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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Knowable and Unknowable Hidden Variable theories

Following a recent interesting question about the collapse of the wave function (link at the bottom). It seems that the wave function is just a mathematical way to give predictions of various outcomes ...
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When will a wave function collapse if the observer was only a camera and the video was watched later in time?

If the only observer for the Schrödinger's cat experiment was a camera filming the box from the outside while the box was opened automatically without direct human intervention, and the only ...
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Oddities in relational quantum mechanics

I am reading an article about the interpretation of quantum mechanics called Relational Quantum Mechanics, and I come across an idea: RQM is based on an ontology given by physical systems described ...
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2answers
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Indistinguishability of Quantum States and its Consequences [closed]

In the book Quantum Computation and Quantum Information, there is a discussion about how if states are not orthonormal then there is no quantum measurement capable of distinguishing the states. I am ...
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Am I correct in understanding that in the many-worlds interpretation the Universe is considered as a single quantum object?

Among the tags there is also a topic of interpretation, so I hope that the question will not be closed. In the many-worlds interpretation, the wave function acquires an onotological meaning, that is, ...
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3answers
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What is the place of probability in quantum mechanics? [closed]

I have some phenomenological problems with understanding probabilities in quantum mechanics, and I suspect that the reason for the confusion is that scientists themselves have not yet fully decided. ...
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Observation in Many Worlds

In the "many worlds" interpretation, observation appears to split the observer into a new "world". How does this happen?
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Has quantum collapse been ruled out?

This morning, a new arXiv paper 2105.13519 appeared providing detail of an EPR steering experiment showing that if it is assumed that the EPR steering requires quantum collapse, then more than one bit ...
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Does the history of the universe change when the initial conditions change in superdeterministic theories?

In quantum mechanics, superdeterminism is a loophole in Bell's theorem, that allows one to evade it by postulating that all systems being measured are causally correlated with the choices of which ...
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Histories of the Universe under Different Initial Conditions

The history of the evolution of the Universe (we are talking about the observable part) on ultra-large scales (larger than the scale of galactic superclusters) under any initial conditions would be ...
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Are Many-Worlds and Copenhagen different Theories, not just Interpretations?

Consider a sub-system in a pure state, expressed on the basis of the observable $O$, whose only eigenstates are $|a\rangle$ & $|b\rangle$. The state is $\frac{1}{\sqrt{2}}(|a\rangle+|b\rangle)$. ...
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Many worlds interpretation and probabilities

How is the many worlds interpretation (MWI) of QM consistent with the probabilistic interpretation of the wave function (given by Born's interpretation)? For example, say a particle has a 90% chance ...
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3answers
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Is there any experiment where QM can predict individual results?

This is my question: Is there any actual experiment or observation that only needs to be performed once (rather than repeating it a hundred times and analyzing the ensemble), the result of which can ...
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Whose state (or wavefunction) changes (or collapses) upon observation: System's or Observer's?

I was learning about Qubit measurement and the basics of Quantum computing. The instructor forced a lot on the following statement : Assume an isolated system S. Let an observer O interact with the ...
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Quantum Physics: Are entangled electrons in absolute states?

I was having a discussion about quantum physics with a friend, and we came to realise that we perceived the same situation in two very different ways. After searching online, we still weren't able to ...
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1answer
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Many worlds is nonlocal too after all according to some physicists?

Not a physicist but I have understood that MWI is unique in that it preserves local dynamics. There is a wavefunction - not in spacetime but in some more abstract space. But the worlds with spacetime ...
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Interpretation of QM references [duplicate]

Could anyone give me some good references for studying interpretation of QM?
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Why can't the superposition in Schrodinger's cat simply be interpreted as ignorance?

This is something I've dug into for a while, and what I am wondering about is the following argument, which I haven't necessarily seen before. First, we'll take the Wigner's friend variant, because to ...
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Gauge invariance prohibits the existence of other universes?

I'm only a student, so most likely misunderstood. The Wikipedia article on Relational quantum mechanics says: "The universe is the sum total of everything in existence with any possibility of ...
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What are the weaknesses, if any, of the relational interpretation of quantum mechanics?

Carlo Rovelli's 1996 relational interpretation of quantum mechanics (RQM) seems to solve many of the quandaries of traditional theories, including the Copenhagen interpretation (what privileges the ...
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What is the meaning of the word 'momentum' in quantum physics? (Especially in the problem that I will describe below.)

In undergraduate quantum physics class that I am taking in this semester, I had to solve a problem about quantum Zeno effect. The problem describes the thought experiment which is trying to determine ...
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1answer
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How is many world interpretation of quantum mechanics compatible with no cloning theorem?

In many worlds interpretation of the quantum mechanics all possible outcomes of a measurement are realized, however, in different universes. Everytime a measurement occurs we register one outcome and ...
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6answers
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What problem is the Many-Worlds Interpretation actually solving? Is it a reframing of the measurement problem?

Before I state my question I want to say I am in no way an expert/professional in this field. I read quite a bit on the subject and I consider myself familiar with the basic concepts but I really want ...
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6answers
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I understand what it represents, but what physically is the wave function?

In quantum mechanics, I understand that the wave function represents the state of a particle and that the square of the wave function tells us the probability of a particle being found at a particular ...
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On the spacetime significance of Feynman diagrams (and Witten diagrams)

This post is just a thought about Feynman diagrams and their interpretation. When I draw a FD, my intention is to provide a direct way to calculate terms in a series expansion. Now, from what I ...
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Is the statistical interpretation of quantum mechanics a $\psi$-epistemic model?

Let us consider the statistical interpretation of quantum mechanics, as put forth by Leslie Ballentine in Rev. Mod. Phys. 42, 358, 1970. Recently, the PBR theorem and follow-up work (e.g. this paper) ...
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Reason we always observe a single dot when a particle hits a detector screen?

I am trying to determine whether this is simply a brute fact or does it tell us something deep about the nature of reality? Is there any particular reason we see a dot appear rather than a triangle or ...
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1answer
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Philosophical foundations for the choice of quantum operators?

My current understanding is that a quantum system can be in a superposition of possible outcome states that are eigenstates of a particular operator on the wavefunction. However, it is also my ...
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Why don't we observe superpositions?

Say we are doing the Stern-Gerlach experiment. Here's my understanding of what decoherence tells us. The particle starts in a superposition of spin up and spin down, but then gets entangled with the ...
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Why are certain “pointer states” stable under decoherence?

Is it simply a brute fact that certain pointer states are more robust? Are there any philosophical investigations into why these are the states that nature prefers?
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1answer
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Preserving locality in psi-ontic interpretations of QM?

Specifically in the many-worlds interpretation, if the wavefunction is considered to be real before a measurement it seems that locality is impossible. When the wave hits a detector screen, it would ...
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2answers
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What is the interpretation of zero probability in physics?

Impossibility of an event implies vanishing of it's probability. But the reverse is not true. This post in math stack exchange posts says why zero probability doesn't necessarily mean impossible ...
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Is the many-worlds interpretation really just an interpretation?

Is the many-worlds interpretation just a different interpretation to quantum mechanics or does it contain some different predictions? In other words, is it possible theoretically to conduct an ...
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1answer
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How does the Bohm interpretation/pilot wave theory explain particles getting spontaneously created and destroyed?

Pilot wave theory says that classical particles are riding on waves. Quantum field theory says that particles are the excitations of a field. Both of these descriptions seem like essentially the same ...
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Am I correct in understanding that prior to measurement, a quantum particle does not exist and absolutely nothing exists? [closed]

Once I asked this question to my teacher, and he replied that in the framework of quantum mechanics it is pointless to ask such a question. He said that quantum mechanics does not describe ontology, ...
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Particles in an interferometer in a gravitational field

Let's assume one has a standard interferometer, consisting of an incoming beam which gets splitted in beam I and II and then culminated again. Now the interferometer is placed in a gravitational field,...
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1answer
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Measurement accuracy in quantum mechanics?

Here's some classical background to this thought experiment. Let us first consider a classical scale ruler (called A) of a continuous classical variable. Rulers must be discretised. Let's compare this ...
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About the Interpretations of Quantum Mechanics

I have studied physics and I'm finishing my postgrad related to Quantum Physics. I'm doing a quick work involving fuzzy setsand I started to study Quantum Logic to direct my work to this field. Now I ...
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1answer
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Many Worlds locality and EPR experiment

I've read in Sean Carroll's book (Something Deeply Hidden) that the Many-Worlds interpretation of quantum mechanics might be the only way to avoid instantaneous effects of entanglement, by having the ...
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Interpretation of 2nd law of thermodynamics and observation in quantum mechanics

The fundamental lesson of quantum mechanics has been that an observation "disturbs" the system under analysis as exemplified in Schrodinger's cat thought experiment or wave-function collapse ...
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Many Worlds, Bells Inequality, and visualizing how the worlds split

This is possibly not a question of pure science/math, and it might be inviting a fair bit of speculation and imagination, but it's a lingering question I have. Bell's Inequality proves that the spin, ...
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Interpretation of Feynman's propagator

What is the interpretation of the Feynman's propagator $$D(x-y) :=\langle 0 |\phi(t,x)\phi(t',y)|0\rangle~?$$ As far as I understand, it is the following. $|D(x-y)|^{2}$ is the probability density of ...
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Is there a limit of wave function splitting?

It is possible to split the wave function (for example using a semi mirror like in Wheeler delayed choice experiment). I wonder what happens if we split it many times. My "though experiment" ...
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1answer
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How does the many-worlds interpretation look like in bra ket notation?

If I understand correctly the many worlds interpretation says the universe is continously splitting into multiple branches and quantum measurements occur when decoherence causes a quantum state to ...
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Correct interpretation of $\langle x | \psi \rangle$?

Suppose $|x\rangle$ is an eigenvector of the position operator $\hat{x}$ and let $|\psi\rangle$ be an arbitrary state on this Hilbert space. What is the correct interpretation of the complex number $\...
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On realistic interpretations of quantum mechanics - single quantum systems and measurements [closed]

I am interested in realistic interpretations (in the sense of "quantum state realism" or "wavefunction realism") of the behaviour of a single quantum system interacting with a ...
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Does the 'No-Superdeterminism' assumption of the 2020 Wigner's friend experiment excl backwards/block-wise/holistic consistency & limited nonlocality?

In "A strong no-go theorem on the Wigner’s friend paradox" authors conclude that one of three possible options is necessary for reconciling quantum physics with more classical physical ...
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What interpretation can have a negative conditional entropy in quantum information? [closed]

So, I'm studying the basics in quantum information and many texts and papers have interpretations for entropy, relative entropy and conditional entropy, but none has an interpretation for a negative ...
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In quantum mechanics, do quantum systems not exist before measurement? [closed]

If a quantum system manifests itself only during measurement, and if the wave function is only our knowledge of a quantum system, maybe it does not physically exist at all before measurement? Maybe a ...
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Does the Minev experiment challenge the “many worlds” interpretation of QM?

Minev's PhD thesis, "Catching and Reversing a Quantum Jump Mid-Flight" and the Nature article that summarized it (arXiv) showed that one could monitor the quantum state of transitions that ...

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