My husband is watching YouTube and there’s a man discussing quantum entanglement.
His description: There are two particles. They can be either green or red, but they are both colors until they’re measured. Once you measure one, though, it automatically determines that the other is the same. No matter how many times you measured, or how far you separated the particles, the two would always be the same color.
Why does one being one color guarantee that the other one would be? How do they “know” to always be that color? And what sort of implication does that have for science/real world, other than being really cool?
In: Physics
basically, you start with 1 particle that you put into a superposition between red and green, you dont know if its red or green, and the math behind it says the particle isnt secretly definitively one or the other
Now you make another particle interact with that one so the new particle will be red/green depending on the other one (which even it doesnt know)
These particles are entangled now. unless they are disturbed, when 1 collapses, the other will for sure collapse to the corresponding state.
We have no idea how the particles communicate. it could be that they can “talk” to each other, but if they can, it has to be faster than light. it could be that there is some hidden variable that both now share, but if it is, we have no idea what this hidden variable is. This has huge scientific implications because no matter what the answer is, we are wrong about something that we currently think is true.
This has major implications for the real world, the biggest practical one being cryptography. Right now, if you want to connect to amazon, you have to use an asymmetric encryption protocol to exchange keys with amazon, but in a quantum network you could exchange entangled qbits instead. when these collapse both you and amazon will have the same random sequence of bits, which you can use to encrypt messages. no one else can intercept these bits since the collapse is random.
One pop-sci implication that is actually impossible is FTL communication. its tempting to say “Oh, just entangle 2 qbits, and then I set mine to red, so yours automatically flips, and vice versa, now I can send messages!” But this is 100% impossible. the act of setting a qbit to a value breaks existing entanglements.
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