# Is quantum entanglement unaffected by fields/forces?

San K
Is quantum entanglement unaffected by fields/forces?

Forces = the, yet known, four fundamental forces

i.e. Is quantum entanglement "friction-less"?

Assumption: Anything that is effected by fields and forces can, at the most, interact/move at the speed of light.

Quantum entanglement "interactions" are thought to happen instantaneously.

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## Answers and Replies

QuantumHop
Apparently the only thing that affects a quantum entangled particle is the initial observation of one of the pairs, knowing one state of one pair instantly provides information about the state of the other entangled pair no matter where it is in the universe.

Frankly I've never found this to be impressive although I'm almost certainly missing an important point.

Putting the experiment into a macroscopic state its like pulling two differently coloured balls out of a bag and placing each one in a box, next the box is separated by some distance and somebody looks inside and instantly knows the colour of the ball in the other box no matter where it is.

I don't get it, what's the big deal?

Gold Member
Frankly I've never found this to be impressive although I'm almost certainly missing an important point.

Putting the experiment into a macroscopic state its like pulling two differently coloured balls out of a bag and placing each one in a box, next the box is separated by some distance and somebody looks inside and instantly knows the colour of the ball in the other box no matter where it is.

I don't get it, what's the big deal?

The example you give does not, in fact, yield any "strange" results. Bell spoke of this too, the example is usually called Bertlsmann's socks.

http://cdsweb.cern.ch/record/142461/

The issue is that the nature of an observation by Alice seems to affect the results Bob experiences. You don't notice that for identical tests (black and white, i.e. color pairs where the observation of one tells you the value of the other with 100% certainty. The strange part only arises when the outcome is expressed as a chance (25% or 75% or similar). As an example: 120 degrees (rather than 0 or 90 degrees).

Maui
Apparently the only thing that affects a quantum entangled particle is the initial observation of one of the pairs, knowing one state of one pair instantly provides information about the state of the other entangled pair no matter where it is in the universe.

Frankly I've never found this to be impressive although I'm almost certainly missing an important point.

Putting the experiment into a macroscopic state its like pulling two differently coloured balls out of a bag and placing each one in a box, next the box is separated by some distance and somebody looks inside and instantly knows the colour of the ball in the other box no matter where it is.

I don't get it, what's the big deal?

You are missing the point. There is always some uncertainty about characteristics of a quantum system. When these uncertainties become joint, people say the new system is entangled. Now you have uncertainties that can be spread over vast distances of space. This is nowhere close to a sock being somewhat red and somewhat blue depending on the other sock being less blue and more red. The socks analogy isn't a professional level treatment of the situation and is more suited to high school students finding out about it. Entanglement is not a classical phenomenon and can't be classically described or explained.

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QuantumHop
@ DrChinese & Maui

I posted this question here.