properties of the measuring device with properties of the system being measured; the properties of the measuring device are assumed to be things that we can "read off" directly from the measuring device (like where a pointer points on a dial, or what numbers appear on a digital readout) and which then tell us something about the system being measured.

For a more technical description, you could try this Insights article:

https://www.physicsforums.com/insights/the-7-basic-rules-of-quantum-mechanics/

Note that I didn't use the term "collapse" at all in the above. Rule 7 in the above Insights article talks about that; but note that the term "collapse" in the literature on QM very often does not mean Rule 7, but rather indicates the use of some particular interpretation of QM that goes beyond the 7 Basic Rules. So it's often not possible to answer questions about "collapse" independently of a specific interpretation of QM. Discussion of QM interpretations, here at PF, should be done in the subforum of this one on Quantum Interpretations and Foundations.

have the electrons of stuff we observe everyday already under-gone this change?

Unless we take special precautions to isolate a particular quantum system in a lab, everything is always interacting with other things. But these interactions are not a single "change", they are a continuous process that is always going on. Isolating a quantum system in a lab so it only interacts and gets "measured" at a particular time that we control is a very unusual thing.

 

[EPR]

That’s not what happens. The particle is always described by a wave function; a measurement changes the wave function but doesn’t make it go away.

The wave function is a mathematical abstraction from Hilbert space. It's not even there before the measurement so how can it go away or stay in place

 

[EPR]

Right, but isn't nuclei particles also just waveforms governed by the wavefunction :)

Anyhow, appreciate very much the responses.

Waveforms are theoretical. Their "waveness" is inferred by their particle-like properties in experiments..
Since your question is about our daily life experience(and has little to do with qm as it is known), be advised that we(as large macroscopic bodies) are always dealing with the particle aspect of quantum systems. There is no exception to this.
QM serves the purpose of explaining how those particles move and interact as they neither move classically(with trajectories), nor have definite properties at all times.

Your OP question is very interesting, but deeper than can be addressed with the currently known facts. It's thought that decoherence plays a leading role how macroscopic objects stay classical but why they manifest classically and these laws like F=m.a arise and not some others is generally unknown.

 

[StevieTNZ]

https://books.google.ca/books?id=PEpfZ3Ul8u8C&printsec=copyright&redir_esc=y#v=onepage&q&f=false

Sorry but that book does not look layman-friendly at all.

It is actually a very good layman friendly book. That's one of the reasons I purchased a copy and read it in its entirety.

 

[atyy]

You left out a very important one: 4) the Hilbert space (which describes the available degrees of freedom). States that are described by "water" might not even share a Hilbert space with states that are described by "wine"

Informally, we can consider them different excitations of the same quantum fields. In that sense, they share the same Hilbert space.

 

[PeterDonis]

Informally, we can consider them different excitations of the same quantum fields. In that sense, they share the same Hilbert space.

I suppose if you are willing to consider the Hilbert space to be, heuristically, the Fock space of all of the Standard Model fields combined (i.e., one could have anywhere from zero to an unbounded number of "particles" of each type), you could do this. Then the problem would be to show that there is a nonzero transition amplitude between the "water" subspace and the "wine" subspace of this overall Hilbert space.

 

[VECT]

If I see an audio version of that book I'll listen to it, no promises.

Look I'll be honest here, as much as all of physics is interesting to people here, to the general public, it's really just two things:

-Relativity: Black-Hole (FTL, time-travel..etc.)
-Quantum Physics: Interpretation of the Measurement Problem

And as for that second subject..

On one hand you have physicists who goes off on a tangent talking about the profession's glorious past all the way back to Copernicus and Newton and how people like Schrodinger regretted to ever delve too greedily and too deep; and who now is trying to fend off the masses with equations and technicalities because really there's nothing disreputable going on here please don't cut my fundings.

Then on the other hand you have full blown zealots from every denomination of every religion and mysticism that's still around since stone age going "told ya".

I try to get my itching questions answered without posting on forums so the can of worm don't get stirred, but it's pretty hard sometimes.

I'll be sure to post further questions down in the quarantine zone you guys setup if I have them.

 

[atyy]

I suppose if you are willing to consider the Hilbert space to be, heuristically, the Fock space of all of the Standard Model fields combined (i.e., one could have anywhere from zero to an unbounded number of "particles" of each type), you could do this.

Yes, that's what I was thinking. There is the problem that a Fock space is not the appropriate space in a rigorously constructed interacting relativistic quantum field theory, but since the standard model is not there yet, I thought it's ok to give an answer at the non-rigorous level that the interaction picture is still used in most books.

Then the problem would be to show that there is a nonzero transition amplitude between the "water" subspace and the "wine" subspace of this overall Hilbert space.

That's different from what I was thinking of, but it does make sense to ask whether there is a nonzero transition amplitude between the water and wine subspaces. This corresponds to saying, if we make the measurement "Is this wine?" on water, will we receive the answer "yes" with some non-zero probability.

What I was thinking of is that if we have 2 different vectors in the same Hilbert space, then one needs a rotation to change one vector into another. So the question is whether one could devise a time-dependent Hamiltonian that one could apply to make the transition. I imagine that it would be mathematically possible. However, I imagine that it would not be physical (even in principle) as some conservation laws are likely to be broken (but am not sure). In the unlikely case that no conservation laws are broken, I imagine it would be way beyond practical experimental control (like the Schroedinger's cat thought experiment).

 

[DennisN]

Look I'll be honest here, as much as all of physics is interesting to people here, to the general public, it's really just two things:

-Relativity: Black-Hole (FTL, time-travel..etc.)
-Quantum Physics: Interpretation of the Measurement Problem

I'd say various topics in cosmology also seem quite popular with the general public, e.g. Big Bang, expansion of the Universe, size and shape of the Universe, to name a few things (edit: and I can add dark matter and dark energy too; actually there are quite a lot of interesting topics in astrophysics/cosmology ).

And regarding more hypothetical concepts, String Theory and multiverse theories also seem to be quite popular with the general public.

I try to get my itching questions answered without posting on forums so the can of worm don't get stirred, but it's pretty hard sometimes.

For scientific questions and scientific answers, you have come to the right place.

 

[VECT]

I do have another question now considering what people have said.

For everyday molecular bounds, do say the particle probability cloud have to evolve into some kind of 100%-0% state for the molecules to be stable? Or do the proposed varying degree clouds enough to keep everything normal.

And if varying degree particle clouds are enough to keep up everyday appearances, then why does it matter/what difference does it make what form the wavefunction evolve to?

 

[PeroK]

I do have another question now considering what people have said.

For everyday molecular bounds, do say the particle probability cloud have to evolve into some kind of 100%-0% state for the molecules to be stable? Or do the proposed varying degree clouds enough to keep everything normal.

And if varying degree particle clouds are enough to keep up everyday appearances, then why does it matter/what difference does it make what form the wavefunction evolve to?

A molecule is a system of several particles. A hydrogen atom is a proton and an electron; a hydrogen molecule is two hydrogen atoms; and, water is two hydrogen atoms and an oxygen atom. The molecule is typically in its ground state, which is the lowest energy state for that collection of particles, and is stable.

If you take a classical view then you may ask where precisely are the individual particles in this ground state configuration? What QM says is that well-defined positions of these particles are not part of the theory. The theory tells you that the molecule is in the stable ground state, which is not evolving over time.

The relevant wave function is for the entire water molecule: the constituent particles themselves do not have individual wave-functions that are free to evolve. This is another important, non-classical aspect of QM.

From this you can infer the chemical and physical properties of water. There's no need to measure every water molecule to check it is in the ground state.

In any case, in order to explain everyday phenomena you need to build on QM: from chemistry to fluid mechanics etc.

 

[VECT]

The relevant wave function is for the entire water molecule: the constituent particles themselves do not have individual wave-functions that are free to evolve. This is another important, non-classical aspect of QM.

But then if you zoom out again you can say the relevant wave function is for the entire block of water molecules and the constituent molecules themselves do not have individual wave-functions and are free to evolve...etc.

And then if you zoom out enough at certain point stuff just become classic in description and lose their quantum weirdness.

So pretty much nobody really knows right now then.

 

[bhobba]

Quantum theory is not a very good description of the observed reality.

I think what you are trying to say is QM does not conform very well to our classical world intuition. It is an excellent description of observed reality.

Let's processed on that basis; otherwise, the mentors may delete it because it is based on a falsehood.

Thanks
Bill

 

[PeterDonis]

For everyday molecular bounds, do say the particle probability cloud have to evolve into some kind of 100%-0% state for the molecules to be stable?

The molecule is in a "100%-0%" state. It's just not in a "100%-0%" state of position. It's in a "100%-0%" state of energy. There is no single "100%-0%" state; there are different such states for different observables. A "100%-0%" state of position would not be stable; a "100%-0%" state of energy is.

 

[PeroK]

But then if you zoom out again you can say the relevant wave function is for the entire block of water molecules and the constituent molecules themselves do not have individual wave-functions and are free to evolve...etc.

And then if you zoom out enough at certain point stuff just become classic in description and lose their quantum weirdness.

So pretty much nobody really knows right now then.

Quite quickly it becomes computationally impossible to use QM and nothing but QM. You have to build layers of understanding with new concepts at each layer. A good example, perhaps, is biology. You start with QM, build fundamental chemistry on top of that, organic chemistry on top of that, then cell biology, anatomy and animal behaviour etc. It's not a failure of QM that you can't explain animal behaviour purely in terms of QM. QM is the theory of fundamental particles and you need layers of scientific theories that build on it.

Another example is the computer you are using. Ultimately, everything that happens on a computer is binary stuff at a fundamental electronic level (which is also built on QM). But, you can't expect to describe a word processor in terms of computer hardware fundamentals, nor in terms of QM.

The precise way that the classical world emerges is, of course, very hard to model - although I don't think there is too much difficulty is seeing why quantum "weirdness" gets washed out by sheer statistical averages.

 

[bhobba]

The wave function is a mathematical abstraction from Hilbert space. It's not even there before the measurement so how can it go away or stay in place

The meaning of the wave function is interpretation dependant. It can be real or just a mathematical abstraction. One interpretation is based on Gleason's Theorem where it is just an aid to calculating probabilities. Probabilities are also interpretation dependant, but most think they are not 'real' in the sense a physicist would think as real - but again, philosophers argue about that. Hence, one interpretation is it is just a conceptualization, it is not 'real' and can instantaneously change etc. But either way, it is part of the theory and, in principle, can always be assigned some 'value'. Actually, according to decoherence, it is more complicated - but that will take us way off-topic.

Thanks
Bill

 

[EPR]

I think what you are trying to say is QM does not conform very well to our classical world intuition. It is an excellent description of observed reality.

Let's processed on that basis; otherwise, the mentors may shut it down because it is based on a falsehood.

Thanks
Bill

While I agree, you need QT and a set of additional assumptions(a new structure) to explain the classical reality. This was the intent of the quoted passage.

The quantum is very unlike the classical and while I agree that QT explains a wider range of phenomena, it fails to explain the observed classical world in a single, agreeable fashion.

 

[PeterDonis]

while I agree that QT explains a wider range of phenomena, it fails to explain the observed classical world in a single, agreeable fashion

This is a claim about interpretations and is off topic here. Discussions about QM interpretations belong in the interpretations forum. QT makes accurate predictions about the results of experiments, and that is what is on topic in this forum.

 

[VECT]

The molecule is in a "100%-0%" state. It's just not in a "100%-0%" state of position. It's in a "100%-0%" state of energy. There is no single "100%-0%" state; there are different such states for different observables. A "100%-0%" state of position would not be stable; a "100%-0%" state of energy is.

Okay well then now I have to ask:
-How many different observables for particles are there right now?
-Energy, position, spin?..etc.
-Is the Energy observable also subject to some sort of uncertainty principle?
-Given that variation in the Energy observable theoretically disrupt molecular stability, what potential theoretical macro disruptions (if any) can be caused by variations in these other observables?

 

[VECT]

Quite quickly it becomes computationally impossible to use QM and nothing but QM. You have to build layers of understanding with new concepts at each layer. A good example, perhaps, is biology. You start with QM, build fundamental chemistry on top of that, organic chemistry on top of that, then cell biology, anatomy and animal behaviour etc. It's not a failure of QM that you can't explain animal behaviour purely in terms of QM. QM is the theory of fundamental particles and you need layers of scientific theories that build on it.

Another example is the computer you are using. Ultimately, everything that happens on a computer is binary stuff at a fundamental electronic level (which is also built on QM). But, you can't expect to describe a word processor in terms of computer hardware fundamentals, nor in terms of QM.

The precise way that the classical world emerges is, of course, very hard to model - although I don't think there is too much difficulty is seeing why quantum "weirdness" gets washed out by sheer statistical averages.

The spirit of what I was trying to ask is less about a workable model predicating everything from QM variables up to macro variables. At the moment I am just trying to get a picture of what are the potential theoretical macro variations given hypothetical induced variabilities (artificial or otherwise) in QM parameters.

But if all the quantum "weirdness" just gets washed away by sheer statistical averages once stuff gets to the macro scale, then like what I was wondering, what's the point of QM. If things don't actually have the potential to cascade upward into any meaningful impact, all the QM properties people are painstakingly calculating might as well be scribbles on a wall..

edit: other than quantum computer, that thing doesn't need to cascade up all that much, but you get my point

 

[PeterDonis]

-How many different observables for particles are there right now?

What do you mean by "right now"?

Observables are things that can potentially be measured. There are theoretically an infinite number of them, but none of them are "right now", they're just observables.

Is the Energy observable also subject to some sort of uncertainty principle?

Sort of. The obvious conjugate observable would be time (energy <-> time by analogy with momentum <-> position), but time is not an observable in QM. (We are talking about non-relativistic QM here; quantum field theory, which is what you need to do relativistic QM, is a different thing with its own set of issues.) However, it turns out that there is a way to relate the uncertainty in energy to something associated with time: roughly speaking, the "time uncertainty" $\Delta t$ of a system is the expected time for the system to undergo a significant change, and this $\Delta t$ has the kind of uncertainty relation with $\Delta E$, the uncertainty in energy, that you would expect: $\Delta E \Delta t \ge \hbar$.

However, none of that even matters unless you are measuring the energy, and measuring the energy of a molecule means interacting with it and potentially disrupting it. See below.

Given that variation in the Energy observable theoretically disrupt molecular stability

No, measuring the energy observable can disrupt molecular stability, because measurement is an interaction. But if a molecule is just sitting there, not being measured, there is no "variation in the energy observable". See further comments below.

what potential theoretical macro disruptions (if any) can be caused by variations in these other observables?

You seem to be thinking of a quantum system that is just sitting there, like a molecule, as having continuous "variation" in "observables". That's not correct. A quantum system that is just sitting there is just sitting there. To see any "variation" you have to measure it. More precisely, to see any variation in a particular observable, you have to conduct a measurement of that observable on a large number of identically prepared quantum systems and then do statistics on the results. "Variation of an observable" isn't even a concept that makes sense for a single quantum system.

 

[VECT]

By "right now" I mean at the current stage of physics how many of those infinite number of observables have we observed and incorporated in QM (specifically the ones for particle). You mentioned Energy and Position, anything else?

I should clarify, when I say "variation" I always mean induced significant variation of say an hypothetical artificial nature, NOT natural fluctuations. In another word, variation caused by measurement/interaction...etc.

The whole point of the thread and my line of questioning is just me trying to get an idea what are the theoretical scope of change on a macro scale can possibly be caused by hypothetical artificial manipulation of variables at the quantum scale.

 

[DrChinese]

But if all the quantum "weirdness" just gets washed away by sheer statistical averages once stuff gets to the macro scale, then like what I was wondering, what's the point of QM. If things don't actually have the potential to cascade upward into any meaningful impact, all the QM properties people are painstakingly calculating might as well be scribbles on a wall..

Of course they matter!

The purpose of science is to provide a useful description of some scope of patterns of behavior, be it quantum physics or chemistry or cosmology or biology. When you more from one field to another, that scope can be quite different - by definition! That's because different variables become more or less significant. Gravity is an important factor in describing galaxies, but not so important when discussing most quantum physics or chemistry.

Yet gravity still operates everywhere, as does quantum physics. So the point of QM is to describe what patterns emerge at that level. Clearly, quantum mechanics helps us to understand why a water molecule is shaped as it is - this is not explained by chemistry. And the shape of a water molecule is directly responsible for explaining human cell structure and operation - which would not be possible without that shape.

Just because you can't see every quantum rule in effect with your own eyes does not mean they are not being used to build up from a micro to macro layer. As mentioned by PeterDonis and others: the fact that electrons are in a stable energy state (even though their position is undefined) is critical to explaining the structure of atoms (and molecules). And therefore important to explaining much chemistry and in turn biology.

 

[DrChinese]

By "right now" I mean at the current stage of physics how many of those infinite number of observables have we observed and incorporated in QM (specifically the ones for particle). You mentioned Energy and Position, anything else?

I should clarify, when I say "variation" I always mean induced significant variation of say an hypothetical artificial nature, NOT natural fluctuations. In another word, variation caused by measurement/interaction...etc.

The whole point of the thread and my line of questioning is just me trying to get an idea what are the theoretical scope of change on a macro scale can possibly be caused by hypothetical artificial manipulation of variables at the quantum scale.

There have literally been hundreds of experiments on different quantum observables that take the following form:

1. Place the observable into an entangled state. This means the observable has no well defined value, as per your original post's premise.
2. Collapse the observable via macroscopic measurement - something a scientist can see and record.
3. Analyze the results and compare to to the theoretical predictions of QM.

Of course, for most people these experiments are boring - because the results always closely agree with the predictions of QM. Here is an example where 2 electrons (in 2 diamonds in different locations) are entangled. Then the 2 electron spins are observed as the electrons collapse* into a specific spin state.

https://arxiv.org/abs/1212.6136*Keep in mind that the term "collapse" can have different meanings and connotations. Some quantum interpretations don't include collapse models, so the term is used here in a generic form describing what we know about an observable after a measurement.

 

[VECT]

Not single particles. I meant disruption on a macro scale with particles changed en-masse

For example one of the previous question I asked was the thought experiment of changing water to wine what QM variables need to be changed

People listed below:
1) the quantum state (in many cases this is also called the wave function)
2) the Hamiltonian (which governs how the state changes with time)
3) the observables (which govern what measurements can be made)
4) the Hilbert space

The latest question I was asking is somewhat backward from above; if every above variables are NOT artificially manipulated EXCEPT for "Position" (which IS arbitrarily manipulated), what kind of macro properties (chemical or otherwise) can potentially be affected? (and an extension of the question is that the same thing done but to another QM variable other than Position..etc.)

And yes, realistically at the moment these QM properties can't be manipulated at will...etc. But just as a thought experiment, what can happen?

 

[PeterDonis]

The whole point of the thread and my line of questioning is just me trying to get an idea what are the theoretical scope of change on a macro scale can possibly be caused by hypothetical artificial manipulation of variables at the quantum scale.

This question is so broad that I don't think any meaningful answer can be given. If any "hypothetical artificial manipulation of variables" is allowed, then that would have to include transferring any arbitrary amount of energy (or any other conserved quantity, such as angular momentum) to or from the system, and adding or removing any arbitrary number of quantum degrees of freedom to or from the system (i.e, no limits on how many molecules, atoms, electrons, quarks, etc. I can put in or take out). That doesn't meaningfully exclude anything. Sure, you could turn water into wine that way: just take a sufficient number of water molecules and exchange them for a sufficient number of whatever molecules you need to make wine. Or use whatever chemical, nuclear, etc. reactions you need to convert water molecules to whatever other molecules are required.

 

[VECT]

any hypothetical artificial manipulation of quantum variables

It excludes directly changing variables at any other level. So you can't directly just turn water molecules into wine molecules (or better yet, dump the glass of water into a sink and fill it with the nearest wine bottle).

You can turn whatever variables theoretically needed at the quantum level to turn those water molecules into other molecules (if that's theoretically possible, never mind how, which was point of that question).

So now this question is if you can arbitrarily change en-masse just the Position variable on say all the particles in that same glass of water, what could you do to that glass of water?

Maybe I'm trying to write a sci-fi story here. I know these questions are unusual but I wouldn't be asking them on this forum if I could found out the answer from some books.

 

[PeterDonis]

any hypothetical artificial manipulation of quantum variables

Which just switches the problem to what counts as "quantum" variables. And that turns out to not be a meaningful restriction at all. See below.

you can't directly just turn water molecules into wine molecules

Why not? That would be manipulating quantum variables. I just artifically run the "water molecule annihilation operator" and the "wine molecule creation operator" enough times. All done at the quantum level.

if you can arbitrarily change en-masse just the Position variable on say all the particles in that same glass of water, what could you do to that glass of water?

Um, move it? That's what you're doing when you pick up the glass of water and move it somewhere else.

Or did you mean change the Position variable by a different, arbitrary amount on each individual particle? Sure, again, just run the appropriate "annihilation operator" for each particle at its "before" position and run the corresponding "creation operator" for each particle at its "after" position.

Maybe I'm trying to writing a sci-fi story here.

No, you're just asking a question without any meaningful constraints at all. Basically you're saying "what could I do if I could hypothetically convert any arbitrary quantum state into any other arbitrary quantum state". And the only possible answer to that is "anything".

 

[PeterDonis]

It excludes directly changing variables at any other level

You can't. Any change of "variables" whatever can be done at the quantum level, and for any change of variables at some other level, you can in principle write down a "quantum level" change that amounts to exactly the same thing. So all you're doing by saying "at the quantum level" is making any change whatever possible.

 

[VECT]

I see what you are saying, and also surprisingly, you did answer the question I had in mind :)

Appreciate it.

 

[StevieTNZ]

Another good book you could try reading is https://global.oup.com/academic/product/quantum-physics-9780190250713?cc=nz&lang=en& - "Quantum Physics: What Everyone Needs To Know" by Michael G Raymer.

 

[Nugatory]

But if all the quantum "weirdness" just gets washed away by sheer statistical averages once stuff gets to the macro scale, then like what I was wondering, what's the point of QM.

There are micro scale phenomena that we care about. We care that atoms are stable and elements have the properties that they do, and these are both predicted and explained by quantum mechanics. Chemical bonding and pretty much all the rest of chemistry is based on quantum mechanics. The semiconductors in the silicon chips that support the entire electronics industry work on quantum mechanical principles.