B What percent of everyday-life electrons are collapsed?

[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.