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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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If Pilot Wave Theory is non-local, how does the pilot wave change over time?

My understanding is that Bohmian Mechanics (pilot wave theory) is non-local, meaning that effects propagate faster than light. Are these effects in fact instantaneous in that model? How would an ...
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0answers
40 views

Does quantum mechanics conserve information after a measurement? [duplicate]

I understand that QM without observers is unitary and conserves information. My problem starts when there is a measurement. It is my understanding that the measurement problem has not been adequately ...
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129 views

Does the Copenhagen interpretation reject probabilistic causation or does it merely reject deterministic causation?

Does the Copenhagen interpretation of quantum mechanics reject probabilistic causation or does it merely reject deterministic causation? I read that the Copenhagen interpretation rejects causation, ...
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1answer
149 views

Is there a difference between observation and entanglement?

I have very basic knowledge about quantum mechanic. I started wondering if there is any difference theoretically between observation and entanglement between subject and object. I.e. if we simplify ...
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1answer
262 views

Are particles really in a superposition before you observe the particle [closed]

So if I understood correctly, Schrodinger's Cat is a thought experiment that puts a cat inside a box, and there's a mechanism that kills the cat with 50% probability based on a quantum process. The ...
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1answer
87 views

Since photons do not experience time (nor distance in that case), why did Einstein think it was “spooky action at a distance”? [closed]

A photon travels at c, so it experiences no time or distance. I imagine from the photon's perspective, it's rather just like a simple dot on some kind of 4D manifold. So it begs the question of why ...
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1answer
91 views

How does the Copenhagen interpretation support the Pauli-principle?

In QM the Copenhagen interpretation states that there are behind the probalities no real values like spin-state. Now in the Pauli-principle electrons can't have both the same spin in the same 'orbit', ...
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0answers
176 views

Is 'interpretation' in quantum mechanics the same as 'interpretation' in probability?

I heard all 'interpretations' of quantum mechanics give exactly the same answer to every measurement so they are all equally correct. Is that the same 'interpretations' as in probability? Context: ...
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1answer
167 views

How does the many-worlds interpretation explain that humans see just one world?

when I first heard about the many-worlds interpretation it was in the "popular" version about the universe "splitting" on the random events meaning one copy of the observer would see one outcome, and ...
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3answers
287 views

Is the wavefunction unique to the observer?

I know this may be beating a dead-horse, but I'm still puzzled by this topic even after reading so many other related SE questions/answers and online articles. I will be using the Copenhagen ...
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2answers
92 views

Yet Another Double-Slit Question [closed]

I'm not a physics graduate, I studied the subject to high school level but don't 'know the math'. But I'm interested in philosophy of science, and have read a number of popular books on the topic (e.g....
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792 views

Is the Many Worlds Interpretation deterministic?

Is the Many Worlds Interpretation deterministic? Considering that you can determine all of the possible outcomes of a wavefunction (pretty much impossible but still), the only random thing that ...
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110 views

Does photon bunching mean two photons fall on the same detector in both effects?

In Hong-ou-Mandel interferometers, it means the two photons exit the same output port of the beamsplitter and fall on a single detector but in the case of the Hanbury Brown and Twiss effect, does ...
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979 views

Decoherence. Does it solve the measurement problem? Is it discontinuous? When does it occur?

I am trying to better understand the current scientific consensus (to the extent that such a thing exists) on the interpretation of quantum physics. I understand that this is still very much an active ...
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1answer
232 views

Why parallel worlds in MWI do not interact with each other?

The quantum-mechanical " Schrödinger's cat " theorem according to the many-worlds interpretation (MWI). In this interpretation, every event is a branch point; the cat is both alive and dead, even ...
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2answers
198 views

How can you be a realist and not posit an ontological model?

I have a specific technical question about how to formalize models for quantum interpretations. My question arises from the talk Why I am not a psi-ontologist, by Rob Spekkens at the Perimter ...
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1answer
141 views

Is QED without measurement a local hidden variable theory?

An interesting thought experiment would be to create a large quantum wave-function describing both a pair of electrons with entangled spins and the equipment needed to measure the electrons' spins. In ...
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2answers
173 views

Does many world interpretation of quantum mechanics also apply to macroscopic objects?

Since macroscopic objects have more particle like nature and they are always being observed (interact) with their surrounding, does MWI also applies here and if yes then what is its significance. Is ...
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What are the differences between a $\psi$-epistemic ontological model and a $\psi$-ontic model of quantum mechanics, exactly?

I am confused about the differences between a $\psi$-epistemic ontological model of quantum mechanics and a $\psi$-ontic one. The way I understand it, a $\psi$-epistemic model says that every quantum ...
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2answers
51 views

Necessity of World splitting in Many-World-Formalism

I am reading descriptions about many world formalism, where the idea of "one wavefunction for the whole universe" makes sense to me. Everything goes so well until I read the "world splitting part": I ...
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11answers
8k views

Does the Many Worlds interpretation of quantum mechanics necessarily imply every world exist?

I know the Many Worlds interpretation is controversial among physicists, but it's been a pop culture hit nonetheless. I frequently see people making statements like, "Well in another universe I'm a ...
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0answers
176 views

Why is the wavefunction not a hidden variable?

Consider the following standard case of an entanglement experiment: We prepared two electrons A and B with states $$\lvert A\rangle=a_1\lvert \uparrow\rangle+a_2\lvert \downarrow\rangle$$ $$\lvert B\...
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2answers
636 views

How do we know certain aspects of QM are unknowable?

In a course on modern physics we are beginning to get into probability amplitudes and the inherent unknown in some things, say the position of an electron in an orbital. How do we know that these ...
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2answers
547 views

How does QFT account for localization (into a finite volume of space), in practice?

In Quantum Field Theory there is until yet no agreement (as far as I know) on the issue of localization of particles. When one talks about a 'particle' in QFT, one usually means a single-particle ...
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3answers
158 views

Is the Schroedinger picture outside the contemporary maintstream?

By the Schroedinger picture, I mean the notion that atoms exist in a superposition of states, as opposed to the Copenhagen picture, which I understand to mean that in a system of atoms, all the atoms ...
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1answer
46 views

What happens that doesn't allow our measurement?

Suppose pair production results in an electron and positron pair in an entangled system. One person (A) measures the electron and another person (B) measures the positron. Another property of this ...
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3answers
413 views

Is the energy of single photon defined by uncertainty relation? What is the pulse duration of sigle photon beam?

Coherent sources can have ultra short pulse durations provided there is at least one photon in frequency that span broad bandwidth (and are coherent)? Does that mean that the pulse duration is ...
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3answers
201 views

Does the Copenhagen interpretation say that a tree only has definite mass after I look at it?

Assume that the Copenhagen interpretation holds. Imagine a Universe, a nearly identical copy of our Universe, that contains only our Earth and me (i.e., I'm the lone conscious being and the lone self-...
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1answer
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Pilot waves and quantum eraser; pilot wave simulation

I recently watched this video about the quantum eraser experiment on PBS spacetime: Link. Has an experiment like the quantum eraser been tried with the pilot wave theory, ie bouncing droplet ...
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0answers
77 views

single Observer iterpretation, experiment design

I am thinking of an interpretation of QM in which there is a single Observer (O). That is, its mind's history is marking a special path on the many-world graph, which we identify with reality. This ...
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181 views

Quantum Mechanics Vs nonlocal causality

There is an article in Physics world.com dated August 18, 2016, titled "Quantum Mechanics Trumps Nonlocal Causality. The author of the article Philip Ball quotes one of the experimenters ( i.e. ...
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4answers
1k views

Outcome of Mach-Zehnder interferometer experiment

I am reading David Deutsch's The Beginning of Infinity. In chapter 11, he explains the basics of quantum theory and gives evidence for the many worlds (Everett) interpretation. The argument uses a ...
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2answers
337 views

Can the Copenhagen interpretation and the many-worlds theory be somehow reconciled? [closed]

Is it possible that, at the moment of observation, a timeline is created where an object is in a state which contrasts its state in the current timeline? Using Schrodinger's cat as an example, let's ...
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1answer
57 views

What happens with QM particle at constant velocity? [closed]

In QM particles have wavefunctions that disperse quite fast. The FWHM for gaussian wavepacket increases in time as $\Delta x(t)= \Delta x_0\sqrt{1+(t/\tau)^2} $, $\tau=2m(\Delta x_0)^2/\hbar$ What ...
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9answers
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On a measurement level, is quantum mechanics a deterministic theory or a probability theory?

Quantum mechanics is a non-commutative probability theory. As such, it fundamentally behaves differently from classical probability theories. This manifests itself most pronouncedly in the uncertainty ...
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2answers
231 views

By what logic does one come to support a certain interpretation of quantum mechanics?

I have been on Wikipedia reading up on the various interpretations of quantum mechanics. I am entering my final semester as an undergraduate and have taken a QM course, so I am familiar with the basic ...
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1answer
411 views

Feynman path integral interpretation of the Aharonov Bohm effect [closed]

I have recently been reading about the interpretation of the Aharonov-Bohm effect via Feynman's path integral (see viXra:1403.0950). I do not know whether I am missing something, but I do not ...
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2answers
407 views

De Broglie- Bohm Quantum Theory

From what I have read the Standard Model of Particle Physics uses quantum mechanics,special relativity, along with other assorted mathematics to make predictions and provide a framework for QED, QCD, ...
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1answer
153 views

Is the MWI symmetric in time?

Reading the blog of Sean Carroll (I recognize he isn't the only voice) has made me more sympathetic to the notion of many worlds, but reading Susskind (also not the only voice) has made me think that ...
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1answer
157 views

Probability in QM: derivation or interpretation? [duplicate]

It is known that coordinates $C_k\in\mathbb{C}$ of the QM-state vectors $|\psi\rangle$ has an interpretation as probability weights $p_k$ in the whole state through the formula like $|C_k|^2=p_k$. We ...
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4answers
157 views

Information, entanglement and EPR

I'm currently trying to understand why superluminal information transport is not possible. Therefore, I would like to get some help concerning the definition of information or the general setting. ...
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1answer
110 views

Different postulates and statistical interpreations of quantum mechanics

Hi I have a query about the difference of two aspects of the statistical interpretation of quantum mechanics given in the popular introductory quantum mechanics books "Introduction to Quantum ...
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2answers
481 views

Do conservation laws contradict quantum mechanics? [closed]

Take for example the double-slit experiment interpreted in the Copenhagen sense. The particle leaves as an object with mass, yet passes through the slits as a massless wave, only to collapse again as ...
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1answer
373 views

Calculate the entropy per atom in Bohmian Mechanics

Bohmian mechanics description of a large number of interacting atoms would require a large phase space due to the large number of classical degrees of freedom. The entropy per atom is given as the ...
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3answers
962 views

Is Bohmian Mechanics incompatible with loop corrections?

For those who continue to be unsatisfied with Quantum Mechanics (QM), Bohmian Mechanics (BM) is an alternative worth considering. It is sometimes claimed that BM is equivalent to QM, but Lubos Motl ...
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1answer
282 views

How is no-conspiracy theory compatible with determinism? [closed]

Bell's theorem states that any physical theory that incorporates local realism and the no-conspiracy assumption cannot reproduce all the predictions of quantum mechanical theory. Hence, we cannot ...
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5answers
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What is the explanation for the interference patterns in MWI?

In Young's double-slit experiment, MWI states that in some "worlds" the particle goes through one slit, and in others it goes through the other. If this is so, why do we get an interference pattern? ...
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1answer
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What is the difference and/or similarity between multiple universes in inflation and in quantumphysics? [duplicate]

Some theories propose that there are more universes. In one of them it is said that there are parallel universes, due to inflations after the big bang that created them. But in the two-slit ...
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1answer
153 views

In the many worlds interpretation of q.m. what makes a superposition af states split in two sepearate ones?

I was wondering, what agent makes a superposition of, let´s say, the two spins of an electron, máke them split into two separate ones (up and down). And is this not in contradiction to the law of ...
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2answers
324 views

Bell's theorem and fluid-mechanical experiments using droplets: are local hidden-variable theories possible after all?

Recent fluid-mechanical experiments by the groups of Couder in Paris and Bush at MIT, mimic a surprisingly wide range of quantum effects. The essential ingredient of these fluid-mechanical systems is ...