Spooky Physics: Signals Seem to Travel Faster Than Light

[Moontanman]

Originally Posted by Thunderbird

I do not think anyone has got their mind completly around this as yet. Our minds just are not capable to grasp quantum level particle physics. What we can do however is attempt to leave the Newtonian framwork behind and accept that the building bocks of reality are not separate solid objects, but more akin to how we see a spectrum light, that the world we think we know so well my in fact be a hologram.

I have always been able to visualize higher dimensions relatively easily but this one thing escapes me. On the one hand they say no information is transfered but then they say information on one particle defines the other no matter how far away it is. Like saying white is white except when it's black.

[Boerseun]

Coming from a bit of a different angle, I think the brick analogy might have obfuscated matters slightly.

A physical property such as the colour of a brick might not be the best example, because what happens at the quantum level is that one property gets modified when another property gets probed. When you look at a brick to determine the colour, you do not change any other property - the brick stays exactly the same.

On the quantum level, if we determine the brick to be yellow, we had to somehow probe the brick in such a way that another property gets modified. Sorta like Heisenberg will have it - you can know the velocity of a particle or its position in space, but not both - probing the velocity changes the position, and determining the position alters the velocity.

So, bringing the brick analogy closer to quantum mechanics, if we were to observe the brick to be yellow, the act of observation changes the brick into a rubber duck. Which means that if you're discussing quantum "entangled" bricks, you can't use it for information interchange, because the entanglement works both ways - you paint the Earth brick yellow as a signal which can be modulated so that information can pass to a brick observer on Jupiter, who notices the colour change, but his observation instantaneously changes both the Earth-brick and Jupiter-brick into rubber ducks. Some other property will be sacrificed in probing any one specific property.

Bricks aren't the best example, because they exist at the macro level where there are no disruptive actions needed in probing it.

But don't let me fool you, however. I still don't get it.

[modest]

I agree completely with MTM and I'm a bit surprised no one yet has.

You can't paint earth. All you can do is measure the color and the color is random. Whatever color you measure, you know someone on Jupiter will measure the opposite - but it is still random from Jupiter's perspective. Thus no FTL.

As wiki has it:

Now suppose Alice is an observer for system A, and Bob is an observer for system B. If Alice makes a measurement in the {|0>, |1>} eigenbasis of A, there are two possible outcomes, occurring with equal probability:

1. Alice measures 0, and the state of the system collapses to |0>A |1>B.
2. Alice measures 1, and the state of the system collapses to |1>A |0>B.

If the former occurs, then any subsequent measurement performed by Bob, in the same basis, will always return 1. If the latter occurs, (Alice measures 1) then Bob's measurement will return 0 with certainty. Thus, system B has been altered by Alice performing a local measurement on system A. This remains true even if the systems A and B are spatially separated. This is the foundation of the EPR paradox.

The outcome of Alice's measurement is random. Alice cannot decide which state to collapse the composite system into, and therefore cannot transmit information to Bob by acting on her system. Causality is thus preserved, in this particular scheme. For the general argument, see no-communication theorem.

Quantum entanglement - Wikipedia, the free encyclopedia

~modest