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Politics : Should God be replaced? -- Ignore unavailable to you. Want to Upgrade?

To: TigerPaw who wrote (24383)	7/6/2006 3:58:55 PM
From: one_less	Read Replies (2) \| Respond to of 28931

"Communication definitely does not travel faster than light, I think you may have misread on of the articles. They are often written in a sensational way, usually about combining slowed light beams in a refractive medium." You are mistaken. Communication is shown to occur instantaneously over distance in model quantum demonstrations. Perhaps you are confusing sound waves with quantum communication, I don't know, but you are simply wrong on this one.

To: TigerPaw who wrote (24383)	7/6/2006 4:20:03 PM
From: one_less	Respond to of 28931

"Communication definitely does not travel faster than light, ... Quantum entanglement was originally discovered in 1935 by the Austrian physicist Erwin Schrödinger. Two entangled particles can only be described by their joint behaviour. This has the intriguing consequence that measurements on one of the particles give random results, but the results of both particles will always be perfectly correlated – no matter how far apart the two particles are. As an example: this would mean for the two imaginary “entangled dice” shown above, that although each throw of a dice shows a random result Between 1 and 6, the throw of the second would always give the same result. Albert Einstein called this astonishing behavior “spooky action at a distance”. According to theory, these correlations should be maintained over arbitrary distances. Modern applications: Global quantum key distribution can be achieved by combining separate quantum communication links. Each of two ground stations establishes an individual quantum key with a satellite as it passes over. When both keys have been established, the system on the satellite has both separate keys. By sending a logical combination of the keys (e.g. bitwise XOR) openly to one of the ground stations, the key of the other ground station is full retrieved without giving away any usable information on the keys. quantum.at

To: TigerPaw who wrote (24383)	7/6/2006 4:37:30 PM
From: one_less	Respond to of 28931

And in Computing: "Quantum mechanics is also nonlocal, in that distant and non-interacting systems may be entangled." "Classical information theory agrees with everyday intuition: if you want to send a message using an object which can be put into one of N distinguishable states, the maximum number of different messages that you can send is N. For example, a single photon can have only two distinguishable polarisation states, say "left-handed" and "right-handed". So if you send a message by preparing the polarisation of a single photon and transmitting it, it is obvious that you can send no more than two distinguishable messages, i.e, one bit of information. Obvious, but false." Miracle 1: ...These operations, although performed only on one particle, affect the joint (entangled) quantum state of the two particles. This cannot be verified by measurements on the two particles separately. But by measuring both of them jointly, using the quantum gate M, Bob can determine which of the four operations Alice performed, and so receive one of the four messages. Thus the technique effectively doubles the peak capacity of an information channel. Miracle 2: They are developing techniques that might allow quantum teleportation too. But the theoretical results, whether they are practicable or not, are already of considerable importance, because they force us to fundamentally revise our concept of information in physics. cam.qubit.org