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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2
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0answers
55 views

Are there any connections between James–Stein estimator and quantum mechanics?

Very nice statement from wiki: When three or more unrelated parameters are measured, their total MSE can be reduced by using a combined estimator such as the James–Stein estimator; whereas when ...
8
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2answers
466 views

Is the collapse of the wave function inherently time asymmetric?

Schroedinger's equation, as we all know, is time symmetric. In quantum field theory, we have to come up with a more sophisticated CPT reversal, but the essential point remains unchanged. However, the ...
0
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1answer
369 views

Worlds branching or diverging in Many-Worlds Interpretation? [closed]

In recent years there seems to have been a growing discussion surrounding MWI's ontology. In the 2010 volume "Many Worlds?", Simon Saunders has a chapter dedicated to discussing whether the worlds in ...
12
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4answers
3k views

What errors would one learn from Eliezer Yudkowsky's introduction to quantum physics?

Eliezer Yudkowsky wrote an introduction to quantum physics from a strictly realist standpoint. However, he has no qualifications in the subject and it is not his specialty. Does it paint an accurate ...
5
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3answers
421 views

Information conservation during quantum measurement

Consider the following experiment. I take a spin-$\frac{1}{2}$ particle and make a $\sigma_x$ measurement (measure the spin in the $x$ direction), then make a $\sigma_y$ measurement, then another ...
5
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0answers
131 views

Does it make sense to speak of amplitudes of finite closed boundaries in QFT?

A example of amplitude in Relativistic Quantum Mechanics or specifically in QFT is the amplitude of a field configuration on a space-like hyper-surface of space-time to "lead" to another field ...
0
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2answers
123 views

How do you properly analyze decoherence when the system-environment interaction is strong?

The standard decoherence analyses work something like this. Split the universe into a system and its environment, and split the Hamiltonian as the sum of the system Hamiltonian, environment ...
4
votes
1answer
160 views

Event-by-Event Simulation of Quantum Phenomena

I just recently stumbled over http://rugth30.phys.rug.nl/dlm/ and http://www.sbfisica.org.br/bjp/files/v38_26.pdf As the title suggests these are presentations of mathematical models capable of ...
6
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4answers
722 views

Is QFT mathematically self-consistent?

After recently going through a short program of self-study in quantum mechanics, I was surprised to find a quote attributed to Feynman essentially saying he was extremely bothered by the computational ...
2
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1answer
339 views

M-theory and many-worlds interpretation

I am getting some confusion on whether M-theory accepts many-worlds interpretation. Can anyone show me the reasons or rebuttals for the possibility of the many-worlds interpretation in M-theory? ...
6
votes
8answers
883 views

Is the quantum analog of a probability distribution the wave function or the density matrix?

Classically, probability distributions are nonnegative real measures over the space of all possible outcomes which add up to 1. What they mean is open to debate between Bayesians, frequentists and ...
5
votes
4answers
633 views

Quantum Physics and the Law of Large Numbers

On page 1 of this recent paper by Bousso and Susskind we read. This question is not about philosophy. Without a precise form of decoherence, one cannot claim that anything really "happened", ...
2
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4answers
234 views

Are Everettian branchings global or local?

Everett's theory of quantum mechanics is about the wavefunction of the whole universe holistically. If a branching occurs very far away at the Andromeda galaxy, do I also branch? Are branchings global ...
2
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2answers
231 views

Is there a manifestly Lorentz invariant formulation of the many worlds interpretation?

First, I give an absurd example. A conscious observer lives on Earth at time t. A light-year away, at a space-like separation, a nuclear bomb chain reaction goes off. A nuclear bomb chain reaction is ...
1
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0answers
101 views

Identifying fragments when there is a superposition of fragments in quantum Darwinism

In Zurek's theory of quantum Darwinism, information about the pointer states of a system imprint themselves upon fragments of the environment carrying records about the state of the system. ...
1
vote
3answers
278 views

Is energy conserved in decay of hydrogen atom in superposed state?

This looks like a paradox. Let's say we have an hydrogen atom. Superposition of states could be possible for electrons. But if an electron is in a superposition, I guess it could decay into a lower ...
2
votes
4answers
271 views

Why should the observed probability distributions in quantum mechanics always align with the pointer basis of decoherence?

It has always been claimed decoherence solves the problem of the preferred-basis for observed probability distributions, but why should this be the case? If there is only one world, and there are ...
3
votes
3answers
541 views

Defining Measurement in Quantum Mechanics

I should begin by saying that I am a total newbie when it comes to Quantum Mechanics. Therefore my question might sound metaphysical to people who know their stuff. So please forgive. What I am ...
1
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3answers
681 views

What are specific arguments against the ensemble interpretation (as promoted by L. Ballentine)?

Leslie Ballentine develops in QM: A Modern Development an interpretation based on the ensemble interpretation, and responds to most criticisms. My question: what criticisms still exist against this ...
10
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5answers
2k views

Consequences of the new theorem in QM?

It seems there is a new theorem that changes the rules of the game in the interpretational debate on QM: http://www.nature.com/news/quantum-theorem-shakes-foundations-1.9392 Does this only leave ...
3
votes
3answers
432 views

If the multiverse and many-worlds don't exist, how should we interpret probabilities?

If the multiverse of eternal inflation and the many-worlds of quantum mechanics don't exist, how should we interpret the meaning of probabilities? If there is only one copy of the universe out there, ...
3
votes
2answers
2k views

What is the meaning of Wheeler's delayed choice experiment?

Wheeler's delayed choice experiment is a variant of the classic double slit experiment for photons in which the detecting screen may or may not be removed after the photons had passed through the ...
5
votes
1answer
669 views

What is the meaning of the Fourier transform of Feynman propagator?

I know $K(a,b,t)$ is the probability amplitude of find a particle that starts at point a in b in a time t later. There is also an expression that sometimes is called green function: ...
3
votes
1answer
577 views

Does this new quantum experiment rule out the possibility of a many-worlds interpretation?

This brand new published result (nature): Experimental non-classicality of an indivisible quantum system by Radek Lapkiewicz, Peizhe Li, Christoph Schaeff, Nathan K. Langford, Sven ...
2
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0answers
68 views

Complementarity between the laws of physics? [closed]

Is this following proposal plausible, worth considering, or dismissable as lunatic fringe science? What if the universe isn't really what we think it is but some universal quantum computer where we ...
3
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0answers
310 views

Does the extended probability ensemble interpretation of quantum mechanics make any sense?

Gell-Mann and Hartle came up with the extended probability ensemble interpretation over here. Basically, they extended probability theory to include real numbers which may be negative or greater than ...
8
votes
2answers
1k views

Is the “consistent histories” interpretation of QM a “many worlds interpretation” in disguise?

The so called consistent histories interpretation is claimed to be a correction of the Copenhagen Interpretation. One of its aim, as much as I can see is to show that observers don't have any special ...
1
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0answers
114 views

Can events unhappen for a conscious program on a reversible quantum computer? [closed]

Some time far into the future, humans have made the technology breakthroughs to construct decoherence-proof reversible quantum computers with quantum fault tolerance. They have also solved the hard AI ...
5
votes
1answer
265 views

Uniqueness of quasiclassical consistent histories

The current zeitgeist here is on interpretations of quantum mechanics, so let me add my own two cents here. As you may know, consistent histories is an alternative interpretation proposed in a series ...
-1
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2answers
383 views

Consciousness and quantum mechanics [closed]

Quantum mechanics is very mysterious. Consciousness is often brought into play to explain quantum phenomena. Is this only a matter of convenience, or is consciousness inherent to interpreting quantum ...
5
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2answers
401 views

What happens when particle-antiparticle pairs annihilate in MWI?

The many-worlds interpretation of quantum physics is built around a configuration space, where the position of a particle is three components of the position of that universe. What happens with ...
11
votes
3answers
388 views

Is it possible to define a “it went through two slits” observable?

This concerns the famous two-slit experiment. Electrons or photons or your favorite particle, doesn't matter. As we all know, the attempt to detect which slit the quanta pass through leads to loss ...
2
votes
3answers
244 views

What's the worst thing about the tomographic approach to QM?

I saw a paper on arXiv that referenced this approach to an ontology of QM: Phys.Lett. A213 (1996) 1, S. Mancini, V. I. Man'ko, P.Tombesi Symplectic tomography as classical approach to quantum ...