## “Proof” That Faster Than Light Communications Are Impossible Is False

There are theories everywhere, and the more ingrained they are, the more suspiciously they should be looked at. From the basic equations of relativity it is clear that if one adds speeds less than the speed of light, one will get a speed less than the speed of light. It is also clear that adding impulse to a mass will make it more massive, while its speed will asymptotically approach that of light (and, as I explained, the reason is intuitive, from Time Dilation).

The subject is not all sci-fi: modern cosmology brazenly assumes that space itself, after the alleged Big Bang, expanded at a speed at least 10^23 c (something like one hundred thousand billion billions time the speed of light c). The grossest, yet simplest, proof of that is simple: the observable universe is roughly 100 billion light years across, and it is ten billion years old. Thus it expanded at the minimum average clip of ten billion light years, every billion years. 100c/10 = 10c, according to standard cosmology. One could furiously imagine a spaceship somehow surfing on a wave of warped space, expanding for the same obscure reason same obscure reason as the Big Bang itself, that is…)

The question naturally arises whether velocities which are greater than that of light could ever possibly be obtained in other ways. For example, are there communication speeds faster than light? (Throwing some material across will not work: its mass will increase, while its speed stays less than c.)

Textbooks say it’s not possible. There is actually a “proof” of that alleged impossibility, dating all the way back to Einstein (1907) and Tolman (1917). The mathematics are trivial (they are reproduced in my picture below). But the interpretation is apparently less so. Wikipedia weirdly claims that faster than light communications would allow to travel back in time. No. One could synchronize all clocks on all planets in the galaxies, and having faster than light communications would not change anything. Why? Time is local, faster than light data travel is nonlocal.

The problem of faster than light communications can be attacked in the following manner.

Consider two points A and B on the X axis of the system S, and suppose that some impulse originates at A, travels to B with the velocity u and at B produces some observable phenomenon, the starting of the impulse at A and the resulting phenomenon at B thus being connected by the relation of cause and effect. The time elapsing between the cause and its effect as measured in the units of system S will evidently be as follows in the calligraphy below. Then I use the usual Relativity formula (due to Lorentz) of time as it elapses in S’:

Equations help, but they are neither the beginning, nor the end of a story. Just an abstraction of it. The cult of equations is naive, interpretation is everything. The same thing, more generally, holds for models.
As Tolman put it in 1917: “Let us suppose now that there are no limits to the possible magnitude of the velocities u and V, and in particular that the causal impulse can travel from A to B with a velocity u greater than that of light. It is evident that we could then take a velocity u great enough uV/C^2 will be greater than one.
so that Delta(t) would become negative. In other words, for an observer in system S’ the effect which occurs at B would precede in time its cause which originates at A.”

I quote Tolman, because he is generally viewed as the one having definitively established the impossibility of faster than light communications. Tolman, though is not so sure; in his next sentence he turns out wishy washy: “Such a condition of affairs might not be a logical impossibility; nevertheless its extraordinary nature might incline us to believe that no causal impulse can travel with a velocity greater than that of light.”

Actually it is an effect those who have seen movies running in reverse are familiar with. Causality apparently running in reverse is no more surprising than the fact that two events at x1 and x2 which are simultaneous in S are separated by:  (x1-x2) (V/square root (1-VV/CC)). That introduces a sort of fake, or apparent causality, sometimes this before that, sometimes that before this.

(The computation is straightforward and found in Tolman’s own textbook; it originated with Henri Poincaré.[9][10] In 1898 Poincaré argued that the postulate of light speed constancy in all directions is useful to formulate physical laws in a simple way. He also showed that the definition of simultaneity of events at different places is only a convention.[11]) . Notice that, in the case of simultaneity, the signs of V and (x1-x2) matter. Basically, depending upon how V moves, light in S going to S’ takes more time to catch up with the moving frame, and the more so, the further it is, the same exact effect which explains the nil result in the Michelson-Morley interferometer; there is an underlying logic below all of this, and it’s always the same).

Tolman’s argumentation about the impossibility of faster than light communications is, in the end, purely philosophical and fully inconsistent with the closely related, and fully mainstream, relativity of simultaneousness.

Poincaré in 1900 proposed the following convention for defining clock synchronisation: 2 observers A and B, which are moving in space (which Poincaré called the aether), synchronise their clocks by means of optical signals. They believe to be at rest in space (“the aether”) from not moving relative to distant galaxies or the Cosmic Radiation Background and assume that the speed of light is constant in all directions. Therefore, they have to consider only the transmission time of the signals and then crossing their observations to examine whether their clocks are synchronous.

“Let us suppose that there are some observers placed at various points, and they synchronize their clocks using light signals. They attempt to adjust the measured transmission time of the signals, but they are not aware of their common motion, and consequently believe that the signals travel equally fast in both directions. They perform observations of crossing signals, one traveling from A to B, followed by another traveling from B to A.”

In 1904 Poincaré illustrated the same procedure in the following way:

“Imagine two observers who wish to adjust their timepieces by optical signals; they exchange signals, but as they know that the transmission of light is not instantaneous, they are careful to cross them. When station B perceives the signal from station A, its clock should not mark the same hour as that of station A at the moment of sending the signal, but this hour augmented by a constant representing the duration of the transmission. Suppose, for example, that station A sends its signal when its clock marks the hour 0, and that station B perceives it when its clock marks the hour t. The clocks are adjusted if the slowness equal to t represents the duration of the transmission, and to verify it, station B sends in its turn a signal when its clock marks 0; then station A should perceive it when its clock marks t. The timepieces are then adjusted. And in fact they mark the same hour at the same physical instant, but on the one condition, that the two stations are fixed. Otherwise the duration of the transmission will not be the same in the two senses, since the station A, for example, moves forward to meet the optical perturbation emanating from B, whereas the station B flees before the perturbation emanating from A. The watches adjusted in that way will not mark, therefore, the true time; they will mark what may be called the local time, so that one of them will be slow of the other.[13]

This Poincaré (“–Einstein”) synchronisation was used by telegraphers as soon as the mid-nineteenth century. It would allow to cover the galaxy with synchronized clocks (although local times will differ a bit depending upon the motion of stars, and in particular where in the galactic rotation curve a star sits). Transmitting instantaneous signals in that networks would not affect causality. Ludicrously, Wikipedia asserts that faster than light signals would make “Bertha” rich (!!!). That comes simply from Wikipedia getting thoroughly confused, allowing faster than light signals for some data, and not for other data, thus giving an advantage to some, and not others.

***

Quantum Entanglement (QE) enables at-a-distance changes of Quantum states:

(It comes in at least three types of increasing strength.) Quantum Entanglement, as known today, is within Quantum state to within Quantum state, but we cannot control in which Quantum state the particle will be, to start with, so we cannot use QE for communicating faster than light (because we don’t control what we write, so to speak, as we write with states, so we send gibberish).

This argument is formalized in a “No Faster Than Light Communication theorem”. However, IMHO, the proof contains massive loopholes (the proof assumes that there is no Sub Quantum Reality, whatsoever, nor could there ever be some, ever, and thus that the unlikely QM axioms are forever absolutely true beyond all possible redshifts you could possibly imagine, inter alia). So this is not the final story here. QE enables, surprisingly, the Quantum Radar (something I didn’t see coming). And it is not clear to me that we have absolutely no control on states statistically, thus that we can’t use what Schrödinger, building on the EPR thought experiment, called “Quantum Steering” to communicate at a distance. Quantum Radar and Quantum Steering are now enacted through real devices. They use faster-than-light in their inner machinery.

As the preceding showed, the supposed contradiction of faster-than-light communications with Relativity is just an urban legend. It makes the tribe of physicists more priestly, as they evoke a taboo nobody can understand, for the good reason that it makes no sense, and it is intellectually comfortable, as it simplifies brainwork, taboos always do, but it is a lie. And it is high time this civilization switches to the no more lies theorem, lest it wants to finish roasted, poisoned, flooded, weaponized and demonized.

Patrice Ayme’

https://en.wikipedia.org/wiki/Relativity_of_simultaneity

As Wikipedia itself puts it, weasel-style, to try to insinuate that Einstein brought something very significant to the debate, the eradication of the aether (but the aether came back soon after, and there are now several “reasons” for it; the point being that, as Poincaré suspected, there is a notion of absolute rest, and now we know this for several reasons: CRB, Unruh effect, etc.):

In 1892 and 1895, Hendrik Lorentz used a mathematical method called “local time” t’ = t – v x/c2 for explaining the negative aether drift experiments.[5] However, Lorentz gave no physical explanation of this effect. This was done by Henri Poincaré who already emphasized in 1898 the conventional nature of simultaneity and who argued that it is convenient to postulate the constancy of the speed of light in all directions. However, this paper does not contain any discussion of Lorentz’s theory or the possible difference in defining simultaneity for observers in different states of motion.[6][7] This was done in 1900, when Poincaré derived local time by assuming that the speed of light is invariant within the aether. Due to the “principle of relative motion”, moving observers within the aether also assume that they are at rest and that the speed of light is constant in all directions (only to first order in v/c). Therefore, if they synchronize their clocks by using light signals, they will only consider the transit time for the signals, but not their motion in respect to the aether. So the moving clocks are not synchronous and do not indicate the “true” time. Poincaré calculated that this synchronization error corresponds to Lorentz’s local time.[8][9] In 1904, Poincaré emphasized the connection between the principle of relativity, “local time”, and light speed invariance; however, the reasoning in that paper was presented in a qualitative and conjectural manner.[10][11]

Albert Einstein used a similar method in 1905 to derive the time transformation for all orders in v/c, i.e., the complete Lorentz transformation. Poincaré obtained the full transformation earlier in 1905 but in the papers of that year he did not mention his synchronization procedure. This derivation was completely based on light speed invariance and the relativity principle, so Einstein noted that for the electrodynamics of moving bodies the aether is superfluous. Thus, the separation into “true” and “local” times of Lorentz and Poincaré vanishes – all times are equally valid and therefore the relativity of length and time is a natural consequence.[12][13][14]

… Except of course, absolute relativity of length and time is not really true: everywhere in the universe, locally at rest frames can be defined, in several manner (optical, mechanical, gravitational, and even using a variant of the Quantum Field Theory Casimir Effect). All other frames are in trouble, so absolute motion can be detected. The hope of Einstein, in devising General Relativity was to explain inertia, but he ended down with just a modification of the 1800 CE Bullialdus-Newton-Laplace theory… (Newton knew his instantaneous gravitation made no sense, and condemned it severely, so Laplace introduced a gravitation speed, thus the gravitational waves, and Poincaré made them relativistic in 1905… Einstein got the applause…)

### 31 Responses to ““Proof” That Faster Than Light Communications Are Impossible Is False”

1. paul051 Says:

Very instructive point of view.
Many thank’s.
P.

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• Patrice Ayme Says:

You are welcome Paul!
encouragement always appreciated here!
Actually I am going to add another sentence to make it even clearer that Tolman’s argumentation is, in the end, purely philosophical and fully inconsistent with the closely related, and fully mainstream, relativity of simultaneousness.

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• paul051 Says:

Dear Patrice,
my quantum physics and Schrödinger’s equations are a little far from me on the time beeing.
However, might be cause of another fields of knowledge, I am right with you when thinking « c » is not an absolute wall if considering just one universe.
My best.
P.

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• Patrice Ayme Says:

Things are progressing now anew. Exhuming the 1935 (!) work of Schroedinger, among others, has brought up the concept of Quantum STEERING. Turns out not all Quantum Entanglement is steering. Nor is all steering Bell Nonlocality. The field is advancing, because of the requirements of the Quantum Computers (which already exist!)
Quantum Field Theory is interesting, and has brought fundamental progress. But, in a way, it was a distraction from the main mysteries of Quantum Mechanics.

BTW, most of basic QM was in De Broglie’s thesis, including the Schroedinger equation. However De Broglie didn’t work on non locality directly. However, his “DOUBLE SOLUTION” theory is a way to explain naturally nonlocality without hidden variables…

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2. Gmax Says:

So as usual the pundits are wrong. Communication faster than light may be possible. Seems like the Einstein bandwagon is full of s**t too. Alpha Centauri here we come! How do you think faster than light could work

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• Patrice Ayme Says:

Pundits are NOT always wrong. However, it’s striking that a zillion Nobels in physics didn’t notice this. Typically, because, I would guess, they don’t think the subject worthy of their attention. There is also nonsense going on around Black Holes, with time reversal curves.
I don’t have a mechanism for faster than light comm. However my own SQR may allow to do so at some peculiar distance (by singularizing in a peculiar time frame, within the no-loss collapse radius, that would cause no DM loss in the entangle paired particle… All speculation, but possible in the world of imagination).

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3. SDM Says:

Your statement that the observed size of the universe at 100 billion light years at a calculated age of 10 billion years as derived from the Big Bang theory leads me recall one of your earlier blog posts concerning the age of the universe where you had made a case for the age of the universe being much older based on the speed of light.
If in fact the universe is much older using that premise what does that say to whether or not there can be speeds in excess of light? The calculated age of the universe appears to hinge on this relationship. If speeds in excess of light speed can be determined, it would appear that the age of the universe would be in even more dispute until the actual maximum speed could be established. Or does quantum theory bypass that?

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• Patrice Ayme Says:

Dear SDM: Good questions all. When I talk physics, I am always divided between what I know is the official discourse, and what I know, which often goes beyond. I remember once a gentleman who used to comment on the site years ago, and knew quite a bit of physics (although he never claimed to have a PhD). Once I said in passing something about the graviton, the name for the gravitation field quantum. I asserted something about the spin of the graviton, and he replied angrily that all physicists knew that the graviton had spin two, and I was so ignorant, I didn’t even know that. Well, no, I knew what they knew, and that the fundamental field is the Ricci tensor, corresponding to spin 2, but actually it’s not really a theorem that the quantum of gravitation must have spin two. Some may not. Sure I was ignorant, he never commented again. If one talks to flat earthers about curvature, they may get angry.

In the case of cosmology, a few things are certain: the universe is at least 100 billion light years across (a bit less than that, demonstrated, but it’s growing all the time…), and it is evolving. The so-called Lambda Cold Dark Matter is the ruling cosmology. It asserts a universe around 12 billion years old, which INFLATED at 10^23 C. They don’t really have the proof that’s possible: it necessitates an INFLATON field nobody has seen, but there is a whole cottage industry about it, with babies universes all over the place.

I hold that we now have two cosmic inflation mechanisms, both mysterious, only one of them in direct evidence: Dark Energy (although an emeritus prof in Geneva wrote a paper recently claiming both DM and DE are illusions…). So I simplify to one, on the ground we don’t know enough about hyper-stars (my neologism) to be sure they can’t generate stuff we attribute only to the Big Bang. Indeed, bigger and bigger stars are revealed, and the results from gravitational astronomy reveal already there is much of the big picture in astrophysics which is wrong (there are too many Black Holes of impossible masses colliding for conventional astrophysics to be true…)

If we got the big picture in astrophysics wrong, there is no need for a Big bang, hence no need for Cosmic Inflation, etc… That’s what I think should be seriously considered.

However, sometimes, to make a smaller argument, on a smaller subject, I fake mainstream, and adopt Lambda CDM for the purpose of the subject at hand.

The universe beyond the event horizon (furthest galaxies we can see) is receding from us at speed in excess of light speed. That’s conventional physics.

If the universe NEVER experienced Cosmic Inflation, then it’s got to be as old as I said, hundreds of billions of years, because far away it looks everywhere the same, so, naturally, physicists believe that means it has a common source (the second part of the argument is conventional). Quantum Mechanics is the Deus Machina of the whole thing. I discussed my idea with Feynman (no less!), and he found it would change everything (he had cancer at the time, and by happenstance this brought no paper).

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4. SDM Says:

Would time dilation also require great distance – non-locality?

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• Patrice Ayme Says:

Time dilation is a fact. A theoretical fact, and an experimental fact. Its existence is 100% observed and understood.
Nonlocality is also a fact, theoretical and experimental.
At first sight, they have nothing to do with each other in my mind. However, that maybe a problem with my mind. I have been thinking vaguely on the definition of time. Nonlocality would enable universal time if it could be made to transmit Faster Than Light communications.
But, as I said in the essay Poincare’ Synchronization is already good enough to establish universal time over the entire galaxy, if civilization spreads there.

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5. ianmillerblog Says:

Hello Patrice,

I am not so sure you can assert the Universe is 100 billion light years across. It might be, but we cannot see anything further than the 13.5 billion light years because any further away (unless we have the start of the Universe wrong) the light has not got here yet, so we cannot see it. Similarly, I am far from convinced that there was such rapid inflation initially and there are other ways to explain the evenness of the temperature. But I agree; you cannot prove faster than light communications are impossible, but merely they are if you believe Einstein’s relativity theory, Strictly speaking, Einstein’s relativity really only follows for electromagnetism because the c^2 simple refers to electromagnetic constants.

I think you know my view on entanglement – it doesn’t work the way everyone seems to think it does. The rotating polariser experiment is odd because the entanglement of photons only occurs because of the conservation of angular momentum, but then the analysis as they apply Bell’s inequality argues that rotating the experiment creates two new variables, which denies angular momentum conservation by Nöther’s theorem. Assuming it is there, then denying it is, in my opinion, faulty logic.

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• Patrice Ayme Says:

The real number, as found in the last ten years, is around 92 billion light years.
It is a consequence of the expansion of the universe. A photon has a proper time in its comoving frame: think of little light clock transversal to photon progression.
However, as the underlying metric stretches, the comoving frame covers more and more distance.
It’s as if the photon crawled over an expanding balloon. Maybe it crawled for 14 hours, meanwhile the balloon has stretched by a factor of 3, so it has covered three times the distance.
In accord with the current observational data, we assume that the universe is spatially flat. In a spatially flat Friedman Robertson Walker model, the r−t part of the metric is of the form
ds^2=dt^2−a^2 (dr^2)
where the scale function a depends on time. For a photon, ds= 0, and we can then show that the proper distance traversed by a photon since shortly after the Big Bang is given by L= ∫dr= ∫dt/a. For a matter-dominated solution, a is proportional to t^(2/3), so L=3t. This is close to the L/tL/t ratio of about 3.3 given by the most realistic models. It also makes sense that the result is somewhat greater than 3, because the universe has now entered a DE era in which its expansion is accelerating.
***
I don’t believe in the inflation:
https://patriceayme.wordpress.com/2013/12/19/universe-100-billion-years-old/
Once again, I use philosophy to cut through the crap, in this case the inflation crap (scuze me, it’s late here…).
***
My essay pointed out that the “proof” of impossible FTL coms is a PHILOSOPHICAL OPINION (not hard core equations). MOREOVER, that philosophical opinion is INCONSISTENT with the mood imparted by the (demonstrated!) relativity of simultaneity (shown by Poincare’, not Einstein, first)
***
There are THREE TYPES of Quantum entanglements.
The essence of Bell Locality (the type you discuss) is that measuring spin of Photon 1 along x modifies it along y. So if one measures spin of ENTANGLED Photon 2 along the z axis, immediately after measuring Photon 1 along x, the measure of Photon 2 along z will be AFFECTED.
And that goes FLT.
And that can, and has, been checked experimentally: one can verify later.
So measuring spin on Photon 1 has changed spin of Photon 2 at Faster Than Light (Aspect was first to do this, with special equipment). He got the Wolf Prize in physics for it.
What is NOT understandable in what I just described?????
***
BTW, there are now experiments which demonstrate nonlocality NON statistically.

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• ianmillerblog Says:

I think we agree on inflation.

As for Aspect, my argument is simple – there are not enough true variables to put into the Bell Inequalities. Thus the entanglement depends on conservation of angular momentum, which in turn depends on rotational invariance of space. Then Aspect partially rotates his apparatus and claims that gives two new variables. He might as well have moved the experiment to the other end of the lab!

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• paul051 Says:

What metrics could be avaliable sometimes after the Big Bang ?

Might be no one…

And before, might be no one ?

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• Patrice Ayme Says:

As it is among Big Bangers (!), a big deal is now made between before or after year 380,000…
Before that, there are indeed arguably no metrics.
The problem with cosmic inflation is that one has not seen it since. Except in the minds of those who see baby universes exploding all over, such as Linde in Stanford…

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• Patrice Ayme Says:

OK, agreement on inflation.
What Aspect did was to measure spin along x for P1, then chose, Monte Carlo like, a direction y, and measure spin of P2 along y. The choice is done FTL. So he ran the Monte Carlo faster than light could have made it from P1, then rotated the polarization device along y. Same experiment was run since with electrons.
All loopholes have been closed… except for the one I just opened, namely that FTL doesn’t contradict Relativity. Hahaha!
https://patriceayme.wordpress.com/2017/12/16/proof-that-faster-than-light-communications-are-impossible-is-false/

Since ‘Greenberger–Horne–Zeilinger’ (GHZ) states have been made in the lab. The results of three specific experiments, involving measurements of polarization correlations between three photons, lead to predictions for a fourth experiment; quantum physical predictions are mutually contradictory with expectations based on local realism, in a non statistical way

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6. Ian Miller Says:

ianmillerblog
on December 21, 2017 at 9:34 pm said:
Patrice, Io Saturnalia! (Here, of course, it is the summer solstice, and we have a wretched drought to go with it.)

In fairness to Einstein, I doubt he actually thought of the photon as a point, because if it were, Maxwell would be totally wrong. It has to have size, and now the question is, how much size? However, in my Guidance Wave interpretation, the waves transfer energy, and the square of the amplitude reflects the energy, therefore the wave has to regenerate itself, so it is really a pulse travelling on a line. I also invoke Euler’s complex number representation and argue the wave becomes real at the antinode, and I attribute that it is here the conservation laws are imposed on the particle. So the wave actually defines an inertial field when it is real.

If you want something even more out of the box, there is enhanced attraction when the waves mutually reinforce when real. This suggests a a slightly different origin for gravity, and if correct, gravity would cease to be constant but would attenuate to zero as the number of particles decreased. The reason for the constancy of gravity is the predominant waves would be due to quark motion, and all matter is made of only two quarks predominantly. However, gravity is so weak I can’t see that being observed.

So, Merry Christmas, wrap up well, and all the happiest waves for 2018!

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• Patrice Ayme Says:

Wretched drought in California too. This is it! Last year was freakish wet, and now the centennial drought is back, big time. Speaking desert rainfall so far this year. Time to grow cacti… Trees are dying by the millions. Soon they will burn like never before…

You make an excellent point about the e-m Maxwell wave…. However Einstein couldn’t be any clearer:
“Energy, during the propagation of a ray of light, is not continuously distributed over steadily increasing spaces, but it consists of a finite number of energy quanta LOCALIZED AT POINTS IN SPACE, MOVING WITHOUT DIVIDING…”

This is arguably physics’ biggest mistake….
All these possibilities show we are just scratching the surface…

In my own theory, SQPR, the particle, when propagating dissolves in a sort of amoeba, the full matter wave W, which expands through (“phase”) space at the speed of light, c, when in translation. It becomes asymptotically a linear wave L (the one QM works with). However, W is nonlinear, hence unstable: nonlinear waves are a fight between singularization and dispersion. If too much amplitude gathers somewhere in its amoeba body, it starts to go singular there, gathering its mass-energy in that spot. It does this at speed TAU, which is something to be determined. Just out of spite, I will give it the cosmic inflation speed of 10^23 C… Now this process will happen without loss at short range, within a fixed time T.
If the diameter of the amoeba is greater than (TAU) T, when singularization-localization starts, singularization will lose some mass-energy, Dark Matter is produced. And also the famous Cosmic Redshift and the Cosmic Background Radiation (as a DM for cosmic photons). We are talking serious revisions, here…

Happy Solstice (Sol-Still works in summer as in winter)!
Just curious: how dry is New Zealand now, and where do you live? Auckland??

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7. Jason Says:

Hi Patrice. Does this mean then that technically FTL communication would allow for message to be sent backward in time?

If that is the case and a message could be received, say 1 year back in time, what would be the result.

Say, for example, if 1 year ago a person baked an apple pie on Nov 1/2017 and you sent a superluminal message backward in time to that day or the day before instruct the person to bake a cherry pie what would be the result?

Would the person then bake a cherry pie and those that came to eat the pie then have their experience changed so that they ate a cherry pie (block universe, same reality) OR would this be an alternate universe/reality with the change?

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• Patrice Ayme Says:

Hi Jason! From now on your comments will go through without preliminary moderation.

I generally do not associate time and light GLOBALLY. Right, locally distance D, time T and speed of light c are related by: D/T = c. However this is true only at the limit of the ultrafilter of neighborhoods centered at a “point”.

The paradoxes of “going back in time” come from confusing physics of spacetime, valid only at a point, and physics of spacetime, at other points. True one can make loops (holonomy groups). As in standard differential geometry, though, they exhibit parallel transport, and deviation, after making a loop expressing curvature: that’s why Einstein called it “Allgemeine”, GENERAL Relativity… No need for alternate universes…

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• Jason Says:

Thank you for your reply. I don’t quite follow. Does this mean ftl communication may allow for message to the near past allowing a change like warning of a disaster after the fact?

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• Patrice Ayme Says:

In one word, no. I think the usual logic is confused. First to have considered the subject was Poincare’, the guy who really invented Relativity knew about the problem of simultaneity, and LOCAL TIME (he invented the concept).
It’s not because an event appears before another that it CAUSED it. Or, more pertinently, it’s not because an event X appears before an event Y that Y didn’t cause X. (Actually that’s well known, say in medicine…)

If one moves fast in a ship F relative to Earth (E), towards Proxima Centauri (PC), events in the Centaur, in PC, will appear before those on Earth E.

This is a reasoning from a site trying to show that FTL implies causality violation:

According to us, on Earth, the order of events is thus: we see the light from the event hit us. We call Proxima Centauri on the FTL phone. The Proximal Centaurians do whatever they want to do in response to that call, and then they see the light of the event.

What does the ship see? They see the phone call received on Proxima Centauri. Then they see the phone call placed from Earth. Effect precedes cause: causality is violated. In fact, if the ship had a FTL phone set up in the right way, they could call Earth before Earth placed the call. They could even tell Earth “hey, don’t make that call to Proxima Centauri we just saw you make.” Then what?

What’s wrong there is that Relativity predicts APPARENT causality violation in a “fixed” frame (say the Earth and PC fixed frame) as viewed from a FAST reference frame. It’s not mysterious: light needs more time to catch up… The same would happen with sound… So yes, FTL may make it look as if time flowed backwards in the E-PC fixed frame…
But it’s no big deal. From F one cannot communicate backwards in time with E just because one saw a FTL message from E received on PC!

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• Patrice Ayme Says:

BTW, I have an incoming essay which touches upon FTL and Quantum Theory, in what I call “Quantum Justice”. Turns out Quantum Theory is incoherent, self-contradictory in this realm, and this long held position of mine was officialized in a paper just published in Nature… A paper which looks in detail to the old and famous paradox known as “Wigner Friend”….
Nature
NEWS 18 SEPTEMBER 2018
Reimagining of Schrödinger’s cat breaks quantum mechanics — and stumps physicists
In a multi-‘cat’ experiment, the textbook interpretation of quantum theory seems to lead to contradictory pictures of reality, physicists claim.

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8. Jason Says:

Are you in any way implying it may be possible to send a message backward in time (warning or similar)? Paradoexss be damned of course.

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9. ronaldscheckelhoff Says:

Non-local faster than light communication has already been experimentally proven. Also, it’s in production. By the mid nineties, they had already determined why it was that all of the famous experiments failed to show that quantum communications or “signalling” was possible.

It’s simple. You CANNOT measure a quantum system in a very worthwhile way by using classical measurement means. You have to use a quantum measurement procedure to measure quantum communications and Qbit teleportation effectively.

One of the first experiments used nuclear magnetic resonance techniques, and indirectly measured Qbit teleportation by using phase decoherence in a carbon atom.

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• Patrice Ayme Says:

Hi Ronald and welcome! Your next comment will go through without “moderation”. I am intrigued by your assertions, which are news to me. Are you alluding to EPR style interactions? I call that the “QUANTUM INTERACTION”… As it is I don’t know how to use it to communicate… The point being that we can’t chose the outcome at the departure point of the message… so we can’t write a message!… to start with!

Now it’s true that any Quantum Measurement is nonlocal…

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10. ronaldscheckelhoff Says:

Hi Patrice,

“Now it’s true that any Quantum Measurement is nonlocal …”

Of course! 🙂

I guess I meant to compare the coarse measurements available in the context of the classical days of long ago – versus indirect molecular level measurements.

EPR? So, we may be talking about the same thing. The old experiment from the nineties used trichloroethylene molecules, like thus:

Cl Cl
\ /
C1 = C2
/ \
H Cl

They used the Brassard two-part Bell. They teleported the state of data Qbit C2 to target Qbit H. “Interaction” between data and target was prevented via magnetic nuclear resonance refocusing.

For second part of Bell, they needed to be indirect, so performed a projection measurement using the phase decoherence of the carbon nuclei, where the state of the computational basis became diagonalized.

This is my amateur synopsis of the article from the Nature article of November, 1998. Are we talking (writing) about the same thing?

Anyway, just to mention – I have no formal physics training – only a bushel basket or so of books, and too much time. So, any laughter won’t be taken badly at all.

– Ron

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11. ronaldscheckelhoff Says:

Oops, the spacing got trashed. Sorry.

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