Messages can be exchanged instantaneously through particle entanglement. It is easy to figure out how to do it using the Bell-state Quantum Eraser. I'll give a cut & paste explaining the Bell-state eraser, then explain further if some of you can't see how a message can be sent by using the eraser. "Figure 6.5. Experiment 4 - Bell-state Quantum Eraser. The Bell-state quantum eraser has one more feature: each slit is covered by a substance that changes the polarization of a photon. Consequently, the left-hand slit will receive photons with a counter-clockwise polarization, and the right-hand slit will pass photons with a clockwise polarization. Note: Polarization does not affect interference patterns. Initially, neither detector shows an interference pattern. Since we control the polarization of photons passing through the slits and we know the polarization accepted by each slit, we can deduce which way the photons travelled (counter-clockwise through the left; clockwise through the right). Thus no interference patterns are detected. However, if we rotate the polarizing filter in front of detector A so that the polarizations of the photons that hit the detector are the same (that is, we can no longer distinguish between clockwise and counter-clockwise polarizations), then the interference pattern appears at both detectors! How do the photons arriving at detector B know that the polarizations have been "erased" at detector A?" http://www.joot.com/dave/writings/articles/entanglement/spookiness.shtml All that needs to be done is to use two fiber optic cables of the same length, then transmit a stream of entangled photons from a laser through the cables. One photon from each entangled pair through each of the two cables, as explained above. Locate the observers at the far ends of the cables with the polarizing filters. If neither observer is polarizing the light at his end of the cables, an interference pattern is shown on both screens. When one observer begins to polarize the light at his end, the interference pattern will disappear at the other observer's location, replaced by the circle pattern. This happens instantly, regardless of the length of the fiber optic cables. All one observer needs to do to send a message to the other observer is to use a Morris code by varying the time he reverses from polarized to non-polarized states at his end. The identical code will be shown instantly at the other location. Note that the laser at the beginning of the experiment has to continously send entangled photons through the cables, since they do not travel faster than light, but the observers at the other ends can communicate instantaneously by using the entangled photons that arrive through the exact same lengths of cables. I am not commenting on how useful such a method may be, only that information can be exchanged faster than light.
I try to answer - see below. Like Dinosaur, I am not completely sure of myself (been a long time since I went thru Bell's math, which I encourage all interested to do as it is not as difficult as calculus.) but I think I know what the "QT boys" would say if NO measurement is ever made at the distant location and even what can happen there, "later." A correct understanding of this is why I dislike Zephyr's red and blue flashing planet analogy. True, it makes a simple classical analog of how it is possible to instantly know what is being observed at some distant location, but it misses the main point of QT. It helps promote the type of miss-understanding (or ignorance) displayed by MacM precisely because IT IS CLASSICAL, NOT QUANTUM. The thing that often gets MacM into trouble is that QT violently disagrees with common classical experience. (So does SRT, but that is another story.) The essence of QT entanglement, if forced into Zephyr's model, is that the planet is on each flash is emitting BOTH red and blue flashes yet when A observes red, distant B observes only blue. I.e. until "an observation" is made, somewhere, the system is in a "mixed state." Any observation on either will do to force the system into a "pure state" or "eigen state” to keep the original German word, still used in most English QT courses. (Eigen is a math term, in use long before QT was known.) To be general, if the "mixed state" of “object” (particle or photon) is A + B with state A and state B each being 50% or equal in "strength," then observation on either separate object, will make it a pure eigen state, either A or B and the other, still unobserved object, is at the same time forced into the other state. That is, the amount of A and B states in the universe is statistically* unchanged by the observation. (Counting the two "joined" or "entangled" particles in the mixed state as one A and one B because BOTH are "half A" and "half B") Now that the distant object has been forced into a pure state it can be changed, or naturally evolve** into other possible states, even interacting with another object to form a new mixed state. (It has been liberated - no longer tied to its original partner, who most likely no longer exist as “observation“ killed it.) For example, if the distant object is a photon and the local observation forced the distant photon into pure vertical polarization and it is not destroyed by a simultaneous distant observation, then it could enter an "optically active" crystal, such as ADP, and emerge as a horizontally polarized photon. Hope this helped. _________________________________________ *I think this word required as the original mixed state could have been 40/60 % of A & B respectively. (At least in principle. - I do not know if any unequal mixed entangled state has ever been made, but see no reason why it could not exist.) I am not absolutely sure, but think that in this case, on 1/5 of many identical repetitions of simultaneous*** local and distant measurements, the results of both measurements will both be "state B." I.e. You get: A&B results+ A&B results+ A&B results+ A&B results+ B&B results on average to be still a 40/60 mix favoring B after the mixed state has been forced into two pure eigen states. (I have never seen this “statistical state conservation law” -It just occurred to me as I was writing this, but I think it true, and unfortunately for me, probably already well known. - If not, please refer to it as the “BT rule.“) Note also, in Zephyr's red&blue light emitting planet with unequal intensity in the lights, sometimes, both observes "see blue" if blue was dominante light emitted. Also, even if the above 40/60 % in favor of state B exists in the original mixed state, then very rarely the result can be, I think, A&A. (I am very uncertain about this, but I suspect that this is possible, but rare, even if blue or B is dominant. I am certainly getting in over my head for sure now. This would mean, if true, that in the 50/50 mixed state, one can not be sure that the result is A&B every time.) **It is ironic that the evolution is completely deterministic! Only an “observation” can make a random outcome. What is the essential nature of an “observation”? - Answer that and go straight to Stockholm for your prize. ***All in one frame, of course. (Reference frames are “universe wide.”)
A refinement of the Bell-state Quantum Eraser exercise I outlined above would be the following. Launch a detector/double slit device along with a crew for a future Mars mission. Launch a laser to emitt the entangled photons to a location mid-way between the Earth and Mars. The entangled photons do not need to be emitted through a fiber optic cable in this exercise, only one stream of the entangled photons toward Mars and their counterparts emitted towards Earth. Same as above, by measuring the photons arriving at the Earth with the polarizer, the pattern will change from the interference pattern to the non-interfered pattern at the Mars location. If the laser emitting the photons is not exactly midway between Earth and Mars, the communication will not be exactly instantaneous, but still much faster than a radio signal beamed from Earth to Mars at the speed of light. Remember, you are measuring members of the entangled pairs that have arrived on Earth at approximately the same time their counterparts have arrived on Mars. Why could this not work if the laser were powerful enough to emitt enough entangled photons so the pattern could be ascertained at each location (Mars and Earth)?
The least amount of sure information is called a "bit" - For example, I have written either a one or a zero on the paper before me. Your knowing which gives you have one bit of information. Please tell me how (operational details) you can use QT entanglement to send even one bit from point A to point B. A lot of people, me included, say you can not do this via QT entanglement. For example, you write a one or zero on your paper, and tell me which it is via QT entanglement experiments.
Each photon only interfers with its self, not with any other. Very low intensity, long photographic exposures still show the inteference pattern (proving the above) even when there is essentially zero chance that two exist at the same time.
Better read the information at the link I gave, Billy T. Or, are you stating that the information is incorrect? Are you familiar with Bell-state erasers? Again: "Initially, neither detector shows an interference pattern. Since we control the polarization of photons passing through the slits and we know the polarization accepted by each slit, we can deduce which way the photons travelled (counter-clockwise through the left; clockwise through the right). Thus no interference patterns are detected. However, if we rotate the polarizing filter in front of detector A so that the polarizations of the photons that hit the detector are the same (that is, we can no longer distinguish between clockwise and counter-clockwise polarizations), then the interference pattern appears at both detectors!" http://www.joot.com/dave/writings/articles/entanglement/spookiness.shtml
No. Wife says I must eat dinner now, so I will try to look later. But please tell me if there are always photons passing thru your two slits. If yes, then there is alway the inteference pattern on screen as each interfers with itself and thus of course has its own polarization, not matter how you force that polarization to be at some distant point.
I never said you could asshole. I use that friendly adjective because you saw fit to referance my name once again above and comment about my ignorance even about a subject for which I have had little comment. You would do well to give specific examples of my ignorance rather than your shotgun techniques. Keeping in mind "Ignorance" means lack of knowledge, not what is my case which is rejection of what you call knowledge. That sir is not ignorance. You seem ignorant of the meaning of ignorance. All your huff and puff has not addressed the issue of information being transmitted by the entangled particles. This has nothing to do with mankind developing a communication system using particle entanglement but only the fact that these particles must be sharing information FTL. Address that issue since it is the only one I have commented on. Question: "Do you argue that entangled particles DO NOT transmit information to the other particle when it changes state"? If not by what mechanisim do you suggest the other particle knows to also change? BTW: Be sure to read my post above regarding the definition of communication.
Yes, there are always ENTANGLED photons passing through the slits at both locations. That's the whole point. You are speaking of regular photons, Billy T, not entangled photons at both locations.
2inquisitive, Could you post a diagram or a sketch? I'm having difficulty envisaging it. Are all of the entangled photons polarized, with the orientations of the polarizing filters determining whether the photons' true paths are known and an interference pattern produced? If so, I don't see how the presence or absence of an interference pattern on Earth will dictate whether or not one occurs on Mars. Can't photons reaching Earth's receiver build up an interference pattern (because their paths through the slits are unknown) while their entangled counterparts at Mars do not (because their paths are determined)?
Yes, when the photons are split by the crystal, the entangled photons will have opposite polarizations. There are plenty of illustrations at the link provided. Oh, and when the polarizations of the photons are determined at one location, it causes the interference pattern to disappear at the OTHER location as well. That is how my example works, by detecting the changing patterns at the other location. By turning the polarizing filter at one location, the pattern at the other location can be monitored for a sequence, like short-long-short-short-long, etc. by altering the rate at which the polarizing filter at one end is rotated.
Ok, but how will determining photon paths (thus cancelling the interference pattern) at one detector force a result at the distant receiver?
This has nothing to do with the path of the photons, only polarizations which do not destroy the photons.
If the polarizing filter is not used, the photons can be thought of as passing through both slits, causing an interference pattern. If you force the photon to 'opt' for one or the other by using a polarizing filter, interference does not occur. I thought that this was the basis for your communication system.
By BLOCKING one slit, the photon can be thought of as passing through only one slit. Polarizing the slits does not block the slits, the photon can still pass. Read the link, please. These types of questions are answered. You have to know something about the Bell-state eraser before you can understand my proposed experiment. http://www.joot.com/dave/writings/articles/entanglement/spookiness.shtml
I'm out of my depth but I don't see how an interference pattern is produced at all at detector A if there is no double slit there.
OK, I have now had time to read your reference: but either I do not understand of it has some errors. (I was glad to see it also told you that each photon interfers only with itself.) It states: "Note: Polarization does not affect interference patterns. Initially, neither detector shows an interference pattern. " First sentence is true as one normally understands it to be polarization of the incident stream of photons, but the second sententence is also true as they have reversed polarizing filters separately covering only one slit each. The electric fileds of photons passing thru one slit when reaching the screen is orthogonal to that same photon traveling via the other slit (orhogonal electic fields can not add to zero. (no interference, so in their case, the first sentence is false.) If strength of the E field of one photon was 2 before coming to the slits and 1 each while passing thru the two slits, then the orthogonal E fields at the screen add to square root of two, which when squared (intensity of light is porportional to the square of the field) is 2. The original intenensity was 4 (the square of field strength 2) so as expected, half of the intensity has been lost in passing thru the two reversed slits. I will leave it as an exercise for you to show that if a vertically polarized beam is split into two parts, still vertical polarized, an one part passes thru a polarizor inclined at angle alpha and the other thru polarizer orthogonal to first, then they are recombinded that half the intensity is lost, regardless of angle alpha. Point being that with orthogonal polarizers separately covering the two slits, half the intensity is lost and there is no interference in what remains. There is more confusion as the article progresses.
No information has been transimitted, not even one bit. Part of this is the dificulty of comunicating with you as you have little experience with QT state functions. They need not be localized in 3D space and are one thing. if for any reasons (natural deterministic evolution under Schroedinger equation of by "Observational interference" a ramdom change is made in this one thing, this one thing is everywhere changed. - no signal sent any where. No "commuication" of informations. You simply are ignorant of the the details of QT and i agree that this is not an insult, only a statement about your state of knowledge which make it hard for you to appreaciate that no infomation has been sent anywhere. Nor can it be, via entanglement.) If you want to invent some new definitions (Not those developed by Shannon, years ago) and nonconventional ideas about communication (does not require the abillity to send even one of Shannon's bits etc., feel free, but do not expect the world to get into step with you. instead expect lot of problems speaking to people who are not ignorant about these standard terms and definitions.) - I will try to get to rest of your post if it merit reply later. A lot appeared while eating my dinner and I want to read first.
No I am speaking about ANY photon. It will interfer with its self if the part of it passing thru only one slit is not "twisted" (repolarized) wrt the part of it pass thru the othe slit. Regardless of of the state of polarization or any changes in the state of polarization (be they by a local ADP crystal or a observation of its entangled partnern on other side of universe) made prior to passing thru both slits, that one photon will (Normal condition): interfer withitself. (abnormal condition with reversed polarizer covering only one slit each: not interfer with its self.) PS - I have mentioned ADP crystals as they are very optically active, but not very non-linerar so unlike the crystals of BO, which are non - linear in the induced fields created by the passing photons, ADP is not used to make to phase and polarization locked sub harmonic photons out of one. ADP is good for rotating plane of polarization and particular interesting because they can be switched by appling an external electric field (I worked briefly with them years ago. wonderfully fun to grow - I made a few nearly perfect single crystals big as my thumb.)
Your claimed solution is BS pure and simple. Frankly I really don't care what others say or have said. Nor do I care what you say. YOU are speaking from ignornace of how it actually transpires physically so your arguement is based on ignorance. You now suggest some wave function exists everywhere in the universe simultaneously and collpasing the wave, or what ever has the affect of change everywhere simultaneously. What a load of double talk crap. If that is the best they can do they should find other occupations.
