# Regarding time dilation and particle entanglement [closed]

I have a question regarding time dilation and particle entanglement. As I have read a few forums and questions here, I am aware both aspects do not contradict each other. Still, a question that I am having remains quite unanswered.

Imagine we are using a fictional device that relies on entangled particles to transfer information from a station on Earth and a space ship. Regard this as a communication device, that provides "real-time" communication, since it is not subjected to the delays that time lag causes with radio waves. The communication is established as a two way, and each end is responsible for sending signals for its state and receiving data from the other end. There is no central system in between, the two ends communicate directly to each other. For the sake of the question, please assume the device simply exists, rather than discuss whether is it possible at all to create such.

Now, the scenario involves a direct audio and video communication (like a Skype conference call) between the station and spaceship.

What would be the experience of the communication for both parties as the ship is launched in space and hypothetically reaches relative speed to the one of light?

I personally assume that the Einstein paradox of both clocks slowing down will not be present, as the quantum entanglement should provide real-time communication. Still as the speed difference becomes significant, I assume the guys on earth would observe slower rate of signals coming from the space ship due to the time dilation, thus they will see it slowing down to still image. On the contrary, the ship crew could see the events on earth getting faster and faster. At such point a meaningful real-time video and audio communication (supposedly supported by the device) would probably be impossible.

What are you thoughts on this?

Update: (regarding the answer of fellow user vnb)
The device does not transmit information faster than light. The communication is immediate in terms of reflecting the action on any of the parties and immediately presenting it to the other (which I believe is achievable via quantum entanglement). Thus, the speed of the information flow will be the maximum possible speed of decoding the particle's state of the receiving reference frame.

Therefore the purpose of the question is, what would be the possible twists and distortions of the information that the other party receives when one of the parties is affected by time dilation?

• Your edit is self-contradictory. If one of the parties learns information about what the other party is doing to their system immediately - i.e. simultaneously - then information is being transmitted faster than light. This is not possible using quantum entanglement. – Emilio Pisanty Dec 2 '13 at 10:07
• @EmilioPisanty I am not quantum entanglement expert, so I am not arguing, but isn't the state of an entangled particle immediately updated on its counterpart? I rely on this principle to provide iformation immediately to participant B as participant A's information has been recevied by the entangled particles in A's device.There will be processing time for the device to decode and display the information that is relevant to the reference frame of the device, as is the response speed of the participants, which I believe are insignificant compared to the radio communication delays we know – Ivaylo Slavov Dec 2 '13 at 10:16
• Measuring on A will indeed cause the state of B to collapse 'instantaneously' (or at least can be seen to). However, the measurement outcome in A is random, which makes the final state in B to be random. If A can communicate (at $v\leq c$) the results of his measurement, then B can make sense of the result. For more information see e.g. this answer, and others on this site. – Emilio Pisanty Dec 2 '13 at 10:37
• I think I am getting the point - neither A nor B have a basis to compare the state of a particle in order to detect a particular change, i.e. the means to decode a message. – Ivaylo Slavov Dec 2 '13 at 10:45

Basically what you're asking is if information can be transmitted faster than the speed of light. According to quantum mechanics, it is impossible to use quantum entanglement for transmitting data faster than light. This is know as Eberhard's theorem; more details about can be found here (I'll try to provide a link with full access to the article). Entanglement or the spooky action at a distance, as Einstein called it, has to do with the correlations that you see when comparing the measurements on a entangled pair. However, if you were look at data from a particles where each constituted one half of an entangled pair, without being able to compare it with the data from measurements of their twins, it will just look random. So you'll have an unreadable message. Also this article might be useful.

At the AQRTP Workshop we considered the question of whether quantum nonlocality was a possible medium for FTL communication. In the context of standard quantum mechanics there is good reason for believing that it is not. Eberhard has proved a theorem demonstrating that the outcomes of separated measurements of the same quantum system, correlated by nonlocality though they are, cannot be used for FTL observer-to-observer communication. A possible loophole in Eberhard's theorem could arise if, following the work of Nobel Laureate Steven Weinberg, one modifies conventional quantum mechanics by introducing a small non-linear element into the standard QM formalism. It has been shown that in slightly non-linear quantum mechanics, the observable nonlinear effects that would arise would make possible FTL communication through nonlocality.

• Thank you for the information and links. I will read them and probably consider your answer. There is one thing though - I never had in mind for information to be delivered faster than light. Instead, I wanted to get more clarity on how that information will look like when exposed to time dilation. My thesis is that quantum entanglement will ensure immediate data exchange between the parties, which would be as fast as any party can send information. So, the problem is need that information be made readable. – Ivaylo Slavov Dec 2 '13 at 9:47
• It's not so much "immediate" as outside time. No matter which observer looks first, or if there is no absolute first (spacelike separation), they get correlated answers. Note that the times are different depending on your reference frame: so what can "immediate" mean? – JDługosz Nov 21 '14 at 10:51

these papers are predicting the possibility of measuring a particle or electromagnetic waves to move faster than light without violation of Lorentz transformation or causality. According to the papers It could solve many paradoxes related to special relativity, Twin paradox, Ehrenfest paradox, Ladder paradox and Bell's spaceship paradox. in the papers it is considered as new understanding to special relativity depending on the concepts of quantum theory (Copenhagen School). It is new understanding for the time dilation and length contraction. What it is proposed in the papers is agreed with and interpreting the experimental results of quantum tunnelling (Gunter Nimtz experiments) and quantum entanglement. Recently, there are some voices in physics asking for the variability of the speed of light, one of them the Portuguese cosmologist and professor in Theoretical Physics at Imperial College London JoÃ£o Magueijo. In 1998, Magueijo teamed with Andreas Albrecht to work on the varying speed of light (VSL) theory of cosmology, which proposes that the speed of light was much higher in the early universe, of 60 orders of magnitude faster than its present value. This would explain the horizon problem (since distant regions of the expanding universe would have had time to interact and homogenize their properties), and is presented as an alternative to the more mainstream theory of cosmic inflation. the papers are agreed and interpreted the variability of the speed of light which is introduced by Magueijo. Recently also two forthcoming European Physical Journal D papers challenge established wisdom about the nature of vacuum. In one paper, Marcel Urban from the University of Paris-Sud, located in Orsay, France and his colleagues identified a quantum level mechanism for interpreting vacuum as being filled with pairs of virtual particles with fluctuating energy values. As a result, the inherent characteristics of vacuum, like the speed of light, may not be a constant after all, but fluctuate. Meanwhile, in another study, Gerd Leuchs and Luis L. SÃ¡nchez-Soto, from the Max Planck Institute for the Physics of Light in Erlangen, Germany, suggest that physical constants, such as the speed of light and the so-called impedance of free space, are indications of the total number of elementary particles in nature. The dependency of the speed of light on the vacuum energy is adopted in the papers, which is the lost key of unifying between quantum theory and relativity (special and general). There are other papers related to the same subject posted in http://vixra.org/author/azzam_almosallami

I think these answers are missing the point of the original question. Let's accept that meaningful "knowledge" cannot be encoded using entanglement experiments and focus of the information which can be exchanged by assuming that in order to finally compare the results of the experiment, the entangled particles are all measured at some regular interval during some carefully chosen segment of the ship's relativistic voyage... and that after the experiment is done, the ship decelerates and returns to it's point of origin with the records of it's experimental results attached to local time-stamps. Let us say that we have enough particles to do this and we have agreed on a sequence to measure the particles in. Since each measurement would have been done at a pre-assigned local moment, in principle, one could use what we do know about relativity to attempt to make these measurements very near "simultaneously" ...However, even if this is done, there appears to be one confusing aspect to this scenario which I think our original poster was trying to articulate. Since the "zero" plane (plane of simultaneity) of a light cone in one inertial frame is at a different angle from the plane of simultaneity in another inertial frame, which, if either, will turn out to reflect the preferred definition of simultaneity? If time really does dilate in a non-symmetrical way during, say, acceleration, then what would we make of the decoded communications once we compared the sets of measurements? Would one "video" appear to run slow while the other runs fast? Would it appear as if space had been distorted or would the image look how it did to each observer even though the information was given to the other person if we had data about that?

• Finally, someone to see the problem from my perspective :). I am to blame as I did not explain my question well enough, yet you seem to have understood me -- I do not care how the information is transmitted, but if it were transmitted in a real-time manner for both ends, how would it look like? I share the concept ship decelerates and returns to it's point of origin with the records of it's experimental results attached to **local** time-stamps and I am assuming this would result in an distorted flow of information - event order is preserved but the "play" speed would vary for both parties. – Ivaylo Slavov Oct 27 '16 at 7:20

Let's discard the quantum entanglement part of it because that's throwing everybody off. Let's say we invent ansible (as per Ender's Game). Regardless of how quickly perceived time passes, both ends of the communication would share the same "now". A 100hz wave that is received by someone with a .5 time gradient would receive a 50hz wave. The receiving equipment in the spaceship would need to buffer the communications so that the person wouldn't get bored while listening to it.

For reference, quantum entanglement is only considered to be a connection between two quantum states because the majority of quantum physicists don't want to believe that entangled particles would behave deterministically. There is a religious argument that suggests that such a state eliminates free will. Nonetheless, quantum entanglement is perceptually identical to two particles with matched wave forms. If you interrupt one, it gets out of sync with the other, but it doesn't affect the other.