Wouldnt wave function collapse allow for instant information transfer?

[RoGeorge]

I know I shouldn't try
...

No, you should try more often.
Much appreciated, and thank you for taking the time to write it.

[woofy]

If we create a pair of entangled particles and send them on their way, then current thinking suggests that they share properties such as spin, until they are measured we don't know which is spin up and which is spin down. Indeed they are both at the same time.
Suppose we measure particle A and find it is spin up, we know that when we measure particle B it will be spin down. Having communicated with particle A faster than the speed of light particle B is now spin down. B carries on for a bit and is eventually measured where we confirm it is spin down.

Now what has happened. B not only had an unknown state but it was both at once until A was measured, then it became spin down as the "wave function" collapsed, then carried on as spin down. What was the difference between the B before A was measured and after? Has it somehow changed? Is there a hidden variable in there we cannot see but determines that it will be measured as spin down?

If so then why not hidden variables in the first place and avoid all this spooky action FTL stuff?

The quantum world really screws with your head.

[RoGeorge]

[to what] the mathematical construct we call a wavefunction corresponds to in reality

About using math to prove physics hypotheses, or about using math to understand physics, I don't think it is possible at all.

(Let's put aside for a while the "understanding" part.  Understanding means to be able to simulate an outcome in your mind, which usually happens after some training and interaction with the new thing, such that the brain can develop an intuition about that new thing.  Math helps with understanding, but it is not enough.  You (you means anybody) also need to experiment and practice with the new thing, otherwise you think you understood, when in fact you only know, but didn't understood yet.)

Saying math can not prove physics, because math came into existence starting from the physical world, starting from how it manifests.  We wanted to count the sheep, and came out with algebra, wanted to measure the land, and came out with geometry.

The rules and axioms in math were distilled starting from the properties of the physical world, and from how it behaves.  Later, we've noticed (we the humans) that algebra/geometry/calculus and who knows what other branch of mathematics are equivalent.  Either of these math domains can be used to solve the same problem.  I think they (math branches) are all equivalent, because they came into existence for describing the same thing, our physical world.

I think the biggest advantage of mathematics (when compared to other analysis methods), comes from the fact that math only included rules that were based on physics laws, math didn't include any human beliefs, or social norms in it.

Now, if math was made according to the physical world, then trying to use math to prove physics would be just like a circular definition:  Physics is like it is, because math validates it, and math is like it is because we made math according to physics.

Mathematics is very useful in physics (not asking to ban math), but I don't think math can be used to prove physics.


Another thing regarding math limitations, math came into existence based only a narrow slice of the entire physics.

We are aware only of a small part of all the manifestations of the physics laws.  We keep extending, and keep deducing what we can not observe, we keep extending both the math and the physics, but the fact that we've only started from a small slice of the universe when inventing math, might also be an indicator that math is incomplete, and that there might physics laws that requires a new and more complete mathematics we do not have yet.

Math is only a representation of physics, and most probably an incomplete one.  There is still hope for math to be a complete representation already, but this would be true only if physics is indeed reducible at a small number of fundamental laws, and if we were lucky enough that all of those fundamental laws were already represented here on Earth, while we were counting sheep and measuring land and distilling math axioms.


On the same line of thought (about what axioms do we use in math deduction, or about what tokens do we use in human thinking), it is expected to arrive to strange, or contradictory, or even wrong conclusions, when adding ad-hoc axioms (like consciousness of an observer, social norms, religion, etc.).

Same kind of useless results (as in not verifiable, and with no technological application), I see when extra dimensions are added for no apparent reason (like in string theory), or when laws of physics are postulated as irreducible, claiming that all is a big mess and all the order we see is just a coincidence so stop looking for the fundamental laws of the universe and just take it as it is.

Another such (rather damaging) idea is that the universe is like a video game, a simulation, which idea is a modernized of the "brain in a vat", which is a modernized Plato's cave.  At least with Plato's cave there was a moral in it, but in the simulated universe there's only a shroud, yeah could or could be not.

[Nominal Animal]

The quantum world really screws with your head.

It definitely does.  For me, trying to truly understand it is like trying to understand fine dining etiquette as a cat or a dog.  Sure, one can learn the rules, but the dog does it because it wants to follow the/your rules, and the cat because, uh, it decided to see what the fuss is about; the concepts of "fine dining" and "etiquette" are simply utterly irrelevant and untranslatable to them.

Sometimes it is just better to inhale the kibble and go take a nap.

About using math to prove physics hypotheses, or about using math to understand physics, I don't think it is possible at all.

For the reasons I outlined above, I really don't have an opinion on such at all.

I've fully accepted I will never know the "true reality" –– but would love to, oh so much! –– and am satisfied to try and not add to the confusion (maybe even contribute a tiny little bit?), so that perhaps, just perhaps, someday somewhere someone might.

[RoGeorge]

Is there a hidden variable in there we cannot see but determines that it will be measured as spin down?

If so then why not hidden variables in the first place and avoid all this spooky action FTL stuff?

That is a question debated since the very beginning of quantum mechanics, all physicist and not only them, tried to figure out the answer.  Meanwhile 100 years have passed, and it is still unclear what is happening. 

At some point, somebody came with an experiment idea that was supposed to settle the debate.  It was about observing some probabilities, where a mathematical inequality or equality, was suppose to give a definitive answer, so the name "Bell inequality".  Experiment was performed, the inequality was there, which was suppose to mean "it's not like the gloves", no hidden variable.

All good so far, just that the experiment was not easy to follow, and might have included unintended wrong assumptions.  Many pointed out the possible inconsistencies, both in math and in the experimental results, and that was called "patching the loopholes".  After a wile some physicists claimed all the loopholes were addressed, and no doubt was left.

Some years ago, in one of the decisive experiments, the inequality was to be observed eventually by plotting a chart with the results.  If the plotted line were to be with straight segments (like this /\) then it's a hidden variable like the pair of gloves idea.  If instead of straight segments, the plot were to be curved like a bell shape, then it was all spooki and no gloves.

Well, the plot from that experiment was curved, so no hidden variable.  In 2022 the Physics Nobel Prize was related to the Bell experiment.

Some are still not happy with that conclusion.  For example I think there are still other reasons that could have curved those lines, more exactly the detection noise.  I do not have any training in physics, so it doesn't weight much what I believe, but there are others not yet convinced, too, and some of them are physicist claiming they spotted inconsistencies.

My main argument for not believing the curve shaped of that plot is a definitive evidence doesn't even come from the physicists, but from this paper:

A Classical System for Producing “Quantum Correlations” by Robert H. McEachern
https://vixra.org/abs/1609.0129

There are some followups to that paper, that illustrate how the same results observed in the Bell test might be produced by randomness alone (or else said caused by the detection noise), and not as a proof for absence of hidden variables:  https://vixra.org/author/robert_h_mceachern

The paper is not mine, the author is not a physicist (the author is astrophysicist by profession, IIRC), and the paper is self-published on viXra (not arXiv).  However, the paper made all the sense to me, and I took it as a solid disproof of the Bell test interpretation, because it shows a counterexample.  No matter how watertight a demonstration would be, a counterexample invalidates it.

[HuronKing]

Unfortunately, photons are more complex than gloves 

 And while "complex" is definitely the wrong word for the quip to be exactly right, it is an excellent example of how we don't even have intuitive terms to describe this yet!  The only word that comes to my mind here is "weird", but it's even less descriptive!

It's doubly funny because "complex" is exactly the word and pun I wanted to make. I don't have time to catch up on all the discussion that's happened (I see you've written another long and insightful post) so forgive me if I retread old ground.

But for me, what the quantum entanglement paradox suggests is how important understanding sampling is to the outcome of the experiments. But, not in a "the experimenter affects the measurement" kind of way - like say, touching a material to find out how hot it is will change the temperature of the material, because you're interacting with it with the temperature of your own measurement device (your hand).

No, the results are more 'fundamental' than that (Heisenberg's Uncertainty is more than just Observer Effect, it's a law of nature) and it requires a firm and deep grasp of "complex analysis" to understand what's going on. And, I think it's more intuitive than we give it credit for - once you're willing to accept Fourier Analysis. 

These two videos are my favorites on the topic:




I didn't understand this connection to undergraduate electrical engineering mathematics until I was well into my career and decided to learn some quantum electrodynamics and watched a lecture where Feynman seemed irritated at a line-of-questioning from a student about wave-particle duality, and Feynman kept saying,
"No, a photon is a particle, it's a particle, stop saying it's a wave, no, it's a particle..."

And seeing quantum physics, and its built-in 'weirdness,' as just Fourier Transforms being done on particles. It also led me to see how obvious it should be that there are no-hidden variables - if we accept Fourier Analysis as correct. I sleep much more easily at night. 

[HuronKing]

I'll have to watch this one later - came out just last year and the YT comments seem to imply it's better than either of the two previous videos!


I'm emphasizing this because I think it is much, much harder to grasp why quantum mechanics has to be the way that it is without grasping Fourier Analysis.

[RoGeorge]

if we accept Fourier Analysis as correct

I'm not very sure what Fourier Analysis is.  If it is about Fourier Transform, yes, the FT is correct in a mathematical way.  In physics, however, it is not that easy to say when FT results make sense or not.  In order for FT to work, it needs the concept of infinity.  In the real universe, however, everything seem to be bounded in a way or another.  Infinite is not real.

Even if it were for infinite to be real and applicable in physics (real as in heaving examples in the physical universe, examples independent of our own thought and imagination), it still remains the problem of mapping from physics to math, and back to physics after some math processing.  That is why we always have to check if math results make sense, then have to validate them experimentally.  Not saying the encoding/decoding between physics and math was incorrect, saying only that it is tricky, and that we do not have any known tool to prove the encoding/decoding to/from math was made correctly, other then double checking the results experimentally.

There are more traps with mathematics.  It doesn't have any axioms related to causality, or to time.  Causality and time are present everywhere in physics, but in math they are absent.  These two treats, causality and time, are left to be represented by our skills in encoding/decoding a problem between the physics domain and the math domain.  Very prone to error.

Mathematicians have no problem operating with infinity, having some infinities bigger than others, and so on.  Math is all about building an entire world on a set of axioms, but the axioms can be changed.  In contrast with math axioms, the physics laws can not be changed, or selected upon our wish.

At first, the math axioms were deduce from the physical observations alone.  Then the axioms were modified, or extended, giving birth to different worlds, some results were contradictory (e.g. sum of angles in a triangle is not mandatory 180), but they were coming from different sets of axioms, so no problem, mathematically it is correct.  With time, the set of axioms were changed, either to cover more of the physical world, or to allow more advance in math.  In time, math became a world in itself.  At first, all the math results were about the physicality of our world, but not any more.  1:1 mapping between math and physics was long ago.  Now, a math result may or may not be applicable back to physics.

Math is great when applied with care, and when the conclusions are validated experimentally.  But math is not evidence.  My point is, the FT can work great and be correct mathematically, yet entanglement can no more than synchronized waves. 


More arguments for entanglement as being synchronized waves, entanglement does not lasts forever, as suggested in all popular science.  That would be only in an ideal situation.  In practice the decoherence happens rather fast, just like two oscillators that were once synchronized then separated and let to run freely.  This is the main reason why quantum computers in practice only have a handful of qubits.  The wave synchronization (of whatever quantum object is used as a qubit) is perturbed, the fancy word is decoherence, or disentangling.  This is no different than oscillators getting out of sync.  Yes, they qubits are really small and easy to be perturbed and put out of sync.

Another hint that entanglement has nothing weird, is that entanglement happens only when the particles are put in close vicinity (or even born together).  It is known that oscillators that are close enough that they can interact, tend to synchronize, and get in lock with each other.  It happens at macroscopic scale, too.  In EE for example, if you try to do intermodulation distortions, you might sometimes need an isolator between the two generators when summing their waveforms.  If they can exchange energy and if they are of a close frequency, the two instruments will tend to get in sync and lock to a single frequency (which is unwanted in this case).

I do not know why the spin pairs, best guess is that is because that's the state with minimum energy, thus the most stable and the most probable to be encountered, but I don't have an understanding of spin (understanding as in growing an intuition about it).


The puzzling property to me is not entanglement, but quantization.  Why something that is very small can only exist as a certain "chunk", called quanta?  This is a property that seems to be present in everything from the physical world, as long as it is very small.  I suspect it is related with the fact that infinity can not exist in the physical world.

Side note, similar with infinite, the concept of "nothing" is also not real, as in not present in the physical world.  Just like the infinite, nothingness is an imaginary construct.  Nothingness can not exist in the physical world.

Talking about nothingness being only an imaginary construct and not real, because it is related with infinite being imaginary, and because it was asked in this thread a page ago:

What is nothing?

[RoGeorge]

watched a lecture where Feynman seemed irritated at a line-of-questioning from a student about wave-particle duality, and Feynman kept saying,
"No, a photon is a particle, it's a particle, stop saying it's a wave, no, it's a particle..."

Feynman irritated at a student is no surprise.    He was kind of a jerk in real life.  Smart, yes, but arrogant even for his times, and unpleasant to work with.  Not my opinion, only repeating what I've seen on camera, what were saying other physicists that worked directly with Feynman.  He was not exactly the nice and charismatic character, as pictured in the YT interviews with Feynman talking about the beauty of a flower.

Was that lecture, by any chance, about the many paths interpretation (Feynman's Path Integral)?

That interpretation requires particles, and it assumes the particle somehow follow all the possible wiggling trajectories, an infinity of them.  Why would a photon do that?  The many path idea was not originated by Feynman, but somehow his name remained associated with the many path interpetation, same like E=mc² was published in physics journal 2 years before Einstein published his E=mc² ( https://www.scientificamerican.com/article/was-einstein-the-first-to-invent-e-mc2/ ), yet somehow the formula remained associated only with Einstein's name.

Feynman have had some contribution to the many path idea, even if the paternity was not entirely his, and the many path has some application (IIRC the integral path is the nicest explanation for the backskattering).  Though, the many path is not real, the photon does not wiggle through the entire universe, taking all the possible paths before hitting a screen 2 meters away from the light source.  That interpretation is imaginary and in math only, and the photons are not particles.  I think photons are waves, small packets of undulations.

TL;DR, I guess intimidating a student was to defend the many paths interpretation, I don't think Feynman didn't consider photons as waves.

[m k]

A quantum object can't exchange energy, if it does it stops being a quantum object.
Means that entanglement of quanta remains.

Before a probability wave collapse its energy has an equal possibility to be anywhere around a surface of the wave.
After a collapse the probability disappears completely and all the energy is where interaction happens and nowhere else.

The probability is in operation here, not the wave.
The wave is a specifying name, it's there only because probability has a shape of a wave of real world.

Quantization is a result of an experiment.
It just defines that there are steps, not that there are nothing between steps.
The nasty part is that if step is 2 it can't be reached with double 1.
Intensity doesn't do things here, so very intense 1 is still just 1.

OT, pretty much.
If infinite hotel is full, it still has infinite free rooms.

[HuronKing]

Thanks for your reply! I think we are mostly on the same page but I have a few comments I'd like to make.

...In the real universe, however, everything seem to be bounded in a way or another.  Infinite is not real.

That's not what infinity means in integration mathematically - nor is that how it's applied to physical problems.

In fact, this statement is actually nonsensical and easily disproved with a counterexample.

Can I not, as the 3rd video above shows, put a particle onto a circular path? Can I not roll that particle around the circular path in either direction, forever? That is, the possible number of rotations of the particle ARE unbounded because it is free to travel around the path once, twice, thrice.... up to infinite number of times, in either direction (clockwise or counterclockwise around the loop).

Yea. you might say "well the ball can't roll in a circle forever because the universe might actually end...* but that doesn't accurately describe the system of the ball. A function whose domain is negative infinity to positive infinity describes *everything* the ball could ever do. It's not that mysterious or universe-breaking.

That is why we always have to check if math results make sense, then have to validate them experimentally.

Absolutely - and that's what's wonderful about the mathematics of quantum mechanics is that it yields very testable predictions and in many cases led directly to the discovery of entirely new phenomena (the existence of positrons is something that just "fell out" out of Dirac's equations because solutions in the complex plane can have two solutions).

The puzzling property to me is not entanglement, but quantization.  Why something that is very small can only exist as a certain "chunk", called quanta?  This is a property that seems to be present in everything from the physical world, as long as it is very small.  I suspect it is related with the fact that infinity can not exist in the physical world.

You should watch the 3rd video I posted. It's actually *because* of infinity that matter must be quantized because the wave number has to be a whole positive integer to encompass every possible period of the function over the whole domain. The specific timestamp where this starts to be explained is here:
https://youtu.be/W8QZ-yxebFA?si=3giGjzlnnhNCs6A-&t=648

[Feynman] was kind of a jerk in real life.  Smart, yes, but arrogant even for his times, and unpleasant to work with.  Not my opinion, only repeating what I've seen on camera, what were saying other physicists that worked directly with Feynman.  He was not exactly the nice and charismatic character, as pictured in the YT interviews with Feynman talking about the beauty of a flower.

Hah, yea, I'm not suggesting Feynman was a particularly pleasant person by remarking on him - nor am I giving him sole credit for his contributions as obviously he shared the Nobel Prize for Path Integral Formulation.

All I mean to say is that my insight to this came from listening to him get annoyed with a student and emphasize that we have a world of particles whose behavior is probabilistic because you can't know their states to arbitrary precision (because of Fourier).

I personally don't like the term "wave-particle duality." I think it does more to confuse students than help them understand what is going on. Maybe it helps other people and that's great! But in my experience helping engineering students with this - they spend so much time slogging through Fourier stuff for signal processing, that it's amazing how quickly they grasp the 'obviousness' of quantum mechanics at more than an academic level - you start to see why quantum mechanics is the more fundamental law of nature. I like this video which explains why F = ma is a consequence of quantum mechanics:



Is light a particle or a wave? It's a particle - whose position and momentum is not determinant but probabilistic.