Einstein & Bohr Debate: Epistemological Paradox

[martinbn]

But that is precisely the point at issue, so you can't just assume it.

But if the smallest parts do not exist objectively, what does it mean for the other ones, made from them, to exist obectively.

 

[PeterDonis]

if the smallest parts do not exist objectively, what does it mean for the other ones, made from them, to exist obectively

You'd have to ask the people who claim that the smallest parts don't exist objectively unless they are measured. Unfortunately Heisenberg is no longer around to ask. But such interpretations do exist, so you can't just rule them out by fiat.

 

[bhobba]

Wait! What's wrong with that!? They do exist objectively.

Here in the macro world - yes. But, without specifying any particular interpretation, the idea of existing objectively has been modified somewhat. In QM what is going on between observations the theory is silent on. That puts a 'cloud' over the whole idea of objective reality existing at all times. It still may - but the theory does not affirm it.

Thanks
Bill

 

[bhobba]

But if the smallest parts do not exist objectively, what does it mean for the other ones, made from them, to exist obectively.

Well Freeman Dyson sorted that one out when he figured out why objects here in the macro world are solid. In the microworld things are a lot more fuzzy. There is of course an area of 'overlap' and there all sorts of 'strange' things happen eg
https://www.nist.gov/news-events/ne...ks-demonstrate-direct-coupling-vibrating-ions

As technology advances expect even weirder effects.

Thanks
Bill

 

[martinbn]

You'd have to ask the people who claim that the smallest parts don't exist objectively unless they are measured. Unfortunately Heisenberg is no longer around to ask. But such interpretations do exist, so you can't just rule them out by fiat.

Which interpretations are those? Just to be clear. There are interretations, in fact that is the standard theory, in which observables do not have values until measured. But i am not aware if iterpretations that say that the quantum systems do not exist, and at the same time the classical systems do exist.

Of course all this may be just semantics. If by exists people(Heisenberg) mean all/some observables have definite values, then i agree, but that is just strange use of language.

 

[martinbn]

Here in the macro world - yes. But, without specifying any particular interpretation, the idea of existing objectively has been modified somewhat. In QM what is going on between observations the theory is silent on. That puts a 'cloud' over the whole idea of objective reality existing at all times. It still may - but the theory does not affirm it.

Thanks
Bill

That is not quite true. The theory says that between measurements the system's state evolves according to the Schrodinger equation.

 

[Lynch101]

I meant that they exist as much as the stones and trees do.

This might be an esoteric bridge too far, but if we were to drill down into the idea that "stones" and "trees" exist, we can see that "stones" and "trees" are just concepts without any intrinsic existence. Each is made up of their constituent parts with the term "tree" and "stone" being the conceptual label for what is, in truth, a more complex process.

EDIT: to say that "trees" and "stones" exist is akin to a category mistake (or perhaps an inverse category mistake).

 

[atyy]

But if the smallest parts do not exist objectively, what does it mean for the other ones, made from them, to exist obectively.

They are only "made" from them in the quantum state. So the "made from" does not have the same level of reality as the measurement outcomes. Basically, it is not saying that the true constituent parts (which we have not identified and may have no straightforward relation to "electrons") from which real things are made don't exist. It is saying that we are agnostic about the reality of "electrons", "photons" etc that are concepts we use to construct the quantum state.

 

[vanhees71]

You'd have to ask the people who claim that the smallest parts don't exist objectively unless they are measured. Unfortunately Heisenberg is no longer around to ask. But such interpretations do exist, so you can't just rule them out by fiat.

This statement is one of the examples why I'm very critical against Heisenberg's mostly philosophical writings. QT doesn't say that things only exist when measured but that no matter in which state an object is prepared in there are always observables whose values are indetermined, and these values are objectively indetermined, i.e., there's no unknown "hidden variable" which we just don't know but that these values are just indetermined. This does not imply that the object doesn't exist at all. I don't know, how, from the quantum-theoretical foundations, one can come to such an absurd conclusion.

 

[Lord Jestocost]

But if the smallest parts do not exist objectively, what does it mean for the other ones, made from them, to exist obectively.

As a physicist I would say: At the end, it’s up to you (and thus up to your psychological predispositions) when you think of appearances as experiences of “existing objects” ("object" means that it can be given a description in its own right).

Here I am in line with Wheeler^* who states: "In today’s words Bohr’s point – and the central point of quantum theory – can be put into a single, simple sentence. 'No elementary phenomenon is a phenomenon until it is a registered (observed) phenomenon.'”

^* J. A. Wheeler in “Law without law” in "Quantum Theory and Measurement“ (edited by John Archibald Wheeler and Wojciech Hubert Zurek), Princeton, New Jersey 1983, pages 182-213

 

[PeterDonis]

i am not aware if iterpretations that say that the quantum systems do not exist

I actually overstated what I take to be Heisenberg's position. He did not, as I understand it, claim positively that quantum systems do not exist if they are not being measured. He only claimed that you could not say positively that they do exist if they are not being measured.

 

[PeterDonis]

The theory says that between measurements the system's state evolves according to the Schrodinger equation.

The theory says that the mathematical object, the state vector (or wave function), evolves according to the Schrodinger equation between measurements.

But the claim that the state vector describes an actually existing, individual quantum system is interpretation-dependent; not all interpretations make that claim. Some interpretations say it only describes our knowledge about the probabilities of possible measurement results; some interpretations say it describes statistical properties of an ensemble of systems that are prepared by the same preparation procedure. In either of these interpretations, no claim is necessarily made that individual quantum systems exist when they are not being measured. One can add such a claim to the interpretation, but one is not forced to.

 

[vanhees71]

Take an electron. If you know that there is an electron at one time and you also know the Hamiltonian you can precisely calculate the probability whether an electron does exist or not. If more than 1 (relevant) electron is involved in an experiment, of course you can't say whether an individual electron exists but only the number of electrons at any time. Also note that the state of one electron doesn't need to be a pure state, i.e., it doesn't need to be described by a state vector but by a statistical operator as part of a larger system. This is all interpretation independent!

 

[Morbert]

But if the smallest parts do not exist objectively, what does it mean for the other ones, made from them, to exist obectively.

There's an important distinction between assertions about properties of a system, and assertions about primitive objects/parts that make up a system. The latter category implies a primitive ontology (PO) approach, which is at odds with a neo-Copenhagen approach. I'm not aware of any PO approach that asserts primitive objects as subjective and the systems they make up as objective.

 

[martinbn]

There's an important distinction between assertions about properties of a system, and assertions about primitive objects/parts that make up a system. The latter category implies a primitive ontology (PO) approach, which is at odds with a neo-Copenhagen approach. I'm not aware of any PO approach that asserts primitive objects as subjective and the systems they make up as objective.

That is what i was trying to say too.

 

[bhobba]

But the claim that the state vector describes an actually existing, individual quantum system is interpretation-dependent; not all interpretations make that claim.

Exactly. That is one of the important consequences of Gleason's Theorem. It shows, amongst other things, the state can be nothing but an aid to calculating probabilities. It also depends on some other things like non-contextuality - but it does not change the conclusion. An example of such an interpretation is the Ensemble Interpretation of Einstein:
https://www.informationphilosopher.com/solutions/scientists/ballentine/AJP72.pdf

Note - others may point out, correctly, Einstein was not its originator, and there is debate if it is the same as Ballentine's version.

Thanks
Bill

 

[dx]

I am puzzled by why Einstein continued to oppose the statistical character of quantum behavior even after Bohr defeated him at every objection Einstein raised. With all her mastery of analysis and differential geometry, I don't know why he continued to resist this aspect of quantum theory. As Bohr said,

I might even say that not even the dear lord himself knows what an expression like "playing dice" means in this context.

 

[bhobba]

I'm am puzzled by why Einstein continued to oppose the statistical character of quantum behavior

That is common misconception. His views on QM changed as his objections were all answered - except maybe EPR. He eventually believed it correct, but incomplete. He had no real worry with its probabilistic nature - after all he did fundamental work on statistical mechanics. His real concern was with the idea the wave-function was a complete description of a quantum system. Gleason's theorem was not known then and that proves it can be looked on as just an aid to calculation rather than a complete description of anything. So that part of Copenhagen is simply interpretive - although I am not sure it is part of modern versions of Copenhagen. It is certainly not part of Consistent/Decoherent Histories that many say is Copenhagen done right. It's the interpretation Feynman reportedly was converted to after attending a seminar on it by the guy next door to his office at Caltech - Gell-Mann. Einstein had his own interpretation (by own I mean the one he held - not that he invented it), that does not consider the state in any sense 'real', that is, basically, what we call the Ensemble Interpretation today (I posted it above but for reference will post it again):
https://www.informationphilosopher.com/solutions/scientists/ballentine/AJP72.pdf

In that interpretation a state is considered a conceptual ensemble of possible outcomes depending on the observation. It is not in any sense real or complete - just a abstraction useful in understanding calculating probabilities.

The only issue I have with Einstein was not that his views on QM were wrong - basically I think they were correct. It was that even past his prime he was capable of doing valuable work in the field, but insead left it to the younger generation and worked on his unified theory.

Thanks
Bill

 

[physika]

these values are just indetermined. This does not imply that the object doesn't exist at all.

I agree:

...and the logical contradiction, the "observer" exist, but the not yet "observed" not exist..

 

[Demystifier]

My contribution to understanding the dialogues between Bohr and Einstein:
https://arxiv.org/abs/1203.1139

 

[vanhees71]

I agree:

...and the logical contradiction, the "observer" exist, but the not yet "observed" not exist..

Again: This has nothing to do with an observer. Only because some observable is not determined, this doesn't imply that the quantum system doesn't exist. If I have prepared an unpolarized electron, it's spin is completely indetermined. That doesn't mean that the electron doesn't exist or even that the spin doesn't exist. The spin component ##\sigma_z## is an observable, which always can be measured and in this sense it always exist, but depending on the state the electron is prepared in, it may not have a determined value, which simply means that you cannot predict, given the state, what you will get as a measuring result when measuring this observable. All you know is the probability with which you find one of the possible values (in this case ##\hbar/2## or ##-\hbar/2## with probability 1/2 for each outcome). This probability can of course only be measured by measuring ##\sigma_z## on a suffuciently large ensemble (for a given level of significance for its value) of equally prepared electrons, i.e., an ensemble, and not by a single measurement.

 

[physika]

Again: This has nothing to do with an observer. Only because some observable is not determined, this doesn't imply that the quantum system doesn't exist. If I have prepared an unpolarized electron, it's spin is completely indetermined. That doesn't mean that the electron doesn't exist or even that the spin doesn't exist. The spin component ##\sigma_z## is an observable, which always can be measured and in this sense it always exist, but depending on the state the electron is prepared in, it may not have a determined value, which simply means that you cannot predict, given the state, what you will get as a measuring result when measuring this observable. All you know is the probability with which you find one of the possible values (in this case ##\hbar/2## or ##-\hbar/2## with probability 1/2 for each outcome). This probability can of course only be measured by measuring ##\sigma_z## on a suffuciently large ensemble (for a given level of significance for its value) of equally prepared electrons, i.e., an ensemble, and not by a single measurement.

not inteded to you,

aimed to the phrase:

Is the moon when nobody looks?

I agree:

-----

apart

...and the logical contradiction, the "observer" exist, but the not yet "observed" not exist

I posted that way, don't know what happened, the page blip.

.

 

[physika]

His real concern was with the idea the wave-function was a complete description of a quantum system.

a sort of Psi Epistemic stand.
.
.

 

[Mary Conrads Sanburn]

THE EINSTEIN ESSAYS
The Bohr-Einstein Debate
A narration through the “Debate of the Century”
Jørgen Veisdal
Sep 25, 2019 · 18 min read
The year is 1905. Newly graduated with a Ph.D. in physics, Albert Einstein publishes the paper Über einen die Erzeugung und Verwandlung des Lichtes betreffenden heuristischen Gesichttspunkt (“On a Heuristic Viewpoint Concerning the Production and Transformation of Light”). In it, he proposes a revision to one of the fundamental laws of physics to account for the behavior of light as both a particle and a wave, work for which he would later be awarded the Nobel Prize (1921). Eight years later in 1913, in the paper On the Constitution of Atoms and Molecules, Part II Systems Containing Only a Single Nucleus, Danish physicist Niels Bohr adapts Ernest Rutherford’s 1911 model of the atom to Max Planck’s quantum theory to introduce a new model of the atom — the Bohr model, both earning himself his own Nobel (1922), as well as setting the stage for a coming quantum revolution in physics.
Fast forward 12 years. Building on the work of both Einstein and Bohr, Werner Heisenberg introduces matrix equations which remove the foundational elements of space and time from the then increasingly popular quantum mechanical model of physics. Building on this work, Max Born in the following year proposes that mechanics are most effectively understood not as causal links but as actions resulting from probability, not distinct causation. With Heisenberg’s solution of the Schrödinger equation for a scattering problem the following year, the now well-known Heisenberg uncertainty principle is introduced, leading Born and Heisenberg to declare that quantum mechanics was now “complete and irrevocable”.
In less than 25 years, starting with Planck’s 1900 discovery of the black body radiation law, to Einstein’s discovery of the photon, to Bohr’s redefinition of the model of the atom, to Heisenberg and Born’s refinement of quantum mechanics, physics in the first quarter of the twentieth century went from fully deterministic to seemingly indeterminate.
The Fifth Solvay International Conference (1927)
The Bohr-Einstein debate is generally considered to have begun during the Fifth Solvay International Conference on Photons and Electrons. The conference was held in October 1927 in Brussels, Belgium. Continuing on since the successful inaugural conference of 1911, the Solvay gatherings are devoted to outstanding preeminent open problems in physics, and occur approximately every three years. From 1913 to 1961, every gathering revolved around open problems in quantum theory. Chaired by Hendrik Lorentz in 1927, the official topic of the conference was “photons and electrons”. In practice, the 1927 conference revolved around the growing dispute between two then nascent schools of physics: those fascinated and enthralled by the new developments in quantum theory, and those still clinging to the superseded deterministic paradigm. The former was lead by Niels Bohr and the latter by Albert Einstein.
The Copenhagen interpretation
The open problem during the 1927 Solvay conference was how physicists should interpret the recent results of physicists Werner Heisenberg and Max Born, the now so-called “interpretation question” of quantum mechanics. Born and Heisenberg, fervent in their view, promoted the following (simplified) view:
“Physical systems do not have definite properties prior to being measured. Quantum mechanics can only predict the probability distribution of given measurements’ possible results.”
This because, as the view goes, the act of measurement affects the system being measured. This causes the set of probabilities to reduce to only one of the possible values immediately after the measurement — the so-called wave function collapse. In other words, prior to the measurement of (for instance) the position of an electron, its location is best described by a probability distribution (a wave function). In the act of measuring the position of the electron, the device measuring or observing the electron influences the probability distribution. After the measurement, due to the influence of the observer, the position of the electron is now best defined by a single value (e.g. a Cartesian coordinate).
Definition
“Despite an extensive literature which refers to, discusses, and criticizes the Copenhagen interpretation of quantum mechanics, nowhere does there seem to be any concise statement which defines the full Copenhagen interpretation.”
Despite statements such as the one given above by John G. Cramer in 1986 and many more both before and after it, for the purposes of this article we can colloquially state the Copenhagen interpretation as
The Copenhagen Interpretation of Quantum Mechanics
Physical systems generally do not have definite properties prior to being measured, and quantum mechanics can only predict the probability distribution of a given measurement's possible results. The act of measurement affects the system, causing the set of probabilities to reduce to only one of the possible values immediately after the measurement.
More specifically, we can define it as synonymous with a sum of the concepts of indeterminism, Bohr’s correspondence principle, Born’s statistical interpretation of the wave function and Bohr’s complementarity interpretation of certain atomic phenomena. The term itself stems from Heisenberg who worked as an assistant under Bohr at his institute in Copenhagen while he formulated his uncertainty principle, and can been traced to Heisenberg’s 1930 textbook The Physical Principles of the Quantum Theory in which he states that
"On the whole, the book contains nothing that is not to be found in previous publications, particularly in the investigations of Bohr. The purpose of the book seems to me to be fulfilled if it contributes somewhat to the diffusion of that Copenhagen spirit of quantum theory if I may so express myself, which has directed the entire development of modern atomic physics."
- Excerpt, “The Physical Principles of the Quantum Theory” by Werner Heisenberg (1930)
History
In the years from 1925 up until the conference in 1927, the quantum revolution that had been taking place had been propelled mainly by three revolutionary ideas:
In 1925, Werner Heisenberg introduced matrix equations that removed the Newtonian elements of space and time from quantum mechanics;
In 1926, Max Born proposed that quantum mechanics were best understood by probabilities;
In 1927, Heisenberg had formulated his uncertainty principle defining the mathematical model to describe the fundamental limit of the precision with which certain pairs of physical properties of a particle (known as complementary variables) can be known.
Heisenberg’s first breakthrough idea was first proposed in his paper Über quantentheoretische Umdeutung kinematischer und mechanischer Beziehungen (“Quantum Theoretical Re-interpretation of Kinematic and Mechanical Relations”) which appeared in Zeitschrift für Physik in September 1925. Reportedly, Heisenberg in correspondence with Wolfgang Pauli had been working on the paper while recovering from hay fever. The purpose of the paper was to attempt to describe the energy levels of a one-dimensional anharmonic oscillator via observable parameters such as transition probabilities for quantum jumps (Segrè, 1980). The paper laid the groundwork for what is now known as matrix mechanics, which Heisenberg later developed in collaboration with Born and Pascual Jordan.
[. . .]
https://www.cantorsparadise.com/the-bohr-einstein-debate-baa0929a78b5
This is a very lengthy article. I love it!

 

[RUTA]

/ l

Summary:: Quantum physics

Im reading a book called “Quantum” the deabate between Einstien and Bohr. I’ve read reviews on it and this one particular review said the book doen’t delve into the “epistimological paradox” theat caused the two debaters to take their stand in their arguement. My question is, what was their “stand” in regards to this epistimological paradox?

See Adam Becker’s book “What is Real?” https://www.physicsforums.com/insights/interview-with-astrophysicist-adam-becker/

 

[bhobba]

My question is, what was their “stand” in regards to this epistimological paradox?

To answer the question head-on, the epistemological difference between Einstein and Bohr is Einstein was a realist. He believed in an objective world out there independent of anyone’s beliefs, linguistic practices, conceptual schemes, and so on. Within that view of the world, there are many different nuanced positions. Einstein was also an epistemological opportunist; he simply took the one that served his purpose the best. The point to take away, though, is he was a realist. Bohr was an instrumentalist believing science reveals nothing except what is observable. Science is just a tool allowing the prediction of observations but does not reveal any hidden aspects of nature that may explain those laws.

Feynman, too was an opportunist - believing it to be just one 'trick' that scientists can try to unlock natures secrets. He was quite anti-philosophy - which is rather strange because it is philosophy itself.

In modern times I think most (but not all - see the writings of Penrose, for example) scientists are really neither; they are like Stephen Hawking believing in some form of Model-dependent realism:
https://en.wikipedia.org/wiki/Model-dependent_realism

I, too, am in that camp, although I was once in Prenose's camp. But like Feynman, as far as nuances go, I am an opportunist.

Thanks
Bill

 

[RUTA]

It's ironic that Einstein insisted on a "constructive" account of entanglement when he could have produced a "principle" account using his relativity principle. He gave up on "constructive efforts" for explaining time dilation and length contraction, so I wonder why he never considered doing likewise for entanglement. I read some quotes indicating that perhaps he was not really happy with special relativity in the absence of a constructive counterpart, so maybe he didn't even want to go that way with EPR? https://sciencex.com/news/2020-10-einstein-opportunity-spooky-actions-distance.html

 

[Andrew Mason]

Einstein was also an epistemological opportunist; he simply took the one that served his purpose the best. The point to take away, though, is he was a realist. ...

Feynman, too was an opportunist - believing it to be just one 'trick' that scientists can try to unlock natures secrets. He was quite anti-philosophy - which is rather strange because it is philosophy itself.

Feynman is hard to categorize. He wasn't 'anti-philosophy': he was just opposed to a non-scientific philosophy posing as science (which to him was like people arguing over whether an interpretation of a Rorschach diagram was correct). His entire career was an attempt to explain nature so his motivation in that sense was a philosophical one. He was fascinated by the fact that nature seemed be explainable in different ways without contradiction. He remarked on this in his Nobel lecture:

​

"I would like to interrupt here to make a remark. The fact that​

electrodynamics can be written in so many ways - the differential​

equations of Maxwell, various minimum principles with fields,​

minimum principles without fields, all different kinds of ways, was​

something I knew, but I have never understood. It always seems​

odd to me that the fundamental laws of physics, when​

discovered, can appear in so many different forms that are not​

apparently identical at first, but, with a little mathematical​

fiddling you can show the relationship. An example of that is the​

Schrödinger equation and the Heisenberg formulation of quantum​

mechanics. I don't know why this is - it remains a mystery, but it​

was something I learned from experience. There is always​

another way to say the same thing that doesn't look at all like the​

way you said it before. I don't know what the reason for this is. I​

think it is somehow a representation of the simplicity of nature. A​

thing like the inverse square law is just right to be represented​

by the solution of Poisson's equation, which, therefore, is a very​

different way to say the same thing that doesn't look at all like​

the way you said it before. I don't know what it means, that​

nature chooses these curious forms, but maybe that is a way of​

defining simplicity. Perhaps a thing is simple if you can describe it​

fully in several different ways without immediately knowing that​

you are describing the same thing."​

AM

 

[stevendaryl]

In modern times I think most (but not all - see the writings of Penrose, for example) scientists are really neither; they are like Stephen Hawking believing in some form of Model-dependent realism:
https://en.wikipedia.org/wiki/Model-dependent_realism

I, too, am in that camp, although I was once in Prenose's camp. But like Feynman, as far as nuances go, I am an opportunist.

What does Penrose believe that is different from most scientists?

("Prenose" means you were born before noses were invented...)