Nobody understands quantum physics?

[vanhees71]

Does it? Hasn't it widened the field (quantum cryptography, quantum "teleportation", quantum computing)?

Sure, but all this is just standard quantum theory, and it's possible, because entanglement is the correct description of Nature and not "realism", i.e., all Bell experiments prove (together with the validity of locality in the sense of microcausality of relativistic QFT) that the observable don't take determined values, i.e., there's "true randomness" in Nature, which is not due to our ignorance of the exact state as in classical statistical physics. E.g., if you have a two-photon Bell state (say the polarization-singlet state) then the single-photon polarizations are maximally random, i.e., the reduced statistical operator describing them is $\hat{1}/2$, i.e., the single photons are perfectly unpolarized.

My conclusion is the exact opposite. I'd rather give up the "sacred" locality than realism. For me, realism means accepting the results of experiments as real; it does not mean we have to believe in the existence of photons with definite polarization states.

You can't give up locality without giving up the most successful quantum theory ever, i.e., local (microcausal) relativistic QFT the Standard Model is based on, which is more successful than the HEP community wishes for!

I agree that we are in the posession of a very good description, but I doubt that we have found the best formulation. Obviously you can't conceive of the possibility that quantum theory (after almost a century!) may be in a situation similar to that of electrodynamics before 1905.

Of course, the current understanding is incomplete, but not because of some philosophical quibbles about the interpretation of the present QT formalism but because we don't have a satisfactory quantum theory of gravitation and/or a quantum theory of spacetime. It's well possible that a future solution of this problem will result in a completely new paradigm with the classical spacetime model(s) used in our contemporary physics being an "emergent phenomenon".

 

[WernerQH]

We're obviously talking past each other!

 

[A. Neumaier]

After the magnet the spin component in direction of the field is (almost completely) entangled with position, i.e., in each of the two partial beams "selected" by the magnet you have a well-prepared spin component.

No. You have two well-prepared spin components, one in the up beam and one in the down beam. Prepared is a single particle in a superposition, so immediately before the measurement is taken, it "is in" both partial beams. The measurement decides on one of the two spots where the particle can possibly be recorded. (More precisely, after - and not before - the measurement has been taken, it is known at which of the two spots the screen responded.)

The question is when, in a quantum description of the detector, the definite value is obtained.

Thus: in the quantum description of the measurement device, at which time is the up spot (or the down spot) obtained?

We should be careful not to attribute a property like $+1$ to the object of measurement. would only be attributed to the classical datum post-measurement.

But after the measurement, this property is a definite property of the quantum measurement device. Thus it must have been somehow obtained dynamically!

 

[vanhees71]

No. You have two well-prepared spin components, one in the up beam and one in the down beam. Prepared is a single particle in a superposition, so immediately before the measurement is taken, it "is in" both partial beams. The measurement decides on one of the two spots where the particle can possibly be recorded.

Yes, and if I select a particle from this beam, it's in a definite spin state.

Thus: in the quantum desxcription of the measurement device, at which time is the up spot (or the down spot) obtained?

It's obtained when the detector registers the particle, when else?

But after the measurement, this property is a definite property of the quantum measurement device. Thus it must have been somehow obtained dynamically!

Sure, how else?

 

[gentzen]

The measurement decides on one of the two spots where the particle can possibly be recorded.

In which interpretation? Do you have a reference to back up that assertion (with respect to a specific interpretation)?

 

[A. Neumaier]

Yes, and if I select a particle from this beam, it's in a definite spin state.

The SG experiment has no selection. How do you select a particle without adding a filter before the screen?

It's obtained when the detector registers the particle, when else?

Sure, how else?

The classical behavior of macroscopic matter, including matter used for measurements, can be understood from quantum many-body theory.

What is to be explained is how the definite macroscopic measurement result read from the measurement device, interpreted by quantum many-body theory, is obtained through the interaction with the silver atom prepared in a superposition.

The measurement decides on one of the two spots where the particle can possibly be recorded.

In which interpretation? Do you have a reference to back up that assertion (with respect to a specific interpretation)?

My statement just means that after (and not before) the measurement has been taken, it is known at which of the two spots (where the particle can possibly be recorded) the screen responded. This comes directly from the observational facts, and is independent of quantum physics, hence independent of any interpretation of it.

 

[vanhees71]

The SG experiment has no selection. How do you select a particle without adding a filter before the screen?

I select a particle by taking it simply from the region, where the particles have the spin component I like to get. Of course, I can also block the other beam with some filter. That doesn't make a difference.

What is to be explained is how the definite macroscopic measurement result read from the measurement device, interpreted by quantum many-body theory, is obtained through the interaction with the silver atom prepared in a superposition.

It's a silver atom reacting with the detector material by e.g. kicking out an electron, which then is electronically registered or in the original setup it got stuck on the plate and could then be made visible with photographic development (or initially due to the smoke from cheap cigars ;-)).

My statement just means that after (and not before) the measurement has been taken, it is known at which of the two spots where the particle can possibly be recorded, the screen responded. This comes directly from the observational facts, and is independent of quantum physics, hence independent of any interpretation of it.

Of course, you don't know where each individual silver atom will end up, but you know that if you select silver atom from one of the regions that you have a particle with a determined spin component. That's always the case with probabilistic statements. This indeed has nothing specifically to do with quantum physics.

 

[gentzen]

My statement just means that after (and not before) the measurement has been taken, it is known at which of the two spots (where the particle can possibly be recorded) the screen responded. This comes directly from the observational facts, and is independent of quantum physics, hence independent of any interpretation of it.

That way to put it is fine for me. My worry with the initial statement that "the measurement decides" is that people tend to interpret that literally. And I was also unsure whether you did this too, with the intention to ridicule some specific interpretation. (That is why I asked for a reference.)

 

[A. Neumaier]

I select a particle by taking it simply from the region, where the particles have the spin component I like to get. Of course, I can also block the other beam with some filter. That doesn't make a difference.

If you have only one particle prepared, you don't know which region to choose.

It's a silver atom reacting with the detector material by e.g. kicking out an electron, which then is electronically registered or in the original setup it got stuck on the plate and could then be made visible with photographic development (or initially due to the smoke from cheap cigars ;-)).

But in the quantum description, the silver atom is in a superposition of position states, whose quantum evolution in the interacting system particle+detector does not lead to a definite macroscopic measurement result of the detector.

 

[vanhees71]

If you have only one particle prepared, you don't know which region to choose.

I know which region to choose, given the spin state I want to investigate. Of course, I don't know beforehand, whether I get something to experiment with or not. I only know the probabilities whether I get a particle or not. It's a conditional probability: If I get a particle, then I know it's in the wanted spin state. If I don't get a particle, I know it's in the other region with the other possible spin state. As you said before, that's as with any probabilistic description, not specific to "quantum probabilities". Obviously, I don't understand, where you think the problem is.

But in the quantum description the silver atom is in a superposition of position states, whose quantum evolution in the interwacting system particle+detector does not lead to a definite measurement result of the detector.

Let's describe the particle with a wave function for simplicity. You can of course also describe it by a general mixed state, but the qualitative results we are discussing here are the same.

You prepare a silver atom to have a pretty well defined momentum in one direction and be quite well located in the transverse direction (you can use a Gaussian wave packet). When released it's running through the magnetic field. The wave function develops such that after the magnet it's peaked around two positions due to the deflection by the inhomogeneous magnetic field dependent on the spin component in direction of the magnetic field. This implies that particles in the region around either peak has a well-determined spin component in the direction of the magnetic field, i.e., that the spin component and the position is entangled. That's all that's need to select either of the spin states, i.e., you consider simply only particles in the one or the other region.

A definite "outcome" at the detector is of course described by the interaction of the atom with the detector material, and it's random for each single atom whether the one or the other detector will detect the particle. I still don't get where the problem might be.

 

[LittleSchwinger]

A definite "outcome" at the detector is of course described by the interaction of the atom with the detector material, and it's random for each single atom whether the one or the other detector will detect the particle. I still don't get where the problem might be.

I think A. Neumaier might be asking how the outcome being definite at the detector is modelled quantum mechanically, i.e. where in the model of the atom+detector is this definiteness seen.

 

[Fra]

I think A. Neumaier might be asking how the outcome being definite at the detector is modelled quantum mechanically, i.e. where in the model of the atom+detector is this definiteness seen.

It must be modelled by the hamiltonian of the detector+atom. ie. the process of measurement, is a physicainteraction in the hamiltonian of the bigger hilbert space. This is IMO a simple motivator for trying to unify physics and inference in deeper way (which is what I keep nagging about).

At each level the hamiltonian is somehow "given". But what if we ould understand the measurement process, shouldnt that help us with emergent hamiltonian of bigger systems?

It seems to me the definitness of an outcome is defined relative to the orignal observer (to which the term "outcome" refers to). Which is the detector in this example. Thus in the quantum mechanical description of detector+atom, there notion of definite outcome of an internal parts is undefined.

/Fredrik

 

[vanhees71]

But an "outcome" is due to a macroscopic observable, e.g., a visible spot on a photoplate and as such via coarse graining a classical description is adequate. As any classical phenomenon it's the result of sufficient coarse graining and the associated decoherence which leads to a "definite classical outcome".

 

[Fra]

But in the QM description of atom+detector, the "macroscopic variable" is now also a quantum system.

/Fredrik

 

[Fra]

as any classical phenomenon it's the result of sufficient coarse graining and the associated decoherence which leads to a "definite classical outcome".

Taking this ultimate method of explanation, you are force to effective consider the whole universe as a quantum system. But, how do you confirm that model by experiment? (ie as per the high standards you are used to from particle experiments?) THIS is my problem. I understand the idea of decoherence, but that does not solve the problem.

/Fredrik

 

[Morbert]

But after the measurement, this property is a definite property of the quantum measurement device. Thus it must have been somehow obtained dynamically!

"Therefore, the program of computing what the effect of the [measurement] disturbance was and correcting for it is, in general, impossible. Accordingly, the two basic tenets of the theory of macroscopic measurement are both violated. Either the interactions cannot be made arbitrarily weak because of the phenomenon of atomicity, or if we wish to accept this and correct for it, we cannot do so because we do not have a detailed, deterministic theory of each individual event" --Schwinger

Using QM to resolve the "somehow" in your message above is presumably impossible. We can't use quantum theory to predict in detail what events will occur. We can assign probabilities to possible alternative histories of events during the measurement process, but no dynamics will ever explain why one history actually occurs over other alternatives.

 

[A. Neumaier]

But an "outcome" is due to a macroscopic observable, e.g., a visible spot on a photoplate and as such via coarse graining a classical description is adequate. As any classical phenomenon it's the result of sufficient coarse graining and the associated decoherence which leads to a "definite classical outcome".

Please point to a paper describing this in a measurement context.

Standard coarse-graining would produce a definite classical outcome independent of the atomic input. Thus something more must be going on that turns the unitary dynamics into a bistable system with two macroscopic outcomes that depend stochastically on the state of the atom.

 

[A. Neumaier]

Using QM to resolve the "somehow" in your message above is presumably impossible.

You presume this, but many don't. The quest for answering this is the measurement problem.

We can't use quantum theory to predict in detail what events will occur. We can assign probabilities to possible alternative histories of events during the measurement process, but no dynamics will ever explain why one history actually occurs over other alternatives.

According to some interpretations that you take as being unquestionably assumed - but not in all!

In Bohmian mechanics, one can (at least in principle) predict in detail what events will occur, at the expense of introducing degrees of freedom that are nowhere used in practice.

In my thermal interpretation, one can also (at least in principle) predict in detail what events will occur, without introducing degrees of freedom that are nowhere used in practice.

 

[Morbert]

You presume this, but many don't. The quest for answering this is the measurement problem.

I'm not going to disparage any academic projects that attempt to ground QM's probabilistic character in something more deterministic, but I will defend QM against the charge of having a measurement problem insofar as I think a probabilistic interpretation can be discussed and applied in a consistent and unambiguous manner.

In my thermal interpretation, one can also (at least in principle) predict in detail what events will occur, without introducing degrees of freedom that are nowhere used in practice.

I will have a look at this again. iirc The thermal interpretation frames the response rate of a detector as an "event" in and of itself, as opposed to a statement about the likelihood of events?

 

[Demystifier]

Perhaps in lack of interest in dealing with the real problems?

You mean like world peace and cancer cure?

 

[vanhees71]

I meant of course real problems in physics as a natural science... Looking for cancer cure is also much more promising using biology and medicine rather than philosophy. Concerning world peace, I guess one can use philosophy for both making it better or worse... But that's now way off-topic!

 

[LittleSchwinger]

But an "outcome" is due to a macroscopic observable, e.g., a visible spot on a photoplate and as such via coarse graining a classical description is adequate. As any classical phenomenon it's the result of sufficient coarse graining and the associated decoherence which leads to a "definite classical outcome".

Yeah I agree, just thought I'd clarify what I saw the question to be.

 

[A. Neumaier]

I will defend QM against the charge of having a measurement problem insofar as I think a probabilistic interpretation can be discussed and applied in a consistent and unambiguous manner.

There is no measurement problem as long as one treats the detector as a classical object, as in the Copenhagen interpretation.

But once one jointly claims (as vanhees71 does)

• that there is no split between quantum and classical, and
• that coarse-graining explains everything about the detector,

the measurement problem becomes unavoidable.

For then (and only then) one must explain in particular why when fed with a single particle in a spatial superposition, the detector produces a definite outcome that depends stochastically on the superposition. Decoherence is of no help here, as Max Schlosshauer (who wrote the definitive book about the matter) acknowledged.

I will have a look at this again. iirc The thermal interpretation frames the response rate of a detector as an "event" in and of itself, as opposed to a statement about the likelihood of events?

No. Each single response is an event, and the rate of events is predicted by POVMs, as everywhere in quantum mechanics. What is different in the thermal interpretation is that the necessary link between measurement and eigenvalues is denied - POVMs work independent of any eigenvalue analysis.

 

[Morbert]

(My emphasis)

But once one jointly claims (as vanhees71 does)

• that there is no split between quantum and classical, and
• that coarse-graining explains everything about the detector,

the measurement problem becomes unavoidable.

For then (and only then) one must explain in particular why when fed with a single particle in a spatial superposition, the detector produces a definite outcome that depends stochastically on the superposition. Decoherence is of no help here, as Max Schlosshauer (who wrote the definitive book about the matter) acknowledged.

Modelling the interaction between the particle in spatial superposition and the detector array with a quantum theory will result in a new superposition state that entangles the particle with the detector. Decoherence and Quantum darwinism would select the sample space of outcomes most robust to observation, but would not select a definite outcome.

My question: Why is this a problem? Why must we explain in particular the definite outcome? Why can't we accept QM as always treating all possible outcomes on equal footing apart from their probabilities? Perhaps vanhees71 has some stronger sense of "explains everything about the detector" in mind, or perhaps not.

Each single response is an event, and the rate of events is predicted by POVMs, as everywhere in quantum mechanics. What is different in the thermal interpretation is that the necessary link between measurement and eigenvalues is denied - POVMs work independent of any eigenvalue analysis.

Ok, but it is the rate of events that is explained/predicted, as opposed to the particular event of a single run right?

 

[Demystifier]

Why must we explain in particular the definite outcome? Why can't we accept QM as always treating all possible outcomes on equal footing apart from their probabilities?

Because one of the goals of theoretical physics is to explain observations. We observe definite outcomes, we don't observe all possible outcomes on an equal footing.

 

[Demystifier]

I meant of course real problems in physics as a natural science... Looking for cancer cure is also much more promising using biology and medicine rather than philosophy.

Show me one important paper in theoretical physics that does not contain any philosophy! There is no such paper, some philosophy is always there, at least in Introduction. What bothers you is not some philosophy, but too much philosophy. I don't like too much philosophy either, but my "definition of too much" is different. There is no universal criterion of how much philosophy in a scientific work is OK, and how much is not. It's completely subjective.

 

[Demystifier]

"Therefore, the program of computing what the effect of the [measurement] disturbance was and correcting for it is, in general, impossible. Accordingly, the two basic tenets of the theory of macroscopic measurement are both violated. Either the interactions cannot be made arbitrarily weak because of the phenomenon of atomicity, or if we wish to accept this and correct for it, we cannot do so because we do not have a detailed, deterministic theory of each individual event" --Schwinger

Using QM to resolve the "somehow" in your message above is presumably impossible. We can't use quantum theory to predict in detail what events will occur. We can assign probabilities to possible alternative histories of events during the measurement process, but no dynamics will ever explain why one history actually occurs over other alternatives.

Impossible ... we cannot do ... no dynamics will ever explain. Do you mean by QM as we understand it today, or by any theory that will ever be developed?

 

[haushofer]

Show me one important paper in theoretical physics that does not contain any philosophy! There is no such paper, some philosophy is always there, at least in Introduction. What bothers you is not some philosophy, but too much philosophy. I don't like too much philosophy either, but my "definition of too much" is different. There is no universal criterion of how much philosophy in a scientific work is OK, and how much is not. It's completely subjective.

Take General Relativity; the main motivation behind its development was Einstein's conviction that there should be more behind the equivalence principle than Newton makes us believe.

Other people would shrug their shoulders and tell us to shut up and calculate.

I never understood how people can do science without philosophy.

 

[Fra]

I never understood how people can do science without philosophy.

Self denial. Just like Popper tried to deny all except deduction.

/Fredrik

 

[Fra]

Other people would shrug their shoulders and tell us to shut up and calculate.

The other obvious difference is that application of existing corroborated theories (which are the "fruits" of the scientific process) is easy to do without philosophy. But to think that one would progress science and create new theories/fruits with "shutting up and calculate" attitude seems to lack insight in how creativity and learning works.

This is why "pure interpretations" that does not aspired to eventually progress into a new better theory, are not very interesting for me, I see interpretations as a sign of your own expectations of in which direction we think we will find the next generation of theory.

/Fredrik

 

[vanhees71]

Take General Relativity; the main motivation behind its development was Einstein's conviction that there should be more behind the equivalence principle than Newton makes us believe.

Other people would shrug their shoulders and tell us to shut up and calculate.

I never understood how people can do science without philosophy.

I think Einstein at the time when he started to think about a relativistic description of gravitation was still pretty much down to earth and more physicist than philosopher, although he was always also interested in philosophy and at good terms with the Viennese Circle and Moritz Schlick, but the main motivation was a scientific one, i.e., to describe gravity consistently within relativity. Roughly it started with his review article about relativity in 1907, and then it took him 10 years to finally arrive at the final answer, i.e., GR. I don't think that philosophy helped him much in this creative effort. The difficulty was mainly mathematical, i.e., to understand the meaning of gauge invariance, which in GR is general covariance. The decisive physical fundament was of course clear to Einstein much earlier, i.e., the equivalence principle and the "equivalence" of inertia and sources of the gravitational field.

 

[LittleSchwinger]

Well QM and QFT are stochastic theories. Morbert and vanhees71 are just saying it gives you the probability of an outcome, it doesn't tell you which specific outcome occurs. Nobody has a theory that actually tells you which outcome occurs.

 

[vanhees71]

With all the Bell tests ruling in favor of QM and QFT, I'd say Nature simply behaves stochastically, i.e., observables don't take predetermined values, if the system is not prepared in a state, where this is the case.

 

[gentzen]

Well QM and QFT are stochastic theories. Morbert and vanhees71 are just saying it gives you the probability of an outcome, it doesn't tell you which specific outcome occurs. Nobody has a theory that actually tells you which outcome occurs.

Are you replying to somebody specific? If yes, to whom?

Edit: Oh, your post was nearly at the same time as vanhees71's previous post. So I guess you are replying to Fra. I guess that is the problem with vanhees71's rule that you are replying to the latest post, if nothing else is indicated.

 

[haushofer]

I think Einstein at the time when he started to think about a relativistic description of gravitation was still pretty much down to earth and more physicist than philosopher, although he was always also interested in philosophy and at good terms with the Viennese Circle and Moritz Schlick, but the main motivation was a scientific one, i.e., to describe gravity consistently within relativity. Roughly it started with his review article about relativity in 1907, and then it took him 10 years to finally arrive at the final answer, i.e., GR. I don't think that philosophy helped him much in this creative effort. The difficulty was mainly mathematical, i.e., to understand the meaning of gauge invariance, which in GR is general covariance. The decisive physical fundament was of course clear to Einstein much earlier, i.e., the equivalence principle and the "equivalence" of inertia and sources of the gravitational field.

I don't understand your distinction between being "physicist" or "philosopher". He wanted to understand the "true nature of gravity" in the conviction that you could go beyond Newton's understanding. A similar question would be what the true nature of the wavefunction is. That's physics.

 

[LittleSchwinger]

With all the Bell tests ruling in favor of QM and QFT, I'd say Nature simply behaves stochastically, i.e., observables don't take predetermined values, if the system is not prepared in a state, where this is the case.

Certainly, that's clearly what the actual formalism says and what experiments support.

 

[LittleSchwinger]

Are you replying to somebody specific?

No, just the general conversation.

 

[Fra]

Nature simply behaves stochastically, i.e., observables don't take predetermined values, if the system is not prepared in a state, where this is the case.

Would you say that probability distributions are predetermined? ie. before the observer has acquired and processed enough data?

/Fredrik

 

[vanhees71]

Yes, they are, since they are given by the quantum state at the time of observation (using the Schrödinger picture in this argument), which is determined by the state preparation before the observation by unitary time evolution.

 

[Fra]

which is determined by the state preparation before the observation by unitary time evolution.

For this to hold you must have perfect knowledge of the hamiltonian. How do you infer this hamiltonian at a time scale that does not even allow acqusition and processing of enough data to even experimentally estimate a distribution from statistics of detected events?

/Fredrik

 

[vanhees71]

But this problem you also have in classical physics, i.e., if you don't know the Hamiltonian precisely you cannot precisely calculate the state of the system from the initial conditions.

 

[Fra]

Yes, but in classical physics things are predetermined and the inference refers only to the physicists ignorance. Ie. it has no deeper significance than that.

So how it works in classical mechanics is no argument as the standards of inference in classical mechanics is poor. The ambition here is in my eyes higher and this is the best thing with qm in all its incompleteness. There is no going back.

I am not advocating classical mechanics, i just try to illustrate that QM requires a massive amount of bg ingo to make perfect sense. You seem to entertain the idea that arbitrarily large systems obey QM. I would even want to claim that is philosophy. As it cant be corroborated in less than cosmoloigcal time.

So the conclusion is supposed to be that QM as an effective theory are only and can only be corroborated for small, shortlived subsystems. I think this should be clear??

But I agree there is no absolute scale where this happens. I think the scale is a relative one. Ie relative complexity and lifetime of the observer vs observed. The larger objecta you try to describe by QM, the more information must the observer handle. And how much information can you squeese into any part?

/Fredrik

 

[Simple question]

Nobody has a theory that actually tells you which outcome occurs.

True. But don't you think this a problem, especially for those philosopher that are all about "computing outcomes" ?

I'd say Nature simply behaves stochastically

The widest claim of all. Clearly false. It is the theory that is stochastic. Nature is probed trough clicks and events.
And Bell's proved that the observed randomness is NOT classic (simple), but quantum. So practically the theory treat entangled system as spacialy extended, which is also not "simple".

Six page's into this thread shows at least 5 very different take on QM, so yes, this little experiment showed it is safe to say that nobody-understands-quantum-physics

 

[LittleSchwinger]

True. But don't you think this a problem

No.

 

[Morbert]

Because one of the goals of theoretical physics is to explain observations. We observe definite outcomes, we don't observe all possible outcomes on an equal footing.

The goal of explaining why one outcome occurred instead of possible alternatives might be a personal one, but it cannot be insisted as a goal of theoretical physics. By this I mean a theory concerned with probabilities for alternative possibilities, but not the actualisation of one possibility, is not inherently a problem to theoretical physics even if it motivates particular research programs like Bohmian mechanics.

 

[vanhees71]

Yes, but in classical physics things are predetermined and the inference refers only to the physicists ignorance. Ie. it has no deeper significance than that.

Yes, and QT teaches us that things are not predetermined, and the randomness for the outcome of measurements is an inherent property of Nature and not due to the physicist's ignorance. That's the great result of Bell's theoretical work and the outcome of the corresponding experimental "Bell tests".

 

[martinbn]

Take General Relativity; the main motivation behind its development was Einstein's conviction that there should be more behind the equivalence principle than Newton makes us believe.

Other people would shrug their shoulders and tell us to shut up and calculate.

I never understood how people can do science without philosophy.

I think this is a very misleading example. The development of general relativity was a result of Einstein solving physics motivated problems with hardcore mathematics not philosophy. The philosophy part, like the hole argument, actually slowed him down. Only when he was able to shrug off the philosophy he made progress.

 

[Simple question]

The goal of explaining why one outcome occurred instead of possible alternatives might be a personal one, but it cannot be insisted as a goal of theoretical physics.

Fine, you are happy with a theory that does not match observations, unless you make a thousands of those in highly artificial and fragile setup. Nobody's here is contesting your personal right to stop doing science, stop searching. But I've just learned from you that you cannot insist that science is about searching explanations.
Good motivational speech that I missed at university.

And maybe one day, your fate is going to be decided by one quanta of light going through one slit.
Maybe then it will dawn on you that you would have been interested after all to know how Nature is going to determine where that quanta will end-up.

 

[vanhees71]

Indeed, I think the hole problem was a disgression, but on the other hand it might have helped Einstein to find the answer, i.e., the discovery of the fact that "general covariance" is a "local gauge symmetry" (Noether symmetry of the 2nd kind) rather than a "true symmetry of Nature" (Noether symmetry of the 1st kind). Of course, this was only finally understood by Noether's groundbreaking work, published in 1918 (but already worked out some years earlier).

 

[Morbert]

Fine, you are happy with a theory that does not match observations

Quantum theories are the most experimentally verified theories we have.