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 Be the first pioneers to continue the Astronomy Discussions at our new Astronomy meeting place...The Space and Astronomy Agora Still More Problems Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response ToPosted by Harvey on October 28, 2003 16:14:44 UTC

Bruce, I looked at those references, and I didn't see much in the way of showing how entanglement message sending would not conflict with special relativity (just info on superluminal tunnelling, etc).

The problem that I see with sending an instantaneous signal using entangled particles, is that it would be possible to send a message into the past if Bob were to measure the particles while travelling at a relativistically significant velocity. That is, if Bob and Alice synchronized their clocks at 10am, and Bob took off at 80% light speed (assuming instant acceleration, just to make it easy to follow), then at 12:30pm (Alice's time) would be 11:30am for Bob (time-dilation factor 0.6 * 2.5 hours = 1.5 hours). If Bob 'sent' an instant message response to that message back to Alice in 22.5 minutes later (according to his reference), then Alice would receive that message at 11:07am according to her clock (i.e., earlier than she sent her original message to Bob). This is because for Bob the time he sent his response is 112.5 minutes into his trip, but with the time dilation factor of 0.6 those 112.5 minutes is 67.5 minutes for Alice. If the trip started at 10am, then Bob's response has been 'received' when her clock shows 11:07am (i.e., Bob is responding to a message that Alice hasn't 'sent' yet).

So, it would seem to me that sending instant messages is contrary to special relativity. I would appreciate it if you could show me where I am wrong...

(on earth) sent a message after Bob were travelling near light speed, Alice's clock would