The typical and the exceptional in physics

[Mentz114]

A Priori Reality (APR)

Shared Model of Objective Reality (SMOR) apparently doesn't convey the right meaning. Let's call it A Priori Reality (APR) instead. It's the intuitive fundamental version of reality people all share, unless they're damaged.
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All classical well-accepted theories of physics already are APR-legal but it's very instructive to analyze them and see that's true. Quantum Theory, however, isn't, at the moment, leading to an interpretation quagmire. Then there are radical theories that aren't APR-legal at all. They really need work.

My internal model changes as I learn more physics. In fact I think that is the point of doing it, for me anyway.

Also, how does mathematics fit into this. Is mathematics is always true (uniquely) in APR ?

A somewhat late edit -
Einsteins clocks and rulers seems to cover classical physics because we can use those concepts as common existential currency. But neither clocks nor rulers exist in the microscopic realm so using them in that context leads to interpretational differences.

 

[ddd123]

I don't agree with all of the above, for example we use tangent planes because it's mathematically easier than to mess with nonlinear behavior. In special relativity we use Lorentz transforms directly. But the APR there fits in as the receiver of the past light cone information and not a whole simultaneity plane. Also the flat Earth illusion is broken if you've been on the ISS or one of those stratosphere capable jets.

I think APR is catching things late, the envisioned reality can change. What can't change are the a priori forms and thinking caregories: space&time, quantities&logic. APP: a priori perception, for lack of a better term ("perception" can and does involve thinking, those blind from birth that suddenly gain sight can't make sense of it iirc).

Physical theories all must translate back to APP. That's why APP is impossible to avoid for physics. For example the aforementioned AdS/CFT entanglement creates spacetime model stretches the limits on this. Entanglement is still defined in spatio-temporal terms (x or p basis, or even spin has a connection with spatial categories) unless you go to the abstract Hilbert space. The non-Kolmogorovian axioms of probability of the aforementioned article, used to make Bell type correlations compatible with locality, stretch the boundaries of logic (but you simply split the usual thinking into parts). In any case with quantum physics the new problem is that you don't have one modification to do to your reality model, you have dozens possible ones, in general each mutually exclusive with the others, and there's no way to definitively choose.

Can we figure out why that is? Does APP help?

 

[ddd123]

Here is an attempt in such a direction, using APP as a "guide": https://arxiv.org/pdf/1405.3492.pdf

One of the most obvious sensations is the pressure of your chair upwards on your bottom. One thing that you do not feel is a gravitational force (what we call “weight”) acting downwards on you, though the Newtonian theory tells us that there is such a force: there is a lack of correlation here between experience and Newtonian gravitational theory. In General Relativity, on the other hand, there is perfect correlation between experience and theory because in GR there is no gravitational force acting downwards on you: we are always, wherever we are, weightless. Perhaps one reason GR is so immensely satisfying to learn is that it accords with our experience in this way. The phenomenon of lack of sense-experience of a downwards force of weight occurs in everyday situations far removed from the physical regimes of strong curvature in which the full theory of GR reveals itself. Sorkin is suggesting that partial evidence for a theory of quantum gravity may be similarly close to us, although the full theory of quantum gravity is expected to manifest itself only in extreme regimes.

 

[zonde]

@zonde, I understand your view better now. We have somewhat different ideas of SMOR. That name "Shared Model of Objective Reality" is perhaps misleading. To you it's sort of "common sense physics". You want to fine-tune it, as little as possible, to match experiments. Whereas I mean a very basic model which reflects the way our brains are wired. It can't be changed (without major brain surgery). It determines and defines how we perceive reality: space, time, objects, motion. It must be dealt with as is. The problem, it doesn't match advanced experiments, but physics must. Physics doesn't have to be common-sensical, elegant, Occam's razor compliant, etc: those are luxuries, extras.

So there's a fundamental tension between SMOR and physics. I'm proposing the way to deal with that situation. We can't change, or ignore, either SMOR or physics (i.e., experimental results). Their inter-relation must be exposed and regularized. I'll try to show what I mean in another post, and think I'll change that misleading name.

Well, it seems we have different agenda and that makes harder to agree on some basic stuff.
As I understand you believe that we could discover some interesting models by discarding some unnecessary basic assumptions.
I believe that we could discard some not very interesting models by establishing which basic assumptions we can't discard.

Let's call it A Priori Reality (APR) instead. It's the intuitive fundamental version of reality people all share, unless they're damaged. Cats and monkeys also have it, for the most part. All animal brains (more or less) work that way. Any information we sense, know, or remember, has to exist within the APR framework or model. See Kant's categories, etc, for more on the subject. Someday I need to specify it more exactly if anyone's interested. APR governs all human experience.

I think that humans had very different model of reality than cats and monkeys even before there was physics around because of much more advanced communication between individuals.

 

[secur]

Thanks for responses! Sorry for delay, my health suddenly made a U-turn. Should be back on track soon ...

 

[Jilang]

Hope so. Kind Regards.

 

[secur]

APR can lead to another "endless debate" worse than QM interpretations. Fortunately we don't need to define it exactly. APR analysis works with any reasonable APR specification.

Remember APR is a priori reality. People tend to include a posteriori aspects of reality, that depend on experience.

I need to develop the theory a bit more in the light of your comments, then apply it to Bell and QM interpretations (the original goal). The best way to clarify the APR idea is to use it. BTW it's more about the observer, whose intuitive concept of reality is APR.

I don't agree with all of the above, ...

Neither do I. That's just a first cut. Furthermore, the way you interpreted it is bound to be somewhat different than what I intended. This is an iterative and inter-subjective (inter-PF-poster) process.

How does mathematics fit into this. Is mathematics always true (uniquely) in APR ?

Yes, it is. Let's ignore finite math (arithmetic, number theory, combinatorics, group theory). Calculus, diff eq's, continuous fields, lie algebras etc are the foundation of dynamical physics. They are extremely APR-analyzable. These concepts wouldn't exist without our APR physical intuition.

In this context probably the most important aspect of APR is: it's local. Experience, observation, happens at one instant in one place to one observer. The derivative describes ("tames") a continuous curve by analyzing what happens to it locally, at a single point. Thus the curve can be dealt with quantitatively, rigorously. That's typical "applied APR theory". Tangent plane is particularly useful because as you approach a single point - the only place an observer can be - every derivative except the first becomes negligible.

A lot of math is not manifestly APR-compliant like Lagrangians, or an integral over a Cauchy surface. But (I claim) the calculations are always based on an APR-compliant process.

for example we use tangent planes because it's mathematically easier than to mess with nonlinear behavior.

It's easier precisely because it's APR-legal, i.e., intuitive.

In special relativity we use Lorentz transforms directly. But the APR there fits in as the receiver of the past light cone information and not a whole simultaneity plane.

Right.

Also the flat Earth illusion is broken if you've been on the ISS or one of those stratosphere capable jets.

Such knowledge is not APR, but a posteriori. Also, APR governs how you experience your current environment, in this case, your seat inside the jet. Sitting there, (looking down at the Earth, which is not your current environment) you don't feel you're flying at mach two. The space around you feels like stationary 3-d Euclidean, like sitting on Earth. When you land you'll again intuitively "know" the Earth is stationary. And, you "know" the land around you is flat - APR is completely unaffected by your recent experience. Intellectually (even before you flew in the stratosphere) you knew Earth is actually round and spinning, but APR intuition doesn't know that. Admittedly the point is debatable.

My internal model changes as I learn more physics. In fact I think that is the point of doing it, for me anyway.

That internal model is precisely your current version of PR, NOT APR. APR includes only the basics. Your knowledge that time passes. That objects can move when pushed on, but retain their identity even so. Etc. You didn't learn that in physics class!

Einstein's clocks and rulers seems to cover classical physics because we can use those concepts as common existential currency.

"Common existential currency" is similar to APR. The clocks and rulers reduce, or represent, concept of space and time to the way we actually measure them. They are part of an "extended" APR model used in this particular analysis.

What can't change are the a priori forms and thinking categories: space&time, quantities&logic.

Those categories are, indeed, core APR.

APP: a priori perception, ... for lack of a better term ("perception" can and does involve thinking ...)

Perception is part of essential brain equipment, and in APR. But how the brain works in detail is irrelevant to our current purpose. Remember the Subjective Reality Principle can be stated "All our information consists of quantitative measurements". For physics that's the right approach: just assume we learn the value of the measurement, don't worry about how. Admittedly we must see the experiment and read the results, requiring perception, visual processing, qualia, whatever. But we should ignore such in physics almost entirely. They muddy the waters for no benefit. All we care about is the result: a quantitative measurement. The measurement or observation is localized in space and time, associated with the property of an object, and has other abstract properties. Forget qualia.

One of the most obvious sensations is the pressure of your chair upwards on your bottom. One thing that you do not feel is a gravitational force (what we call “weight”) acting downwards on you, though the Newtonian theory tells us that there is such a force: there is a lack of correlation here between experience and Newtonian gravitational theory. In General Relativity, on the other hand, there is perfect correlation between experience and theory because in GR there is no gravitational force acting downwards on you: we are always, wherever we are, weightless. Perhaps one reason GR is so immensely satisfying to learn is that it accords with our experience in this way.

That's the APR attitude, alright!

As I understand you believe that we could discover some interesting models by discarding some unnecessary basic assumptions. I believe that we could discard some not very interesting models by establishing which basic assumptions we can't discard.

Our two "agendas" are compatible. BTW, perhaps your concept of "necessary" assumptions is what I've called the "core" APR. The part that any version of APR should include. Unnecessary assumptions might be applicable for special purposes but generally should be pruned.

I think that humans had very different model of reality than cats and monkeys even before there was physics around because of much more advanced communication between individuals.

I'm reluctant to include anything that had to be "figured out" in APR. But it's really not important at this stage. We need to understand the overall concept, then go ahead and apply it to specific areas to see how it works.

 

[ddd123]

It's easier precisely because it's APR-legal, i.e., intuitive.

Are you suggesting that, since our maths is probably that way because of how our brain works, then linearization is easier (or non-linearity harder) also because it's so apt when thinking in terms of APR? That may also be why Kant's categories are themselves inexplicable, because we can't understand the brain analytically (i.e. it's too nonlinear).

Perception is part of essential brain equipment, and in APR. But how the brain works in detail is irrelevant to our current purpose. Remember the Subjective Reality Principle can be stated "All our information consists of quantitative measurements". For physics that's the right approach: just assume we learn the value of the measurement, don't worry about how. Admittedly we must see the experiment and read the results, requiring perception, visual processing, qualia, whatever. But we should ignore such in physics almost entirely. They muddy the waters for no benefit. All we care about is the result: a quantitative measurement. The measurement or observation is localized in space and time, associated with the property of an object, and has other abstract properties. Forget qualia.

Qualias are indeed beside the point, but I'm not sure I agree about the brain's functioning. For instance, not only the flat Earth APR is debatable, but also that locality is core APR. Magical thinking, which surely precedes rational thinking, has always had non-local qualities, e.g. https://en.wikipedia.org/wiki/Powder_of_sympathy .

Given such leeway in determining this APR, for me it turns out we wouldn't be able to agree on any fundamentals, except for a "core" that indeed coincides with basic perception-cognition.

 

[zonde]

Our two "agendas" are compatible. BTW, perhaps your concept of "necessary" assumptions is what I've called the "core" APR. The part that any version of APR should include. Unnecessary assumptions might be applicable for special purposes but generally should be pruned.

As I understand your "core" APR does not include assumption that there is reliable communication between individuals. So this is the point where I see incompatibility between our "agendas".

 

[secur]

Are you suggesting that, since our maths is probably that way because of how our brain works, then linearization is easier (or non-linearity harder) also because it's so apt when thinking in terms of APR?

Yes ... linear, also 2nd order, is intuitive, IMHO. For instance average and standard deviation are intuitive, not skew and kurtosis. A ball falling under influence of gravity only (parabola) is easy to judge, but a spitball much harder for a batter to hit.

That may also be why Kant's categories are themselves inexplicable, because we can't understand the brain analytically (i.e. it's too nonlinear).

Yes ... he was making the same mistake we're in danger of making. He thought you could nail down APR, list its elements definitively and finitely. No, we can only approximate it. But also, Kant's inexplicable by nature. He often didn't understand himself, either.

I'm not sure I agree ... that locality is core APR. Magical thinking, which surely precedes rational thinking, has always had non-local qualities ...

That's true ... the way I see it physical effect (like a push) is inherently local, a "contact transformation". But information is intuitively non-local. We see something far away and have no idea that there has to be an EM field mediating. Intuitively we get that info directly at a distance. As you say, magical thinking seems to be counter-evidence. Yet even primitives know it's magical - out of the ordinary - to influence physically someone who's at a distance, by sticking pins in a doll or etc.

The key to resolving such questions is NOT to examine them closely, although they're worth looking into a bit. Rather, move along to actually applying the APR concept to physics. That is, philosophy-of-physics, such as QM interpretations. In any given APR analysis there's only one or two, at most a few, APR characteristics that matter. If people have different opinions about them, that mirrors their different opinions on QM interpretations. But transferring that disagreement to APR makes those differences much easier to manage and categorize, since APR is the true underlying source of confusion. At least, that's the idea.

Given such leeway in determining this APR, for me it turns out we wouldn't be able to agree on any fundamentals, except for a "core" that indeed coincides with basic perception-cognition.

You're right, we won't be able to agree on the fundamentals (nor the "core"), therefore let's not try. What we can agree on is the concept of APR and how it's used.

As I understand your "core" APR does not include assumption that there is reliable communication between individuals. So this is the point where I see incompatibility between our "agendas".

Right, to me the "deepest" core has no such communication. However for physics we aren't at that deepest level. What we could call "core physics APR" is pretty high level (compared to deepest core) and does, I agree, include reliable communication.

I'll intend to produce a brief overview of the rest of APR theory - couple of pages - and show how it's used in Bell experiment. Give me a day or so. Then you'll see we don't have to agree 100% on these fine points, but can sort of bypass them, and still get useful work done. If, that is, you can remain interested.

Tamurlaine was noted for rejecting the old strategy of destroying all the enemy's towns one after the other. Instead, if a town was too strong to reduce right away, he'd go around it, leaving the siege in place, and attack the rest of the country beyond it. Sooner or later those towns left behind would give up. (Then he'd chop off all their heads and make a big pile to warn others not to be so stubborn.) That's analogous to my strategy regarding some of these fine points. Leave them unresolved, charge ahead, and hope they'll work themselves out one way or another.

 

[ddd123]

Yes ... he was making the same mistake we're in danger of making. He thought you could nail down APR, list its elements definitively and finitely. No, we can only approximate it. But also, Kant's inexplicable by nature. He often didn't understand himself, either.

Oh, yes, but what I meant to say there was that the categories, for Kant, cannot be derived from something else, since you would need the categories themselves to do it. Their origin thus belongs solely to the noumenon (that is, the inaccessible real outside our head we were talking about earlier). And this inaccessibility is manifested within physics as the nonlinearity of the brain's functioning. If you could ultimately decipher the brain's functioning, in an analytical sort of way, you would then be able to explain the categories.

 

[secur]

The question of Kantian a priori reality takes us too far from the point. APR, for current purposes, can include whatever standard physics makes sense. The point I was trying to motivate is the following "Sim principle". It can be justified starting with a priori human intuition, and so on, but it's too much trouble. So I'll just state it.

"Sim principle": The best way to evaluate any physics idea, like a QM interpretation, is to simulate it. If it's able to match experimental results, in a real-time simulator, then it's "valid". Otherwise it's just invalid "vaporphysics".

Of course you may disagree with the sim principle but let's see where it leads, by applying it to Bell experiment.

The built-in capabilities of the underlying simulator program ("sim") comprise our a priori assumptions. To start, they're classical physics, including relativity with its speed-of-light limit. Thus, when simulating photons, sim takes account of travel time, delaying the signal appropriately. BTW all relativistic calculations would be done in the sim's rest frame, WLOG.

An observer, like Alice or Bob, can be a person, or more likely a computerized detector unit. As a generic non-anthropomorphic term for any type of observer, let's use "point of view", pov.

Consider the following simple design of the Bell gedanken which has the essential ingredients, WLOG.

Alice (A) and Bob (B) are povs, which include her (or his) entire lab with scientist and equipment. They do the following again and again, N times: receive photon from E, set detector angle, measure photon's polarization (generically called "spin" direction), record it. Assume, for now, that A always makes her detection before B (in the sim rest frame). This simplifying assumption can (indeed, must) be dropped later on, but doesn't affect the essential idea.

After all photons have been emitted, they check that the list of detections matches QM prediction: random 50/50. The answer should be "yes" (almost always, statistically). Then they each send their results to F.

Emitter (E) emits two entangled photons. It's activated, we can suppose, by a timer at regular intervals. Sends one to A, the other to B. This pov becomes important when considering "hidden variables". It can be modified to send entangled particles instead of photons.

A Final (F) pov is required. This is not usually mentioned. It receives the two lists of detection results, one from A, the other from B, and calculates correlations according to some formula like Bell's inequality. It answers "yes" if QM predictions are satisfied. For example for Bell's inequality, it outputs "yes" when the correlation calculations violate the inequality. Including F ensures that all detections must be completed before the calculation can physically be done. Since that's mathematically necessary, there's no loss of generality.

Each detection in the list has a time-tag, detector setting, and spin (polarization, actually) value +1 or -1.

The prediction is that all three answers will be "yes": i.e., QM is right. Interestingly, it turns out that when A and B are spacelike separated it's classically impossible to get the "yes" answer from F. Sometimes called quantum "weirdness". So we can expect the experiment not to work at first, since sim's "a priori reality" is classical.

We write a new sim procedure, "Bell PR", for the Bell experiment from the above description. It allows setting initial values of pov positions and other parameters. BTW this simulation is only a gedanken, but it would be easy enough to write it.

Each simulated pov, A and B, requires a calculation routine to predict (probabilistically) the result of their detection. It's based on the "wavefunction" of the photon. For now it's a Bell state. Ignore the (important) fact that this wavefunction must actually be generated by the Emitter and communicated to A and B along with the photon. Since it's always the same, just hard-code it into A and B routines for the time being.

Now we run our simulated experiment, and find it doesn't work: F answers "no". Looking into it, we notice that B's formula for calculating his detection result includes A's detector setting and spin result. So we need to put in a new signal (a message, physically consisting of photons) for A to send these two values to B. Since she goes first this is the only signal needed. BTW this is called, by physicists, "collapsing the wave function". Bob must wait until he gets this signal before generating his answer. If he's forced (by the sim time step) to make the calculation before getting A's information, he uses random numbers for it.

Assuming A and B are close enough, the experiment now works (F says "yes"). Fortunately we didn't have to change the sim program itself: we didn't have to modify a priori assumptions. But we have messed up the Bell PR procedure: the signal from A to B is not part of the real experiment. The real Alice and Bob don't need such a signal since they don't have to do calculations, just read their detectors.

Unfortunately when we spacelike-separate A and B povs, it fails again. Although A and B still say "yes", F says "no". It turns out it's impossible to modify Bell PR to fix this. So we have to take the extreme step of modifying speed-of-light delay from A to B, making the signal with A's detector setting and results an instantaneous transmission. Great, now it works, F says "yes".

Finally we run the sim test suite to make sure our changes to the fundamental speed-of-light sim routine didn't screw up any previously known physics. The test is Ok.

To summarize: first we had to insert the extra signal from A and B - not part of the real experiment. Then, we had to make it instantaneous. It turns out both those mods are needed for any QM experiments where separate povs share a wave function. They always need instantaneous data from the other's environment to simulate their QM measurements correctly. Generally we can't know which pov goes first, so their cooperation is more complex, requiring multiple signals. This is not classical behavior. From the sim point of view, this is the essence of QM weirdness.

As far as the programmer is concerned, he's done. His job was to program sim to match this experiment. Admittedly he had to change the real experiment a bit, and even change one sim routine. That's bad. But it's the only way to do it! Physicists will just have to live with it (he figures). These extra FTL signals constitute the "programmer's QM interpretation". It does the least violence to existing physics, i.e., requires the fewest and easiest changes to the program.

Unfortunately many physicists aren't happy with it and come up with other QM interpretations. AFAIK every one of them requires massive rewrite of the whole program - and even then you probably can't get it to work.

Dozens of posts ago, I mentioned that I'd come up with a new argument in favor of the collapse interpretation. This is it. When simulating Bell or any QM experiment the only way (apparently) is to "collapse" the wave function FTL; then it works 100%. Therefore, this interpretation is best. If you claim there's no nonlocal "influence" you need to explain how to simulate Bell experiment, and other standard QM experiments, without it. Assuming, that is, you sign up to the "sim principle".

 

[morrobay]

After all photons have been emitted, they check that the list of detections matches QM prediction: random 50/50. The answer should be "yes" (almost always, statistically). Then they each send their results to F.

Emitter (E) emits two entangled photons. It's activated, we can suppose, by a timer at regular intervals. Sends one to A, the other to B. This pov becomes important when considering "hidden variables". It can be modified to send entangled particles instead of photons.

A Final (F) pov is required. This is not usually mentioned. It receives the two lists of detection results, one from A, the other from B, and calculates correlations according to some formula like Bell's inequality. It answers "yes" if QM predictions are satisfied. For example for Bell's inequality, it outputs "yes" when the correlation calculations violate the inequality. Including F ensures that all detections must be completed before the calculation can physically be done. Since that's mathematically necessary, there's no loss of generality.

The prediction is that all three answers will be "yes": i.e., QM is right. Interestingly, it turns out that when A and B are spacelike separated it's classically impossible to get the "yes" answer from F. Sometimes called quantum "weirdness". So we can expect the experiment not to work at first, since sim's "a priori reality" is classical.

Unfortunately when we spacelike-separate A and B povs, it fails again. Although A and B still say "yes", F says "no". It turns out it's impossible to modify Bell PR to fix this. So we have to take the extreme step of modifying speed-of-light delay from A to B, making the signal with A's detector setting and results an instantaneous transmission. Great, now it works, F says "yes".
.

I do not understand why the (F) position cannot answer with a yes in agreement with A and B that are 20 km apart and spacelike separated : (F) receives the detection results from A and B via EM signal and calculates correlations. . These outcomes from A and B do violate an inequality and QM predictions are met, as can be calculated by (F) In diagram below F is positioned at the source.

 

[zonde]

I do not understand why the (F) position cannot answer with a yes in agreement with A and B that are 20 km apart and spacelike separated : (F) receives the detection results from A and B via EM signal and calculates correlations.

You can't do that in classical simulation that obeys speed of light limit (because of Bell's theorem obviously).

 

[zonde]

If you claim there's no nonlocal "influence" you need to explain how to simulate Bell experiment, and other standard QM experiments, without it. Assuming, that is, you sign up to the "sim principle".

If one modifies a priori assumptions of sim there is additional approach how we can evaluate if these modifications are (un)acceptable.
We take Bell telephone (hypothetical FTL communication device) and try to explain it within proposed new framework. If we can do that it would be obvious that it's hidden way of introducing nonlocality. For example, if we allow retrocausality we can explain Bell telephone by saying that message of sender travels back in time to the event when sender and receiver devices where produced at the same location and then the message travels forward in time together with device to the receiving event.

 

[secur]

@morrobay, @zonde's answer to your question is right ... The sim is classical (until, later, we modify the speed-of-light limit). So when A and B are spacelike-separated B can't receive A's information (her detector setting and result). So he uses random numbers instead. As Bell shows, in this case, they won't violate the inequality.

F's distance is not relevant. The reason for including F is just to ensure all observations are finished before F's calculation. Note, I've been reading some papers by Bell-deniers Joy Christian and Walter Hess. They try to get QM correlations classically. This "F" is included to rule out some of their "tricks". IOW if, in their papers, the experiment was designed this way, their mistakes would not have been made.

... if we allow retrocausality we can explain Bell telephone by saying that message of sender travels back in time to the event when sender and receiver devices where produced at the same location and then the message travels forward in time together with device to the receiving event.

The "sim principle" declares retrocausality invalid because it's impossible to simulate. We can't make the simulator respond now to information generated later. One could argue that retrocausality is valid physics, therefore sim principle is wrong. But, I'm pretty sure, "If you can't sim it you can't prove it." And if you can't prove it it's not physics. That would apply to retrocausality, MWI, consistent histories, others. So sim provides a rigorous way to dismiss a lot of "vaporphysics".

 

[ddd123]

The "sim principle" declares retrocausality invalid because it's impossible to simulate. We can't make the simulator respond now to information generated later. One could argue that retrocausality is valid physics, therefore sim principle is wrong. But, I'm pretty sure, "If you can't sim it you can't prove it." And if you can't prove it it's not physics. That would apply to retrocausality, MWI, consistent histories, others. So sim provides a rigorous way to dismiss a lot of "vaporphysics".

We started from trying to understand our a priori assumptions better and ended up imposing those a priori assumptions on reality - I missed that gap. In fact, my idea was kind of the opposite: trying to see that our a priori assumptions are biased in an anthropocentric way, and how (if) it's possible to remove that bias, even negatively (for example by concluding what reality is not). How about this: https://arxiv.org/abs/1211.7081 .

I think "the Universe is not a computer" can follow from "there is no preferred reference frame".

 

[Mentz114]

''
The "sim principle" declares retrocausality invalid because it's impossible to simulate. We can't make the simulator respond now to information generated later. One could argue that retrocausality is valid physics, therefore sim principle is wrong. But, I'm pretty sure, "If you can't sim it you can't prove it." And if you can't prove it it's not physics. That would apply to retrocausality, MWI, consistent histories, others. So sim provides a rigorous way to dismiss a lot of "vaporphysics".[/USER]

I'm not sure that 'retro-causality' cannot be simmed. The sim program could branch into many sims ( the original sim begins simming) and then return to the main time-line when one of the sub-sims triggers it. Not classical though.

 

[zonde]

Retrocausality can be simulated using metatime. Only then we don't have stable reality as progressing further in metatime can change reality.

 

[Mentz114]

Retrocausality can be simulated using metatime. Only then we don't have stable reality as progressing further in metatime can change reality.

I believe, in the EPR sim, all four branches can be simmed ahead and the reality made to fit one that obeys the controlling symmetry.

 

[zonde]

I believe, in the EPR sim, all four branches can be simmed ahead and the reality made to fit one that obeys the controlling symmetry.

That would be MWI, right? Ok, but what if there are two spacelike separated events F1 and F2 where A and B datasets are matched and correlations calculated? And then results from both F1 and F2 again are sent to two spacelike separated events (say future A and B) and so on. That way reality can remain undetermined infinitely.

 

[secur]

We started from trying to understand our a priori assumptions better and ended up imposing those a priori assumptions on reality - I missed that gap.

It [sim principle] can be justified starting with a priori human intuition, and so on, but it's too much trouble.

You're right, there's a gap, as I admitted. Yesterday, to address this point, I produced a couple pages of theory with paragraphs about space, time, objects, motion ... etc. It looked extremely tl;dr. I decided it was necessary to give some idea where it was all headed so jumped ahead to sim (which BTW is not my "final" point either, but good enough for now). We need to go back and fill in that gap. But it seems best, first, to take a look at the concrete example of Bell experiment to focus the discussion.

In fact, my idea was kind of the opposite: trying to see that our a priori assumptions are biased in an anthropocentric way, and how (if) it's possible to remove that bias, even negatively (for example by concluding what reality is not).

That's one of my ideas also. The paper you reference is very a propos:

When we want to predict the future, we compute it from what we know about the present. Specifically, we take a mathematical representation of observed reality, plug it into some dynamical equations, and then map the time-evolved result back to real-world predictions. But while this computational process can tell us what we want to know, we have taken this procedure too literally, implicitly assuming that the universe must compute itself in the same manner. Physical theories that do not follow this computational framework are deemed illogical, right from the start. But this anthropocentric assumption has steered our physical models into an impossible corner, primarily because of quantum phenomena. Meanwhile, we have not been exploring other models in which the universe is not so limited. In fact, some of these alternate models already have a well-established importance, but are thought to be mathematical tricks without physical significance. This essay argues that only by dropping our assumption that the universe is a computer can we fully develop such models, explain quantum phenomena, and understand the workings of our universe.

This is precisely the attitude I'm against. Haven't read the paper yet but am confident I can show (to my satisfaction at least) that he's wrong. It would be a good exercise.

I think "the Universe is not a computer" can follow from "there is no preferred reference frame".

But we all know that statement is false. Correct is, "we don't know whether there's a preferred frame or not". More important: I'm not saying or even implying that the Universe is a computer! My point is purely about philosophy-of-physics. Namely, a good test for validating any theory is whether it can be simmed. Certainly that can't be proved, but it can be justified, supported, made plausible. Finally, it's not true that lack of a preferred ref frame makes it impossible to simulate reality. That's easy enough to demonstrate.

I'm not sure that 'retro-causality' cannot be simmed. The sim program could branch into many sims ( the original sim begins simming) and then return to the main time-line when one of the sub-sims triggers it. Not classical though.

Well, I didn't define sim much. What I mean, it has to be like a real-time simulator (with unlimited computing power). At the end of time step t0 every parameter - position, etc - must be finally updated. The state must be completely defined before proceeding to the next time step. This is a fundamental "axiom" of any real-time simulator. That makes your suggestion impossible, although that could be debated.

Retrocausality can be simulated using metatime. Only then we don't have stable reality as progressing further in metatime can change reality.

I believe, in the EPR sim, all four branches can be simmed ahead and the reality made to fit one that obeys the controlling symmetry.

No such approaches are allowable in a sim following the axiom mentioned above - although you may disagree? More likely, you may see no reason to impose that axiom. That can only be justified, not proved; it's a matter of opinion, because it's philosophy not physics.

That would be MWI, right? Ok, but what if there are two spacelike separated events F1 and F2 where A and B datasets are matched and correlations calculated? And then results from both F1 and F2 again are sent to two spacelike separated events (say future A and B) and so on. That way reality can remain undetermined infinitely.

I wrote the above before seeing this from @zonde. He's making the right argument to show that such approaches simply can't be simmed.

 

[ddd123]

But we all know that statement is false.

I said "can follow from". But a preferred frame for the whole Universe seems just about the most anthropocentric idea I can think of pertaining to physics. So there's coherence in the deduction.

Finally, it's not true that lack of a preferred ref frame makes it impossible to simulate reality. That's easy enough to demonstrate.

I'm completely missing this, what do you mean?

 

[secur]

@ddd123, Having read Wharton's paper https://arxiv.org/abs/1211.7081 I see it's not entirely relevant, although it is in the ballpark.

First, he's creating a strawman. He claims we all agree with Seth Lloyd: “It’s a scientific fact that the universe is a big computer”. That's ridiculous. The topic is banned on PF! Only fringers maintain it. Historical note, 40 years ago, and 20 years ago, I was persona non grata for even hinting this. True, one of these days it will suddenly become obvious to everyone. That's the way good new ideas are: first they're heresy, then they're dogma. Both stances are bad, ideas are never entirely right or wrong, but that's just the way we do science these days. Admittedly, the transition is so quick it's easy to miss; but, AFAIK, it hasn't happened yet.

More important, I'm not proposing "Universe is computer". I'm saying if we can't sim it we can't understand it. A theory or idea that can't be simmed can't be proven, disproven, falsified, verified. It's vaporphysics. True, the universe (in the final analysis) is not only unsimmable, it's entirely beyond our comprehension. But, as @Ken G pointed out, that doesn't matter. We never were talking about the universe itself: we can't. Instead we're talking about our ideas about the (imagined, hypothetical) universe. And those ideas are entirely comprehensible, and must follow logical reasoning, as embodied in the "sim principle". Nothing Wharton says really contradicts that, in fact he supports it, if anything.

But a preferred frame for the whole Universe seems just about the most anthropocentric idea I can think of pertaining to physics.

One of my main points is that our model of the universe (not the universe itself) is - must be - essentially anthropomorphic. As Kant pointed out.

Finally, it's not true that lack of a preferred ref frame makes it impossible to simulate reality. That's easy enough to demonstrate.

I'm completely missing this, what do you mean?

Let's assume there really is no preferred frame (although it's impossible to know that). Here's how the sim programmer would proceed. (BTW I did mention this, en passant, in my "sim principle" post.) The programmer would immediately declare a "Master sim reference frame". Most convenient would be the one defined by isotropic Microwave Background Radiation. Then, he'd do all relativistic calculations from that "base" reference frame. Exactly as Einstein always started with a "K" frame before considering K', K'' etc. And, most GR problems use this "co-moving" frame in exactly the same way. The Principle of Relativity guarantees that this procedure works: all frames are equivalent so we can always choose the most convenient "preferred frame".

There is also a more difficult way to program it. Treat each observer independently, as though it's a huge virtual reality game. They all have to broadcast their state, at each time step, to all other participants. Thus we can "honor" Einstein's BU pov, and never identify (for the programmer's convenience) a single preferred frame. No sane programmer would do this. Race conditions, deadlock would ensue. It would be a nightmare to ensure everyone's data was always consistent. But it can be done, and would be a good exercise, if only to demonstrate that you get the same answers either way.

You may come up with examples where my technique fails: you don't get the same answers either way. I'm pretty sure any such would be what I'm calling vaporphysics. Perhaps "intuition-based physics" or "experimentally-unfalsifiable physics" would be better, neutral terms.

 

[Dale]

Closed pending moderation, probably longer.

 

[Nugatory]

Speaking for myself here... I don't worry overmuch about what consenting adults are doing in the privacy of the 20th page of an interpretations thread. Just be sure that the children aren't watching.

However, the goings-on in this thread are starting to bother the neighbors; there have been multiple complaints in the last 24 hours. It's also far diverged from the original topic, so it is time to close it.