It is named after Einstein, Podolsky, and Rosen, who published the idea in 1935
I saw this guy speak on C-span, I'd never heard of EPR before, makes ya look at things a bit different.
Posted on 06/16/2004 1:54:18 PM PDT by vannrox
TED: 2:55 pm EDT June 16, 2004
UPDATED: 3:03 pm EDT June 16, 2004
In a step toward making ultra-powerful computers, scientists have transferred physical characteristics between atoms by using a phenomenon so bizarre that even Albert Einstein called it spooky.
Such "quantum teleportation" of characteristics had been demonstrated before between beams of light.
The work with atoms is "a landmark advance," H.J. Kimble of the California Institute of Technology in Pasadena, Calif., and S.J. van Enk of Bell Labs in Murray Hill, N.J., declare in Thursday's issue of the journal Nature.
Two teams of scientists report similar results in that issue. One group was led by David J. Wineland of the National Institute of Standards and Technology in Boulder, Colo., and the other by Rainer Blatt of the University of Innsbruck in Austria.
Teleportation between atoms could someday lie at the heart of powerful quantum computers, which are probably at least a decade away from development, Wineland said. Although his work moved information about atomic characteristics only a tiny fraction of an inch, that's in the ballpark for what would be needed inside a computer, he said.
His work involved transmitting characteristics between pairs of beryllium atoms, while the Austrian work used pairs of calcium atoms. Each atom's "quantum state," a complex combination of traits, was transmitted to its counterpart.
Key to the process was a phenomenon called entanglement, which Einstein derided as "spooky action at a distance" before experiments showed it was real.
Basically, researchers can use lab techniques to create a weird relationship between pairs of tiny particles. After that, the fate of one particle instantly affects the other; if one particle is made to take on a certain set of properties, the other immediately takes on identical or opposite properties, no matter how far away it is and without any apparent physical connection to the first particle.
It is named after Einstein, Podolsky, and Rosen, who published the idea in 1935
I saw this guy speak on C-span, I'd never heard of EPR before, makes ya look at things a bit different.
That's true, provided that nothing goes faster than light.
You are implicitly introducing a third reference frame interacting with the first two reference frames thereby creating a second inertial frame whereby the causal loop can be set up.
Not at all. I used two reference frames, the Earth's and the traveller's. That was sufficient to set up a closed time-like loop. If there's another reference frame, identify it (by velocity).
I already addressed the Lorenz transformation at the point I wrote that "the single inertial frame cannot twist in such a way as to make events in one locale's absolute future appear to be in that locale's past" [from that same locale's perspective].
That's true, provided that nothing goes faster than light.
But nothing is going faster than light in your hypothetical. The starship is travelling at 'merely' 99% luminal velocity. The communication is not "going" anywhere at all. It simply 'is' somehow..
If there's another reference frame, identify it (by velocity).
You are implicitly assigning a reference frame to the communication itself, but based on our parameters (quantum entanglement 'ansibles') the communication has no reference frame.
=)
Tut, tut! In reply #110, you said:
But superluminal transportation would not enable one to send messages from the future into the past.
So if we've gone off-topic, it's down to you. In any case, I hope I've demonstrated that the above statement is wrong.
In this "spooky action at a distance" quantum entanglement we're discussing, nothing is moving anywhere in the course of the FTL communication. Rather, you are extrapolating a series of actions upon the entangled particles at the other end by observing changes to the entangled particles on your end
But the same argument works for instantaneous communication. In that case, the "ack" is received on January 30, 2999. The key point is that the "ping" event, as received by the traveller, is simultaneous with a much earlier time on Earth as measured in the traveller's frame than it is as measured in the Earth's frame. That's the physical GEOMETRY of the situation, and it has nothing to do with how the information is sent.
So what's the solution? Why can't we use quantum entanglement to send messages back in time, if both relativity and quantum mechanics are correct? It's because quantum entanglement doesn't involve any communication of information. This article is very misleading in that regard; I'm sorry, but there it is. As they say in statistics, correlation is not causality. This is mere correlation. It can't be used to send anything: not "ping", not "ack", not Bones McCoy. It's simply a reflection of the limits of information in the physical universe.
The signal is.
You are implicitly assigning a reference frame to the communication itself
So make it infinitely fast. The argument still works. In fact, it's simpler.
Yes, I realize that is what current theory requires, but we are pretending here that either (a) quantum entanglement does permit communication of information; or (b) that quantum entanglement in conjunction with a classic interpretation device can permit the appearance of communication of information.
I am not proclaiming that it would work. I am only confronting the causality issues in the event that it does happen to work. I'm also not even trying to deal with the concept of a starship itself travelling at superluminal velocities, because that introduces a whole 'nother set of weird science I don't wanna deal with. =)
At the point where I said superluminal "transportation" I was simply wrong. Junior and I quickly hashed it out but what I should've said was superluminal "transmission"; I used the term "transportation" due to others using the term, but I realized shortly thereafter that the terminology was misleading and inaccurate.
No, it isn't. Information is being communicated but nothing is 'going' anywhere. If it were quantifiable, then it would not be "spooky" action, now would it? =)
So make it infinitely fast. The argument still works. In fact, it's simpler.
I don't see how unless you introduce a third reference frame interacting with the first two (which in principle is always the case anyhow, which is why I said that the causality problem is ultimately unresolved).
Bones, is that you?
You're still wrong. Look, the transmitter sends its signal on January 1, 3000. On the starship, it's some other date as measured in the Earth's frame, because time is moving more slowly there as viewed from Earth. (The exact date depends on when the clocks were last synchronized.) Whatever that date may be, it is simultaneous with January 30, 2999 on Earth, as measured in the starship's frame. So if the starship is going to send an "entanglement signal" right back again, when would the starship expect it to be received, if not on January 30, 2999? Why would it get there later? In order to get to Earth on January 1, 3000 (which it would have to, to preserve causality), the signal would have to take 0.9166/0.6 = 1.53 years to travel the 0.8 lightyears to Earth...a speed that's about half as fast as light. (If you wonder where the factor of 0.6 came from, remember, Earth's clocks are running slow in the starship's frame.) Why would it do that? The starship travellers are going to wonder who broke the ansible!
This from a viewer who remembered watching the original Star Trek eps in the early 60's. I even wrote a letter protesting the show's cancellation!
Yes, but Earth does not receive transmissions in the starship's frame. Earth receives transmissions in its own frame and each reply transmission is received later than the preceding transmission. Therefore, no causality violation.
I have a link bookmarked somewhere that explains all this much better than I'm (obviously) doing so I'll try to find it and post it ASAP.
Tell that to the people on the starship! Why is Earth's reference frame privileged? All events in the universe occur in every frame of reference, and all frames of reference are equally valid. You can't say, "well, the math works out for the people on Earth, but not for somebody somewhere else".
If the Earthlings send their "Happy New Year 3000" message on January 1, 3000, and it's received by the people on the starship instantaneously, there's already a problem. The people on the starship know for a fact that it's January 30, 2999 back on Earth. They take one look at the message and say, "this is from the future". Causality is already out the window with the very first event.
Another test planned:
Newly devised test may confirm strings as fundamental constituent of matter, energy
Why is the starship's reference frame privileged? This is getting back to what I said before: you are privileging first one frame and then the other depending on who is transmitting. You can't do that!
The people on the starship know for a fact that it's January 30, 2999 back on Earth.
That's not how time dilation works.. The people on the starship know for a fact that it's December 30, 2999 on the starship. If they are keeping track of the time dilation effect, they know for a fact that it's January 1, 3000 back on Earth. Whatever the case, the reply transmission will be received on Earth at a later time than their initial communique, and there will be no causality problem.
Make that January 30, 2999 on the starship - or whatever! (same difference)
It isn't. The physics has to work out in all frames, so I'm perfectly well entitled to do my calculations the starship's frame. The point is that the result had better be the same in both frames. As long as everything goes no faster than light, it will be, but as soon as you have something going faster than light, you get crazy results. As is the case here.
The people on the starship know for a fact that it's December 30, 2999 on the starship. If they are keeping track of the time dilation effect, they know for a fact that it's January 1, 3000 back on Earth.
Wrong. You are assuming that two events that are simultaneous in one frame are simultaneous in all frames. That is not the case, nor can it be the case. The axes of simultaneity are not parallel between the two frames.
Maybe some will find this interesting: Interval in the Theory of Relativity. It discusses interval invariance (it's not the link I mentioned before - still looking for that).
Well, no they're not, but they can be figuratively depicted as such insofar as they're relevant in the circumstances discussed here... In the 'real world' the axes would be distorted by the time dilation effect. That was assumed..
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