A thought experiment initially proposed to argue that the description of physical reality provided by quantum mechanics was incomplete. It involves a pair of particles prepared in an entangled state; if the position of the first particle were measured, the result of measuring the position of the second particle could be immediately predicted.
Questions tagged [epr-experiment]
151 questions
54
votes
4 answers
Has Jaynes's argument against Bell's theorem been debunked?
As a student of theoretical physics I'm well acquainted with the multitude of crackpot ideas attempting to circumvent Bell's theorem regarding local hidden variable theories in quantum physics.
Recently, however, I've been working on my master's…
Timsey
- 1,057
32
votes
6 answers
Bell's theorem for dummies, how does it work?
I've been reading up on theoretical physics for a few years now and I feel like I am starting to get an understanding of particle physics, at least as much as you can from Wikipedia pages. One thing I have tried to understand but fails to make…
jeffpkamp
- 503
28
votes
1 answer
The choice of measurement basis on one half of an entangled state affects the other half. Can this be used to communicate faster than light?
It is often stated, particularly in popular physics articles and videos about quantum entanglement, that if one measures a particle A that is entangled with some other particle B, then this measurement will immediately affect the state of the…
Emilio Pisanty
- 137,480
17
votes
6 answers
What counts as information?
What counts as information? In e.g. the EPR experiment why is one entangled particle knowing instantaneously the state of the other not counted as 'information'.
Edit
Following a discussion in the comments to giulio bullsaver's answer I have…
15
votes
13 answers
Could the Heisenberg Uncertainty Principle turn out to be false?
While investigating the EPR Paradox, it seems like only two options are given, when there could be a third that is not mentioned - Heisenberg's Uncertainty Principle being given up.
The setup is this (in the wikipedia article): given two entangled…
Ehryk
- 3,311
14
votes
6 answers
What was the need for doing experiments to prove quantum entanglement?
This question comes from someone who is interested in Physics but with no theoretical background.
In 1936, EPR presented the thought experiment which later came to be known and quantum entanglement.
I understand that the thought experiment reflects…
Black Dagger
- 1,283
13
votes
10 answers
Is quantum entanglement mediated by an interaction?
You can get two photons entangled, and send them off in different directions; this is what happens in EPR experiments. Is the entanglement then somehow affected if one puts a thick slab of EM shielding material between the entangled photons? Have…
Marton Trencseni
- 3,105
13
votes
2 answers
Has Jaynes' argument for quantum mechanics as a possible theory of inference been debunked?
To my understanding, there is currently no scientific consensus on which interpretation of quantum physics is the correct one, if any. The most famous one, perhaps for historical reasons, is the Copenhagen interpretation, though I'm always unsure to…
Timsey
- 1,057
12
votes
2 answers
EPR-type experiments and faster-than-light communication using interference effects as signaling mechanism
I understand that faster-than-light communication is impossible when making single measurements, because the outcome of each measurement is random. However, shouldn't measurement on one side collapse the wave function on the other side, such that…
user1247
- 7,509
9
votes
2 answers
Tracking down the locality assumption in a CHSH inequality derivation
CHSH inequality requires both locality and realism. I will equate here realism with counterfactual definiteness.
Now counterfactual definiteness tells us that given two different measurements on the same object, described by random variables $C_1$…
SMeznaric
- 1,584
9
votes
2 answers
Quantum field theory version of EPR paradox
I've always been wondered that people speaking of EPR paradox formulate it only in terms of non-relativistic quantum mechanics and not quantum field theory which being a relativist generalisation of quantum mechanics seems to be a more fundmental…
9
votes
3 answers
Why would classical correlation in Bell's experiment be a linear function of angle?
Sorry if it's a newbie question, but I have trouble understanding the following part in the Wikipedia's explanation for the Bell's theorem:
With the measurements oriented at intermediate angles between these basic cases, the existence of local…
Lou
- 519
8
votes
2 answers
Can observations of entangled particles affect their unobserved counterparts?
There are two experiments that are often used to explain Quantum Mechanics: the two-slit experiment and the EPR paradox. I am curious what would happen if you combined them.
Imagine an experiment where you fire pairs of entangled particles at two…
Nick Retallack
- 189
- 3
8
votes
5 answers
Wavefunction collapse in relativity
It is well accepted that quantum theory has well adapted itself to the requirements of special relativity. Quantum field theories are perfect examples of this peaceful coexistence. However I sometimes tend to feel little uneasy about some aspects.…
user1355
8
votes
5 answers
How do we show that no hidden variable theories can replace QM?
I've always hit two big stumbling blocks in conceiving of the proof or disproof of hidden variable theories as being even valid idea, let alone an answerable question... I feel I must be misunderstanding some very fundamental things.
Quantum…
jheriko
- 209
- 2
- 7