Does instantaneous communication implies a preferrred Lorentz frame?

[Demystifier]

Illusion of free will is like doing stuff after hypnosis.
When people after hypnosis do stuff as they were commanded during the hypnosis, they do not think that they do it because they have no choice. They think that they do it because they want to. Thus, they have an illusion of free will. Nevertheless, they do what they was commanded to, so their actions are not really free will actions.

 

[Fredrik]

You cannot choose to do inconsistent stuff. For example, you cannot chose to turn to the left and to the right at the same time. If you ask what happens if you try, the answer is that you never try to do such inconsistent stuff. You try only one of this two options at a given time, and whatever it is, you think that it is because you have chose to.

I agree with this of course. But I strongly disagree with your conclusion. Turning left and right at the same time doesn't even make sense. To build a computer that replies with the NOT of what it receives isn't inconsistent. To build a computer that replies with the same message it receives isn't inconsistent. To put the second computer on a spaceship traveling at c/10 isn't inconsistent. None of the details in the scenario I suggested is inconsistent by itself, and we only get a paradox if we succeed to do all of them. So I can certainly choose to do any of them, but according to you I won't choose to do all of them. I can tell you right now that I would need a very good reason not to do all of them. And if I choose to quit without a good reason, it's not going to seem like free will to anyone, least of all me.

And if I do get a good reason, something like a series of quantum tunneling accidents involving my floor so that I keep losing pieces of my legs, it would make me feel even more strongly that the illusion of free will is gone.

To preserve the illusion of free will, I think the event that prevents the paradox must happen a long time before I even start to think about these things. For example, I might not get born at all. I don't think it's enough that I don't get my hands on a spaceship, because if the technology ever exists, it will sooner or later be in the hands of someone with similar ideas. I think the most reasonable option by far is that nothing that even resembles intelligent life will evolve in a special relativistic universe with tachyons that can in principle be detected in a short time.

As you can see, I can't prove that I'm right, at least not right now. But I feel very strongly that your view can't be correct, and I suspect that I would be able to come up with a much stronger argument if I had a good definition of what "illusion of free will" means.

Edit: What about the scenario I described earlier, where the experiment puts you in a position that gives you a good reason to believe that choosing the action that prevents the paradox will kill your child? There's nothing inconsistent about this scenario. Would you choose to kill your child, and still consider the illusion of free will to be intact?

I'm choosing to go to sleep now. I'll read the replies when I wake up.

 

[RUTA]

OK, I'll elaborate. Let's use the standard terminology by calling the first computer I mentioned "Alice", and the second one "Bob". I'll be describing things using Alice's rest frame, so Alice's world line coincides with the time axis. For simplicity, we will consider 1-bit messages that are instantaneous in the emitter's frame. (This is just for simplicity. We would end up with the same type of paradox even if the speed of a message in the emitter's frame is just slightly higher than c. It would just be more difficult for me to describe the experiment). Bob's world line is a line with slope 10 (i.e. velocity 1/10) through the point (1,10). That event is simultaneous in Bob's frame with (0,0) in Alice's frame (because if the slope of his world line is 1/v, the slope of his simultaneity lines is v). So if Bob sends an instantaneous message to Alice at (1,10), it will reach her at (0,0).

Alice is programmed to reply at the event (1,0). The program says that the reply must be 0 if the message received at (0,0) was 1, and vice versa. (The reply is the logical NOT of the message she received). The message that Alice sends at (1,0) is received by Bob at (1,10). Bob is programmed to reply immediately with the same bit that he received.

Now suppose that Alice receives 1. She replies by sending 0. Bob receives the message and replies by sending 0. Alice receives 0.

Bob is moving at v = 1/10 relative to Alice and his worldline passes through (1,10), so it also passes through (0,0). We're using Alice's coordinates so she is always at x = 0. [Note: Bob's worldline passes through (0,0), not the relevant sfc of simultaneity.] A hypersfc of simultaneity for Bob passing through (1,10) has slope 1/10 so it passes through (0,9.9), which precedes (1,10) by t = 0.1 in Alice's frame. Bob sends a signal (ONE) to Alice along this sfc of simultaneity, so Alice receives ONE at t = 9.9 and sends a signal (ZERO) to Bob alg a t = 9.9 sfc of simultaneity in her frame (slope of 0). This sfc of simultaneity intersects Bob's worldline before he sent his ONE at t = 10. The exact values of time for Bob don't matter and the signal itself (ONE or ZERO) that he sends doesn't matter. Whatever Bob sends at t = 10 is inverted at t = 9.9 and returned to him in his past (t = 9.9), so he can't possibly send the same thing he receives. Thanks for the explanation, Fredrik!

 

[RUTA]

I agree with this of course. But I strongly disagree with your conclusion. Turning left and right at the same time doesn't even make sense. To build a computer that replies with the NOT of what it receives isn't inconsistent. To build a computer that replies with the same message it receives isn't inconsistent. To put the second computer on a spaceship traveling at c/10 isn't inconsistent. None of the details in the scenario I suggested is inconsistent by itself, and we only get a paradox if we succeed to do all of them. So I can certainly choose to do any of them, but according to you I won't choose to do all of them. I can tell you right now that I would need a very good reason not to do all of them.

I agree with Fredrik. IMO, if it is possible, there has to be something in physics to make it work -- a physical mechanism bearing on brain states and/or computer electronics. This appears to require new physics. If it isn't possible, then we need something in physics to rule it out, which again seems to require new physics because there's nothing in SR per se that forbids superluminal worldlines.

 

[tetis]

Well, 'abandon relativity' is a bit strong. You mean 'abandon the Einstein-Minkowski interpretation of relativity'. You just want the neo-Lorentzian interpretation of relativity - which is perfectly in agreement with experiment.. As Bell said:

I think it's a deep dilemma, and the resolution of it will not be trivial; it will require a substantial change in the way we look at things. But I would say that the cheapest resolution is something like going back to relativity as it was before Einstein, when people like Lorentz and Poincare thought that there was an aether - a preferred frame of reference - but that our measuring instruments were distorted by motion in such a way that we could not detect motion through the aether. ... that is certainly the cheapest solution. Behind the apparent Lorentz invariance of the phenomena, there is a deeper level which is not Lorentz invariant. ... what is not sufficiently emphasized in textbooks, in my opinion, is that the pre-Einstein position of Lorentz and Poincare, Larmor and Fitzgerald was perfectly coherent, and is not inconsistent with relativity theory. The idea that there is an aether, and these Fitzgerald contractions and Larmor dilations occur, and that as a result the instruments do not detect motion through the aether - that is a perfectly coherent point of view. ... The reason I want to go back to the idea of an aether here is because in these EPR experiments there is the suggestion that behind the scenes something is going faster than light. Now if all Lorentz frames are equivalent, that also means that things can go backwards in time. ... [this] introduces great problems, paradoxes of causality, and so on. And so it is precisely to avoid these that I want to say there is a real causal sequence which is defined in the aether.

So as Zonde says, superluminal signalling violates causality only if one assumes a locally Minkowski structure for spacetime, and not with Lorentz. Historically, Minkowski structure was developed for a local physics. If Nature turns out to be nonlocal, then we might consider revising that structure.

Aniway I think isn't so simple go back to Lorentz Poincaré Larmor Fitzgerald aether after then Einstein go forward to general relativity. A consistent general aether theory includind gravitation could pretend probabilly an entirily new formulation of physic's laws. Actually quantum gravity could be a candidate to realize these new laws, but in that case doesn't need to go back to aether, the local quantum field theory, without requiring, in nosense, a violation of the causal principle, require that vacuum breaks full Lorentz symmetry for massless sector of the theoy [1] and on the other side Einstein's equation solution require to specify some degree of freedom for the metric [2], Einstein considered this circumstance just like a relict of the old aether, but in a general covariant version, and without any need to restaurate an absolute sincronization [3]. Extension of Einstein equations are considered nowday [4] which admit new fields, sometimes these fields resemble to the true time vector of the old Lorentz Poincaré Larmor Fitzgerlad theory, that is removed in general relativity.

[1] Haag: "Local quantum physics"
[2] Wheeler Misner Thorpe: "Gravitation"
[3] Abraham Pais "Subtle is the Lord"
[4] Bekenstein: "Relativistic gravitation theory for the modified Newtonian dynamic paradigm",
http://prola.aps.org/abstract/PRD/v70/i8/e083509

So i think there are a lot of reason in order to think to an objective simultaneous section arising from local field quantum theory, from observational data, but no one is conclusive and the arguments pointed out from the OP are in fact wrong arguments. None the quantum field theory requires a violation of causality arising from EPR effect, none classical tachyons are required in order to threat the EPR effect, none the conventional character of simultaneity in relativity require to drop out the causality in order to have the EPR. Aniway a Bohmian formulation should be coherent with extension of general relativity and not necessarily with full general relativistic local quantum field theories.

 

[DrChinese]

Bob is moving at v = 1/10 relative to Alice and his worldline passes through (1,10), so it also passes through (0,0). We're using Alice's coordinates so she is always at x = 0. [Note: Bob's worldline passes through (0,0), not the relevant sfc of simultaneity.] A hypersfc of simultaneity for Bob passing through (1,10) has slope 1/10 so it passes through (0,9.9), which precedes (1,10) by t = 0.1 in Alice's frame. Bob sends a signal (ONE) to Alice along this sfc of simultaneity, so Alice receives ONE at t = 9.9 and sends a signal (ZERO) to Bob alg a t = 9.9 sfc of simultaneity in her frame (slope of 0). This sfc of simultaneity intersects Bob's worldline before he sent his ONE at t = 10. The exact values of time for Bob don't matter and the signal itself (ONE or ZERO) that he sends doesn't matter. Whatever Bob sends at t = 10 is inverted at t = 9.9 and returned to him in his past (t = 9.9), so he can't possibly send the same thing he receives. Thanks for the explanation, Fredrik!

I'm sorry I am so dumb, but I just don't follow.

Alice's clock is always moving forward and Bob's clock is always moving forward. But they may not be moving forward at the same rate. Instantaneous Communication (IC) implies that there could be another party, let's say Chris. Chris sends out the time to Alice and Bob via IC. Regardless of their frame relative to Chris, they will always receive timestamps that are moving forward, even if they are different than their own. They will at least agree that at any point, they can see the delta between their own time clock and Chris'.

Now, how does the hypersurface of either Alice or Bob matter? A relativistic hypersurface won't come into play because all communication is by IC. You have a preferred frame because of Chris I guess, how does a causal loop problem appear?

According to Chris's clock (which both Alice and Bob are aware of) which is initially sync'd to both Alice and Bob:

a. Alice at t=0 (per her and Chris' clock) sends a 1.
b. Bob receives a 1 at t=0 (per his and Chris' clock).
c. Bob sends a 0 after some very short delay, let's say it reads t=1 per Chris' clock but t=2 per Bob's clock.
d. Alice receives a 0 at t=1 per Chris' clock but it is t=20 per her clock.
e. Alice sends at 0 to Bob at t=2 per Chris' clock but it is t=21 per her clock.
f. Bob receives a 0 at t=2 per Chris' clock but it is t=2.1 per Bob's clock.

So I guess it seems to me that everyone's clocks are advancing. Of course I do not believe that IC is possible. I am simply saying that IF there were such, how does the paradox arise? I know I should probably understand this, but I don't. HELP!

 

[RUTA]

I am simply saying that IF there were such, how does the paradox arise? I know I should probably understand this, but I don't. HELP!

Draw an X-Y graph. Y is Alice's time coordinate (t) and X is Alice's spatial coordinate (x). Alice's worldline is the t axis, i.e., x = 0 for all t. Bob is moving to the right at v = 0.1. His worldline (slope 10) passes through the origin (0,0) and through the point (x = 1,t = 10). Spatial slices for Alice (t = constant) are horizontal lines, slope = 0. Spatial slices for Bob are NOT horizontal lines, they're lines of slope 0.1. That's how everyone can measure the same speed of light even when they're in relative motion, i.e., they disagree on spatial length and temporal duration because they don't agree on which events are simultaneous (to measure the length of an object, you need to know where its ends are at the same time). So, the point on the t axis simultaneous with (1,10) according to Alice is (0,10). But for Bob, the point on the t axis simultaneous with (1,10) is (0,9.9), i.e., a line of slope 0.1 at (1,10) passes through (0,9.9). So, when Bob sends an "instantaneous signal" in his frame towards Alice from (1,10), that signal gets to Alice at (0,9.9). Now when Alice sends an "instantaneous signal" in her frame towards Bob from (0,9.9), that signal gets to Bob at (0.99, 9.9). Those three points make a triangle -- event 1 at (1,10) to event 2 at (0,9.9) to event 3 at (0.99, 9.9) back to event 1 at (1,10).

Now let's follow the sequence of events. Bob sends a signal from event 1 to Alice at event 2. She sends the inverse signal from event 2 to Bob at event 3. Thus, no matter what Bob sends from event 1, he receives the opposite signal at event 3, which is BEFORE event 1. Therefore, he cannot send the same signal he receives, but he receives a signal from Alice before he sends his, so what prevents him from sending the same signal?

 

[Fredrik]

Bob is moving at v = 1/10 relative to Alice and his worldline passes through (1,10), so it also passes through (0,0).

No, I meant that Bob is at x=10 at t=1. The slope of his world line in the spacetime diagram (with time in the "up" direction) is 1/v=10, not v, so his world line (if he's been moving at constant velocity for a long time) intersects Alices world line at t=-99.

The line that goes through (1,10) and (0,0) is a simultaneity line for Bob. It's Minkowski orthogonal to his world line. Its slope is dt/dx=(1-0)/(10-0)=1/10=v.

I didn't read the rest of your post since the first sentence got it wrong...or maybe you're just drawing the time axis to the right in your spacetime diagrams? The conventional way to draw them is to have time increasing in the "up" direction.

 

[Fredrik]

Now, how does the hypersurface of either Alice or Bob matter? A relativistic hypersurface won't come into play because all communication is by IC.

You still seem to be making the mistake of defining an IC to be instantaneous in all frames. In the scenario I'm describing, Alice is sending a message that reaches the destination at the same time it was sent (or very shortly thereafter) in her rest frame. This sort of message is what we mean by an IC in this scenario. The world line of the message will coincide with one of her simultaneity lines, because an IC message is defined as a message that follows one of her simultaneity lines. That's what it has to do to be instantaneous to her in a universe where special relativity is a good theory (which btw implies that the preferred method of clock synchronization is by light signals). Maybe it should be called an I_AliceC message instead.

The IC message that Bob sends follows one of his simultaneity lines. This is what IC means here, so maybe I should call it I_BobC.

Also note that we're not trying to use these messages to find out what mathematical model of space and time we should be using. We're assuming that this is happening in a universe where spacetime can be approximated by Minkowski space, at least on the time and distance scales that we draw in our diagrams.

I know I should probably understand this, but I don't. HELP!

I think that if you go back and read my description (in #24) again, and keep in mind that the world lines and simultaneity lines we're talking about are in Minkowski space (where simultaneity for an inertial observer is well-defined), and that "instantaneous" in this context is defined as "following a simultaneity line of the emitter", you won't have any difficulties understanding it.

 

[RUTA]

No, I meant that Bob is at x=10 at t=1. The slope of his world line in the spacetime diagram (with time in the "up" direction) is 1/v=10, not v, so his world line (if he's been moving at constant velocity for a long time) intersects Alices world line at t=-99.

The line that goes through (1,10) and (0,0) is a simultaneity line for Bob. It's Minkowski orthogonal to his world line. Its slope is dt/dx=(1-0)/(10-0)=1/10=v.

I didn't read the rest of your post since the first sentence got it wrong...or maybe you're just drawing the time axis to the right in your spacetime diagrams? The conventional way to draw them is to have time increasing in the "up" direction.

You had written, "Bob's world line is a line with slope 10 (i.e. velocity 1/10) through the point (1,10)," and "That event is simultaneous in Bob's frame with (0,0) in Alice's frame," so one of those two statements had to be corrected. I chose to correct the point of simultaneity, i.e., (0,9.9) instead of (0,0). With that one change your story makes the point, as I explained to Dr. Chinese in post #37.

 

[Fredrik]

You had written, "Bob's world line is a line with slope 10 (i.e. velocity 1/10) through the point (1,10)," and "That event is simultaneous in Bob's frame with (0,0) in Alice's frame," so one of those two statements had to be corrected.

The second statement is equivalent to the first, so no correction is necessary. A line through (1,10) with slope 10 goes trough (0,-99), not (0,0). And the corresponding simultaneity lines have slope 1/10 (because a simultaneity line is Minkowski orthogonal to the world line), so the simultaneity line through (1,10) goes through (0,0).

Edit: RUTA found a mistake here. The (0,-99) above should be (-99,0). Bob's world line intersects the time axis (where x=0) at t=-99, as I said in #38.

 

[DrChinese]

You still seem to be making the mistake of defining an IC to be instantaneous in all frames. In the scenario I'm describing, Alice is sending a message that reaches the destination at the same time (or very shortly thereafter) in her rest frame. This sort of message is what we mean by an IC in this scenario. The world line of the message will coincide with one of her simultaneity lines, because an IC message is defined as a message that follows one of her simultaneity lines. That's what it has to do to be instantaneous to her in a universe where special relativity is a good theory (which btw implies that the preferred method of clock synchronization is by light signals). Maybe it should be called an I_AliceC message instead.

You are correct, and I can see the idea of what you are saying. But it seems to me to miss the idea of IC with a preferred frame (which I thought was the central question in the thread - if you assume that there are only worldlines like we currently believe, then you don't have a preferred frame). I would imagine that would require us to have the following:

a) the speed of light is observed to be the same in all reference frames.
b) some method of IC not involving light.
c) possibly leading to a preferred reference frame (although I understand that may or may not be a strict consequence of assuming b).

So I imagine IC by some channel - obviously I don't actually believe this - in which light is not the medium. Maybe it is instead some undiscovered mechanism. I picture a type of spacetime in which the distance from "here" to "there" in one dimension is much shorter than in the other (traditional) directions.

We don't have to devote any more time to me, I understand now what everyone else is assuming in the example that I did not. Thanks!

 

[RUTA]

The second statement is equivalent to the first, so no correction is necessary. A line through (1,10) with slope 10 goes trough (0,-99), not (0,0). And the corresponding simultaneity lines have slope 1/10 (because a simultaneity line is Minkowski orthogonal to the world line), so the simultaneity line through (1,10) goes through (0,0).

Slope = (Y_final-Y_initial)/(X_final-X_initial). Your final point is (1,10) and your initial point is (0,0). Slope = (10-0)/(1-0) = 10. His worldline goes through (0,0) and (1,10). You're right about the simultaneity lines having slope 0.1 (= v), which means the simultaneity line of slope 0.1 through (1,10) goes through (0,9.9).

Your numbers give (10- -99)/(1-0) = 109 for the slope of Bob's worldline. I think you want the final point to be (10,1) instead of (1,10), then your other points work as you say.

 

[Fredrik]

Slope = (Y_final-Y_initial)/(X_final-X_initial). Your final point is (1,10) and your initial point is (0,0). Slope = (10-0)/(1-0) = 10.

The conventional way to draw a spacetime diagram is to have time increasing in the "up" direction, and most people (including me) would say that a horizontal line has slope 0, not infinity. The slope of a line in a spacetime diagram is therefore dt/dx, which for the line through (0,0) and (1,10) is 1/10=v. This is a simultaneity line for an inertial observer moving with velocity v, because it's Minkowski orthogonal to a line that represents inertial motion with velocity v.

His worldline goes through (0,0) and (1,10).

The conventional intepretation of that statement would be that his speed is ten times the speed of light. (He has moved 10 light-years in 1 year). I'm not sure what you're doing, but it's either very wrong or very unconventional.

 

[Neo_Anderson]

Superluminal communication is not ruled out by relativity. Tachyons have Lorentz invariant dispersion relations, and therefore obey relativity. But comminication with tachyons has some peculiar features, such as receiving a reply before the message is sent, etc. So there are some difficulties with causality, but this is not strictly a requirement of relativity.

But I thought that there was nothing that can't say the effect can precede the cause. It's possible to have an effect come before a cause, provided that both occur, no? I know it's an odd thing to think about, but there's nothing physically impossible with it, isn't there?

 

[Fredrik]

But I thought that there was nothing that can't say the effect can precede the cause. It's possible to have an effect come before a cause, provided that both occur, no? I know it's an odd thing to think about, but there's nothing physically impossible with it, isn't there?

See post #30 for some comments about what you're asking.

The problems associated with receiving a reply before the message was sent are much more severe than just "effect preceding cause". See #17 and the clarifications in #24.

 

[zonde]

Zonde, your view of free will does not coincide with mine. In your view, a random event also appears as a free will event, which does not in my view. In my view, a free will event is an event that is not controlled by any fixed physical laws, either deterministic or probabilistic. Clearly, if physical laws as we currently know them describe EVERYTHING, then free will does not exist.

Physical laws are developed based on observations and experiments. If physical law poorly describes physical reality then it's useless or simply wrong. So assuming that there is something like free will physical law either should incorporate it (that is not allowed by your definition) or be discarded and the phenomenon considered random (that too is not allowed by your definition).
So it seems to me that your view states impossibility and is useless. Can you show it otherwise?

 

[zonde]

That seems like an odd definition, especially considering that we're talking about a mathematical model of the universe that's just a 4-dimensional manifold with a bunch of curves in it. Cause and effect are just words that identify the direction of increasing entropy in the subset of the manifold that we're considering.

But why do you identify cause and effect with increasing entropy? Cause and effect is related to time and we have common piece of equipment called "clock" to make measurements of time. How do you measure increase in entropy?

(Drop a glass bowl so that it shatters against the floor. The only reason to say that the drop caused the shattering and not the other way round is that entropy is increasing in that direction).

Sequence of events is the reason to say that the drop caused the shattering (by definition).

I would say that free will implies a lot more. The mind would have to be something more than just a bunch of physical interactions in the brain, and whatever it is, it would have to be able to change the outcome of some of those interactions. That sounds like paranormal nonsense to me, and even those who disagree with that would have to agree that there's no good evidence for this kind of free will. The illusion of free will is more interesting. I don't know the best way to define it, but I certainly feel like I have it when I press the "submit reply" button to post this.

I think that this 4-dimensional mathematical model of the universe creates illusion that you can foresee the future. That is not so. Deterministic laws are good for accumulating information about the past because for the past you can retrospectively sort information in more relevant and less relevant. And you have to do things like that because there is limited amount of information you can keep.
But you can not with certainty predict what information will be relevant in the future.
Now if you can not predict with certainty the future how can you know what changes certain action can possibly make? You can only try and see. And that is your free will what you will try and what you will not.
For example you can try rational things that will lead to highly predictable outcome and you can try irrational things that can lead to quite unpredictable outcome.

 

[Demystifier]

None of the details in the scenario I suggested is inconsistent by itself, and we only get a paradox if we succeed to do all of them.

Exactly. The idea is that nature works globally.

So I can certainly choose to do any of them, but according to you I won't choose to do all of them.

I am saying that you cannot choose to do all of them, because nature works globally.

I can tell you right now that I would need a very good reason not to do all of them. And if I choose to quit without a good reason, it's not going to seem like free will to anyone, least of all me.

The reason nature quits is because nature wants to avoid inconsistencies. The reason is of a global nature. However, our subjective consciousness is used to interpret nature in terms of LOCAL reasons. On the other hand, in this case local reasons do not exist. So, how our subjective consciousness will interpret it? My idea (which I cannot prove because I don't completely understand how consciousness works) is the following: As consciousness is unable to see the global reasons, consciousness will interpret it as happening without a reason. That is, it will interpret it either as a local random event, or an event caused by local free will. Nevertheless, the true nature of the event is neither random nor free. Instead, it is determined by the principle of global self-consistency.

Edit: What about the scenario I described earlier, where the experiment puts you in a position that gives you a good reason to believe that choosing the action that prevents the paradox will kill your child? There's nothing inconsistent about this scenario. Would you choose to kill your child, and still consider the illusion of free will to be intact?

I don't know how exactly my brain will behave in this situation (except that I know that its behavior will be consistent with all other circumstances). Perhaps I will feel as a schizophrenic person who feels that he must do something, despite of knowing that it is wrong. So yes, in this case my (illusion of) free will may be intact, in the same sense the (illusion of) free will of a mentally ill person may be intact.

Or perhaps I will feel that my hands are moved by some external force. In this case, I will feel that I don't want to kill my daughter, but something else moves my hands.

 

[Fredrik]

But why do you identify cause and effect with increasing entropy?

We're talking about a manifold with a bunch of curves in it. Cause and effect aren't really meaninful concepts in that context. I was just suggesting one way of giving those words meaning again. You suggested another by saying that the earlier event is the cause. I think mine is more natural because if you ever observe a series of events with decreasing entropy, e.g. thousands of tiny pieces of glass jumping up from the ground to form a glass bowl, would you really think of the earlier event as the cause? Or would you feel that the reason why they jumped in those exact directions was that the result would be a bowl? To use time ordering to define which event is the cause seems very arbitrary, especially since the dynamical laws in the model we're considering are perfectly symmetrical under time reversal. If you know all the positions and velocities at a given time, you can calculate them at any other time, both in the past and in the future. So why do you want to use time? Isn't it because entropy increases as time increases? What other difference is there between the two directions of time?

I think that this 4-dimensional mathematical model of the universe creates illusion that you can foresee the future. That is not so.

It would be so if this model had been an exact description of our universe. Of course, QM makes things a lot more interesting.

 

[Fredrik]

Nevertheless, the true nature of the event is neither random nor free. Instead, it is determined by the principle of global self-consistency.

I just want to say that I completely agree with statements like this. I just don't think global self-consistency in a special relativistic universe with tachyons is consistent with the illusion of free will, and I don't see why you think it is.

I don't know how exactly my brain will behave in this situation (except that I know that its behavior will be consistent with all other circumstances). Perhaps I will feel as a schizophrenic person who feels that he must do something, despite of knowing that it is wrong. So yes, in this case my (illusion of) free will may be intact, in the same sense the (illusion of) free will of a mentally ill person may be intact.

So from my point of view, you went insane enough to kill your own child while trying to set up an experiment that can't possibly be completed because of global self-consistency. That proves to me that you didn't actually have free will, and that's it for the illusion of free will as far as I'm concerned. What could we possibly mean by illusion of free will other than that there's nothing we can do to prove that we don't have actual free will? (I think this is the definition of "illusion of free will" that I've been saying we need).

You could argue that one experiment doesn't prove it conclusively, but if we repeat the experiment a thousand times with different people, and they all choose to kill their children over the alternative, which is to not press a button for a few seconds, I would say that we have proved it as conclusively as anything can be proved in a universe where quantum effects are sometimes relevant.

(Suppose e.g. that an alternative theory competing with QM predicts that an experiment must have result R with probability P(R). Such a theory isn't falsifiable in the absolute sense, but if we do the experiment over and over, and the fraction of results that have been R so far is getting closer and closer to P(R)/2, we would eventually consider the theory to have been "falsified", even though technically it never will be. A theory that only predicts probabilities 0 or 1 doesn't have this problem, since it can be falsified with a single experiment. A theory that predicts non-trivial probabilies is never strictly falsifiable. Instead they satisfy a weaker requirement that I think of as "statistical falsifiability". So we can never really prove that an alternative quantum theory is false. That's what I had in mind when I said that "we have proved it as conclusively as anything can be proved in a universe where quantum effects are sometimes relevant").

 

[zonde]

We're talking about a manifold with a bunch of curves in it. Cause and effect aren't really meaninful concepts in that context.

If you have past and future light cones in your manifold then cause and effect are meaningful.

I think mine is more natural because if you ever observe a series of events with decreasing entropy, e.g. thousands of tiny pieces of glass jumping up from the ground to form a glass bowl, would you really think of the earlier event as the cause?

Ok, if I will ever observe as tiny pieces of glass are jumping up from the ground to form a glass bowl I will agree that your view is more natural. But until then I will consider mine to be more natural. Is it ok?

What other difference is there between the two directions of time?

So for you future is only ever increasing entropy and nothing new? Then maybe we can make a deal - let's the past be for you and the future for me if it the same for you?

It would be so if this model had been an exact description of our universe. Of course, QM makes things a lot more interesting.

It would be nice to see would be model that can handle infinite amount of information.

 

[Demystifier]

I just don't think global self-consistency in a special relativistic universe with tachyons is consistent with the illusion of free will, and I don't see why you think it is.

So from my point of view, you went insane enough to kill your own child while trying to set up an experiment that can't possibly be completed because of global self-consistency. That proves to me that you didn't actually have free will, and that's it for the illusion of free will as far as I'm concerned.

Fredrik, it seems to me that we have just arrived at an agreement, or at least that we are very close to it.
Let me clarify. Assume that relativistic superluminal influences associated to nonlocality of quantum entanglement - exist. Then, due to decoherence at the macroscopic level, in MOST cases of everyday macroscopic life these superluminal influences are NEGLIGIBLE. Therefore, in most cases there is nothing that can destroy the illusion of free will, because the illusion of free will is an emergent phenomenon that appears only at the macroscopic level. That is why the illusion of free will is so effective in practice. Nevertheless, significant superluminal influences at the macroscopic level are possible, at least in principle. This means that, in principle, they can destroy the illusion of free will. But in practice, it does not happen due to decoherence. In this way, hypothetic relativistic superluminal influences (at the fundamental microscopic level) are compatible with the fact we feel the existence of free will (at the emergent macroscopic level).
This is similar to the fact that quantum mechanics at the fundamental microscopic level is compatible with classical mechanics at the emergent macroscopic level.

Do you agree now?

 

[Demystifier]

Let me summarize the final picture how is that possible to have both relativity without a preferred frame and instantaneous communication:

1. At the fundamental microscopic level we have
- Minkowski spacetime (where time and space are treated on an equal footing)
- quantum laws of motion
- both subluminal and superluminal influences
- no arrow of time
- no causality (i.e., no causes and consequences)
- no free will

2. At the emergent macroscopic level we have the illusions of
- Einstein (1905) relativistic space and time (where time and space are not treated on a completely equal footing)
- classical laws of motion
- only subluminal influences
- arrow of time
- causality (i.e., causes and consequences)
- free will

 

[zonde]

And is it scientific i.e. is it falsifiable?

 

[Demystifier]

And is it scientific i.e. is it falsifiable?

At the moment, I don't know.

But the point was to show that it is at least possible (to have both relativity and superluminal influences).
I think it is important to show that it is possible, because there are many "theorems" stating the opposite.

 

[RUTA]

The conventional way to draw a spacetime diagram is to have time increasing in the "up" direction, and most people (including me) would say that a horizontal line has slope 0, not infinity. The slope of a line in a spacetime diagram is therefore dt/dx, which for the line through (0,0) and (1,10) is 1/10=v. This is a simultaneity line for an inertial observer moving with velocity v, because it's Minkowski orthogonal to a line that represents inertial motion with velocity v.


The conventional intepretation of that statement would be that his speed is ten times the speed of light. (He has moved 10 light-years in 1 year). I'm not sure what you're doing, but it's either very wrong or very unconventional.

I do have time in the vertical direction and the slope of a horizontal line is zero. In the examples here it looks like you're writing (Y,X) instead of (X,Y) for your pairs, but that doesn't jive with your previous statement, "A line through (1,10) with slope 10 goes trough (0,-99), not (0,0)." If you're simply switching the X-Y order of the pairs, the slope of the line through (1,10) and (0,-99) would be (1-0)/(10- -99) = 1/109, not 10 as you claim. Again, all your math works if you simply change the (x,t) pair (1,10) to (10,1), since (1 - -99)/(10-0) = 10 is the slope of the worldline through pts (0,-99) and (10,1), and (1-0)/(10-0) = 0.1 for the slope of the sfc of simultaneity through pts (0,0) and (10,1).

 

[DrChinese]

Let me summarize the final picture how is that possible to have both relativity without a preferred frame and instantaneous communication...

So that is how you imagine there is no preferred frame. So what about having a preferred frame? Do you think that is possible? I know most of the Bohmian type theories have this attribute. Are those interpretations inevitably in conflict with relativity?

 

[Demystifier]

So that is how you imagine there is no preferred frame.

What you say that now you UNDERSTAND how is that possible? (If not, then I failed.)

So what about having a preferred frame? Do you think that is possible?

It is certainly possible.

I know most of the Bohmian type theories have this attribute. Are those interpretations inevitably in conflict with relativity?

They are in conflict with relativity at the fundamental microscopic level, but not at the emergent macroscopic level. Although it is consistent, I allways felt that it is somewhat cheap and inelegant, and that one can do better than this.

Now I have done this (relativity at the fundamental level) explicitly. Of course, I have not done it without a price. The price is that causality and free will are only emergent.

 

[DrChinese]

What you say that now you UNDERSTAND how is that possible? (If not, then I failed.)

Didn't mean to imply anything about the perspective itself. Just trying to see all of the alternatives as clearly as possible. My personal goal is to be able to evaluate interpretations based on new experimental and theoretical work which comes out almost daily.