“Spookiness” Confirmed by the First Loophole-Free Quantum Test

Re:“Spookiness” Confirmed by the First Loophole-Free Quantum... by qrybam on Friday August 28, 2015 @03:00AM (#10134049)

Slightly tangential question: I know that entanglement doesn't violate information transfer greater than the speed of light; c. But given that knowing the state of the measured particle means we also know the state of the entangled particle and measuring again could produce a different result, couldn't you conceivably construct a machine which repeatedly measured a number of particles until you reach a desired state for each, therefore constructing a message via the entangled counterpart particles for someone to consume? I suppose you'd need very accurate timing at both locations to know when to attempt to read the message at the destination.

Or am I missing something along the lines of "its not possible to measure the entangled counterparts without affecting something else, therefore making the whole thing impossible"? I'm sure I am but hope someone could explain.

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Re:“Spookiness” Confirmed by the First Loophole-Free Quantum... by SAI_Peregrinus on Sunday August 30, 2015 @03:53AM (#10142653)

The easiest way to think of it is as follows: When you entangle the particles they have opposite states, and each has their state hidden in a box. When you open one box, you know what the state of the other particle must be.

Only there is no box, and the state isn't well defined until you measure it.

Or there is no box, and the state isn't well defined for anything that hasn't interacted with the particles, but upon interacting whatever did the interaction becomes entangled too and sees the defined state of the particles but the rest of the universe wouldn't know the state of whatever did the interacting.

Or there is a box, but it's the size of the whole universe, and every time anything interacts with it (looks inside the box) the box splits up into all the possible things that could have been seen by that interaction and you get lots of universes.

Or a number of other ways to think about the issue depending on your preferred interpretation of quantum mechanics, but no matter how you look at it it's nothing like a normal box.

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Re:“Spookiness” Confirmed by the First Loophole-Free Quantum... by n4r9 on Friday August 28, 2015 @04:31AM (#10134285)

Yes, you're missing something. Measuring one of the particles breaks the entanglement, so that whilst you know the state of the corresponding particle, you can't affect it further.

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