Then either QM is flawed in how it goes about showing that an electron is a wave, or your summarization of QM is flawed. I never asserted that electrons are or are not waves, merely that you didn't show that they were. — Harry Hindu

Again, I was not aiming to re-derive QM from scratch. If you want to know more about why individual electrons are waves, you can Google it.

That was a nice presentation and an interesting discussion. Thanks for putting in the effort! — SophistiCat

Thank you for saying so :)

The "trick" of putting some of the boundary conditions ahead in time makes the point a rather trivial one. Another way to state it would be to note that if there is a fact of the matter about the way the world is going to be at some future time, then there is nothing indeterminate about it. Well, of course. — SophistiCat

In the simple symmetric Minkowski spacetime, yes, it is trivial, and I think that's fdrake's point too. If the idea isn't controversial and the resultant determinism is trivially derived, I will take an "Of course!" But as I said to fdrake, transactional QM itself is still probabilistic. It removes the irreversible wavefunction collapse but which hole will be sent back is still undetermined. The last two images in the OP are essentially a recourse to other physical considerations leading to a conclusion that non-determinism is a case of running away with ourselves.

But the really good question here is the idea of boundary conditions as a "trick". You're right, we can do this in non-relativistic QM too. We'd essentially be forcing a final-state--dependence by hand, mimicking what is justified in the Dirac equation with what is not needed in the Schrödinger equation. My argument here is that the form of the equation is physically meaningful, i.e. the choice of boundary conditions is not just efficacious. The Copenhagen interpretation derives from the allowance to calculate wavefunctions from an initial state only because it's an approximation to reality, and it is this feature that yields wavefunction collapse and its inevitable probabilism. But this isn't real.

I wouldn't agree with the statement that the wavefunction is non-physical because it has a complex component. We can represent uncontroversially real entities with complex functions, as you are no doubt aware (e.g. the electromagnetic field in classical electrodynamics, and generally any 2D model where complex representation is expedient). — SophistiCat

But these aren't physical either. It is simply that complex exponentials are much easier to manipulate than individual sines and cosines. I'm not trying to do the wavefunction down, though. Whatever its ontology, it is important for predicting experimental outcomes and therefore corresponds to something physical. But no complex quantity can be physical in itself, i.e. we can't observe it in nature.

But if only measurements are real, then nothing about the wavefunction as such is real, not even its absolute square: a probability density is not a measurement. — SophistiCat

That's actually not an uncontroversial statement. The wavefunction is frequently referred to epistemologically as the total of our knowledge about a system. The OP basically states that it encoded more ignorance than knowledge.

Anyway, this is probably a diversion (or not - you tell me). — SophistiCat

No, all good points, especially about the "trick" of boundary conditions.

Hats off to Kenosha Kid. — jgill

Thanks jgill! Math is much harder, I think. My department didn't offer a general relativity course when I was an undergraduate, so I had to sit in on the math department's course to learn about it. Hands down the hardest time I had at uni. Although fluid dynamics comes a close second. Kudos to your friend.

You're confused. Its your OP that fails to show that electrons are waves. You've only been able to show that the beam is a wave. So if a requirement of QM is a belief that electrons are waves, then your OP isn't about QM either. That's all I'm saying. — Harry Hindu

The OP is not deriving QM, merely summarising it. Conversation would be pretty limited in scope if you have to re-derive from first principles everything that you intend to discuss every time.

What is it that i obviously want to discuss, KK? — Harry Hindu

Something wherein electrons are not waves, i.e. something that is not quantum mechanics. And by all means, but elsewhere.

Visuals are not my strong suit, but I'm really trying :rofl: This is an oversimplified example of how, beyond the perfect symmetry of SR, retarded and advanced waves might not need to share the entirety of their histories, in this case in a scattering event.



Time goes from left to right.

Sorry, I thought you meant they were meaningless in general (a bit tired right now), though I'm still not sure about the use of phrases like "for a photon" when it seems like the very idea of a perspective for light or other massless particles just simply doesn't make sense. — Mr Bee

You can still calculate invariant quantities for photons even if you cannot construct a rest frame for them. The proper time is an example.

Talking about the limit as v->c is different from talking about the situation of when v=c. This isn't to say that light does "experience" time or space or that it doesn't but rather that the whole notion is just undefined like 1/0. — Mr Bee

Literally the same in fact. The reason why you cannot have a rest frame for the speed c is that the transforms from other frames are inversely proportional to the square root of (1 - v/c). When v = c, you get 1/0.

Probably a stupid question: if the mapping from a wavefunction to it times its complex conjugate always produces a purely real variable, and that the "advanced wave" is defined by the mapping of this wavefunction to its complex conjugate, how could this be taken as evidence of a coincidence of physical mechanisms (two processes with the same result) when it's actually two names for the same mapping? — fdrake

No, it's a good question. The first part of the answer is that they are both independently solutions to the relativistic wave equation. This is different to the non-relativistic Copenhagen interpretation, in which the advanced wave is not a solution at all, and really is just a mapping from the retarded wave. So just by solving the equation, you get forward and backward solutions.

The second part, which I mentioned but only in a throwaway fashion, is that we don't need to consider the 'hole' taking part in a given process to have the same (future) history as the electron's future. The birth and death of the particle are the two boundary conditions, but things like where the electron appears on the screen can be considered nodes. The advanced wave sent back to the cathode needn't be the same that conjugates the retarded wave beyond the the back screen.

A quick note on this... The OP is very much in the realm of QED, in which all processes really are reversible. If that was the end of it, we really would expect the advanced wave from death to birth to be the conjugate of the retarded wave from birth to death, and there would be no insight. Generally in TQM though, only the advanced wave from the screen to the cathode need conjugate with the electron, which is likely more general. There is no time-reversed equivalent of some electron-producing radioactive decays, for instance.

You propose a complete misrepresentation of the human conceptualization of radiant energy. — Metaphysician Undercover

I propose a rejection of the Copenhagen interpretation of quantum mechanics. Ideas about the nature of radiation that are different to quantum mechanics may well be fascinating, but not relevant.

So are you suggesting that the reference frame of a photon is meaningless as well as the concept of duration and distance? — Mr Bee

The notion of duration and distance is meaningless for a photon, yes. While you can't choose a reference frame with a velocity of c, you can see that the proper duration of a photon is zero by taking the limit v->c.

Wait isn't the concept of a reference frame for the speed of light meaningless? It doesn't make sense to talk about a frame where light is at rest since it's always moving at c, no? — Mr Bee

Yes, but also the concepts of duration and distance. As the new Nobel laureate Sir Roger Penrose says, photons can't get bored.

Sure it does. It shows that your OP is unfounded in asserting that electrons are waves, and is not the rest of your OP built upon that faulty premise? — Harry Hindu

As stated previously, the OP is regarding QM, and nothing outside that framework. Feel free to start a thread on the subject you'd obviously prefer to discuss.

The second experiment doesn't show that each electron is a wave. It shows that electrons don't appear to move through, or are governed by, space-time like other particles, or maybe it is our view of space-time that is skewed. — Harry Hindu

Maybe, but that does not fall within the scope of the OP, which concerns quantum mechanics, not alternative theories to quantum mechanics.

The former has a determinate cause, the latter may be spontaneous. — Metaphysician Undercover

This is also treated in the OP.

The fact that you can treat the two mathematically as one reversible process does not justify your claim that the two are one reversible process. — Metaphysician Undercover

As I said, this is uncontroversial, and the purpose of the OP is not to compare QM with idiosyncratic theories. In QM, this obeys a specific symmetry of the universe that makes it reversible.

LOL. Just read what you wrote, bro. — Harry Hindu

Ha!

The "beam" is the relationship between the individual electrons and according to you is a wave. If the same pattern is created no matter how long the interval between each electron, then it isnt the electron that is a wave because one electron would create the pattern if it were a wave like the "beam" of electrons. — Harry Hindu

Ah, I see the misunderstanding. I meant it as a chronological voyage of discovery. We conclude the beam is a wave from the interference pattern. We then go on to realise that each electron is a wave by reducing the voltage. Unclear, my bad.

Since the problems of quantum theory are a manifestation of the conceptualizations employed (as I described above), then we have to step outside quantum theory to get a handle on these problems. — Metaphysician Undercover

I can see that you're keen to do so, but that is not a logical argument. The particular issue in question only occurs in one interpretation of QM, therefore it is not necessary to go outside of QM to avoid it, nor would I be saying much of anything about it if I did.

As I stressed in the last post, your claim that there is a particle, called an electron, which exists during the in between period, and "spreads out as a wave", is completely unsupported by the conceptualization of "energy". — Metaphysician Undercover

Perhaps in whatever exotic picture of the universe you have. In QM, it's quite a trivial affair. You define a wavefunction with a value of 1 at the initial position and 0 everywhere else as the initial state, and you time-evolve it according to its wave equation. It will disperse quite naturally.

It really makes no sense to attempt at a validation of a temporal continuity of a single electron by introducing different forms of the electron , like "stroboscopic wave-packet" — Metaphysician Undercover

An element of any basis set, such as the positional basis, can be written as a superposition in any other basis. In the case of the two extremes of position and momentum, this is simply the Fourier transform and its inverse.

OK, if that's what you want to discuss, then perhaps you can describe how spontaneous emission and random fluctuations are consistent with determinism. — Metaphysician Undercover

I dedicated quite a portion of the OP to spontaneous emission.

Didn't Shiller say there is more wisdom in children books than philosophy books? — Gregory

Did he say it in a children's book?

It gives to her/his life a meaning, because if there is a better, eternal life after death, then this earthly existence is a pathway, not a stalemate. It leads to something bigger. It has a Meaning. — philosophience wordpress com

That might well introduce some peculiar kind of meaning to the believing mind, although it's not in any sense shown here. But what you're talking about completely subtracts what an atheist would consider meaning, which is precisely given by life's finitude. We have to do things today or tomorrow because there's no eternity to do them forever later. Things matter, everything counts because there's only so much time and nothing lasts.

The great majority of atheists around the world struggle to find a “secular meaning” for their lives. Happily, delusions, self-deceptions and all kinds of distractions – albeit of a different kind than those of the believers – are available to help them endure life. — philosophience wordpress com

This is a great example of how bad ideology always yields bad answers. You cannot have derived this empirically. There's no evidence that atheist artists are less artistically fulfilled than religious artists, that atheist philanthropists are less passionate than religious ones, etc. This sort of thinking is an initio and evidence-independent.

If the pattern is something that "builds up" then the pattern isn't the result of one electron, but many over time. One electron going through every ten seconds makes one dot on the screen every ten seconds that eventually builds up the pattern over time. So each electron behaves like a particle and the relationship between all the electrons is a wave, not that each electron is a wave, or else you'd get the pattern with the first electron. There would be no "building up" if each electron was a wave. — Harry Hindu

I'm afraid not. If there are no other electrons to interfere with, and the electron does not interfere with itself, there is no possibility of interference effects.

However, we can reply back that it is impossible for simple space NOT to exist. It’s inconceivable that simple space CANNOT exist. No matter what, there must always be simple space.

So perhaps if we tried to apply zero to the external world, we could eliminate everything BUT simple space. — telex

Inconceivable = untrue? How Cartesian!

I can say that the concepts employed here are deficient, showing a lack of understanding of the concepts. — Metaphysician Undercover

I welcome identification of any deficiencies. However, the concepts in question are those of non-relativistic and relativistic quantum mechanics, in which I have some background. Just to define some scope, which I had presumed implicit but perhaps is not, the question here is whether the insight gathered from Copenhagen interpretation regarding determinism is valid. This must be judged from within a quantum theory, with additions and subtractions of course, so I will focus on the parts of your response that fall within that scope.

A moving body has velocity, mass, and momentum according to Newtonian principles, but it does not have "energy". — Metaphysician Undercover

Oh dear god.

We understand radiant energy, such as radiant heat, through its absorption, not through an understanding of the process of radiation. — Metaphysician Undercover

Oh crikey!

I believe the macroscopic/microscopic division is not an adequate representation of the real divide. — Metaphysician Undercover

There is no cutoff, which is fine as I am not exploring the realm of the classical limit. It is sufficient to know that a classical limit exists. The relevance of the macroscopic screen is merely that it explores microstates, nothing more.

Conventional wisdom tells us that the wave formulation is far more advanced, providing a much higher degree of understanding of the reality of the situation, so we ought to dispense this conception of empty space with bodies or particles moving around, and replace it with a consistent wave model. — Metaphysician Undercover

This is worth treating. In 1900, things were thought to be either particles or waves. The blackbody radiation spectrum and quantised atomic orbitals turned that on its head: waves were behaving like particles; particles were behaving like waves. It was surprising, hence the "wave-particle duality paradox'.

There is no paradox. There is no preferred basis set for describing waves except for that of the operator a particular measurement device is described by. At one extreme, plane waves -- Eigenstates of the momentum operator -- have well defined momentum and no defined position, but occupy all of space. At the other, Eigenstates of the position operator have well-defined position but no defined momentum. Everything else lies in between.

The double-slit experiment begins with an electron with a well-defined position and, after measurement, ends with an electron with a well-defined position. These need not be precise, though they are typically treated as such. In between, the electron spreads out as a wave, but eventually must reduce, either deterministically or spontaneously, to something more localised. A good basis set that puts wavelike and particle-like extremes on equal footing is the stroboscopic wave-packet representation, on which I wrote my master's thesis. All of the above still holds: we simply replace Pauli exclusion of two electrons being in one kind of state (position) with that of two electrons being in another kind of state (stroboscopic wave-packet). The exclusion principle holds across all such bases (e.g. you cannot have two like-spin electron plane waves with the same momentum, which is what I had in mind for the states k, j', k" and k"', though these could be position, orbital, Bloch, Wannier or stroboscopic states or anything else you might consider, it makes no difference to the argument).

You cannot represent a photon or electron as being emitted. — Metaphysician Undercover

Stimulated emission. Spontaneous emission. Blackbody spectra. Photoelectric effect. Cathode ray tubes. Lasers. The concept of emission is pretty uncontroversial in quantum mechanics.

You obviously have some exotic ideas of your own about how nature is that are at odds with quantum mechanics. I would not try to dissuade you from them. The above is not meant as pro-quantum propaganda, but rather, as I said, to explore ideas within the field and assess their consequences for determinism. The end-game being an attempt to put to bed the 'quantum equals non-determinism' myth. Whether the concepts discussed are true or not is far less important than whether they hold or don't within that particular framework.

MWI is much more severe than Copenhagen in this respect. Entanglement of superposed terms always leads to branching in the former but does not necessarily lead to collapse in the latter, which is minimally reserved for entanglement of measurement apparatus (inc. human beings). In other words, entanglement may occur many times between initial state preparation and collapse in Copenhagen. In principle, precisely when the cat dies could occur any time between the radiation detector triggering and the box being opened, depending on coherence.

Or I guess the whole topic of this thread, where phenomenalism, which is like idealism, boils down to the same thing as physicalism, which is like materialism, even though materialism vs idealism is nominally a clash of opposites — Pfhorrest

I tend to take this as a sign of incompleteness. If two theories with different ontologies yield the same results, there's usually a third that yields the other two under two different sets of incomplete, incorrect, or approximate assumptions. Or else one of the two is incomplete and the other is better. MWI, for instance, appears complete; Copenhagen does not, so MWI might be right, or else something else is right such that, when you omit or approximate true facts or add untrue facts, you can derive MWI or Copenhagen or other.

Either way, I guess your portrait of reality is insensitive to such things. The nodes of the web are frame-dependent due to, at a fine scale, the Higgs mechanism, while the edges are non-inertial. Like a non-inertial plenum or singularity resolved into a discretised web by choice of inertial frame.

To expand on Cat's response, some orbitals have 'nodes' where the probability of finding the electron in that orbital is zero. However, the volume these nodes occupy is also zero, so in practice you can find the electron in any finite volume of space, however small.

Here's an idea... If you're going to go over-the-top on fake tan, do the backs of your hands as well.

Looks like the only way to keep going in pro-fascism America is to hire your own fascists.

https://www.theguardian.com/us-news/2020/oct/11/man-shot-dead-in-denver-during-rival-left-and-rightwing-protests

the mat is under the cat — unenlightened

Mind blown. They keep this bit quiet.

P1. There is stuff.
P2. Stuff is related.
P3. Relations are not more stuff. — unenlightened

:heart:

Ah okay, so MWI-stylee.

Okay, I get it, I dig it, and I almost agree with it.

"Experience" here can be taken as equivalent to QM "observation". When a human observes something, they are still doing the thing that an inert object merely interacting with it does, that causes (or is) wavefunction collapse or entanglement or the splitting of worlds, however you want to interpret it. — Pfhorrest

This obviously isn't the case for the Higgs. For instance, the electron interacts with the Higgs field as it goes through the left slit and is it goes through the right. The observation, in the Copenhagen sense, has not occurred.

It's only massless particles that are lightlike, and so have an existence that (from their frame of reference) consists entirely of the interaction between what emitted them and what absorbed them. — Pfhorrest

Okay... So all elementary behaviours are then creation and annihilation events that, in the frame of reference of the thing being created and annihilated, take no time and traverse no space. I'd go with that.

Then the massive electron as we know it is a series of such events, each timeless but constituting the ticks of the electron's "experience". These are the atoms of experience? And for us macroscopic blighters, the atoms of our experience are similar things: the destruction of a photon from one bit of a car, the destruction of a photon from another bit, and so on, building up over (brief) time the experience of seeing a car. That sort of thing?

Reality is what exists outside and independently of us and that minute by minute imposes on us something that we would not want to know, something that we would prefer that it did not exist. — ThePhilosopher1

Like the username 'ThePhilosopher'. Bet you were gutted!

Put this way, the choice is between: 1) assuming that the wheels of determinism have a little 'lash' between them (indeterminism), and 2) assuming the existence of billions of billions of billions of parallel universes out there... — Olivier5

This is what I mean by your seeming wilful misunderstanding. I did not say the choices were Copenhagen or MWI. I chose my words carefully, you simply choose not to notice them.

:fire: :100:

“Trump said...”.

Sorry, but every time you guys wring your hands about the words coming out Trump’s mouth I know you have nothing. — NOS4A2

That is actually true. If you're citing Trump, you got nothing.

Weaving out a system of axioms is not falsifiable either but that is exactly what mathematicians do all day long. And maths is often called the only pure science. — Heiko

Falsification is a criterion of real science, i.e.the circular process of modelling, prediction and experiment.

The overall thesis is that there is nothing to reality besides the observable features of it, nothing hidden behind our experience, of which our experience is merely a representation -- our experience is direct contact with a very small part of reality (the parts that we are literally in direct contact with — Pfhorrest

Yes, obviously with the 'in principle' caveat: there are potentially possible modes of experience that we will, through localism, dumb luck, or technological limitation, never realise. For instance, when an electron moves from A to B it has a high probability of scattering with many virtual photons. Each virtual photon has a low probability of decaying briefly into a virtual electron-positron pair. Accounting for this is extremely important for making extremely precise comparisons between theory (knowledge) and experiment (technology). It is the fortune if our technological maturity that this can be experienced indirectly by us, and a matter of necessity that it may be experienced by the electron.

I guess that's why I find the primacy of mind and experience in your language (and I think that you do not distinguish between the experience of a person and of an electron) a bit of a barrier. That said, I haven't slept for two days, so...

Massless particles like photons (and the particles that get "blended" into electrons etc by the Higgs) are exactly like the "occasions of experience" that philosophers like Whitehead wrote about, and that in my elaboration upon that (viz the mathematicism stuff above) can be taken as signals passing between the mathematical functions that constitute the abstract object that is our concrete reality. — Pfhorrest

I guess I'm just not seeing the relevance of masslessness. Unless you're drawing a poetic equivalence between light (image, appearance, experience) and matter (the thing itself as an element of objective reality). I will Google Whitehead and "occasions of experience" and see if I get anywhere. :)

This might be off topic, but one thing occurs to me. When we interact with anything, it is overwhelmingly electromagnetic in nature. When we see a tree, photons emitted by that tree are destroyed in our eyes: this is sight. When we feel the tree bark, virtual photons emitted by the charges in the bark are destroyed by charges in us: this is touch. We never destroy charges, only the emissions of charges or systems.

In your literalist interpretation of the creation/annihilation operators of QFT, it is the fields that destroy electrons directly. (The Higgs mechanism is the destruction of an electron with one isospin followed by the creation of another with the opposite isospin. The motion of an electron is the destruction of the electron at one position followed by the creation of an identical electron at another.) Somehow this makes me think of the sort of equivalence between experience and objective reality you're getting at without necessarily being the sort of thing you had in mind.

I'm not entirely sure that's true -- I thought that's just a mathematical artifact from relativity which doesn't necessarily apply to reality. — ChrisM

Well, it's a cosmological model. The whole field is a little sketchy. But on the other hand it might be true, and the possibility must be accounted for. The model is certainly reasonable, and the notion that time itself started with the big bang uncontroversial.

Isn't this why relativity and QM cannot be reconciled -- since relativity breaks down at the smallest scales into infinities? — ChrisM

Not for that reason, although you're right that QM can't handle singularities. But the infinities appear generally in quantum field theories of gravity, except string theory. There are other, probably better, approaches, such as generalising existing quantum field theories to curved spacetimes. It's hard math and slow-going, or used to be anyway.

Let's assume they are 'unforeseen circumstances', doesn't that classify as ignorance? — Tzeentch

Doesn't this then reduce to good intentions? What we're really describing here is expectations. Part of making a moral choice is an expectation of an outcome for a given course of action. The actor can only act on likely outcomes based on prior experience and incomplete reason. An expectation of an outcome of one's own actions is an intent.

So it's at least not absurd to assume some amount of ontological "randomness". — Echarmion

Not at all. It is possible that determinism holds at a statistical level. As I've said a few times, if we ever devise a test to discern whether QM is Copenhagen-like or MWI-like that is inconsistent with the latter, I would consider fundamental determinism falsified.

Until then, we cannot use QM as evidence for or against determinism. And there's no other player in the game. Unknown variables, chaotic systems, the inevitable error bars before and after, these all lead to behaviour obviously more consistent with determinism than randomness.

Since determinism is in principle falsifiable, and any fortuitously constrained non-determinism is not, determinism is the scientific choice.

Good reason to be skeptical. — Metaphysician Undercover

Let's put this in context: it's neither as amazing or alarming as a giant sky lord judging me for masturbating.

Speculative or not, still :cool: — 180 Proof

Oh yeah, it's not a popular interpretation of QM.