Ansible...

[eriador]

Okay, now that scientists have made breakthroughs in quantam teleportation, don't we have ansible technology.

The idea of quantam teleportation is that one can transport the quantam state[\i] of a particle, which is essentially information[\i]. Because teleportation is instantaneous over any distance, we have an ansible on our hands already.

What do you guy's think?

[mr_thebrain]

it was one of my first thoughts actually when i read the news.

[zeroguy]

I can't post a detailed reply right now, but.... gah, it's quantum.

[Oliver Dale]

Can you link me up? I was under the impression that despite soi-disant teleportation experiments, no information has actually been transmitted.

[peterlocke123]

I think that at this point in testingand reproducing the experiment, it's too early to make a decision. However, once there is more known information, you'd think it wouldn't be too hard to create an "ansible" type communications device.

[Oliver Dale]

If by "not too hard" you mean "seemingly impossible" then yeah, I agree.

[peterlocke123]

Well, when they say quantum state of the particle (photon?) couldn't you just asign two different states to mean two different things? Such as binary or morse code or something to that effect?

[eriador]

Can you link me up? I was under the impression that despite soi-disant teleportation experiments, no information has actually been transmitted.

Actually, only information has been transmited. Even though it's not possible to physically move a particle, it is possible to transfer it's quantam state, which is only information. That's what these experiments have done.

peterlocke, that's exactly what I was thinking.

[eriador]

http://www.engadget.com/2006/10/05/dani ... portation/

This article should explain a little bit.

Some choice quotes:

"a breakthrough in the wacky world of quantum teleportation by transporting quantum information over a distance of half a meter (1.6 feet)." (my italics)

"'The goal was to transfer, or teleport, the quantum state of a second light beam onto the cloud.'" (my italics)

[Oliver Dale]

It said nothing about instantaneous transmission. Only teleportation. This leads me to believe the advance is in the mechanism (i.e. the co-entanglement of light and matter), rather than in the defeat of established physics.

[Oliver Dale]

Why does teleportation have to be instantaneous? Teleportation is simply the movement of something from point A to point B without crossing the intervening space. No one said anything about how long it took to get there. It seems to me like instantaneous transportation of information across space (which defies over a hundred years of physics put forth first by Einstein) would have made a bit more of a splash.

[eriador]

Yes, teleportation requires that information is transfered using standard equipment (e.g. copper wire). However, the big deal is the ability to entangle matter. This is what we're looking at, because that is the mechanism they use to transfer the quantam states to and from particles, which is instantaneous over any distance.

[Matty]

Nope, sorry. Quantum entanglement does allow instantaneous action/reaction at a distance, of a kind, but not one that carries useful information. Say two electrons are entangled so that if one is at state A the other must be at state B. I measure the state of E1, and find it is at A. My partner who measured the E2 a lightyear away at the "same time" will find that it is at State B, and we can talk about how cool that is if we meet up later to compare notes. BUT this is not communication because I didn't know beforehand that E1 would be at State A. I found out by measuring, and the measurement determined the state (See Heisenberg Uncertainty Principle). I can never guarantee that E1 will be at State A, so any information I try to send will just be so much noise.

Quantum particles will talk to each other, but won't pass messages for us. Snooty bunch.

And the kind of information-passing that makes teleportation (theoretically!) possible is indeed limited by the speed of light. That's because you still need a wave of some kind to transmit your meaningful information, and nothing goes faster than light.

[peterlocke123]

So basically, Matt, what you're saying is that we don't know the state of E1 until until it's measured, so that way, we can't send a message that would make sense because we won't be able to know which state is which without measuring them.

[eriador]

I think that's what he's saying. You can't measure the state of a particle w/o interfering with it. That grounding in reality kinda burst my bubble. However isn't it possible to do this another way?:


say we have two sets of entangled particles (set A contains P(a,1) and P(a,2); set B contains P(b,1) and P(b,2)). The particles in set A represent a 1 and the particles in set B represent a 0. By disturbing the state of whichever bit (1 or 0) we want to send, we could send information instantaneously.


I'm probably completely wrong, so don't hesitate to tear my idea to shreds.

[peterlocke123]

I'm totally confused Eriador, isn't what Matty said is that you can't do that? Anyway, fairly unrelated...would it be possible to entangle more than two particles? So like a 3 particle entanglement? Possible replication technology to some effect?

[Oliver Dale]

I think that's what he's saying. You can't measure the state of a particle w/o interfering with it. That grounding in reality kinda burst my bubble. However isn't it possible to do this another way?:


say we have two sets of entangled particles (set A contains P(a,1) and P(a,2); set B contains P(b,1) and P(b,2)). The particles in set A represent a 1 and the particles in set B represent a 0. By disturbing the state of whichever bit (1 or 0) we want to send, we could send information instantaneously.


I'm probably completely wrong, so don't hesitate to tear my idea to shreds.

I didn't understand any of that. Do you write textbooks?

[eriador]

Okay, the reason we can't use the state of an entangle particle as a 1 or zero is because when you measure the state, you read the state, but then it changes. However, if you used the change of the states to represent a bit (1 or 0) then you could trade information. The problem is that you would need two sets of entangled particles. When one changed, that would indicate a 1 being sent, a change of the other would indicate a 0.

No, I don't write textbooks, but I was excited about the idea and tend to be pretty obscure/geeky/stupid when I get that way. I hope I've cleared up the confusion.

[peterlocke123]

OOOOOOOOHHHHHH, that's genius! So instead of saying changing from State A to State B is a bit, we say that when Particle 1 changes that's a bit and when Particle 2 changes theat's the other bit. GENIUS!

[eriador]

I don't know about genius. I'm probably wrong, but thank you anyway.

Edit:
I just realized why I am 100% completely wrong. How would you know when it changes: by measuring it and changing it again. To find a change you would have to measure once, then measure it later to see if it's different, but because you'e already measured it, it will have changed anyway. In other words, it won't work.

Damn.

I'm sorry guys, it was just an idea.

[peterlocke123]

But what if it was only one way? You would have the Particle A1 and Particle B1 on Earth (or where ever) and then you would have the Particle A2 and Particle B2 somewhere else. You have Particles A2 and B2 being constantly observed, and then you would be able to notice the changes in states without altering them? Maybe that's not right...

[eriador]

No, that doesn't work. I was assuming one-way communication the whole time. The problem is this:

The state of the particle is 1, but we don't know that, so we test it and find out that it's state is 1, however, in the process, we change its state to 5, so we no longer know it's state. If the bit is sent, it changes to 3. When we test to see if the state of the particle has changed, it's either 3 or 5, both of which indicate a change. Because the changes are not predictable, it can't work.

[peterlocke123]

Would constant observing constantly change it's state? But that would still not work. Hmmmm, anyway, back to my previous question: Can more than 2 particles become entangled?

[eriador]

I have no idea.
What are you thinking of as a use for 3-way entanglement?

[peterlocke123]

Well, multiple planet, spaceship etc communications. Communications to a fleet or something. I don't know. Just a thought.

[eriador]

I don't know, but it wouldn't be that hard to make some sort of computer that can send the same thing over multiple links. It would be pretty simple. So in other words, 3 way entanglement doesn't matter, two way would do the same things.

[peterlocke123]

It would just be a simpler way of doing it, that way you don't need to have a pair of paricles for every one planet. But the other way would work just as well. And if you needed to send different messages it would work better.

[eriador]

Exactly. It would be kinda cool though, if impracticle.

[Soara]

Is there any reason we need an ansible? Being confined, as we are, to earth?

[eriador]

Well, without an ansible, do we have any hope of expanding between stars?

In EG, humans had the ansible before they expanded. I don't think it would have worked if they hadn't had an ansible.

[BeansBrother]

Bump.

Personally, I wish.... I mean, it would be cool and what not, but I really doubt it will ever be possible. And who says teleportation is instantaneous at any distance? Have we tested that? Maybe it just goes the speed of light....[/i]

[Boothby]

Wow...I dug around on my hard drive and came up with this old chestnut:

For those of you who need a quick refresher, the Ansible is the piece of communications equipment that the International Fleet (I.F.) uses to communicate with its invasion force en route to the Bugger homeworlds. It is, in essence, a specialized radio that bypasses the Einsteinian limit of the speed of light. It would miss the point to say that the transmissions travel “faster than light,” as that implies that there could still be some delay between transmitter and receiver. There is no delay; communication is instantaneous. If you’re heavy into “Star Trek,” it’s pretty much the equivalent of “Subspace Radio.” The word “Ansible” was actually invented by Ursula K. Le Guin in 1966 in her novel Rocannon's World.

Since the “Philotic Web” site is the Lake Woebegone of the Internet (all of us here are above average), I almost don’t need to tell you that we should not limit ourselves to thinking of “radio” transmissions as being purely in the audio spectrum. Low bandwidth radio is, if you want to look at it this way, basically Morse code. Improve the bandwidth by increasing the radio frequency, and you get low-grade audio. Increase the frequency even more, and you get high grade audio (think of the shift from AM to FM-from kilohertz to megahertz; yes, they encode the information differently, but the increased bandwidth of FM allows this). Increase the frequency even more than that and you get the capability to transmit Video signals, then digital video, then…who knows what! Somewhere along that continuum is the bandwidth of the Ansible. The Ansible can carry multi-band audio, plus an active database of hundreds of thousands of ships. It can’t carry video, but is probably in the mid-FM range of data carrying capability.

Goodness! If I can take a whole paragraph telling you things I think you already know, what’s going to happen when I think I’m breaking new ground!? In a few moments, you’ll wish you never asked. Hold on tight.

I have found two references to Faster-Than Light communications that bear on the science of the Ansible. The first reference, by John G. Cramer, was published in the December-1995 issue of Analog Science Fiction & Fact Magazine, and was titled “Tunneling through the Lightspeed Barrier”. In that article, he describes tests performed in 1993 through 1994, where quantum tunneling of microwave radiation across an insulating gap led to calculated propagation speeds in excess of the speed of light. What?

According to Cramer, a number of scientists took advantage of a quantum effect called “tunneling” to have a microwave signal jump across an insulator which would normally (assuming Newtonian mechanics) block the signal. When they measured the distance across the gap, and divided that distance by the time it took for the signal to jump the gap, they came up with speeds almost five times the speed of light.

“Tunneling” is an effect that only works in the probabilistic world of quantum mechanics. In quantum mechanics, particles do not exist as a specific thing, in a specific place, with a specific speed. For one thing, the Heisenberg uncertainty principle states that the simple act of measuring a particle for its speed will make the location of the particle unknown to you. The opposite is also true: if you know the position, you cannot know the speed. Particles are therefore described as “probability clouds”. Think of the Gaussian “Bell Curve” from when you took that physics test in school. The Bell Curve is low for the really good and really bad scores, but high for the “average” scores. The Bell Curve shows the probability of a grade being really bad, average, or really good. More people are average; not many are really bad, or really good. Your grade is somewhere inside that Bell Curve. The Bell Curve is a probability cloud of grades for the test.

Here’s where quantum mechanics gets all screwy: In the bell curve, you can find out which student got which grade. In the “quantum mechanics” analogy to the bell curve, the act of finding a particular student in the bell curve would make it impossible to find his or her grade; conversely, if you found a specific grade, you would not be able to tell who had gotten it. But wait, there’s more. Let’s say that some particular aspect of the test made it impossible to get a score between 60% and 75%. You would have a gap for that range, with some students getting below 60%, and some (a few) getting above 75%. Keep this image in mind.

Now, think of a group of electrons or photons. The position of the particles can be-must be-described as a probabilistic “wave function.” This “wave function” is analogous to the bell curve from the previous paragraph. The vertical axis is still probability, but the horizontal axis now represents position away from some referenced center, instead of test scores. The likelihood of finding a particle is highest at the center of the probability curve (central position), and weakest at the edges of the curve (distant position). If you consider the position as relating to a central atom, then distance from that atom is proportional to energy of the electron (greater distance requires greater energy; think of getting satellites into orbit). Now, bring back that image in your mind of the bell curve with a gap in it. The quantum mechanical analogy is called the “forbidden energy gap”. There are certain energies (distances, in our discussion) which are forbidden to the electron. Some of this is naturally involved with the construction of atoms (if you are familiar with the atomic spectra of stars, and the bands-or gaps-in those spectra, this is why); some of these “forbidden energy gaps” may be introduced through the use of…electrical insulators. But think, there is still a small but non-zero probability function on the far side of this forbidden energy gap. In the world of quantum mechanics, there remains the probability that an electron (or photon, whatever) can exist on the opposite side of an insulating barrier. For lack of a better word, physicists call this aspect of electron position “tunneling.” An electron that appears on the far side of the insulating barrier is said to have “tunneled” though the barrier.

But how is this faster than light? Obviously, some time must transpire between the electron being at the near side of the barrier and it appearing at the far side of the barrier. As expected, as the barrier grows physically larger, this transit time increases. But strangely, there is a limiting value to this transit time; at some thickness of the barrier, the transit time no longer continues to increase; it remains constant. The height of the probability curve (the likelihood of finding an electron on the far side) continues to reduce, though. What these scientists discovered was that when you go to this limiting barrier thickness, and beyond, the calculated speed of the particles across the barrier can appear to be faster than light. In other words, when you divide the distance traveled by the time to travel, you get calculated speed faster than the speed of light.

Unfortunately, there is no real way to create a series of insulating barriers between here and a far-distant receiver. Plus, as the barrier thickness increases, the signal strength (the quantity of electrons, if you would) decreases with the probability curve. Repeater stations would also be impractical, as you would need physical contact between a lot of repeater stations to get to the nearest starship!

The second article comes a lot closer to what we think of as the Ansible. The article is from The New York Times, Tuesday, December 16, 1997, and is by Malcolm W. Browne. It is titled “Physicists Report the ‘Impossible’: Teleporting a Particle’s Properties”; it is about a phenomenon first described in the mid 1930’s by Einstein, Podolsky, and Rosen. This phenomenon is called the Einstein-Podolsky-Rosen correlation, and is more commonly known as “photon entanglement.” Apparently, one can create a pair of photons from a single action (such as firing a pulse of Ultraviolet light at a Non-linear crystal, as was done in 1997 in Innsbruck), and the pair of photons thus created are “entangled.” When the photon of ultraviolet light shines on that special crystal, two lower energy photons are emitted from the crystal. Because of the nature of the crystal, one of the emitted photons will be polarized in one direction (let’s say “vertically”, just to continue the discussion), and the second photon will be polarized in the other direction (horizontally, for instance). Because of the Heisenberg uncertainty principle, if you were to measure the state of one of the photons, you would lose a lot of other information. You would cause it’s “state” (really, the condition of the information-the energy-about that photon) to collapse from a probabilistic condition to a measured condition. In collapsing, some of the information about the photon is lost. By measuring the object, you affect the object. But, more importantly, since the two photons we are discussing are “entangled” based on how they were created, when you cause the collapse of the information state of the first photon, you somehow cause a collapse in the information state of the second photon. This mutual collapse occurs simultaneously, regardless of the distance between the photons. All that scientists had to do was develop a method of measuring the states of the two photons, and then they would know the state of a far distant photon, without any time passing between. Faster-than light travel.

From what I have read about the experiments directly (thanks, Ami, for the site http://quantumteleport.cjb.net/; you can also find some info in Scientific American, June 1998) this is what is involved:

Person “A” (call her Alice) is given a particle (“Z”) with a definite, though unknown, state. Person “B” (Bob) desires to get a perfect (by the website article’s definition, “teleported”) copy of Alice’s particle. Person “V” (Victor) creates this “entangled photon pair,” and sends one photon (“X”) off to Alice, the other (“Y”) off to Bob. When the first entangled photon (“X”) strikes Alice’s particle, it incorporates the particle’s state into it’s own (in fact, it becomes entangled with her particle, and incorporates an inverse of the particle’s state, and is now in state “-Z”). Because “X” and “Y” are entangled, the state of Bob’s photon “Y” now collapses into the opposite of this new entanglement sitting in Alice’s hands. Bob’s photon becomes the inverse of inverse “Z”, or………”Z”! Viola! Teleportation-an exact copy of Alice’s particle. Distance between Alice and Bob: whatever you need; millions of miles, if you want. Time between Alice and Bob: ZERO. Here’s a for-instance: at two million miles, light takes 10.75 seconds to travel the distance. But with this quantum method, you know Alice’s information the instant it is created.

Consider a simplified version of the “information/energy state” of Alice’s particle. Let’s assume you have a detector which figures a vertical polarization is a “1”, and a horizontal polarization is a “0”. Now, instead of sending a single pair of “entangled” particles out to Alice and Bob, send a stream of “entangled” particles. Using polarizing crystals, you modulate the polarization states of a series of particles at Alice. Bob’s polarization detector fires off a series of ones and zeroes at the same instant Alice modulates her information. Isn’t this Morse code? Modulate faster; now you have radio. Modulate even faster, and you have video. Get the picture?

I can’t help but make the connection between Orson Scott Card’s “Philotics” and its discussions about “twining” and strings, and Einstein-Podolsky-Rosen’s references to “entangled” particles.

[John Locke]

Eriador is essentially right in his early posts about quantum information transmission.
Yes, the quantum state is changed and is copied across great distances immediately.
For more interesting facts on electrical/information communication, look up the Semantic Web and it's visionary, Sir Timothy Berners-Lee.

[Tyme_Brintain]

from what i read in the series the philotic network sounds alot like the strings inside string theory.

taking this into account, wouldnt it be possible...this is saying that string theory is correct tho, wouldnt it be possible to send an instantaneous information transfer between a pair of electrons that have been parted by changing the actual "vibration" of the string that makes up the particle and therefore changing the particle? one change could be counted as a 1 and another could be counted as a 0 therefore sending binary through a pair of electrons?

or there is also the test that when one pair of electrons is parted the are still somehow "attached" through the direction in which they spin. with the pair of electrons one will spin one way and the other will spin the other way so that they can stay as a pair and not fly apart because of their charges. in the test one electron was taken to one side of a building (although it is theorized that this would work on opposite ends of the earth) and the other was taken to the other side of the building. the spin of one of the electrons was changed and the other instantly change to the opposing spin of the newly changed electron on the other side of the building. using this we could, in theory, send on electron to another planet and induce binary based on a system of changing the spin of the electron on the sending planet, say earth, the the receiving planet, say a colony on Mars or Titan.

these theories are prolly thawed but still it makes sense to me.

[zeroguy]

Aha, I've been meaning to post this link somewhere around here, and this bumped thread will do nicely. I mentioned awhile ago (possibly in another thread) about FTL communication causing paradoxes just like time travel would, but I couldn't be bothered to explain (read: I forgot how it works) the details of why. So, there it is; but if quantum mechanics somehow has a way around that, I'm in no position to contest that.