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Breakthrough Brings Star Trek Transporter Closer
japerr writes to mention The Independant is reporting that a new breakthrough may bring scientists one step closer to a Star Trek style transporter. " A team of physicists has teleported data over a distance of 89 miles from the Canary Island of La Palma to the neighbouring island of Tenerife, which is 10 times further than the previous attempt at teleportation through free space. The scientists did it by exploiting the "spooky" and virtually unfathomable field of quantum entanglement - when the state of matter rather than matter itself is sent from one place to another. Tiny packets or particles of light, photons, were used to teleport information between telescopes on the two islands. The photons did it by quantum entanglement and scientists hope it will form the basis of a way of sending encrypted data."
The gist of the argument is that special relativity divides the universe into three regions of spacetime: the timelike future (which is the set of all points where you COULD be in the future if you could travel at any speed up to and including the speed of light), the timelike past (which is where all events that could POSSIBLY have an affect on you at the present reside) and "elsewhere", which is comprised of all other events. An example of an "elsewhere" event is the state of the Mars rovers RIGHT NOW. I can't possibly know that at the moment because there's about a 30 minute light travel time delay. It's important to realize that FTL communication connects you to an event in "elsewhere" in a causal manner.
If you draw a spacetime diagram for two people, one of whom is moving very fast (at a conventional sublight speed) relative to the other, you'll find that the "elsewhere" of one observer intersects the past of the other. So using FTL communication and sublight engines to send a message to the past would work like this:
1. Bob gets in his fancy spaceship and travels directly away from earth at 90% the speed of light. He travels for 1 year (the time and speed aren't really important, they just allow the message to be sent farther into the past).
2. Alice, on earth, sends Bob an instantaneous message using her FTL communication device. It travels to Bob along what Alice considers to be her "line of simultaneous events" - the line in her spacetime diagram that goes through her present position and on through "elsewhere", to define the "present". It's not necessary for Alice's communication to be instantaneous, but it makes the argument (a little) clearer and doesn't really matter because going 1.0000001x the speed of light is just as impossible as going infinitely fast (as an instantaneous communication device would have to do).
3. Bob receives the message at the exact instant (in Alice's timeframe) as when she sent it. He then sends the message back to Alice using the same FTL device. The difference is that Bob is travelling at 90% of the speed of light, so his "line of simultaneous events" is completely different- it actually intersects Alice's "timelike past".
All of this makes a lot more sense once you get the hang of drawing spacetime diagrams, but it confused me for many years. You might want to google for tutorials on spacetime diagrams or "pole and barn" paradoxes to see some examples of spacetime diagrams...
Sorry to nit, but since we are flexing our geek muscles here (the only muscles I have), Data has actually used contractions on occasion. According to Memory Alpha, "...Data also had trouble using contractions in regular speech although this was part of his programming by Dr. Soong." So apparently, it was possible for Data to use contractions, but not without difficulty and, therefore, rarity.
-- My hovercraft is full of eels.
Wrong. Completely and utterly wrong. You can't send information faster than the speed of light.
Quantum teleportation doesn't work like that. Here's basically how it works: Two quantum particles are entangled. Then they are separated from each other, one goes to point A the other to B. If you do a measurement on A and COMMUNICATE THE RESULT OF THAT MEASUREMENT to where B is. The other guy can do a special measurement on B based on what A's result was. Then the state of A becomes what the state of B was originally. The particles have not moved (the measurements have changed their states, though), but A's state has been "teleported" to B. It's all to do with the fact that the two particles were entangled in the first place.
But the very important point is that you *still have communicate the result of the first measurement*, which means you're limited to the speed of light.
There is still application for encryption since just knowing what the result of the measurement was is not enough without having the actual entangled particle B.
BUT THERE IS NO APPLICATION TO STAR TREK-LIKE TELEPORTATION OR FASTER THAN LIGHT-SPEED COMMUNICATION. And frankly I'm getting tired of seeing the same wrong information getting played in the media like this. And slashdot even, come on guys, you should know better by now. I'm new here, aren't I?
Yes, IAAQP.