is-quantum-communication-faster-than-the-speed-of-light?

MrAl

Joined Jun 17, 2014
11,715
You opened a can of worms! :D

Worm hole transversal (if possible) might violate Causality even within the FTL restriction (if your spacetime has closed timelike curves (CTCs)) for the traveler by becoming a time machine to the past.
https://theconversation.com/time-tr...-you-have-an-object-with-infinite-mass-107063


The time-cops are there to prevent this.
https://www.polygon.com/22537327/loki-tva-time-travel-cops


https://authors.library.caltech.edu/6469/
Billiard balls in wormhole spacetimes with closed timelike curves: Classical theory



https://authors.library.caltech.edu/9262/1/MORprl88.pdf
Wormholes, Time Machines, and the Weak Energy Condition


AUTHORS & AFFILIATIONS
Michael S. Morris, Kip S. Thorne, and Ulvi Yurtsever
  • Theoretical Astrophysics, California Institute of Technology, Pasadena, California 91125
Hello again,

I'll have to watch that last video for sure. He's got some great ideas.

I think i can sum up my view on the universe though maybe in two statements.

#1. There are different interpretations of quantum physics.
#2. When i look back in time, possibly far back, i see an evolution of science regarding the universe. If you look back just a little you can see that every single person who dealt with a theory of some kind though they had it right, or at least that their interpretation was right. As it turns out, almost none of them had it right although they did have a currently workable theory.
#3. 'Acceptance' rules the day, not physics and therefore not physical theories.

Different interpretations means different physics.

Even Einstein thought that entanglement was possible because of "hidden variables" but that was proven wrong. That's one of the greatest minds in history yet he could not accept that something beyond the current knowledge was possible so he had to inject ideas to make it seem plausible.
Also, his theory on relatively seems just a little too convenient to me. I think that he may be the first person to try to encapsulate the behavior of the universe and so it is probably just an elementary theory that needs to be refined. Indeed this idea is actually being through out now.
Can i be wrong about this? Sure, but based on #2 above which has occurred throughout the entire history of time that we know of, it's the general rule. I think there are some things that can never be wrong, but only in some given epoch. That's because knowledge is an ever evolving thing and there may be no end to it if the multiverse really does exist somehow.

I will admit though that i have not worked with quantum theory of any kind in a very very long time. I used to work with the Schrodinger Wave Equation but cant remember much about it other than some general ideas. Interestingly, that is being questioned too now as being 'not real'.

The only thing that doesnt change is change itself (in that things always change not a reference to a 2nd or 3rd or Nth derivative).

Thanks again for the reply and your comments are always welcome, positive or negative :)



When an experiment is performed and something new is discovered, it has to be 'accepted' even if it completely voids the current theory.
 

nsaspook

Joined Aug 27, 2009
13,553
My view on the universe:

1: The universe is lazy, you don't get something for nothing. This is expressed in every physical law we have ever developed, why perpetual motion machines are banned here and in the universe. This is a hard limit to what's possible in any possible theory that's compatible to any possible experiment.
https://oxford.universitypressschol.../oso/9780198743040.001.0001/oso-9780198743040


2: That laziness means some rules/laws won't change in this universe because they obey the prime directive of laziness, minimizing energy usage. Jumping off a 100 story building on earth to a concrete street without a means to break your fall will (to a very, very, very high probability) kill you because that's the path of least effort from the universe. On the microscale we see (interpretations) small random deviations on this laziness but it averages out to zero on average.
 

MrAl

Joined Jun 17, 2014
11,715
My view on the universe:

1: The universe is lazy, you don't get something for nothing. This is expressed in every physical law we have ever developed, why perpetual motion machines are banned here and in the universe. This is a hard limit to what's possible in any possible theory that's compatible to any possible experiment.
https://oxford.universitypressschol.../oso/9780198743040.001.0001/oso-9780198743040


2: That laziness means some rules/laws won't change in this universe because they obey the prime directive of laziness, minimizing energy usage. Jumping off a 100 story building on earth to a concrete street without a means to break your fall will (to a very, very, very high probability) kill you because that's the path of least effort from the universe. On the microscale we see (interpretations) small random deviations on this laziness but it averages out to zero on average.
Well it has been said that time is a factor. Gravity is the tendency for an object to move toward the space with the slowest time. Interesting view.

They are 'claiming' that time crystals are perpetual motion machines, but of course you can never take any energy OUT of them or they would have to stop moving.

Maybe some of the stuff being found out today is so theoretical that even in practice it is theoretical. In other words, it is so perfect that it can act jujst like a theory would say it should act. Without any extra sundry influences it would be like a circuit made entirely of physically perfect parts operating in a perfectly stable environment. Electrons and Photons struck me as being 'perfect parts' but i dont think that is true anymore or else again maybe we run into the theory describing things that are so perfect that they cant be changed because every interaction never actually changes them just the way they interact with other perfect parts.
 

nsaspook

Joined Aug 27, 2009
13,553
The original Time crystals papers didn't claim PM.
https://physics.aps.org/articles/v5/116
Time crystals may sound dangerously close to a perpetual motion machine, but it is worth emphasizing one key difference: while time crystals would indeed move periodically in an eternal loop, rotation occurs in the ground state, with no work being carried out nor any usable energy being extracted from the system. Finding time crystals would not amount to a violation of well-established principles of thermodynamics. If they can be created, time crystals may have intriguing applications, from precise timekeeping to the simulation of ground states in quantum computing schemes. But they may be much more than advanced devices. Could the postulated cyclic evolution of the Universe be seen as a manifestation of spontaneous symmetry breaking akin to that of a time crystal? If so, who is the observer inducing—by a measurement—the breaking of the symmetry of time?
https://www.space.com/38100-the-significance-of-time-crystals.html
Time Crystals Are (Not) Interesting
 

MrAl

Joined Jun 17, 2014
11,715
The original Time crystals papers didn't claim PM.
https://physics.aps.org/articles/v5/116


https://www.space.com/38100-the-significance-of-time-crystals.html
Time Crystals Are (Not) Interesting
Yes the part about no usable energy being extracted is what i expected cause you just cant take energy away and expect something to keep it's motion.

But i've thought about the FTL communications a little more now.
To start, i was saying before that if they can measure the speed of interaction between entangled particles then there must be a way to exploit that. But then i was saying that it might not work because of the speed of observation. However, thinking about it a little more, i dont think the speed of observation means anything because we are not talking about the bit rate, we are talking about communications over vast distances, period. Even a mere 1200 baud (ha ha) would be ok as long as we could get it out to some other location within a time period 1/10000 that it would take a radio signal to get there. For example, we could send a signal to Mars in just 60 milliseconds rather than 10 minutes (average).
Now since they were able to measure the speed of the interaction between the home particle and the far away particle, then we might be able to send a message using a form of pulse width modulation or pulse position modulation or some other digital technique that uses pulse duration as a means of encoding signals. This would mean making a lot of measurements.
The only thing that bothers me here is how do we get a ton of entangled particles to mars. We'd need tons of particles to keep communicating. If we run out of particles one day, then we have to go back to standard radio waves.
So i guess i have to learn how they send entangle particles from one place to another. IT would be interesting if we could send them with radio waves. That would mean that while the crew on Mars was sleeping we could send a boat load of particles so when they wake up we can talk back and forth very quickly.

This all depends on how we get the particles there, and also the speed of interaction of entangled particles that were so far measure to interact at about 10000 times the speed of light, and that is a lower limit.

Since you seem to like debunking things like this perhaps you can try to debunk the measurements of the speed of interaction that were made. If somehow this is not true (that they were able to measure this speed with some accuracy) then all is lost, at least for now.
 

nsaspook

Joined Aug 27, 2009
13,553
I'll debunk your FTL communications hypothesis. It won't work, PERIOD as only correlations, not individual states of the quantum objects are involved in the entanglement.
https://www.ibpsychmatters.com/why-correlation-is-not-causation

Any communications of measurement results MUST be over a classical communications channel. You could entangle all the particle in a small planet but it make no difference as Quantum entanglement DOES NOT transfer (from 0 to any speed => FTL, the actual speed of quantum interaction is meaningless in this context) the information needed to decode the random status of even a planet full of quantum measurements to the smallest fraction of a bit of information.

What you want to do is a violation of this:
https://www.lesswrong.com/posts/DY9...on-at-a-distance-the-no-communication-theorem
https://en.wikipedia.org/wiki/No-communication_theorem

The theorem disallows not only the communication of whole bits, but even fractions of a bit. The primary assumptions in the no-communication theorem are the laws of quantum mechanics and how entanglement works, which are extremely falsifiable. S0 falsify the theorem by showing its assumptions don't hold.

Sorry, you would need to make an experiment in which you would be able to send information, the theorem would then be falsified. All experiments so far have confirmed the no-communication theorem.
 
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Thread Starter

Wendy

Joined Mar 24, 2008
23,476
Other things that have yet to be verified include is there a distance requirement where quantum entanglement breaks down? There's a lot of work yet to be done in this field.
 

nsaspook

Joined Aug 27, 2009
13,553
Other things that have yet to be verified include is there a distance requirement where quantum entanglement breaks down? There's a lot of work yet to be done in this field.
In theory, you would think that any distance we could build a network for classical communications would also work in concert with quantum entanglement. Lot's of work is correct but IMO FTL communications is not one of them.

https://magazine.caltech.edu/post/untangling-entanglement
“It may be tempting to think that the particles are somehow communicating with each other across these great distances, but that is not the case,” says Thomas Vidick, a professor of computing and mathematical sciences at Caltech. “There can be correlation without communication.” Instead, he explains, entangled particles are so closely connected that there is no need for communication; they “can be thought of as one object.”
 

MrAl

Joined Jun 17, 2014
11,715
I'll debunk your FTL communications hypothesis. It won't work, PERIOD as only correlations, not individual states of the quantum objects are involved in the entanglement.
https://www.ibpsychmatters.com/why-correlation-is-not-causation

Any communications of measurement results MUST be over a classical communications channel. You could entangle all the particle in a small planet but it make no difference as Quantum entanglement DOES NOT transfer (from 0 to any speed => FTL, the actual speed of quantum interaction is meaningless in this context) the information needed to decode the random status of even a planet full of quantum measurements to the smallest fraction of a bit of information.

What you want to do is a violation of this:
https://www.lesswrong.com/posts/DY9...on-at-a-distance-the-no-communication-theorem
https://en.wikipedia.org/wiki/No-communication_theorem

The theorem disallows not only the communication of whole bits, but even fractions of a bit. The primary assumptions in the no-communication theorem are the laws of quantum mechanics and how entanglement works, which are extremely falsifiable. S0 falsify the theorem by showing its assumptions don't hold.

Sorry, you would need to make an experiment in which you would be able to send information, the theorem would then be falsified. All experiments so far have confirmed the no-communication theorem.
Ok you seem to be firm in your opinion so i wont argue that point.
But how do you think they measured the 'speed' ?

I asked you to try to debunk the measurement not any opinion i might have, because if you can debunk that then you succeeded in debunking a lot of ideas that might be thought to work one day. My idea is only one of them, possible or not possible.
 

MrAl

Joined Jun 17, 2014
11,715
Other things that have yet to be verified include is there a distance requirement where quantum entanglement breaks down? There's a lot of work yet to be done in this field.
Hi,

Yeah it is unfortunate that this topic is so new in the physics world. But that is why i have an open mind. Several things that were taken to be hard and fast -never-to-be-violated were found to have workarounds, and if there is a workaround to using quantum entanglement for communications then someone may find it one day. And if i might add, i dont believe that any 'explanation' of 'why' something 'absolutely wont work ever' are just part of the theory and so those arguments may fall also when the workaround is finally found.

Im not saying that there definitely is a workaround, i am just saying that there is the possibility and i base that mostly on the history of physics and how the universe behaves regardless what man comes up with to TRY to describe it's operation. The universe is under no obligation to do anything we say it should do, rather the opposite (paraphrasing Neil deGrasse Tyson).

What happens when people study physics is after a while they see things working out exactly like the theories say and it all seems perfectly logical, so they start to adopt it as a religion rather than a science.. Scientists are always getting surprised with new results. If i had a nickle for every time i heard the phrase, "We were not expecting that", i'd be a billionaire :)
 

nsaspook

Joined Aug 27, 2009
13,553
They measure speed with a classical measurement obviously. There's nothing wrong with the physics of the speed measurements or the fact communications is just not possible with a QM correlation.
https://scitechdaily.com/physicists-show-a-speed-limit-also-applies-in-the-quantum-world/
The fact that there is a speed limit in the microcosm was already theoretically demonstrated by two Soviet physicists, Leonid Mandelstam and Igor Tamm more than 60 years ago. They showed that the maximum speed of a quantum process depends on the energy uncertainty, i.e., how “free” the manipulated particle is with respect to its possible energy states: the more energetic freedom it has, the faster it is. In the case of the transport of an atom, for example, the deeper the valley into which the cesium atom is trapped, the more spread the energies of the quantum states in the valley are, and ultimately the faster the atom can be transported. Something similar can be seen in the example of the waiter: If he only fills the glasses half full (to the chagrin of the guests), he runs less risk that the champagne spills over as he accelerates and decelerates. However, the energetic freedom of a particle cannot be increased arbitrarily. “We can’t make our valley infinitely deep – it would cost us too much energy,” stresses Alberti.
Sorry, I only debunk what's wrong, your idea is wrong and it's not just my option your idea is wrong.

Repeat:
https://magazine.caltech.edu/post/untangling-entanglement
“It may be tempting to think that the particles are somehow communicating with each other across these great distances, but that is not the case,” says Thomas Vidick, a professor of computing and mathematical sciences at Caltech. “There can be correlation without communication.” Instead, he explains, entangled particles are so closely connected that there is no need for communication; they “can be thought of as one object.”
 

MrAl

Joined Jun 17, 2014
11,715
They measure speed with a classical measurement obviously. There's nothing wrong with the physics of the speed measurements or the fact communications is just not possible with a QM correlation.
https://scitechdaily.com/physicists-show-a-speed-limit-also-applies-in-the-quantum-world/


Sorry, I only debunk what's wrong, your idea is wrong and it's not just my option your idea is wrong.

Repeat:
https://magazine.caltech.edu/post/untangling-entanglement
Ok but i already knew what your opinion was.
So you agree with the measurements then. That's what i wanted to know.
 

bogosort

Joined Sep 24, 2011
696
To start, i was saying before that if they can measure the speed of interaction between entangled particles then there must be a way to exploit that.
This doesn't make physical sense. Entanglement is correlation, and correlation is a property of states, it doesn't have a "speed".

Now since they were able to measure the speed of the interaction between the home particle and the far away particle, then we might be able to send a message using a form of pulse width modulation or pulse position modulation or some other digital technique that uses pulse duration as a means of encoding signals.
You seem to be imagining that the particles are communicating with each other, that entanglement is some kind of action at a distance. But that is unphysical.

Entanglement is a property of states. Particle A is said to be entangled with particle B when the state of A cannot be expressed without reference to the state of B, and vice versa. To get two particles entangled with each other, they have to be prepared that way in a fancy lab and somehow shielded from the rest of the universe (otherwise they will become entangled with their environment at large, losing their special 2-particle system status).

Now, suppose you manage to transport particle B to Mars and its shield did its job -- the particle's quantum state will be exactly the same as when it was initially prepared. So, you have two entangled particles separated by a 100 million miles or so of space.

Let's say that your preparation involved entangling the spin of both particles in such a way so as to conserve angular momentum, e.g., if particle A is spin up, then particle B is spin down. Back on Earth, you carefully measure the spin of particle A and find that it's spin down along the z-axis. "Instantly", you know that particle B is spin up along the same axis. You send a radio message to your assistant on Mars, and 20 minutes later you hear confirmation that particle B is indeed spin up.

So, did particles A and B communicate superluminously with each other? No, not at all. Their single shared state as a two-particle system was prepared back in the lab and didn't change until the measurements were performed. This is no different than if you were going on a day trip and your wife packed a single pair of socks for you. Your wife prepared the initial state, picking two socks of the same color. Later that day, at the Marriott, the moment you "measure" the sock compartment and see the first sock, you instantly know the other sock's color. Even if your wife had accidentally dropped the second sock while packing it, you'd know its color instantly even though it was thousands of miles away.
 

MrAl

Joined Jun 17, 2014
11,715
Hello again,

To put some of this in perspective as i was trying to do before here is a quote from a famous theoretical physicist who was one of the pioneers of quantum physics.

"The best that most of us can hope to achieve in physics is simply to misunderstand at a deeper level".
 

Thread Starter

Wendy

Joined Mar 24, 2008
23,476
<tounge in cheek> you do realize that casualty have never been verified scientifically?

A good science fiction book on the subject would be“ thrice upon a time” by James P Hogan. It may come very close to his view, there is only one reality, but it is extremely malleable. If it changes we would not know. Because the rewrite covers everything.
 

nsaspook

Joined Aug 27, 2009
13,553
<tounge in cheek> you do realize that casualty have never been verified scientifically?

A good science fiction book on the subject would be“ thrice upon a time” by James P Hogan. It may come very close to his view, there is only one reality, but it is extremely malleable. If it changes we would not know. Because the rewrite covers everything.
<tounge in cheek> It's easy to scientifically verify in our macro-world with statistical probability to a very high order.
Physics causality is at the heart of modern physics.

https://en.wikipedia.org/wiki/Causality_(physics)
Despite these subtleties, causality remains an important and valid concept in physical theories. For example, the notion that events can be ordered into causes and effects is necessary to prevent (or at least outline) causality paradoxes such as the grandfather paradox, which asks what happens if a time-traveler kills his own grandfather before he ever meets the time-traveler's grandmother. See also Chronology protection conjecture.

Determinism (or, what causality is not)
The word causality in this context means that all effects must have specific physical causes due to fundamental interactions.[4] Causality in this context is not associated with definitional principles such as Newton's second law. As such, in the context of causality, a force does not cause a mass to accelerate nor vice versa. Rather, Newton's Second Law can be derived from the conservation of momentum, which itself is a consequence the spatial homogeneity of physical laws.
 

ApacheKid

Joined Jan 12, 2015
1,673
I agree. The probabilistic component in quantum decay event or a electron emitting a photon and transitioning to another state does not mean it is 'uncaused'. But at the same time it does not mean it has a 'cause'. We simply don't know why quantum events happen. Our common sense wants us to believe that such things have a cause. But when it comes to quantum mechanics, we have to throw out common sense. I am not going to be to dogmatic about it. I have been wrong way to many times in my life to state something without mentioning I could be completely off base. :) I understand your point. Thanks for sharing.
How could one ever truly show that anything was uncaused? Even if there were uncaused events, proving there was no cause seems logically impossible.

Having said that, the presence of the universe itself (if it has finite age) must have been uncaused because until the universe existed, material causes were not possible. (which is just a variation of the cosmological argument for God).
 

MrAl

Joined Jun 17, 2014
11,715
<tounge in cheek> you do realize that casualty have never been verified scientifically?

A good science fiction book on the subject would be“ thrice upon a time” by James P Hogan. It may come very close to his view, there is only one reality, but it is extremely malleable. If it changes we would not know. Because the rewrite covers everything.
Hi there Wendy,

Can you elaborate on what you are saying about causality?
I am just wondering because i thought that that was becoming more important in the modern age with even time itself taking a bit of a backstage.
The way i understood it so far was that if something happens, it's not as important what time it happened as much as that it happened at all, and that leads to a simpler way of understanding actions and reactions.
Not sure i am explaining this point right though.
 

Thread Starter

Wendy

Joined Mar 24, 2008
23,476
If something changes in the past the ever present now will adjust to match it. And we would never know. Time as we understand it in the first person may just be an illusion. Time travel may yet indeed be possible, but the consequences for us would be catastrophic. Again, we would never know what could have been.

To use the term rewrite concerning time travel in faster than light travel, is probably an error because our language can't handle the concepts. There may indeed just be one now, and no other.
 
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