Jump to content


Senior Members
  • Posts

  • Joined

  • Last visited

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

bangstrom's Achievements


Atom (5/13)



  1. If the given particles carry an attribute that locally determines the outcomes, there would be no need for a signal. This is the most intuitively obvious explanation but it was one of the first hidden variables ruled out by the Bell test so it is not supported by experimental evidence. I suspect the wave like connection between entangled particles and its instant loss on both ends could serve as a non-local signal that establishes the correlation. BS: I' m familiar with the setup of the classical channel but you haven't explained how the classical channel is necessary for the quantum channel or how it can have an affect on the quantum channel. I don’t recall where Markus said there was no FTL signal. If he did, then I don’t agree. You are right. Singlet states include entanglement. I learned something.
  2. No one is thinking classically and no one is saying entanglement does not exist so your presumptions are 90 degrees off base. The singlet state is: In quantum mechanics, a singlet state usually refers to a system in which all electrons are paired. The term 'singlet' originally meant a linked set of particles whose net angular momentum is zero, that is, whose overall spin quantum number s = 0 {\displaystyle s=0} . From wiki. This is not the same as entanglement where the particle states are indeterminate and the particles frequently far apart. I don't recall that Markus ever equated the two. "Quantum entanglement is also a series of local events, starting from the instant when the entanglement was first created - joigus was quite right in bringing up this (classical) analogy. The difference between them is simply counterfactual definiteness." Markus from p. 22 My objection was to the, "Quantum entanglement is also a series of local events, starting from the instant when the entanglement was first created." This sounded a lot like a 'hidden variable' theory where the entangled particles are anti-coordinated and unchanging in their properties from the beginning especially since this applies to the analogies "joigus" presented which involved EPR style hidden variables. Upon review, I see Markus later explained that his remarks were about the duration of the entanglement and not spin states, in which case, I stand corrected. And we are in agreement about quantum properties not being in fixed positions from start to finish in an entanglement. The particles being entangled is not a hidden variable. The latter involves a hidden variable where the particle spins are established from the beginning and remain unchanged until entanglement is lost.
  3. Apparently, Bell was quoting from the EPR article when he listed what he considered to be 'hidden variables. I agree that local hidden variables have been ruled out by the Bell test. The ruling out of hidden variables by the Bell test is what 'invalidated' the EPR article. No hidden variables means there no hidden variables therefore hidden variables have no speed because they don't exist. I don't see the connection with FTL. The FTL signal is a measured value not necessarily a predicted value from QM. The cosmos doesn't care. All speeds and directions are relative but somehow they manage to exist. Also, the cosmos doesn't care about SR. The classical channel is for measuring the predicted polarity of the teleported signal. It has nothing to do with the preparation and sending of the signal for teleportation. It is for measurement purposes only. The polarity of the teleported signal can not be predicted until the polarity of the particle from the second entanglement has been measured. When the polarity has been observed, then the receiving end can be informed by radio of what polarity needs to be measured and the receiver is set to record the predicted polarity of the incoming signal to verify that the teleportation was successful. Zeilinger can successfully teleport without the classical signal but he needs a measurement at the other end to verify that his teleportations were successful. Otherwise, he is like a target shooter shooting blind and without a target. The classical signal must be sent AFTER the teleportation has taken place to make a prediction and the receiver must be prepared to receive the signal BEFORE the teleported signal arrives. This is an extremely short window of opportunity but it can be done by high speed electronics.
  4. I have answered this several times despite your numerous claims that I never answer a question. It is impossible to send more than one qubit of information at a time via quantum entanglement and this is too little information to be intelligible at the macro level. The signal sent is necessarily random on both ends so a sender can not know what they sent and a receiver can not interpret the results. Also, the sender and receiver of a FTL signal are beyond reach of a light speed signal so neither can know if the other has sent or received the signal until a later consultation. Just because sending instant signaling at a distance is impossible at the Alice and Bob macro level doesn’t mean it is impossible at the quantum particle level. FTL communication is impossible at the macro level. I have repeated that many times. FTL signaling is experimentally demonstrable at the particle level. Quantum particles appear to be able to exchange information instantly and at any distance as if they are side-by-side and they don’t require our explanations or Einstein’s permission to do so. This is why I find so many of the views expressed here as impossible to accept. You and others may claim the EPR article has never been invalidated therefore hidden variables are still in effect. You claim Bell doubted that his inequalities ruled out hidden variables so we can ignore Bell and there is no instant action at a distance since quantum experiments of the last fifty years have never demonstrated any kind of FTL transmission because that violates relativity. Your views appear to be fifty years out of date. This has been demonstrated as false by experiments involving Bell’s inequalities. The idea of quantum systems having definite and unchanging quantum properties while entangled is one of the 'hidden variables' ruled out by the Bell test. Zeilinger among others have demonstrated that a quantum property can be teleported in an instant to a series of entangled particles. Quantum properties are not definite from start to finish and can even be altered by later outside events. As I say, yours is old time physics. I have answered the questions, just not to your satisfaction and perhaps not to theirs, and my "misconceptions' have have been "shown very clearly" out of line with the 1935 EPR article so I'm not buying. I did agree with Markus with the exception of his comment about quantum properties remaining unchanged from the start. That is one of those hidden variables ruled out by the Bell test. It is possible to discuss SR without mentioning entanglement or entanglement without mentioning SR as Markus did. They are two different topics and the discussion about SR was getting circular far off topic in this thread about entanglement. In this "imaginary world" of mine, it appears that one quantum particle can ‘know’ the states of other quantum particles even at great distances and two or more particles can instantly coordinate their behaviors. And lab experiments demonstrating quantum entanglement support this view. John Clauser and Alain Aspect, in the seventies and eighties, demonstrated in separate experiments that quantum entanglement was real, that it acted instantly and that no local effect could be responsible for the coordination between the particles so the entanglement was non-local. Their experiments and those of others have shown that entanglement is characterized by non-locality with the two particles sharing a common wave function such that, when you measure a quantum property of one entangled particle, you instantly know something about the other particle, even if they are a great distance apart- theoretically even galaxies apart. If you look outside your bubble, you should find that this is not just my view but it has become the mainstream common consensus.
  5. The part of the experiment you are ignoring is the part where a photon from the first entanglement enters the fiber optic cable with an unknown polarization only predictable as random and emerges with a predictable polarization that was decided by the later observation of another photon from a second entanglement. The information gathered from the observed photon was ‘teleported’ to the earlier photon while in flight which is only possible if the transmission was far faster than light. The photon in the cable was delayed by its transmission through fiber glass just long enough for the predicted polarization of its newly teleported condition to be transmitted by radio to the receiving station across the river. This enabled the receiving station to verify that the teleported condition of the incoming photon had been successfully completed. The radio transmission to the receiving station was automatically transmitted after the teleportation but before the reception across the river. This is the timing of events that makes the experiment so remarkable in that it demonstrates the successful transmission of a quantum property from the identity of a photon left behind to a photon ‘in flight’ away from the source. This is not possible in classical physics and it supports Bell’s conclusion that the quantum properties of entangled particles observed at the end of an entanglement are not fixed or unchangeable from those at the start and that they can be altered instantly and ‘at a distance’. This rules out the main points of EPR article. Entanglement has long been known to be superluminal so there no need to mention this with along with every description. You appear to be saying there is nothing superluminal taking place with quantum entanglement or with quantum teleportation but the Danube experiment and similar experiments by Zeilinger and others around the world do not support that view. The reason is that I have an unbiased interest following advances in quantum experiments for the past forty years. So far, you have demonstrated almost no understanding of the experimental side of things and your unsupported personal opinions are fifty years out of touch with the revolution in thinking has taken place with and around this years three Nobel prize winners.
  6. Experimenters with entanglement and quantum computing have explained how their FTL transmissions are not in violation of relativity and I have repeated their explanations several times already. Personally, I find their explanations a bit contrived and in violation of Einstein’s second postulate. If that is correct, I will paraphrase Einstein and say, “If there is a FTL signal, I feel sorry for Einstein because the dear Lord has a better way.” Such a signal is consequential and the signal itself can’t be observed but we see what appears to be evidence of a signal sent and signal received. With quantum teleportation, some property of an entangled particle can be observed and instantly teleported to a remote entangled particle even if the other particle was generated by a previous entanglement. This demonstrates that the expected quantum property of an entangled particle can be changed in an instant. The FTL nature of experiments with entanglement has been observed since the late sixties and serious attempts to measure the speed of entanglement have been performed over the past twenty years from Switzerland to China and places in between. So far all of the attempts have found the speed too fast to measure. Quantum "spooky action at a distance" travels at least 10,000 times faster than light https://newatlas.com/quantum-entanglement-speed-10000-faster-light/26587/ There was a radio signal sent to prepare the receiver to receive the incoming signal from the teleportation. It had nothing to do with the generation or transmission of the teleported information. The radio signal was plane old Hertzian all the way. The photon sent through the optical fiber was one of four entangled photons and it was a photon from the first entanglement. The identity of the other free photon remaining behind from the second entanglement was observed which instantly broke the entanglement and established the identity of all four entangled photons including the one in the optical fiber. The revealed identity of the photon in the fiber optic was teleported instantly to to the photon in the cable en route to the receiver. This is the part of the transmission that is instant and non-classical. https://www.nature.com/articles/430849a The radio signal was sent to an electro-optical modulator EOM on the receiver end. An EOM is a bi-refringent crystal between two plates of a capacitor. An EOM can can be used as a variable polarizor. It has no moving parts and the polarization can be rotated electronically by applying the proper DC voltage. The polarization can be oriented to the proper position in nano seconds before the photon arrives in 1.5 microseconds. https://www.nature.com/articles/430849a Also, note the smaller square on the lower left side of the diagram. This is where the two entanglements are generated for the experiment. A strong 150 femto second pulse of UV light from a laser is sent through a BBO crystal to hopefully generate a pair of entangled photons. The UV light that passes through unchanged is reflected back by a mirror to pass through the BBO crystal again to generate the second pair of entangled photons.
  7. The “rest of the statement” was my few words before and after the quote from Bell that you lifted out of text. I think the quote came from Bell’s “Bertlmann’s Socks”. The quote wasn’t the one I was looking for and my reply wasn’t explicit enough. Anyhow, the quote was Bell’s comment about what he considered to be ‘hidden variables’ and ‘hidden variables’ were the things from the EPR article ruled out by Bell’s inequalities. John Bell was not a supporter of hidden variables and his ‘inequalities’ ruled out their presence contrary to Einstein’s EPR article. Aspect and Clauser were the first to demonstrate experimentally that Bell's Inequalities violated the EPR effect. I explained this before Teleportation works without the classical channel. The teleportation in the Danube experiment was accomplished within the time it took three entangled photons to traverse the optical bench and send one teleportation signal to a fourth photon on the way to the distant receiving station and also a radio signal to the same station to set the polarizer. The teleportation signal had to be FTL to reach the photon on route through a fiber optic cable to the receiving station. Can you explain how there is no FTL signal? Here are two videos that explain different aspects of entanglement including the instantaneous transfer of information, hidden variables, and the violation of Bell's Inequalities. https://www.youtube.com/watch?v=0RiAxvb_qI4 https://www.youtube.com/watch?v=US7fEkBsy4A Oh man, trying not to loose your face, you now even have lost sight of what entanglement is. We know that the particles are entangled from the beginning, because they are produced entangled. Do you suggest to show entanglement is real by using particles that are not entangled from the beginning? I didn't answer the question because I thought a "good reader' like yourself would realize that their question made no sense so they must have read some nonsense into something I wrote and check to see what I really did say. If not the first time they asked, then before they asked the same question again. Obviously, entangled particles are entangled from the beginning of entanglement to the end. They don't take a break in the middle and then resume. I said HIDDEN VARIABLES are not there at the beginning or at the end. Hidden variables are not the same as entanglement and the presence of hidden variables was ruled out by Bell et al.. To say that entangled particles are anti-coordinated at the end because they have been anti-coordinated since the beginning, that is one of the hidden variables that was ruled out by the Bell test. The particles are not in a singlet state when entangled. Not my favorite explanation, but the conventional explanation is that the particles are in a state of superposition while entangled. Anything that acts on one particle also acts on the other no matter how far apart they may be. The singlet states do not appear until entanglement is lost.
  8. John Bell? Less so: that is from the EPR-article. And you said somewhere 'EPR is invalidated' (whatever that means...) But now it supports your viewpoint? Wow. If you read the rest of the statement John Bell was listing in the quote the sort of things he considered “hidden variables’ in the EPR article and the hidden variables were what Aspect and Clauser ruled out as invalid fifty years ago. I never claimed to concur with the EPR's hidden variables. What role does the classical channel play in the success of quantum teleportation? As I said, the classical channel only serves to prepare the receiving apparatus to receive the signal when it arrives. I understand the statement to say a classical signal lacks an “immediate interaction”, but if it had a FTL signal, it would no longer be a classical signal. Is that your interpretation or something else?
  9. Yep, that is what characterises entanglement. The directions of the spins are anti-correlated, meaning that we know from the beginning that if we 'add the spins' (when measured in the same direction), we will get zero. "From the beginning"implies one of the 'hidden variables' ruled out by the Bell test. Nope. The 'hidden variables' ruled out by the Bell test are properties of the particles that determine in advance what spins will be measured. The ‘hidden variables’ are not about what spins will be measured. And "from the beginning" implies that the entangled particles carry some prior set of instructions with them about how to respond when measured. Hidden variables are, “either (1) the description of reality given by the wave function in quantum` mechanics is not complete or (2) two quantum operators cannot have simultaneous reality.”- John Bell Neither one of these possibilities explains entanglement where two particles can be observed to be correlated when measured- even if they are beyond reach of a light speed signal. That would give them a simultaneous reality and require some kind of ‘action at a distance’ not permitted by the conventional interpretations of relativity. The only purpose for the classical signal is to set the polarizer to the correct position to receive the incoming signal. The incoming signal is already prepared and on the way by then. The classical channel plays no role in the completed entanglement. In the original Danube experiment and those that followed, the classical channel was for the purpose of preparing to measure the incoming signal from the entanglement experiment which was delayed in transit by being sent through a fiber optic cable. It had nothing to do with the preparation of the signal and was therefore not a requirement. The prospect that entanglement is “fixed from the start” is one of the hidden variables ruled out by the Bell test. This was my objection and I know you never mentioned the direction of spin. That was part of a question from Eise. My question is, what is the material explanation for the correlation? That is, how does local environment of the second observation determine that the second particle be anti-coordinated with the first observation? Their correlation upon observation suggests some kind of a signal from the first observed to the second.
  10. All I saw was incorrectly drawn light cones. Rømer's 'speed' could also be correctly called a dimensional constant. The usage of c as the 'speed of light' in relativity works best when considered as a dimensional constant rather than as a speed. The speed of light in a vacuum is a cliche but how can a speed be relative to a vacuum which is nothing at all and also the same for all observers? This is more like a dimensional constant than a speed. There is nothing classical about quantum teleportation and your claim that correlation is not a hidden variable is your view- not Bell's. The shoes in boxes thought experiment was shown to be invalid by the Bell test. What is this anti-correlation "given" that is maintained throughout periods of superposition and changes of quantum properties. He said the anti-correlation was fixed from the start. This was one of the 'hidden variables' ruled out by the Bell test. The classical signal was sent to set the angle of the polarizer on the receiving end in preparation to measure the incoming photon upon its arrival. It had no effect on the condition of the photon arriving on the other channel. The photon receiving the teleportation signal was sent through a fiber optic cable which gave the receiving end enough time to set the angle of the polarizer. The polarizer was electronic with no moving parts so it could be changed almost instantly. The teleportation was achieved while the entangled photon was in transit. The 'signal' that decided the quantum state of the receding photon had to be far faster than light to catch up with a photon in flight.
  11. Your light cone makes sense. Joigus's didn't. I say the value of c works better in SR as a spacetime dimensional constant than when considered as a speed. In 1676, Olaus Roemer discovered that c was simply a constant relation between measures of observational distance and observational time in the constant ratio of c. He was looking for a speed and discovered a universal constant ratio of time to distance. Unfortunately he called it a speed and it has been known as a speed ever since. The true speed of light is unknown and unknowable because our units of length, time, and c are all mutually defined.The length of a meter is now defined as the distance light travels in 1/c seconds etc..Any attempt to measure the speed of light is like trying to measure the speed of light over the distance of a light year. As I recall, Markus was claiming that the anti-coordination revealed at the end of an entanglement was there from the start. This was one of the first 'hidden variables' ruled out by the violation of Bell's inequalities and debunked by the experiments of Aspect and Clauser. Also, Zeilinger's teleportation demonstrated that an entire series of entangled quantum properties can be reversed remotely and in an instant. This would not be possible if the quantum properties were fixed and unchanging from the start. I agreed with his first statement but the one point about the quantum properties being fixed from the start was where our views parted company.
  12. Entanglement is not a part of relativity and only the ‘second postulate’ and entanglement are not in agreement. The rest of relativity is OK. The end of an entanglement would be in the same light cone but represented as two simultaneous events in different locations. This is entanglement and not classical physics. Your light cones were intelligible because they had no world lines for the entangled particles. The world lines also wandered outside the bounds of the cones and failed to pass through the intersection between past and future. Mainly they demonstrated nothing about entanglement. In classical physics, an electron can only interact with a limited number of other electrons through some form of direct physical contact. However, with entanglement an electron can establish an instant two-way resonant connection with any other electron on its pair of light cones if the intervening space permits. And such a pair can interact as if they are side-by-side even if they are galaxies apart. That is entanglement. Entanglement is what Einstein called, “Spooky action at a distance.” but it has been demonstrated experimentally many times over since Aspect and Clauser. You appear to reject the whole notion of ‘action at a distance’ as well as the violation of Bell’s inequalities in favor of ‘hidden variables’ and the EPR effect. This is why I find your views to be fifty years out of date. Why do you assume I know nothing about electric fields and how a circuit works? This is old stuff to me and it has little to do with the topic of entanglement which you apparently either reject or know little about. I am arguing that entanglement needs no direct physical intervention between two remote particles to precipitate a cause and effect. The particles may be remote from each other, but while entangled, they act as if side-by-side or superimposed. You can’t affect one without instantly effecting the other even when they are beyond reach of a light signal. That is what is called non-local action or action at a distance and it is not classical physics.
  13. Again, a light cone can be about whatever you choose to illustrate. They were your light cones and I didn't see any that quite resembled entanglement. Entanglement would be slightly more difficult to illustrate with a light cone than ordinary events because it would usually require two or more separate but overlapping light cones to illustrate and I have never seen it done. You didn’t explain that was your intention and I still don’t understand what you mean. An illustration of entanglement should require at least two world lines, one for each particle, and each particle would need to stay within its respective light cone. Your illustration on the upper left “most” resembled entanglement but none of them made sense as representative of entanglement. In your picture on the upper left, I see one one event in the future and one in the past but no world lines for the entangled particles Entanglement violates the EPR situation in that one entangled particle can interact with its partner(s) instantly as if the they were side-by-side. Entangled particles need no physical connection to interact- not even light. It is instant action at a distance that violates the EPR. Your illustration on the upper left “most” resembled entanglement but none of them made sense to me as representative of entanglement. "In the same light cone" means that one particle, usually an electron, can interact instantly with any other similar particle within the same light cone provided that conditions between the two permit. This is possible in QM but not in classical physics so that is a major contrast between the two and I wouldn’t call it “nothing.” In the the classical situation, one particle can only interact with another either directly or through some physical interaction. QM needs no physical interaction. The value of c works perfectly well as a universally observed dimensional constant and it behaves nothing like a speed. Just because c is the ratio of distance over time doesn’t mean it is a speed, and since c=d/t is a constant, that should be our first clue that c isn’t a speed. The determinations of the magnetic permeability and the electro permittivity in Maxwell’s equations are static tests and their combination is a constant for the vacuum. They are speed in the dimensional sense but they are not speeds in the sense of something moving.
  14. Entanglement is most like your picture on the upper left where one particle is in the past light cone and the other is in the future. All of our communications, whether involving entanglement or not, is received from the past and sent to the future. John Cramer’s Transactional Interpretation of QM is an extension of the Wheeler-Feynman approach to atomic transitions where EM signaling can be interpreted as direct and instant interaction between emitter and absorber with signals moving both forward and backward in time as a prerequisite to the transmission of energy. Thermodynamics limits our observation of events to the emission of energy from the past and arriving in the present. In Cramer’s and similar models, there is an instant, two-way signaling between the emitter and absorber that precedes any transfer of energy which is why light always travels as if prescient of its destination.
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.