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

learn more… | top users | synonyms

3
votes
0answers
48 views

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 ...
4
votes
2answers
121 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 ...
-1
votes
1answer
69 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 ...
1
vote
2answers
80 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, ...
1
vote
1answer
76 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 ...
1
vote
1answer
92 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 ...
1
vote
4answers
125 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. ...
2
votes
1answer
57 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 ...
-1
votes
2answers
115 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 ...
5
votes
1answer
251 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 ...
2
votes
3answers
315 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 ...
1
vote
1answer
88 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 ...
5
votes
5answers
180 views

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? ...
-1
votes
1answer
59 views

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 ...
0
votes
1answer
84 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 ...
5
votes
2answers
150 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 ...
0
votes
0answers
76 views

Can't many-worlds interpretation explain wavefunction collapse?

According to the many-worlds interpretation when universe splits in interaction, the observer in each universe measures corresponding pure state thus seeing collapse. Well, it may be an interpretation,...
6
votes
4answers
2k views

Does physics claim that every possible world has or will exist? [closed]

Has physics proven that every possible world has or will exist? Someone on-line, who actually seems fairly intelligent, but troll-ish, claims that there is good reasons for it, not from any ...
1
vote
0answers
66 views

Why not measure the velocity of a quantum particle by $\frac{\Delta \vec{x}}{\Delta t}$

Why is it not possible in quantum mechanics to measure the velocity (and thus momentum) of a particle just by two position and time measurements and get it approximately by $$ \vec{v} = \frac{\vec{x}...
0
votes
1answer
46 views

Multiple measurements and the any worlds interpretation

My question has some similarities to but also differs significantly from this question which was described in many of its answers as not being a quantum mechanical measurement and was I think, ...
3
votes
2answers
122 views

When does the world split in MWI

I've been reading Eliezer Yudkowsky's blog post regarding decoherence and many worlds, and although he is not a physics but a strong proponent of MWI, I can basically see why he feels that MWI is a "...
0
votes
0answers
49 views

Interpretation of a case of the double square well

Consider a 'double square well' potential (where $E < 0$) defined as: $$V(x) :=\begin{cases} -V_0~~~~~~~~~~~~~\text{for }\frac{b}{2} < x < \frac{b}{2} + a \text{ and } -a - \frac{b}{2} < ...
0
votes
0answers
36 views

Statement of vector model of angular momentum in Eisberg and Resnick

While serving as a teaching assistant for a sophomore-level Quantum Physics course, I came across the following paragraph in Eisberg and Resnick regarding orbital angular momentum (section 7-8, page ...
3
votes
1answer
87 views

Is the trajectory of a quantum particle a well defined concept and how does this depend on the interpretation of quantum mechanics?

A common statement about quantum physics is that the "trajectory" of a particle is no longer a well defined concept because of the uncertainty relations for position and momentum. If one interprets ...
2
votes
1answer
49 views

Question about Bell's Theorem and hidden variable equations [closed]

I am trying to understand Griffiths explanation of Bell's theorem in chapter 12 of 2nd edition Intro to QM (or the afterword section A.2 in the 1st edition). He starts with given two detectors ...
0
votes
2answers
83 views

Quantum mechanics interpretation clarification

My question is based upon this video here: https://www.youtube.com/watch?v=PC0zHIf2Gkw From 9:00-10:00 Max Tegmark says an isolated galaxy with an observer inside will not evolve according to ...
0
votes
3answers
68 views

Einselection locality in decoherence theory

Consider two polarity-wise entangled photons A and B in an EPR experiment. The process of measuring the polarization of photon A by Alice is described by the decoherence of the 2-photons system ...
0
votes
1answer
124 views

How can all information be localized if local realism is dead?

I'm confused about whether quantum mechanics is local or not. The authors of a recent, much publicized experiment argue that their results "imply statistically significant rejection of the local-...
3
votes
3answers
135 views

Does the canonical commutation relation relate to the fact that momentum is the generator of spatial translations?

In classical mechanics momentum is the generator of spatial translations. This remains true in quantum mechanics. The way we define the momentum operator in one-dimension, for example, already shows ...
1
vote
0answers
101 views

What is the justification for continuing to model space-time as a manifold in string theory?

Background The question I have arises from taking seriously the idea that, in a physical theory, one should first define all physical quantities via (thought) experiment. Justification and ...
2
votes
3answers
221 views

What's so confusing about quantum physics? [closed]

Okay, just right off the bat, I want to make it clear that this is a stupid question. Check out this graph, from SMBC: Ignore the 'political discourse' part and replace it with 'talking about ...
2
votes
2answers
366 views

Does recent paper show Bohmian mechanics is correct?

The following paper was recently featured in a German science magazine (Spektrum der Wissenschaft): "Experimental nonlocal and surreal Bohmian trajectories" (DOI:10.1126/science.1501466) The abstract ...
-7
votes
5answers
223 views

Quantum Theory just lazy physics?

Is it true that physicists decided that because they couldn't predict with certainty the location of an electron at any given time, that they just created equations using probability instead, still ...
1
vote
1answer
99 views

Controlling the universe through the “Many-worlds” interpretation [closed]

I was reading upon a comic when I found some interesting content concerning the "Many-worlds" interpretation and how it could be used in quite an extreme manner. Imagine we had a "END" machine. When ...
2
votes
2answers
74 views

Many worlds and “extreme” worlds

I assume there are worlds in the MWI where extremely improbable things (improbable according to our world) have happened repeatedly. Broken eggs reform themselves repeatedly etc... Will scientists in ...
3
votes
4answers
175 views

Many worlds interpretation of quantum mechanics

From my layman's perspective, it feels like the many worlds interpretation is invoked out of the inability to explain why one observation occurs out of many possibilities. Given no explanation why one ...
5
votes
3answers
168 views

Successor to Copenhagen Interpretation as Orthodox Interpreation of Quantum Mechanics

First, I read the questions FAQ for this and I hope this does not violate the rules. I am not asking for personal opinion, but for observations of hard evidence of trends on this subject. When I ...
5
votes
1answer
124 views

Help needed to understand “On the reality of the quantum state”

I am having trouble to understand the reasoning in the following paper, On the reality of the quantum state. MF Pusey, J Barret and T Rudolph. Nature Phys. 8, 475–478 (2012); arXiv:1111.3328. ...
4
votes
0answers
90 views

Decoherence and interpretations

With quantum decoherence, are there still any "gaps" in our knowledge of quantum mechanics that hint (either in terms of the physics, philosophy, or otherwise) at the need for further interpretation? ...
3
votes
2answers
154 views

How does the Physics work for the Quantum Suicide thought experiment?

On page 5 of this paper written by Max Tegmark, Tegmark discusses a thought experiment called 'Quantum Suicide'. As far as I understand it, this experiment was created to show the experimental ...
2
votes
1answer
63 views

Many-worlds interpretation (MWI) and conservation of energy [duplicate]

I am not an expert of many-worlds interpretation (MWI), and what I say may be stated incorrectly. In that case i welcome corrections. If the MWI is true and it explains quantum theory and it splits ...
2
votes
2answers
139 views

Meaning of “realism” in quantum mechanics

When physicists doing work in quantum measurement, decoherence, Bells' inequalities etc. use the term "realism" what exactly do they mean? I'm looking for answers targeted towards, say, someone whose ...
3
votes
1answer
74 views

Does a particle “exist” between emission and detection?

In considering a simple Young's double slit setup: The classical idea that a particle must exist with defined position and momentum between the source and detection plate leads to philosophical angst,...
0
votes
0answers
64 views

How does one intrepret probabilites in the many-worlds interpretation?

Let's say I flip a coin, and don't look. From the copenhagen interpretation, the state of the coin is: $\frac1{\sqrt2}(i|\text{heads} \rangle - |\text{tails}\rangle)$ If I observe the coin, there is ...
2
votes
2answers
199 views

Can multiple timelines exist according to theoretical physics? [closed]

Multiple timelines is not a reality yet (as of 2016's science and technology), but exists only in Marvel/DC universe. It is something that is used to explain the paradox of time-travel. If you go back ...
0
votes
2answers
217 views

Many-world interpretation: simple physics explanation? [closed]

We went a little off topic in physics class today and my teacher was explaining how quantum physics explains the idea of parallel universes. She believes in a idea called many world interpretation ...
2
votes
3answers
150 views

Does valid interpretations of quantum mechanics always reduce to trivial arguments about the equations? [closed]

This is the editted 'short' version of the question :) Interpretation is very important in physics, but physics is governed by equations. With bare equations, physics would be just mathematics. ...
-1
votes
2answers
179 views

What stands behind the quantum nonlocality appearing in entanglements, and why Bell's inequalities are violated?

I noticed the question whether Bell's inequalities are based on a false premise, (Could Bell's Theorem be based on a false premise?) but I bring another argumentation of the question. Also I ...
2
votes
0answers
92 views

What would be the abilities of a wave function collapsing oracle? [closed]

Although the Bell's theorem dismiss local hidden variables as an explanation of the quantum variability, there is nothing to prevent an observer to see the occurrence of a wave function collapse as ...
-1
votes
1answer
70 views

Probabilistic realism

On consideration of Bell's inequalities and this Why is quantum entanglement considered to be an active link between particles?. Either localism or realism has to be given up. Can't we have a non-...