Hawking believes "God confuses us throwing dice....", why?

[PeterDonis]

are all our physics from the beginning all just maps?

Yes.

 

[Kuzon]

If experiments in the future can determine say the trajectories of the bohmian particles or prove there are really different worlds where the branches exist, then it's no longer an interpretation but a theory? It's just weird that all the intepretations were tailored to match the math of QM as if constraining them to certain dynamics. But you are right that to avoid getting sinked in interpretations for a lifetime.. one must focus on the math and instead spend time to understand road to a fuly interacting non-perturbative quantum field theory.

i agree with everything you said my friend.

 

[Mario Rossi]

Guys what do you think about this: https://phys.org/news/2015-02-big-quantum-equation-universe.html ? Should I open another thread?

 

[Mario Rossi]

In the history of science from Newtonian or even Copernicus, is there any example where the territory is known or are all our physics from the beginning all just maps? If there is a single case where the territory is known.. can you give example what it is?

Are you referring to the Korzybski's "the map is not the territory"? You need to consider that both two the interpretations (thoughts) and the experiences are maps. Remember the human body is limited and need technology (map) to perceive the world (for example in QM). But the important thing is this: "A map is not the territory it represents, but, if correct, it has a similar structure to the territory, which accounts for its usefulness."

 

[OCR]

...Gonsky without going into it...

Gonski, as in Gonski Report ??... without going into it... .

 

[Blue Scallop]

by the way.. are elementary particles like electrons or quarks also maps or territory?

we used vectors or probabilities or other abstract notions to describe them at the fundamental levels or maps.. so the territory should look something like these.. is it not.. or maybe particles could still be pink elephants or output of a Matrix like programme using Zeeghaahehaaa programming language?

 

[bhobba]

Gonski, as in Gonski Report ??... without going into it... .

Yes - it's Gonski - but its just an example.

Thanks
Bill

 

[bhobba]

So if experiments has proven say Bohmian Mechanics.. then what would happen to orthodox QM.

Well first BM is deliberately cooked up to be the same as ordinary QM. So what you are talking about is a BM like theory that differs in some way from QM. In that case QM is proved wrong.

Its so simple I am having trouble even understanding what you are driving at.

The essence of science is correspondence with experiment - its not hard.

All that I can think of is you are not across that interpretations, with a few exceptions such as Primary State Diffusion, are deliberately cooked up to be indistinguishable from ordinary QM. Much of it is simply being more precise on things like probability ie is a level of confidence inside a theorists head or relative frequencies in a practically infinite sequence of the same observation as in the Ensemble Interpretation.

Thanks
Bill

 

[Blue Scallop]

Well first BM is deliberately cooked up to be the same as ordinary QM. So what you are talking about is a BM like theory that differs in some way from QM. In that case QM is proved wrong.

Its so simple I am having trouble even understanding what you are driving at.

The essence of science is correspondence with experiment - its not hard.

All that I can think of is you are not across that interpretations, with a few exceptions such as Primary State Diffusion, are deliberately cooked up to be indistinguishable from ordinary QM. Much of it is simply being more precise on things like probability ie is a level of confidence inside a theorists head or relative frequencies in a practically infinite sequence of the same observation as in the Ensemble Interpretation.

Thanks
Bill

If Primary State Diffusion was right.. is it a map or territory?

Are elemental particles like electrons map or territory?

 

[Mario Rossi]

by the way.. are elementary particles like electrons or quarks also maps or territory?

we used vectors or probabilities or other abstract notions to describe them at the fundamental levels or maps.. so the territory should look something like these.. is it not.. or maybe particles could still be pink elephants or output of a Matrix like programme using Zeeghaahehaaa programming language?

There is not a way to know the "territory", every knowledge is a map including electrons. Maybe it is an accurate map, maybe it is not.

 

[Mario Rossi]

@bhobba @PeterDonis @Lord Jestocost @phinds what do you think about this: https://phys.org/news/2015-02-big-quantum-equation-universe.html ?

 

[bhobba]

If Primary State Diffusion was right.. is it a map or territory? Are elemental particles like electrons map or territory?

Well what's a map? - define it exactly. Whats a territory? - define it exactly.

Atoms were once considered just a theory so many would say its just a map. But then the tunneling electron microscope came along so you can literally 'feel' individual atoms. Did that change atoms from a map to a territory - does it depend on technology?

Its a philosophical minefield, and since you claim to be ani-philosophy why does it worry you? Exactly what does such 'semantics' change? Nothing - precisely nothing.

Thanks
Bill

 

[bhobba]

what do you think about this: https://phys.org/news/2015-02-big-quantum-equation-universe.html ?

A new theory of the beginning of the universe - they are a dime a dozen.

We will see exactly what observation says about it over time - just like any other theory.

Thanks
Bill

 

[bhobba]

There is not a way to know the "territory", every knowledge is a map including electrons. Maybe it is an accurate map, maybe it is not.

Its a philosophical minefield. I agree with you - but what a professional philosopher would make of it - beats me - nor is it suitable for discussion here.

Why not avoid such in the first place? Surely its the easiest way of handling it. It my view anyway.

Thanks
Bill

 

[Blue Scallop]

Its a philosophical minefield. I agree with you - but what a professional philosopher would make of it - beats me - nor is it suitable for discussion here.

Why not avoid such in the first place? Surely its the easiest way of handling it. It my view anyway.

Thanks
Bill

Ok. Just want to convince myself everything is map. Electron is map. Electron could be made up of strings. Strings is map. Strings could be made up of other things.. so it's maps all the way. Therefore in physics there is no territory or ultimate ontology where there is nothing beyond it. So even if Weinberg is right the final theory is pure math, then the pure math is the map still.. and no territory.

Just want to be clear of all the arguments so beginning today it's all math I'd focus and would take me years to understand it. Thanks.

 

[stevendaryl]

Regarding decoherence and the related misunderstanding:

Consider a superposition and its evolution in course of time according to the Schroedinger equation. There is no physical process - how irreversible it might be - which is capable to reduce interference terms exactly to zero. You can "decohere" as much as you want, you will never get rid of the superposition. Why don't people get this into their heads? The whole information which the observer had at the beginning of the measuring process remains thus unchanged during the measuring act. Thus, no increase in entropy takes place and, consequently, no conversion of a pure state into a mixed state can takes place. A superposition remains always a superposition as long as mere physical processes are considered. That's physics! There is no way out! The conceptual transition from quantum to classical ignorance has to be put in “by hand” - the role of the observer.

Right. There is a sense, as you say, that decoherence doesn't change anything, at a fundamental level. But in practice, it changes everything.

1. For practical purposes, we don't want to consider the wave function of the entire universe, but only the state of the system(s) of interest.
2. After decoherence, the system of interest can no longer be described by a pure state (wave function), but can only be described by a mixed state.
3. But a mixed state can be given an "ignorance" interpretation: The system is really in this state or that state, but we just don't know which, and the density matrix can tell us the probabilities.

So in practice, you can pretend that after decoherence happens, the wave function of the system of interest "collapses" nondeterministically into one of a number of possibilities. But there is no physical process for such a collapse--it's just an artifact of our pragmatic decision to focus on a small subsystem, rather than the entire universe.

That doesn't answer any of the fundamental questions about the interpretation of quantum mechanics, but it explains why in practice, we don't need to answer those questions.

 

[stevendaryl]

Ok. Just want to convince myself everything is map. Electron is map. Electron could be made up of strings. Strings is map. Strings could be made up of other things.. so it's maps all the way. Therefore in physics there is no territory or ultimate ontology where there is nothing beyond it. So even if Weinberg is right the final theory is pure math, then the pure math is the map still.. and no territory.

Just want to be clear of all the arguments so beginning today it's all math I'd focus and would take me years to understand it. Thanks.

Well a map is something that corresponds in a mathematically precise way to something else. Or in mathematics, the word "map" refers to the correspondence itself. So the paradigm case is a piece of paper that can be thought of as a portion of a 2-dimensional Euclidean space, and each point on the piece of paper corresponds to a point on the surface of the Earth.

It doesn't actually make sense (to me) to say that something is a map without having a second thing that it's the map of. So an electron can't be a map. If we describe the electron by a wave function, then the wave function can be a map. But not the electron.

Of course, there may be no actual electrons, because our concept of electrons might be just an approximation to what's really going. This might be nitpicky, but I don't consider one theory being an approximation to another theory to be an instance of the map/territory distinction. They are two different relationships. A road map is not an approximation to the surface of the Earth, it's a representation of it.

 

[bhobba]

Ok. Just want to convince myself everything is map. Electron is map.

If you want to look at it that way - go ahead - it's doesn't really matter.

Thanks
Bill

 

[Lord Jestocost]

After decoherence, the system of interest can no longer be described by a pure state (wave function), but can only be described by a mixed state.

That's fundamentally wrong! Please, provide a time dependent Schroedinger equation which comprises a physical process that allows to “cut” the wave function of the considered system into “real” pieces, viz. which leads to an increase in entropy and, consequently, to a physical conversion of a pure state into a mixed state.

You cannot trick quantum theory because of your feeling of what “reality ought to be”!

 

[bhobba]

You cannot trick quantum theory because of your feeling of what “reality ought to be”!

There is no trick.

Consider the entangled state 1/√2 |a>|b> + 1/√2 |b>|a>. The two systems are entangled. But now just observe system 1 - it's not in a pure state but with a little math you will find in many sources, even Susskinds Introduction to QM, shows it is in a mixed state:
https://www.amazon.com/dp/0465062903/?tag=pfamazon01-20

I have posted the slightly tedious math before but its so common there is no need eg see section 1.2.3
http://philsci-archive.pitt.edu/5439/1/Decoherence_Essay_arXiv_version.pdf

Its very very basic.

Thanks
Bill

 

[stevendaryl]

That's fundamentally wrong! Please, provide a time dependent Schroedinger equation which comprises a physical process that allows to “cut” the wave function of the considered system into “real” pieces, viz. which leads to an increase in entropy and, consequently, to a physical conversion of a pure state into a mixed state.

You cannot trick quantum theory because of your feeling of what “reality ought to be”!

I'm sorry. I don't understand what you're saying is wrong. It's just a fact that whatever you consider the system of interest, eventually, that system will interact with the rest of the universe. So you're faced with a choice: Either you have a wave function for the rest of the universe, or you somehow have to switch to a nonpure state for the description of the system of interest.

What are you disagreeing with?

 

[stevendaryl]

I'm sorry. I don't understand what you're saying is wrong. It's just a fact that whatever you consider the system of interest, eventually, that system will interact with the rest of the universe. So you're faced with a choice: Either you have a wave function for the rest of the universe, or you somehow have to switch to a nonpure state for the description of the system of interest.

What are you disagreeing with?

I'm unsure about the level at which you are disagreeing. I was assuming that you understood the mathematics of pure and mixed states. Bill Hobba explains it. If you start with a pure state for a composite system, and you perform a "trace" to eliminate the degrees of system that you are not interested in, then the result is a mixed state. There is no assumption being made that there is any nonunitary collapse going on, it's purely a mathematical transformation that is necessary to keep your focus on the system of interest, as opposed to the entire universe.

 

[stevendaryl]

He didn't talk about it in terms of decoherence, but the mathematics of how mixed states arise from pure states by considering subsystems was described in Everett's original paper on Many Worlds (which is not the name that he used---that was Bryce Dewitt).

Suppose that you have a composite system described by a wave function $|\Psi\rangle = \sum_{\alpha, j} C_{\alpha, j} |\alpha\rangle |j\rangle$, where $|\alpha\rangle$ is a complete set of states for the first subsystem, and $|j\rangle$ is a complete set of states for the second subsystem. You can think of $|\alpha \rangle$ as describing the system of interest--maybe an electron--while $|j\rangle$ describes everything else in the universe. Now $K$ be some operator that only affects the first component. That means that its affect on the composite state $|\alpha\rangle|j\rangle$ is this:

$K |\alpha\rangle |j \rangle = \sum_{\alpha'} K_{\alpha' \alpha} |\alpha\rangle |j\rangle$

Since operators correspond to observables, $K$ represents an observable of the first subsystem alone. Now, let's compute the expectation value of $K$ in the composite state $|\Psi\rangle$:

$\langle \Psi|K|\Psi \rangle = \sum_{\alpha, \alpha', j, j'} C^*_{\alpha', j'} C_{\alpha, j} \langle \alpha' | \langle j' | K | j \rangle |\alpha\rangle$
$= \sum_{\alpha, \alpha', j, j'} C^*_{\alpha', j'} C_{\alpha, j} K_{\alpha' \alpha} \delta_{j j'}$
$= \sum_{\alpha, \alpha', j} C^*_{\alpha', j} C_{\alpha, j} K_{\alpha' \alpha}$

Now, if we define $\rho_{\alpha \alpha'}$ to be: $\sum_j C^*_{\alpha', j} C_{\alpha, j}$, then we have:

$\langle \Psi|K|\Psi\rangle = \sum_{\alpha, \alpha'} \rho_{\alpha \alpha'} K_{\alpha' \alpha} \equiv Tr(\rho K)$

So for measurements only involving the first subsystem, the density matrix $\rho$ is all that we need for computing expectation values. It's a mixed state, in general.

 

[Mario Rossi]

And so, does God confusing us throwing dices (indeterminism)? Does an electron exists when nobody looks at it? If no, why the wave function collapses (maybe this is too difficult for me like you said, if it is, skip it)?

 

[bhobba]

There is no assumption being made that there is any nonunitary collapse going on, it's purely a mathematical transformation that is necessary to keep your focus on the system of interest, as opposed to the entire universe.

Exactly, and that is why it doesn't solve the measurement problem - it just does FAPP - but that is not the same thing.

Still progress has been made in identifying the exact problem.

Thanks
Bill

 

[PeterDonis]

what do you think about this

It's a speculative proposal in an active, ongoing area of research. Which means discussion of it doesn't belong in this subforum. It might possibly be discussible in a new thread in the Beyond the Standard Model forum, if you're careful to limit discussion to how the proposal might be tested.

 

[PeterDonis]

Just want to convince myself everything is map

Who said that? "Everything" doesn't just include our physical models; it includes the things they are models of. The models are maps. What they are models of is territory.

Part of the problem here is vagueness in ordinary language. Consider the word "electron". Does it refer to a particular theoretical model--a part of the Standard Model of particle physics? Or does it refer to the thing, whatever it is, that the theoretical model is modeling? The word is used both ways, so the question "is an electron a map or territory?" doesn't have an answer until you specify what you are referring to by the word "electron". And, of course, once you've specified that, the answer to the question is obvious.

Physics consists of our models; that's why I said all physics is maps. But those models are models of something--or at least they are intended to be. (The models don't always turn out to be accurate, so it's possible that they don't actually refer to anything--for example, back when people thought combustion was due to phlogiston, "phlogiston" was an object in the models--the map--but there was nothing in the territory corresponding to it.)

The reason the map-territory distinction is made is to make it clear that our physical models are distinct from the things they are trying to model. That let's us take a step back, so to speak, and keep ourselves from making commitments based on our models that might be too broad. For example, quantum physics is a model--a map: it can be used to make very accurate predictions about the results of experiments. But there are multiple, mutually inconsistent interpretations of QM, which amount to multiple, mutually inconsistent claims about exactly what kind of territory the map is modeling. Those claims can't be resolved by experiment (because all of the interpretations make the same predictions for all experimental results), so they are off topic for discussion here, because here we focus on claims that can be resolved by experiment.

 

[Lord Jestocost]

And so, does God confusing us throwing dices (indeterminism)? Does an electron exists when nobody looks at it? If no, why the wave function collapses (maybe this is too difficult for me like you said, if it is, skip it)?

Up to now, no serious physicist can answer these questions. Maybe, you will get various answers, depending on the respective interpretation which the responding one is adhering to (very often some implicit, unprovable assumptions are even not disclosed). Nevertheless, all interpretations of quantum theory are myths, or crutches, which should help us to form ideas and conceptions about what’s occurring at the quantum level and which might, perhaps??, help us to make experimentally provable predictions. Myths which - to my mind - centre at the end around one single question: “Which came first — the observer or the particle?” (Vanna Bonta, in "Flight: A Quantum Fiction Novel").

With respect to this, the instrumentalist’s attitude is the most honest one: The formalism of quantum theory provides nothing but calculational recipes to predict the probabilities of various directly observed macroscopic outcomes; the theory is thus about relations and correlations between – so to speak – observable spatial and temporal patterns of “clicks”; about the linkage of pointer readings with pointer readings.

 

[Mario Rossi]

“Which came first — the observer or the particle?”

Yes, this is the main answer. If we try to make an hypothesis on the "came first the observer", what can we think? The universe is prior to the observers, right? If not, so the Big Bang theory is wrong and we must search not the beginning of the universe but the beginning of the observer.

 

[Mario Rossi]

I found a theory made by Penrose and Hameroff, it's called ORCH-OR, what do you think about it?

 

[PeterDonis]

I found a theory made by Penrose and Hameroff, it's called ORCH-OR, what do you think about it?

Please give a specific reference.

 

[Mario Rossi]

Please give a specific reference.

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

 

[PeterDonis]

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

This is a speculative proposal which has not been confirmed. There have been some experiments which the proponents claim support their proposal, but as far as I can see those claims are not generally accepted.

 

[PeterDonis]

This thread is veering off into philosophy and speculation and is now closed.