Does instantaneous communication implies a preferrred Lorentz frame?

[Demystifier]

In any case, our planet is receiving huge amount of negentropy from Sun, as we see 1 hot spot in one place and dark sky around. Earth returns thermal radiations, spread almost evenly in all directions. Life just uses that flux of negentropy. That negentropy is what we get from Sun! Not the *energy* - because Earth emits excatly the same amount of energy into space as it receives from Sun. So there is no surprise that the life started from the plants, not from animals: plants could absord the negentropy directly, while animals - only indirectly.

Think about the Photosynthesis: contrary to C + 02 -> C02 (burning), photosynthes *consumes* energy, not releases it. Why did Nature used it? because of negentropy from Sun.

That's all true, but the chemistry of life does not explain INTELLIGENCE. It is intelligence (of humans, apes, birds, ...) that can change nature in a manner that seems to violate the natural evolution towards more chaotic states.

 

[Demystifier]

For those who are lost and don't see what second law has to do with instantaneous influences, here is a brief recapitulation:
instantaneous message -> message backwards in time -> causality -> flow of time -> arrow of time -> second law
So, it has very much to do with it. It's not offtopic at all.

 

[Dmitry67]

That's all true, but the chemistry of life does not explain INTELLIGENCE. It is intelligence (of humans, apes, birds, ...) that can change nature in a manner that seems to violate the natural evolution towards more chaotic states.

It depends on what we call 'chaotic'
Dead and void universe has less entropy then universe with life.

In our everyday life we call an absense of order a 'chaos'
But it not exactly what is meant by the 2nd law
Perfect Order (low entropy states) are aways DEAD, they can't evolve and think because they are always primitive - they have only few states.

So the more intelligent beings MUST be more chaotic (must have more internal states)

 

[Demystifier]

As a sort of summary of this thread, I have written a dialog containing all mayor objections and the corresponding responses. I attach it as a PDF below.

Additional comments, questions, objections, etc. are wellcome.

 

[Dmitry67]

Looks very good!
It would be interesting to extend this logic, however, to Closed Time-Like loops.
Because the argument:

R: Stop, don’t even bother with the details! It cannot work because a machine is a
macroscopic classical object, and I have already explained that superluminal signals do
not work at the macroscopic classical level.

Does not work there because macroscopic objects are affected by the CTL as well. But may be it is an offtopic.

 

[Demystifier]

Yes, it would be offtopic.

 

[T-Boone]

Other than the MWI, I have never heard of cause/effect time travel paradoxes disappearing in the absence of free will? The "will" portion of the thought experiment is required for the paradox to occur. You receive a valuable antique pocket watch from a strange older man on your 12th birthday...On your 50th birthday you develop a time machine and go back to your 12th birthday and give your younger self the watch. Where did the watch come from originally?

Also, wouldn't backwards time travel allow you to know with 100% certainty both the momentum & location of an electron?

 

[Dmitry67]

check this
http://en.wikipedia.org/wiki/Novikov_self-consistency_principle

 

[T-Boone]

check this
http://en.wikipedia.org/wiki/Novikov_self-consistency_principle

I am familiar with the Novikov principal, but I think that it's not very good because it doesn't really say anything other than the obvious and so it can be considered a tautology. It goes something like this:

"IF time travel is possible, then paradoxes cannot arise from it."

That's all well good but then again, paradoxes cannot arise from anything to begin with! So you could replace the "if" part with whatever you'd like and it's still true. Again, really says nothing other than paradoxes cannot arise. One could however say, that time travel is impossible because it CAN lead to a paradox. Of course, we are talking about time travel to the past.

Also, Novikov doesn't apply to the MWI (Many Worlds Interpretation) because it assumes a singular timeline whereas MWI does not. However, I really don't like MWI because I find it too outlandish & fantastical; it is based on assumption on top of conjecture on top of speculation on top of...poppycock! But it is in vogue now-a-days so I guess there's something to be said for that; but, technically, MWI doesn't really allow for time travel either! But that's a whole other story.

 

[Descartz2000]

I am not a physicist or a neuroscientist, however I have read quite a bit on free-will. It seems whether or not true free-will does occur is an ongoing debate. There is much research indicating that true free-will is an illusion, that is: the ability to make choices without the parameters of previous or current influences (biology, genes, brain function, past experiences, etc). If we look at Libet's studies from the past, and current neuroscience that dare dip into the 'untestable' concepts of free-will, we see that actions within the brain occur initially in an unconscious part and then trickle down into conscious states. When we become aware of these states we conclude that we made a 'free-choice'. Based on these experiments, it seems logical to conclude that free-will is an illusion. Check it out, it seems that brain scientists are able to determine that a subject makes a decision before the subject himself is aware that a decision is actually made. I am not sure how this relates to free choice experiments, but I bet it plays a significant role.

 

[WaveJumper]

Other than the MWI, I have never heard of cause/effect time travel paradoxes disappearing in the absence of free will?

Abscence of free-will is the same as "reality is an illusion". In an anti-realist setting, all paradoxes disappear.
BTW, there is absolutely no way there'd ever be free will, if time travel were possible.

The "will" portion of the thought experiment is required for the paradox to occur. You receive a valuable antique pocket watch from a strange older man on your 12th birthday...On your 50th birthday you develop a time machine and go back to your 12th birthday and give your younger self the watch. Where did the watch come from originally?

Where did the universe come from originally? These kind of causal questions must end somewhere or your neurons will sizzle and fry.

Also, wouldn't backwards time travel allow you to know with 100% certainty both the momentum & location of an electron?

Yes, that's why there'd never be backwards time-travel as depicted in sci-fi movies.

 

[T-Boone]

Descartz2000, I find the free-will & time travel debate quite interesting as well. Like most good debates, the outcomes really depend on the definitions being used. In other words, how you define free will or how you define time will greatly affect the outcome of the debate.

I for one do believe in free will and that backwards time travel is not possible.

 

[T-Boone]

WaveJumper,
I think that the anti-realist point with respect to physics, is really quite pointless as it denies objective reality; the very framework where physics occurs. It can be a good philosophical endeavor to expand your mind and maybe help you think outside the box, but I can't see it meld at all with physics.

As far as your question is concerned (i.e. where the Universe came from) it came from a singularity at the beginning of time: an initial uncaused state from whence the Big Bang emerged. No sizzle & fry here, I assure you! )

And I also agree with you on the fact that backwards time travel is not possible. I'll even go as far as saying that the concept of "backwards time travel" is itself a paradox!

 

[WaveJumper]

WaveJumper,
I think that the anti-realist point with respect to physics, is really quite pointless as it denies objective reality; the very framework where physics occurs. It can be a good philosophical endeavor to expand your mind and maybe help you think outside the box, but I can't see it meld at all with physics.

Non-realism, in the sense of objective reality being very different to the true reality is not at all pointless for physics. In fact, it's the only way forward.

As far as your question is concerned (i.e. where the Universe came from) it came from a singularity at the beginning of time: an initial uncaused state from whence the Big Bang emerged. No sizzle & fry here, I assure you! )

Good for you! I imagine it must feel good to not doubt scientific interpretations, trends and assumptions.

 

[T-Boone]

Non-realism, in the sense of objective reality being very different to the true reality is not at all pointless for physics. In fact, it's the only way forward.

True reality? As opposed to what, fake reality? Objective reality = true reality = what is used in physics.

Good for you! I imagine it must feel good to not doubt scientific interpretations, trends and assumptions.

Did you read anything of what I wrote previously?

However, I really don't like MWI because it find it too outlandish & fantastical; it is based on assumption on top of conjecture on top of speculation on top of...poppycock! But it is in vogue now-a-days so I guess there's something to be said for that; but, technically, MWI doesn't really allow for time travel either!

Sounds like I am doubting & even challenging scientific interpretations, trends and assumptions, don't you think? As far as the Big Bang explanation goes, I was just trying to illustrate that your question (i.e. where did the universe come from originally) could be answered without any sizzling and frying of neurons.

 

[WaveJumper]

True reality? As opposed to what, fake reality? Objective reality = true reality = what is used in physics.

Perception and reality aren't the same. That was the point.

As far as the Big Bang explanation goes, I was just trying to illustrate that your question (i.e. where did the universe come from originally) could be answered without any sizzling and frying of neurons.

That's not an answer, and even if were, you can can bet that it can fry the neurons of any enquring human being. But this is offtopic.

The point is, both GR and QM are at odds with realism and the OP(Does instantaneous communication implies a preferrred Lorentz frame?) touches on both.

 

[T-Boone]

Perception and reality aren't the same. That was the point.

This is a philosophical issue (maybe metaphysics) but what point does it have in physics? I don't understand your point: are you saying that all we have are perceptions? If so, then ins't what you call "real reality" just another perception? Like I said, it's just an exercise in academics but not anything practical.

That's not an answer, and even if were, you can can bet that it can fry the neurons of any inquiring human being.

How is it not an answer? Of course it is. It may not be an answer that YOU like but just because YOU don't like it doesn't mean that it isn't an answer.

As far as it frying neurons, I assume that you are speaking metaphorically. That being said, I think that it really isn't a very complicated theory. I guess it might be difficult for some, but with some clarification I think just about anyone can grasp it. Judging by your posts, I think that you are more than capable of understanding it, so I don't understand why you are being so combative and confrontational.

Now, I'm not saying that "this exactly how it happened with 100% certainty;" what I am saying is that it is the most convincing and least flawed explanation that I have heard.

The point is, both GR and QM are at odds with realism and the OP (Does instantaneous communication implies a preferrred Lorentz frame?) touches on both.

I disagree. There is no instantaneous communication occurring with entangled particles; at least not any FTL communication, which is what I think is being referred to here.

Let me explain: we have 2 identical looking boxes and two balls; one red and one blue. We place one ball in one box and and the other ball in the other box. Now we place the boxes in a bag and jumble them around; now we do not know which is which. These boxes are now entangled vis-à-vis their "ball color" property. Now you and I take one box each; I fly to New York City and you fly to Shanghai, all the while we do not open our boxes. When you arrive at Shanghai, you open your box to discover that your box has a red ball and now you instantaneously know the contents of my box which is in NYC! But what's the big deal? Is there any FTL or any information at all actually traveling anywhere at this point? No. The only traveling (information or otherwise) was done on the airplanes we took to get to our destinations. When things are explained differently, there's no exploding neurons!

-Cheers!

 

[WaveJumper]

This is a philosophical issue (maybe metaphysics) but what point does it have in physics? I don't understand your point: are you saying that all we have are perceptions? If so, then ins't what you call "real reality" just another perception? Like I said, it's just an exercise in academics but not anything practical.

It's definitely not a philosophical issue. It's the task of physics to build a model of the universe. At present there isn't such a thing.
This is fairly offtopic - google "realism in modern physics" or similar, this will help you find lots of information on this topic.

How is it not an answer? Of course it is. It may not be an answer that YOU like but just because YOU don't like it doesn't mean that it isn't an answer.

Scientific paradigms change with the next revolution in physics. We know way too little about space, time, matter and awareness to proclaim the Big Bang as the true model.

I disagree. There is no instantaneous communication occurring with entangled particles; at least not any FTL communication, which is what I think is being referred to here.

Let me explain: we have 2 identical looking boxes and two balls; one red and one blue. We place one ball in one box and and the other ball in the other box. Now we place the boxes in a bag and jumble them around; now we do not know which is which. These boxes are now entangled vis-à-vis their "ball color" property. Now you and I take one box each; I fly to New York City and you fly to Shanghai, all the while we do not open our boxes. When you arrive at Shanghai, you open your box to discover that your box has a red ball and now you instantaneously know the contents of my box which is in NYC! But what's the big deal? Is there any FTL or any information at all actually traveling anywhere at this point? No. The only traveling (information or otherwise) was done on the airplanes we took to get to our destinations. When things are explained differently, there's no exploding neurons!

-Cheers!

You cannot change instantaneously the boxes between Shanghai and NYC. And you can with entangled particles, they don't have definite observables, so with each measurement you get a new correspodning value(same as having to travel from NYC to Shanghai instantaneously, several times in a row) and they always exhibit this strong correlation. The red-blue socks example was likely thought up to shut nosy students up.

The Preferred Lorenz frame likely implies a misapprehension on our part of the concept of Time or there is something fundamental missing from our knowledge in physics(or a combination of both).

 

[T-Boone]

It's definitely not a philosophical issue. It's the task of physics to build a model of the universe. At present there isn't such a thing.

1st of all, not only does physics have A model for the Universe, it has MANY. Among these is the Big Bang (which has different "interpretations" within it as well), the many worlds interpretation, etc. As science progresses and we learn new things, the models change in many ways: some may be discarded, modified, extended, etc. It isn't perfect, but then again, what is?

2nd, realism is most certainly a philosophical issue:
"Realism is a word that can be used in many different ways. It is used mainly in the arts, literature, philosophy, & music...Realist philosophy is a way of thinking about the world in which things have an existence even if no one is studying them (looking, hearing, smelling, touching them). This was different from older philosophers who said that things only exist because of people who are aware of them."

3rd, did you bother to follow your own advice & Google "realism in modern physics"? If you did, you would have noticed that the first 4 hits mention philosophy explicitly; the rest either mention it implicitly, explicitly or both.

Scientific paradigms change with the next revolution in physics. We know way too little about space, time, matter and awareness to proclaim the Big Bang as the true model.

Why do you revel in these platitudes? Who's proclaiming the Big Bang as the TRUE & ONLY model? It is the best approximation we have for now. Do you have a better alternative? I haven't heard one yet.

You cannot change instantaneously the boxes between Shanghai and NYC.

Which is also true for entangled particles; you cannot change instantaneously the entangled particles between Shanghai and NYC.

And you can with entangled particles, they don't have definite observables...

No you cannot. Once they are "observed", that observation becomes definite; just like the box's contents.

...so with each measurement you get a new corresponding value (same as having to travel from NYC to Shanghai instantaneously, several times in a row) and they always exhibit this strong correlation.

It only exhibits a strong correlation when measurements are done in pairs, otherwise there will be no strong correlation. Furthermore, it is nothing like instantaneous travel between Shanghai & NYC.

In a spin anti-correlated entangled pair, if you measure particle A along Y-axis and then particle B along Y-axis the will be opposite. Why? Because they were anti-correlated from the point of the pair's creation. However, if you change Y-axis for particle A and NOT for particle B and then measure them they WILL NOT show a strong correlation.

 

[WaveJumper]

1st of all, not only does physics have A model for the Universe, it has MANY. Among these is the Big Bang (which has different "interpretations" within it as well), the many worlds interpretation, etc. As science progresses and we learn new things, the models change in many ways: some may be discarded, modified, extended, etc. It isn't perfect, but then again, what is?

So if you don't have a single model of how the universe works, why bother pretending that you had one? If i joined your 2 statements that you made in 2 separate posts, would they make sense and not be contradictory:


T-Boone says: "As far as your question is concerned (i.e. where the Universe came from) it came from a singularity at the beginning of time: an initial uncaused state from whence the Big Bang emerged. No sizzle & fry here, I assure you! ). Not only does physics have A model for the Universe, it has MANY. Among these is the Big Bang (which has different "interpretations" within it as well), the many worlds interpretation, etc.

3rd, did you bother to follow your own advice & Google "realism in modern physics"? If you did, you would have noticed that the first 4 hits mention philosophy explicitly; the rest either mention it implicitly, explicitly or both.

I just did. The issue is a matter of philosophy only as much as we do not know how the universe works. That you believe a certain model is true in now way says that all the other models are wrong. It just means T-Boone believes a certain model of the Universe is correct. ANyway, it is the task of physics to find the correct model(if there is one at all), not philosophy and it is work in progress. I referred you to realism in modern physics only to highlight that realism(objects having definite properties at all times) cannot be recovered, not to discuss philosophy.

Why do you revel in these platitudes? Who's proclaiming the Big Bang as the TRUE & ONLY model? It is the best approximation we have for now. Do you have a better alternative? I haven't heard one yet.

You did. In post 118, you proclaimed this(and it strongly implies that "the Big Bang as the TRUE & ONLY model") :

As far as your question is concerned (i.e. where the Universe came from) it came from a singularity at the beginning of time: an initial uncaused state from whence the Big Bang emerged. No sizzle & fry here, I assure you! )

Once they are "observed", that observation becomes definite; just like the box's contents. In a spin anti-correlated entangled pair, if you measure particle A along Y-axis and then particle B along Y-axis the will be opposite. Why? Because they were anti-correlated from the point of the pair's creation. However, if you change Y-axis for particle A and NOT for particle B and then measure them they WILL NOT show a strong correlation.

If you're measuring photons polarisartion at 45 deg, those photons exit the polariser in a superposition of H/V states. Before the measurement, a photon polarised at say 45 deg. to the horizontal is neither horizontally nor vertically polarised. It's in the act of measurement that determines the measured value(H/V). The balls in your example(being macroscopic objects) always have the same defined properties and obviously cannot be in 2 states at the same time(one ball will always be red and the other blue). In your balls example you were attempting to ascribe a rather common-sense, macroscopic view on a phenomenon that is anything but intuitive and common-sensical.
Saying "there exists a strong correlation" does nothing to explain the phenomena, it is merely a label/designation to show that you are able to attach labels/designations to unexplained events. Your previous statement(obviously related to your belief that macroscopic balls were behaving similar to what is going on at the quantum realm):

I disagree. There is no instantaneous communication occurring with entangled particles; at least not any FTL communication, which is what I think is being referred to here.

...is very premature at best, and completely wrong at worst. Your certainty is naive and unwarranted. The fact that you cannot send information through entangled pairs, does not in any way signify there is no causal, nonlocal influence. In fact, the violation of Bell's inequalities demands that either locality or realism must be wrong(or both). If "there is no instantaneous communication occurring with entangled particles" as you assert, then realism is wrong, which was the point i was making with my first post in this thread(post 116), where i said:

Abscence of free-will is the same as "reality is an illusion". In an anti-realist setting, all paradoxes disappear.

responding to your question:

Other than the MWI, I have never heard of cause/effect time travel paradoxes disappearing in the absence of free will?

 

[atyy]

We feel that way because we feel that it's possible to change the future and impossible to change the past. Why do we feel this way? Because we have memories of the past and none of the future. Why is that? Because storing a memory is a process that increases entropy, and entropy is increasing towards the future. Why is entropy increasing? Because the universe started out in a low entropy state. Why did it do that? No one knows.

I thought it was erasing a memory that increases entropy?

I've naively been thinking that we can remember some of the future, in the sense that we can predict it. And the only reason we remember more of the past is that entropy is increasing, due to the initial conditions of the universe.

 

[atyy]

Dmitry67 and PTM19, it is not the question whether life itself is consistent with the second law. As you say, it is consistent.
The question is whether the EVOLUTION of life (in the Darwinian sense) is consistent with the second law. How evolution helps to increase the total entropy of the ecological system?

Evolution produces human beings who think up lots of nonsense, such as MWI, thus increasing entropy :tongue2:

 

[Demystifier]

I've naively been thinking that we can remember some of the future, in the sense that we can predict it. And the only reason we remember more of the past is that entropy is increasing, due to the initial conditions of the universe.

I agree.

 

[T-Boone]

So if you don't have a single model of how the universe works, why bother pretending that you had one?

Way to strawman the argument! I never pretended to have a SINGLE model for how the Universe works. Instead, I simply told you how I believe it works and how it does not "fry & sizzle" one's brain.

If i joined your 2 statements that you made in 2 separate posts, would they make sense and not be contradictory:

(Me) "As far as your question is concerned (i.e. where the Universe came from) it came from a singularity at the beginning of time: an initial uncaused state from whence the Big Bang emerged. No sizzle & fry here, I assure you! )."

(Me) "Not only does physics have A model for the Universe, it has MANY. Among these is the Big Bang (which has different "interpretations" within it as well), the many worlds interpretation, etc."

The fact that there are many models as to how the Universe works is not in itself a contradiction. These models need not be mutually exclusive and even if they were, one could simply pick one and be done with it.

The issue is a matter of philosophy only as much as we do not know how the universe works. That you believe a certain model is true in no way says that all the other models are wrong. It just means T-Boone believes a certain model of the Universe is correct.

Well, if it were just philosophy, then it might be just an opinion but it's not; it's actually much more than just an opinion. It's actually theoretical physics which isn't just philosophy and just an opinion. As I explained, the Big Bang model has more empirical evidence and less speculation than the rest.

Anyway, it is the task of physics to find the correct model(if there is one at all), not philosophy and it is work in progress. I referred you to realism in modern physics only to highlight that realism(objects having definite properties at all times) cannot be recovered, not to discuss philosophy.

Agreed: it is the task of physics to find the correct model and it is a work in progress. I'd like to add, that in all likelihood it will really never be 100% finished. If you think about it, considering that we've practically just come down from trees, I think we've done pretty good so far! But, as I'm sure you'd agree, there is much room for improvement & much more to be learned.

In post 118, you proclaimed this(and it strongly implies that "the Big Bang as the TRUE & ONLY model"):

(me)"As far as your question is concerned (i.e. where the Universe came from) it came from a singularity at the beginning of time: an initial uncaused state from whence the Big Bang emerged. No sizzle & fry here, I assure you! )"
That is one of the best examples of a non-sequitur I've seen in a while! No where in my quote do I state that it is the ONLY model. The only thing you can really say is that I am implying that it's true. Well, I'll say it explicitly: it's true! You can choose not to believe it; there are other alternatives, as I said previously. However, you are already keenly aware of this and I suspect that you only side with whatever model (i.e. supporting science) suits your point at the time; but I'll give you the benefit of the doubt.

If you're measuring photons polarization at 45 deg, those photons exit the polarizer in a superposition of H/V states.

Sure, although I was thinking more along the lines of electron spin but, whatever.

Before the measurement, a photon polarized at say 45 deg. to the horizontal is neither horizontally nor vertically polarized. It's in the act of measurement that determines the measured value(H/V).

I see that you have accepted the Copenhagen interpretation here...

The balls in your example(being macroscopic objects) always have the same defined properties and obviously cannot be in 2 states at the same time(one ball will always be red and the other blue). In your balls example you were attempting to ascribe a rather common-sense macroscopic view on a phenomenon that is anything but intuitive and common-sensical.
Saying "there exists a strong correlation" does nothing to explain the phenomena, it is merely a label/designation to show that you are able to attach labels/designations to unexplained events.

I wonder if you would have told Schrodinger that his cat was macroscopic and not microscopic? Anyways, the analogy still stands as you do not know what the color is. That being the case, the color of the balls are in a superposition of red/blue and once opened, it collapses to one of the colors. However, this is getting off topic; I was just showing another interpretation of what could be going on with entangled pairs.

As an aside, the "strong correlation" term was originally posted by you in post #123. Regardless, entanglement cannot be used for FTL signaling.

(T-Boone: I disagree. There is no instantaneous communication occurring with entangled particles; at least not any FTL communication, which is what I think is being referred to here.)
...is very premature at best, and completely wrong at worst. Your certainty is naive and unwarranted. The fact that you cannot send information through entangled pairs, does not in any way signify there is no causal, nonlocal influence. In fact, the violation of Bell's inequalities demands that either locality or realism must be wrong(or both).

I maintain that there is no FTL communication occurring here as is explained in EVERY experiment: information nor matter never exceeds c. Furthermore, the experiments end after the first set of measurements because after that, their properties are no longer related.

Absence of free-will is the same as "reality is an illusion". In an anti-realist setting, all paradoxes disappear. Responding to your question.

I have no idea how that responds to my question. If reality is an illusion, then what is left to be talked about in any meaningful way? How is that an approach to describing how the Universe works?

 

[WaveJumper]

I see what you are saying about the BB. You worded it too strong in your first reply and i presumed you were too hung up on the notion of scientific models always being correct. Honestly, that's how it sounded.

I maintain that there is no FTL communication occurring here as is explained in EVERY experiment: information nor matter never exceeds c.

Your statement assumes realism is true and realism is just a hypothesis. A hypothesis that is exceedingly hard to maintain.

I have no idea how that responds to my question. If reality is an illusion, then what is left to be talked about in any meaningful way? How is that an approach to describing how the Universe works?

It'd be naive to assume reality has feelings and cares if T-Boone or someone else is able to make sense of it or not. I never claimed humans could understand all of reality, if that is what you believe, you can be certain that it's an utopia.

 

[T-Boone]

I see what you are saying about the BB. You worded it too strong in your first reply and i presumed you were too hung up on the notion of scientific models always being correct. Honestly, that's how it sounded.

Fair enough. I am kind of partial to BB theory...and don't like the MWI; maybe that's why I sounded so harsh!

Your statement assumes realism is true and realism is just a hypothesis. A hypothesis that is exceedingly hard to maintain.

I am guessing that you are referring to:
"...scientific realism is the thesis that the unobservable things talked about by science are little different (in terms of ontological status) from ordinary observable things (such as tables and chairs)."-wiki
I guess, in the face of adversity (i.e. entanglement, etc.) it can be tough, but I am not alone. At least that is comforting thought, so I manage.

It'd be naive to assume reality has feelings and cares if T-Boone or someone else is able to make sense of it or not. I never claimed humans could understand all of reality, if that is what you believe, you can be certain that it's an utopia.

Well, like I said before (post# 129): "that in all likelihood it will really never be 100% finished." Meaning that I think we will never understand 100% of reality.

That being said, I am curious to know about this concept of "reality is an illusion." I don't understand how that can lead to anything profound for if all is an illusion, then what is left?

I presume you might answer "real reality" (as you mentioned in a previous post) but unfortunately one would have to conclude that that too is an illusion, for the same reasons. This is why I think that it leads nowhere.

 

[ThomasT]

Nonlocal entanglement of quantum mechanics suggests the existence of instantaneous communication between distant particles.

Instantaneous communication is a contradiction in terms.

Wrt to just ftl (not instantaneous) propagations, they're not suggested or implied by quantum entanglement -- but rather are considered in connection with quantum entanglement and EPR-Bell tests because they're a cheap solution to the still open problem of the physical mechanism(s) underlying the correlations produced in those sorts of experiments.

What I push forward is the idea that it is causality (i.e., the principle that events can be ordered into "causes" and "consequences") that should be abandoned.

Wrt any set of spatial configurations of some frame of reference, there's an evolution (a preferred direction) in the order away from lower-numbered configurations. This preferred evolutionary direction is called the arrow of time, and its archetypal (idealized) form is that of an expanding 3D spherical wave shell.

The terms cause and effect are just relative placeholders in any time-indexed set of spatial configurations -- ie., by definition, causes happen before effects.

So, instead of pushing to abandon the idea of a preferred temporal order, why not take the radiative arrow of time as fundamental vis the adoption of its archetypal form as the fundamental wave dynamic?

Anyway, this seems to me to be conceptually preferable to taking calculational conveniences as literally corresponding to the real world.

 

[Fredrik]

RUTA sent me a question about the thought experiment I posted in #17 (and had to keep clarifying until #64), and I decided to clean it up a little and post a new version here. This is (my version of) the standard argument for why it can't be possible to send instantaneous messages in a special relativistic universe.

Imagine a computer that's doing inertial motion. We will call it "Alice". I want you to draw a spacetime diagram that represents the coordinates that the inertial coordinate system associated with Alice's motion assigns to the events I'm about to describe. Draw the 0 axis (time) in the "up" direction. Draw the 1 axis (position) to the right. Alice's world line coincides with the 0 axis.

I will write the coordinates (assigned by Alice's coordinate system) of an event as (t,x), not [strike](x,t)[/strike]. When I talk about the "slope" of a line, I mean dt/dx. This means that a horizontal line has slope 0 and a vertical line has slope ∞. The world line of an object moving with velocity v has slope dt/dx=1/(dx/dt)=1/v. The simultaneity lines of the inertial coordinate system associated with the motion of such an object would be drawn with slope v in this diagram. (This follows from the same synchronization argument that's used to associate an inertial coordinate system with an inertial observer. See any book on SR for an explanation of simultaneity and clock synchronization using light signals).

Now I want you to draw a straight line through the events (-4.5,0) and (8,10). Suppose that this line represents the motion of a second computer. Let's call it "Bob". The slope of this line is (8-(-4.5))/(10-0)=12.5/10=1.25, so Bob's velocity is 1/1.25=0.8. Draw another straight line, through the events (0,0) and (8,10). This line has slope 0.8=v, so it's the set of events that Bob considers simultaneous with (8,10).

Now suppose that both computers are hooked up to tachyon transmitters that can send and receive 1-bit messages, i.e. either "0" or "1". We assume that a tachyon emitted by one of these transmitters will move at infinite speed in the rest frame of the transmitter that emitted them. (It isn't necessary to assume that the speed is infinite, but it makes the diagram a bit easier to draw). Suppose also that Alice is running a program with the following instructions:

IF the message received at t=0 is "1" THEN send the reply "0" at t=8
IF the message received at t=0 is "0" OR if no message is received THEN send the reply "1" at t=8​

And suppose that Bob is running a program with these instructions:

IF the message received is "0" THEN immediately send the reply "0"
IF the message received is "1" THEN immediately send the reply "1"​

This leads to the following paradox:

If Alice receives 1 at (0,0), she replies by sending 0 at (8,0). When Bob receives that message at (8,10), he replies by sending 0 at (8,10), so Alice receives 0 at (0,0). If Alice receives 0 at (0,0), she replies by sending 1 at (8,0). When Bob receives that message at (8,10), he replies by sending 1 at (8,10), so Alice receives 1 at (0,0). So if Alice receives a message at (0,0), no matter what that message is, we get a contradiction. If she doesn't receive a message at (0,0), she sends 1 at (8,0). Bob receives that message at (8,10), and replies with 1 at (8,10). So Alice receives 1 at (0,0), and we still have a contradiction.

There are of course a few implicit assumptions in this scenario, and the contradiction we found implies that (at least) one of them must be false. These are some of the possibilities:

• Tachyons do not exist.
• Tachyons exist, but reliable tachyon transmitters do not. So they will sometimes send the wrong message or misinterpret the message they received. (I'm not sure if that's sufficient to avoid the paradox).
• Tachyons and reliable transmitters both exist, but the time it takes to detect a tachyon is greater than vL, where v is the speed of the detector in the emitter's rest frame and L is the distance it has traveled since it was emitted. (This is for infinite speed tachyons. The formula would have to be modified for slower ones. We should also be talking about the time it takes to emit the tachyon, but I'm not attempting to give the complete answer here. I'm just trying to explain the basic idea).

(I'm sure there are other possibilities, but these are the ones I know).

Edit: I'm adding a quote from one of my posts that links to this one.

Since this leads to nonsense results, the most natural conclusion is that there are no particles that move faster than light.

There are a few other possibilities, for example: 1. The time it takes to emit and/or detect an FTL particle grows at least linearly with the distance it travels. (This would prevent the recipient of the first message to send a reply that reaches the sender of the original message before he sent it). 2. The equations of motion of the matter in the universe doesn't have any solutions that describe someone who both chooses to carry out an experiment like the one I described in the post I linked to, and succeeds. (Yes, this one is even weirder than the first one).

 

[dx]

Here's the spacetime diagram of sending and receiving a tachyon before sending it : http://books.google.com/books?id=Yt...and gravitation&pg=PA136#v=onepage&q=&f=false

If the tachyon is sent with a speed u > c to an observer moving with speed v, then the reply can be received before the message is sent if u > [1 + (1 - v²)^1/2]/v.

 

[Fredrik]

Yeah, but my tachyons are faster. :tongue:

Thanks for posting. The difference between that diagram and mine is that (if we rotate the whole page clockwise so that we can read the text easier) the "tachyon outbound" line would be horizontal, and the "tachyon inbound" would be parallel to the t'=0 line. (Again, I only chose infinite speed to make the diagram slightly simpler. This diagram clearly shows that we get the same paradox even with finite speed tachyons).

 

[DaTario]

I read a paper from an author named Riff from UFRJ, Brazil where he shows that in one reference frame you will in a certain situation observe instantaneous communication experiment. In other reference frame the same physical situation will exemplify a delayed choice experiment, In a third reference frame, the same experiment will be captured as an example of Bell experiment.

I think this has to do with your OP.

Best Regards,

DaTario

P.S. sorry for not having here the exact reference, but you may look for Mr. Ryff in UFRJ website and search for his e-mail address.

 

[Demystifier]

There are of course a few implicit assumptions in this scenario, and the contradiction we found implies that (at least) one of them must be false. These are some of the possibilities:

• Tachyons do not exist.
• Tachyons exist, but reliable tachyon transmitters do not. So they will sometimes send the wrong message or misinterpret the message they received. (I'm not sure if that's sufficient to avoid the paradox).
• Tachyons and reliable transmitters both exist, but the time it takes to detect a tachyon is greater than vL, where v is the speed of the detector in the emitter's rest frame and L is the distance it has traveled since it was emitted. (This is for infinite speed tachyons. The formula would have to be modified for slower ones. We should also be talking about the time it takes to emit the tachyon, but I'm not attempting to give the complete answer here. I'm just trying to explain the basic idea).

(I'm sure there are other possibilities, but these are the ones I know).

My favored one:

• If tachyons exist, then one cannot built a machine which would lead to inconsistencies you described. That's because such a machine is not a global solution of the equations of motion describing the behavior of matter interacting with tachyons. (Of course, a similar machine with the difference that it does not interact with tachyons can be built.)

 

[Fredrik]

And suppose that Bob is running a program with these instructions:

IF the message received is "0" THEN immediately send the reply "0"
IF the message received is "1" THEN immediately send the reply "0"​

Typo. (Thanks to RUTA for finding it). This one was supposed to be

IF the message received is "0" THEN immediately send the reply "0"
IF the message received is "1" THEN immediately send the reply "1"​