Linked Questions

15
votes
6answers
2k views

Entanglement, real or just math? [duplicate]

In quantum entanglement when something acts on one particle the other one reacts also, just in reverse (more or less). From what I've read though, anything acting on either particle will collapse the ...
15
votes
5answers
2k views

Why must entangled particles communicate their spin instantaneously? [duplicate]

I'm a complete newbie to Quantum Theory, but I want to know more, so I've been watching few YouTube videos (an example below). https://www.youtube.com/watch?v=ZuvK-od647c All videos I've watched ...
12
votes
9answers
1k views

How do we know a quantum state isn't just an unknown classical state?

When an observer causes the wave function of a particle to collapse, how can we know that the wave function was not collapsed already before the measurement? Suppose we measure the z-component of the ...
4
votes
2answers
768 views

Has anyone actually “seen” entanglement? [duplicate]

I want to know if the following has been done experimentally; after the spin (or any other characteristic with a probability of 50%) of 2 entangled particles has been measured, we change the spin of ...
3
votes
4answers
2k views

How was it proven that a quantum entanglement measurement of particle A, affects properties of particle B [duplicate]

If I understood the wikipedia article correctly, quantum entanglement claims that information travels instantly between entangled particles. An act of measurement on one of the entangled particles ...
1
vote
1answer
52 views

How do we know quantum entanglement really happens? [duplicate]

Quantum entanglement says that we can entangle two particles with an opposite property, separate them, and that they exist in an indeterminate state until we observe one of them. eg. If we create a ...
91
votes
8answers
17k views

Why is quantum entanglement considered to be an active link between particles?

From everything I've read about quantum mechanics and quantum entanglement phenomena, it's not obvious to me why quantum entanglement is considered to be an active link. That is, it's stated every ...
17
votes
4answers
893 views

Why is quantum entanglement surprising? [duplicate]

What about quantum entanglement is suprising, and what makes it a strictly quantum effect?. Suppose we have an particle of spin 0 which decays into two other particles, each with either spin up or ...
15
votes
6answers
3k views

Quantum entanglement and spooky action at a distance

When quantum entanglement is explained in "layman's terms", it seems (to me) that the first premise, that we have to accept on faith, is that a particle doesn't have a certain property (the particle ...
9
votes
2answers
1k views

Has quantum entanglement been demonstrated to be able to take place over infinite distances?

In my poor understanding of quantum physics, quantum entanglement means that certain properties of one of two 'entangled' quantum particles can lead to change over infinitely large distances when the ...
8
votes
4answers
3k views

Quantum Entanglement - an illusion based on a wrong assumption?

Almost all resources I've read about Quantum Entanglement speak about how 'amazing' it is that two entangled particles are bound over any distance, and that the state of one particle determines the ...
7
votes
2answers
90 views

Alignment of axes of measuring devices in a quantum entanglement experiment

Concerning quantum entanglement Wikipedia says: Measurements of physical properties such as position, momentum, spin, and polarization, performed on entangled particles are found to be ...
1
vote
2answers
217 views

Example of experimental or observational proof of quantum indeterminacy before measurement

How do we know that certain properties are indeterminate or undefined until they are measured? Take the example of quantum entanglement, saying that if you have two entangled particles, such as the ...
1
vote
1answer
73 views

How are contextuality and locality related?

I know how quantum non-locality is defined in Wikipedia quantum nonlocality is a characteristic of some measurements made at a microscopic level that contradict the assumptions of local realism ...
4
votes
1answer
72 views

Is spin entanglement conserved in a gravitational field?

Imagine a photon decaying into an electron-positron pair. Which have entanglement such that one is "up" and one is "down". There are a few mini black holes near by so that one of the electrons ...

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