Questions tagged [quantum-interpretations]

This tag is for questions relating to what, if anything, the quantum mechanical formalism and experimental results say about the way the world works.

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Can many-worlds approach testability, if considered in a naively realistic physical context? [closed]

This is more of a conceptual question and may be closed as a result, although in the context of the physics, perhaps it may be accepted. It regards the Hugh Everett, many worlds interpretation of ...
DanielFBest's user avatar
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4 answers
1k views

Do Bell’s inequalities assume determinism?

I was watching a video of Tim Maudlin where he talks about how the CHSH version of Bell’s inequalities do not assume determinism and only assume locality. He said that it is a common misconception ...
Haty Irirn's user avatar
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Quantum Mechanical Limitations of Observation [closed]

Regarding the methods by which "observation" limits our ability to measure the state of quantum systems without fundamentally changing the state of the system.. Is there a theorized method ...
Christopher Halliwell's user avatar
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How many base measurements are there? [closed]

Base understanding: Given an n-dimension array a(x1, x2 ... xn), where each given dimension x is an 1-dimensional array in the set R. The data populating x must be non-redundant measurement of reality....
ingotangjingle's user avatar
2 votes
4 answers
169 views

Does QM recognise empty waves?

If a particle (photon) goes through a Mach-Zehnder interferometer it is accepted in quantum mechanics texts that in passes in both channels after first beam splitter BS1 and propagates there until BS2....
Mercury's user avatar
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Many-Worlds Interpretation: What Ensures Every Physically Possible Scenario is Actualized in Some Parallel Universe?

In the Many-Worlds Interpretation of the Mach-Zehnder Interferometer experiment, one interprets the universe as splitting into two, with photons traveling in different directions in each universe. ...
Tarun Gupta's user avatar
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3 answers
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How do non-local correlations occur in QM without a cause? [closed]

The Copenhagen interpretation of QM ultimately amounts to asserting that non-local correlations occur without a cause since that cause would involve propagation of information faster than the speed ...
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2 answers
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Dictionary between interpretations of field operators

For now, let $\hat{\phi}(x)$ be a quantization of a classical, real scalar field $\phi(x)$. My understanding is that, for fixed $x$, there are three ways to regard the operator $\hat{\phi}(x)$: The ...
JustLikeNumberTheory's user avatar
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1 answer
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Interpretation of nodes of infinite square well

In the infinite square well, there is zero probability of finding a particle at nodes. What is the meaning of this result? Does the particle teleport in the regions between the nodes? Or is it that ...
GedankenExperimentalist's user avatar
2 votes
1 answer
86 views

Relationship of the do-operator in do calculus and the notion of the collapse of wave a function

I stumbled over the "do calculus" in causal modeling https://arxiv.org/abs/1210.4852 and the do-operator which is defined in this post https://stats.stackexchange.com/a/643333/298651 The do-...
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What happens to branching in the Many-Worlds Interpretation of quantum mechanics in the limit when Planck's constant goes to 0?

We learn from quantum mechanics courses that one recovers classical mechanics in the limit when Planck's constant goes to zero. This can be seen in the path integral formulation. This is why ...
Guillaume Laporte's user avatar
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Why is it that we cannot detect any interference after decoherence?

If we assume the many-worlds interpretation of quantum physics is true, what exactly happens during decoherence, that makes it impossible for the different worlds to create interference with each ...
christian's user avatar
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3 answers
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What happens if two people have different knowledge about a state in a quantum mechanical system?

Let’s say I measure the spin of an electron, but I don’t tell you what it is and you don’t measure it yourself. Does that change the wave function for you or does it remain the same either way? If it ...
Name's user avatar
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1 answer
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The Heisenberg Uncertainty Principle (HUP) and "borrowing energy" [duplicate]

Often when physics students are introduced to the HUP for position and momentum, the interpretation is that you aren't able to measure position and momentum for a particle to arbitrary precision at ...
Depenau's user avatar
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How does pilot wave theory explain non-zero momentum measurements? [closed]

The momentum of particles in pilot wave theory is dependent on the phase of the spatial wave function, which is 0 for stationary states. This means that electrons in all excited stationary states of a ...
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Does a Quantum System Really "Jump" to an Eigenstate When Observed?

Warning: This is a highly hypothetical question. I am bothered with Dirac's description of the system when making a measurement. Without quoting his statement (from The Principles of Quantum Mechanics,...
Con's user avatar
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What interpretations are ruled out by the Kochen–Specker theorem?

What interpretations are ruled out by this theorem (such as superdeterminism, Bohmian mechanics, or ensemble interpretations) and does it function similarly to Bell's theorem as a 'no-go' theorem?
Marco Fabbri's user avatar
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Can Leggett-Garg inequality be used to falsify realist interpretations of quantum mechanics?

Can Leggett-Garg inequality be used to falsify superdeterminism, Bohmian mechanics and other realist interpretations of quantum mechanics? https://en.wikipedia.org/wiki/Leggett_inequality https://en....
Marco Fabbri's user avatar
1 vote
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Concerning paths of particles and quantum mechanics [duplicate]

It is well know that scientific tools , eg bubble chamber, can keep track of particle trajectories. Now here is my doubt. Quantum mechanics, which is a statistical theory, says that trajectories do ...
Vittorio Foglietti's user avatar
5 votes
3 answers
786 views

Exact time evolution of Stern-Gerlach (SG) apparatus

Background: I was always under the impression that when considering the Stern-Gerlach (SG) Experiment, the interpretation of the split of the beams is that the spin $1/2$ particle get measured the ...
2000mg Haigo 's user avatar
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Are there testable predictions made by the Copenhagen interpretation that are incompatible with Pilot Wave or vice versa? [duplicate]

As of right now, whenever right now happens to be, has anyone identified any promising experiments capable of distinguishing between the Copenhagen interpretation and the Pilot Wave interpretation of ...
Him's user avatar
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Understanding Wigner’s friend scenario

I recently watched this video https://youtu.be/Wsjgtp9XZxo?si=sIRlAbvAm2wjXRNP and tried (unsuccessfully, because i don’t have the knowledge required) to read Bruckner’s paper. What i am missing, is ...
Marco Fabbri's user avatar
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1 answer
80 views

Why does linearity imply no communication between Everettian worlds?

Scott Aaronson said in this interview https://youtu.be/1ZpGCQoL2Rk?t=3255 that the linearity of Schrodinger's equation prevents us from communicating with other Everettian worlds. Why? Is it analogous ...
ngc1300's user avatar
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Interpretation of density wave observables

Given some Hamiltonian quantum system, one can ask questions about (expectation values of) observables. While some have an intuitive meaning, e.g. energy or magnetisation, I find it hard to grasp the ...
qising's user avatar
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Does a particle still behave as a wave after being detected as a particle?

I just started learning about the intricacies of quantum mechanics in high school and aim to improve my understanding of the wave-particle duality of particles. I was wondering about different ...
spaghettyii's user avatar
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2 answers
205 views

How can the Copenhagen and Everett interpretations of quantum mechanics make the same predictions?

Suppose we have a spin $\frac{1}{2}$ particle in the spin-up state along the $z$-axis, $\lvert \uparrow \rangle$, and after $t$ seconds of evolution under the Schrodinger equation it is in state $\...
MBar2269's user avatar
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2 answers
215 views

What is the consensus among physicists on whether quantum mechanics has non-locality? [closed]

According to this article here by the SEP, Following Bell's work, a broad consensus has it that the quantum realm involves some type of non-locality (for examples, see Clauser and Horne 1974, Jarrett ...
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-4 votes
2 answers
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Does a quantum measurement change the state in the past? [closed]

Consider the following very basic quantum mechanics experiment. At time $t_0$, a system $S$ is in superposition of two orthogonal states $|A\rangle$ and $|B\rangle$, which we could describe by $\frac{...
Riemann's user avatar
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15 votes
9 answers
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What experimental proof of quantum superposition do we have?

My question is both naive and subtle. Naive because I don't know much more than the layman about physics and in particular quantum physics. Subtle because physics is an attempt to model the world, ...
b_habegger's user avatar
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3 answers
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Can there be a local hidden variable theory that works differently for each electron in an entangled pair?

I recently watched a video from Brian Greene that goes over an example of Bell’s inequality. Video here. In this example, he imagines the generation of a pair of entangled particles, each of which is ...
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Does Everett's interpretation of QM necessarily imply "many worlds"?

I've been dabbling in physics/QM for just a few years, and was reading "The One: How an ancient idea holds the future of physics" - my interest was piqued because I've read quite a bit about ...
Leeds48's user avatar
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0 answers
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Intuition behind the Canonical Hamiltonian Ensemble

I read about the canonical Hamiltonian ensemble interpretation here. Say we consider quantum state which with probability $p_\lambda$ evolves under a Hamiltonian $\hat{H}_\lambda$ part of an ensemble ...
Len's user avatar
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1 answer
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What is the mathematical difference between many worlds interpretation and Copenhagen interpretation?

For instance, how would a many worlds theorist calculate an electron orbital differently than someone that prefers the Copenhagen interpretation?
PhysicsNoob's user avatar
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0 answers
37 views

Can a hidden variable theory be seen as a map from unitaries to stochastics with the same dimensions?

In Quantum Computing in Hidden Variables, Scott Aaronson defines a hidden variable theory as something that transforms a unitary matrix mapping $\begin{bmatrix}\alpha_1 & \ldots & \alpha_n\end{...
Jun Inoue's user avatar
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-3 votes
1 answer
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Is quantum spin intrinsic, or a function of some other characteristic? [closed]

In my current understanding, I have been told that the spin of quantum particles is simply intrinsic to them. That, particles are simply right-handed or left-handed... just because they are. To me, ...
blacktopshaman's user avatar
1 vote
3 answers
386 views

Perfect determination and knowability in quantum mechanics?

In classical mechanics, it is postulated that in principle the position and velocity of particles are perfectly determined and can be perfectly known. And it is by using such determined properties ...
The Quark's user avatar
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2 answers
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A question about Born's rule in the Many-worlds interpretation

Can somebody explain the idea of self-locating uncertainty when there's a binary choice of eigenstates for an entanglement? I understand the idea that because you are unsure of which branch you are in,...
Vivin Anand's user avatar
1 vote
1 answer
133 views

Consistent histories vs. relational interpretation and Qbism

I hope that my question will be suitable for this forum: I would like to understand the difference between the so called consistent history approach to QM and several other interpretations. In this ...
truebaran's user avatar
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1 vote
1 answer
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One-body density matrix has occupation numbers greater than 1

TL;DR - I computed the one-body density matrix (OBDM) stochastically via a method in a paper listed below, and it generates non-physical occupation numbers that 1) either has some negative values or 2)...
AlphaBetaGamma96's user avatar
1 vote
1 answer
60 views

In the pilot wave model, why does the wave function depends on the set of particle?

In PWT, the wave function depends on the positions of all the particles. Therefore the velocity of a given particle depends of the positions of the other, it's why the theory is non local. In the ...
vincent woiline's user avatar
4 votes
3 answers
292 views

How do proponents of superdeterminism explain the specific choice of values for the hidden variables that violates the Bell inequality?

I don't have a background in physics, but I have an amateur interest in quantum mechanics, and I recently found out about the notion of superdeterminism. From what I understand, superdeterminism ...
BackusNaur's user avatar
1 vote
3 answers
270 views

Do "cross terms" in a state operator necessarily correspond to a coherent superposition?

In his discussion (Chapter 9.2-9.3) of the measurement problem, Ballentine says "any terms [in the state operator $\rho$] that [are] nondiagonal [in terms of having "mixed projectors" $|...
EE18's user avatar
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1 answer
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MWI and splitting before entanglement

Recently I saw a conversation between Sean Carroll and Slavoj Zizek concerning the MWI. One of the questions that drove Slavoj concerned with this question of Ontology vs. Epistemology, as the way ...
Thomas Jones's user avatar
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1 answer
80 views

Is there any minimalistic version of superdeterminism theory?

Superdeterminism is one wild conjecture which is an alternative to the standard quantum mechanical interpretation and preserves local realism Superdeterminism seems to be too much of a stretch. If ...
Hari Kumar's user avatar
-3 votes
2 answers
186 views

Is spooky action at a distance real or does hidden variables exist? What does it mean in context of free will? [closed]

I am complete amateur at this and research about physics is just a hobby for me. So with that in mind here is my problem: I saw a few debates between physicists about spooky action at a distance vs ...
comp_guy_dude's user avatar
1 vote
2 answers
242 views

What does Aaron O'Connell's experiment prove?

I am a mathematician and a while ago I started studying quantum physics. I know the concept of superposition mathematically, but my question is regarding a famous experiment that Aaron O'Connell ...
Mahmoud Mrowi's user avatar
1 vote
0 answers
26 views

Griffiths Consistent histories MQS state in Mach-Zehnder experiment

In Robert B. Griffiths' Consistent Quantum Theory, he describes a variant of the Mach-Zehnder interferometer experiment where a detector represented by "off" state $\lvert 1\hat{e}\rangle$ ...
David's user avatar
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22 votes
3 answers
2k views

Does the gravitational field of a hydrogen atom fluctuate depending on where the electron "is"?

Let's say I have a hydrogen atom in the lab. "Normally", we would say its electron is delocalized across the ground state orbital. Because electrons have mass, we expect it to exert a ...
Allure's user avatar
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In the many-worlds interpetation, does quantum revival imply that the universe will repeat itself?

Quantum revival is the idea that unitary evolution of the wavefunction implies that evolution of the wavefunction is periodic. Since the many-worlds interpretation stipulates that there is only ...
Steven Sagona's user avatar
2 votes
3 answers
193 views

Does non-local hidden variable theory predict the outcome of an experiment? [duplicate]

I am trying to understand what decides the outcome of an experiment and if there is any theory (e.g. non-local hidden variable theory) that is able to predict the outcome.
Rajaram Venkataramani's user avatar

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