I The typical and the exceptional in physics

[zonde]

Fine, but it is rooted on the trust in a "society view", which suggests something related to social groups ways of thinking.
I mention it because I would find such philosophical stance hard to defend as a premise from which to decide about issues related to physics.

Easy. Scientific knowledge is possession of society. No society, no scientific knowledge.

 

[vanhees71]

I think now this thread really goes way off the track. Of course, the findings of the natural sciences about nature are not just a "society view". This nonsense is sometimes claimed by sociologists, but it's plain wrong. It's the opposite of what's natural sciences are about, namely about reproducible objective observations of nature.

 

[stevendaryl]

Easy. Scientific knowledge is possession of society. No society, no scientific knowledge.

Not that I disagree with anything being said, but there are those who dismiss all talk about the foundations of quantum mechanics as "just philosophy". I don't think that's true, because I think that there is a lot of physics involved in understanding what goes on in quantum experiments. However, when you talk about scientific knowledge being a social construct, I would have to agree with the complaints--at this point, you're really talking about philosophy, not physics.

As I said, it's not that I disagree, but it increases the danger that the thread will be closed due to being off-topic for a physics forum.

 

[vanhees71]

It's not even philosophy, it's plain wrong, and I must say at this point, the thread in fact should be closed!

 

[ddd123]

It's not even philosophy, it's plain wrong, and I must say at this point, the thread in fact should be closed!

Only because of what zonde said? I agree that it's off topic. I was waiting for secur's examples.

 

[zonde]

I think now this thread really goes way off the track. Of course, the findings of the natural sciences about nature are not just a "society view". This nonsense is sometimes claimed by sociologists, but it's plain wrong. It's the opposite of what's natural sciences are about, namely about reproducible objective observations of nature.

Hmm, you are probably missing the context. I proposed "society view" as an way to define objective observations about reality as opposed to definition of "objective" as some sort of absolute knowledge about reality that an individual could posses and that is basically void.

Btw you yourself used the phrase "objective observations of nature". So, in what sense have you used it?

 

[vanhees71]

It's perfectly the opposite of what you claim: It's independent of "society views". Anybody can reproduce the observation and will find the same result, independent of his or her cultural background.

 

[zonde]

It's perfectly the opposite of what you claim: It's independent of "society views". Anybody can reproduce the observation and will find the same result, independent of his or her cultural background.

Hmm, then my only conclusion is that my choice of the term "society view" was very unfortunate as it triggers very strong associations with something rather irrelevant to my point. My idea was that objective is something about what different individuals would agree. And this is basically what you say (you just leave out communication part).

 

[A. Neumaier]

I think now this thread really goes way off the track.

It is completely off topic since post #59 - and should have from there been a different thread with a title such as
''Ontology and epistemology of quantum mechanics''.

 

[secur]

I sort of understand what you mean but I can't agree to your choice of word "subjective" and "reality". Objective/subjective does not mean that we have/don't have some absolute knowledge.

Subjective means what's known or experienced by an individual, a "subject". We have "absolute knowledge" of this, and nothing else.

And "reality" is not any of our models but rather imaginary concept on which all our successful models of reality converge. Reality is like a value of a function which is not defined at particular point but function converges when we take limit to that point.

We can't know "reality", ontology, for certain. In a sense, it's a myth invented by our subjective minds. Having said that, of course I believe in real reality as much as anyone - can't help it.

Bringing results together can be done in practically countless different ways and result of correlation is supposed to be independent form chosen method. This is possible because our chosen method does not alter results. This comes from very basic model that takes measurement records as factual (objective) and it's the same model on which we base "society view" on reality.

Yes "society view" is standard. We realize our subjective realities coincide, so we all believe in objective reality.

If we object to this very basic model then we have to replace it with alternative model in a way that gives us alternative version of "society view" on reality. I don't know about any such proposal and I am skeptical that it's possible.

You might ask: if reality is ratified (and reified) by all, why dispute it? Ok, initially it's an invention of our subjective minds. But since there's so much evidence for it, why not just accept it?

Well, as mentioned above, I do accept it FAPP, for non-relativistic classical physics. But QM and other modern science force us to question "reality" closely. Objective reality is constructed from sense inputs, consensus opinion, and a few more ingredients, notably memory. Every step of the construction makes hidden assumptions. Some of them, it turns out, aren't entirely right.

 

[ddd123]

Subjective means what's known or experienced by an individual, a "subject". We have "absolute knowledge" of this, and nothing else.
[...]
We realize our subjective realities coincide, so we all believe in objective reality.

There's a reason we call it objective and not absolute. Well, of course there's that the latter is stronger, but to clarify in what sense could help:

http://www.etymonline.com/index.php?allowed_in_frame=0&search=object
'from Medieval Latin objectum "thing put before" (the mind or sight)'
http://www.etymonline.com/index.php?allowed_in_frame=0&search=subject
'from Medieval Latin subiectare "place beneath"'

Well, how about something like this. The subject has its mode of perception and cognition, a grid within which he frames the world: this grid he puts underneath an object, what stands in front (maybe, initially, he imagines himself in place of the grid or as the grid, the "eye view": if it's all-encompassing then it's "God's eye view" that can witness a Bell type experiment unfolding, for example). For example, it may well be the Cartesian grid with its pointlike or extended objects within it in Newtonian mechanics.

So objective and subjective aren't really excluding each other. Once an inter-subject is agreed upon, objectivity follows - that's objective! But we choose the grid. That can be a model, criteria...

 

[secur]

We have a Shared Model of Objective Reality (SMOR, let's say), which is constructed from our individual Subjective Realities, via a number of steps. It's not entirely right. In classical physics, for the most part, it was fine. But modern science often contradicts its assumptions. When that occurs we call it "weird" and tend to have trouble dealing with it. Here are seven examples.

1. SMOR assumes 3-d Euclidean space, with independent 1-d time (as Kant, correctly, said). But "real" reality is Minkowskian, even Reimannian. That's part of the "weirdness" of relativity.

SMOR assumes that when we observe the property of an object, it really has that property. Even that can be doubted, but let's suppose it's true.

2. However SMOR also assumes that the object had that property just before we observed it. We don't know that, and it could be wrong. That's part of QM "weirdness". Or I should say it's one way to explain part of QM weirdness, namely the collapse interpretation.

SMOR assumes the past is fixed and unchangeable. OTOH the future is uncertain and doesn't yet exist.

3. But actually the future could "already" (whatever that means in this context) exist, and be unchangeable, just like the past. That's the Block Universe.

4. Or, the past could be changeable for all we know. That's retrocausality, another so-called QM interpretation.

SMOR assumes there's exactly one spatial reality existing along one unique time axis, that we all share.

5. But there might be none. That leads to the present discussion of epistemology vs. ontology.

6. Or, there might be different versions of the one "real" reality for each subjective observer. That's part of relativity "weirdness".

7. Or there might be lots of other "parallel" realities, with their own separate observers. Admittedly there seems to be just one that we experience, but we wouldn't know about the others. That's the Multiple-Worlds interpretation.

And so on. This random listing is haphazard and tedious. The better way is to simply go through the steps by which SMOR was constructed. The "hidden" assumptions are easily uncovered, and listed systematically. Every one can be questioned. It's easy to find alternatives that don't contradict any human experience or experiments. Many of them point directly at a modern theory, or at least some ontological interpretation thereof. Indeed, they cover all so-called "weird" aspects.

Many key theoretical breakthroughs in modern physics have happened simply because someone stumbled on the fact that one of SMOR's hidden assumptions was wrong. There are other hidden assumptions of SMOR, easily revealed by a little systematic analysis, which no scientist has yet doubted. They may be key to future breakthroughs.

Bottom line, the first thing to do is to systematically analyze how we came up with SMOR. @ddd123, that's what you're beginning to do in your post above.

 

[zonde]

You might ask: if reality is ratified (and reified) by all, why dispute it? Ok, initially it's an invention of our subjective minds. But since there's so much evidence for it, why not just accept it?

You have misunderstood me. I say that you can question reality as you like but please consider all the consequences. And I insist that by questioning reality you are questioning scientific approach. So if you accept scientific approach then you implicitly accept reality as well.

But QM and other modern science force us to question "reality" closely.

No. Look, there are two options we can consider:
1) there is more elegant model but it is self contradictory when we get down to it (we assume reality at the start but the model at some point contradicts this assumption).
2) there is less elegant model but it is consistent (we assume reality at the start and we do not run in any contradiction with reality).

You are making implicit assumption that more elegant model must be more valid than less elegant model. But this assumption is wrong as far as scientific approach is considered. Say if more elegant model is falsified by experiment but less elegant model is confirmed by experiment you would not suggest that there is something wrong with scientific method, right?

Objective reality is constructed from sense inputs, consensus opinion, and a few more ingredients, notably memory. Every step of the construction makes hidden assumptions. Some of them, it turns out, aren't entirely right.

Do you suggest that some necessary assumption is provably false? I think you somewhere have taken too strong assumption where we actually need weaker assumption.

 

[secur]

... by questioning reality you are questioning scientific approach. So if you accept scientific approach then you implicitly accept reality as well.

Well, yes and no. Scientific approach, or method, makes most sense assuming a "real" objective reality. Also, it's part of reality, itself. So yes, the two go together. OTOH one can question reality, at the fundamental level, and still engage in normal activities like going to the store for milk, posting on PF, and following the scientific method.

You are making implicit assumption that more elegant model must be more valid than less elegant model. But this assumption is wrong as far as scientific approach is considered. Say if more elegant model is falsified by experiment but less elegant model is confirmed by experiment you would not suggest that there is something wrong with scientific method, right?

I guess the "more elegant" model would be SMOR - is that right? Regardless, I'm definitely not suggesting there's anything wrong with scientific method.

Let's back up a bit. There are two models involved here: SMOR, and the scientific or physical model. The latter is the one you consider "really real", and, if I understand correctly, less elegant. Physical model is right according to scientific approach, of course; that's how it's generated. SMOR is right according to a priori categorical intuition, as defined by Kant.

BTW I'm not citing Kant as an "authority" - not asking you to believe it just because Kant said it. I mention him because, for those familiar with him, he presents this "a priori" concept pretty well, saving me the trouble of explaining it. If anyone is not familiar with him I'll be happy to explain the concept, just ask.

Both models are valid, or "right", in their own sphere. From one point of view, one's better; from another pov, the other is. By comparing them, finding their differences, we obtain insights that are key to understanding modern physics. But we can't learn any new physics! It's "philosophy of physics", or metaphysics, ontology. It make sense of, and sorts out, QM interpretations. It also points the way to potential fruitful future investigation in physics.

Do you suggest that some necessary assumption is provably false? I think you somewhere have taken too strong assumption where we actually need weaker assumption.

Give me an example of a necessary assumption. Or, an unnecessary one. I don't see the distinction. They're all necessary, since some sort of assumption is needed to cover that area. They're all unnecessary, since there are always possible alternatives. An example would clarify the distinction you're making.

Anyway, any "hidden" assumption of SMOR might be provably false - meaning, it might disagree with the scientific physical model. Some have already been proven false, in that sense. Others may never be proven false. But there will never be a time when we can know for sure that a given assumption is definitely compatible with the physics of the "real" world. It must always remain open to contradiction by future experiments. That's the nature of assumptions.

I hope that addresses your questions but am aware it might not, please let me know.

 

[ddd123]

Give me an example of a necessary assumption. Or, an unnecessary one. I don't see the distinction.

This reminds me of Peres' book again, at page 168:

Salviati. [...] The crucial point in Bell’s argument is that although the individual results are unpredictable, their correlations, which are average values, can be computed by quantum theory, or can simply be measured experimentally, irrespective of any theory. The amazing fact is that it is possible to prepare physical systems in such a way that the inequality (6.30) is violated, and therefore the identity (6.29) cannot be valid.

Simplicio. An identity which is not valid?

Salviati. This is of course impossible, therefore there must be a flaw in this argument. Either it is wrong that the observers have a free choice among the alternative experiments (namely, for each pair of particles, only one of the four experimental setups is compatible with the laws of physics—the others are not, for reasons unknown to us), or it is wrong that each photon can be observed without disturbing the other photon. Take your choice.

Simplicio. Both alternatives are distasteful. I prefer classical physics.

 

[zonde]

I guess the "more elegant" model would be SMOR - is that right? Regardless, I'm definitely not suggesting there's anything wrong with scientific method.

Let's back up a bit. There are two models involved here: SMOR, and the scientific or physical model. The latter is the one you consider "really real", and, if I understand correctly, less elegant. Physical model is right according to scientific approach, of course; that's how it's generated. SMOR is right according to a priori categorical intuition, as defined by Kant.

Ok, my guess was wrong and so you misunderstood my replay too. Here is what you said and let me give you different (and hopefully less cryptic) answer:

But QM and other modern science force us to question "reality" closely.

This is not so and here is why. There is pilot wave theory that gives all predictions of standard QM and is consistent with "reality" and "other modern science" (meaning relativity).
So as long as there is at least one valid option that allows us to keep "reality" we can't say that we are forced to question "reality".

Considering your point 1. in list of failures of SMOR it seems you have impression that special relativity rules out preferred reference frame. This is not so. SR is fine even if we declare some inertial reference frame "preferred". And the same applies to FTL of some hypothetical physical phenomena that is currently out of our experimental reach. Such hypothetical FTL phenomena could simply establish domain of applicability for relativity while still be consistent with relativity in the domain where it is tested and verified.

Give me an example of a necessary assumption. Or, an unnecessary one. I don't see the distinction.

Necessary assumption:
- there is universal time;
- past is fixed and unchangeable.
Unnecessary assumptions:
- object has a property even before we observe it;
- future is uncertain and doesn't yet exist.

 

[secur]

There is pilot wave theory that gives all predictions of standard QM and is consistent with "reality" and "other modern science" (meaning relativity). So as long as there is at least one valid option that allows us to keep "reality" we can't say that we are forced to question "reality".

Sorry, that's wrong. Pilot wave requires FTL influence or communication. This is really important so if you don't believe me ask Demystifier :-) The pilot wave must influence the particle's position (beable) faster than light.

Bohmian mechanics is not quite entirely accepted by mainstream, there are unresolved issues, IMHO. However it's probably viable - i.e., can reproduce all QM experiments - so let's assume so.

In that case, if it didn't require FTL influence, it would have to be considered "right" since all other interpretations violate some normal principle of physics. And QM mystery would be solved.

De-Broglie Bohm theory proves that the statement "there is no nonlocal influence" is unjustified. Since this viable interpretation does depend on that, it's impossible to rule it out. And if anyone rejects Bohmian, collapse interpretation also shows this. Gell-Mann claims there's actually something wrong with both those interpretations. I disagree, collapse at least is sound. But he's got the right idea: to justify his statement against nonlocal influence, he must attack these. As long as any viable interpretation exists with nonlocal influence, it can't be ruled out.

The same BTW is true of other things such as Multiple Worlds. If we suppose MWI is truly a valid interpretation (which isn't clear) it proves that multiple worlds might exist. One value of any interpretation lies in this ability to demonstrate the possibility of whatever ingredients go into that interpretation. Thus, we can't say "there is no collapse" until proving the collapse interpretation isn't viable. Which means, can't match some experimental result.

Considering your point 1. in list of failures of SMOR it seems you have impression that special relativity rules out preferred reference frame.

No, not at all. I'm referring to Minkowski space vs. Euclidean. The most important aspect is dependence of time on speed. That's not in SMOR but is in physical world as revealed by modern science.

This is not so. SR is fine even if we declare some inertial reference frame "preferred". And the same applies to FTL of some hypothetical physical phenomena that is currently out of our experimental reach. Such hypothetical FTL phenomena could simply establish domain of applicability for relativity while still be consistent with relativity in the domain where it is tested and verified.

I agree. My previous posts never contradict these facts - on purpose, at least.

Necessary assumption:
- there is universal time;
- past is fixed and unchangeable.
Unnecessary assumptions:
- object has a property even before we observe it;
- future is uncertain and doesn't yet exist.

Thanks, you've given the requested examples and I appreciate that. Unfortunately now you'll have to explain them! I see no fundamental differences here. Any might be right or wrong: viable alternatives exist. In that sense, none are necessary. And each fills in an obvious "hole" in SMOR. That is to say, answers a question which is bound to arise. In that sense, we could say they're all necessary.

Sorry to be obtuse, but why is any of these more, or less, necessary than another?

 

[zonde]

There is pilot wave theory that gives all predictions of standard QM and is consistent with "reality" and "other modern science" (meaning relativity). So as long as there is at least one valid option that allows us to keep "reality" we can't say that we are forced to question "reality".

Sorry, that's wrong. Pilot wave requires FTL influence or communication.

Yes, of course Pilot wave requires FTL! Any realistic model of entanglement requires FTL influence or communication! That's the point. There is no way around Bell inequality violations that is local and consistent with SMOR.

Pilot wave theory is the less elegant model that I meant in my earlier post. More elegant models are some of those that try to keep locality at the cost of being inconsistent with SMOR.

Thanks, you've given the requested examples and I appreciate that. Unfortunately now you'll have to explain them! I see no fundamental differences here. Any might be right or wrong: viable alternatives exist. In that sense, none are necessary. And each fills in an obvious "hole" in SMOR. That is to say, answers a question which is bound to arise. In that sense, we could say they're all necessary.

Sorry to be obtuse, but why is any of these more, or less, necessary than another?

Yes, any assumption can be right or wrong. That's what is meant by "assumption".
But you say that some assumptions have alternatives, right? Are these alternatives consistent with SMOR?
And do you mean that assumptions that I listed as unnecessary are actually required for SMOR? Can you provide your arguments? I will try to provide arguments why they are not necessary.
As I see assumption "object has a property even before we observe it" can be relaxed to assumption "object has a position even before we observe it". This will give us enough certainty to speak meaningfully about SMOR.
Assumption "future is uncertain and doesn't yet exist" is related to assumption that we have "free will". But this requires some philosophical arguments why "free will" is such a game changer as far as SMOR is concerned. As I see it's more important to have some sort of independence of our consciousness and I think this can be achieved even without "free will".

 

[secur]

@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.

Any realistic model of entanglement requires FTL influence or communication! ... There is no way around Bell inequality violations that is local and consistent with SMOR.

True.

Pilot wave theory is the less elegant model that I meant in my earlier post. More elegant models are some of those that try to keep locality at the cost of being inconsistent with SMOR.

Ok - now we're on the same page. You're even a step ahead, because I haven't yet explained why FTL is consistent with SMOR.

But you say that some assumptions have alternatives, right? Are these alternatives consistent with SMOR?

No, they're not, from my point of view. Note, I have firm ideas about SMOR but haven't yet defined it much. I've just mentioned Kant and left it at that. No doubt my view is close to yours and other's, but there's bound to be disagreement. However ignoring that, when we change one of its assumptions to match advanced physics, it's no longer SMOR.

As I see assumption "object has a property even before we observe it" can be relaxed to assumption "object has a position even before we observe it". This will give us enough certainty to speak meaningfully about SMOR.

Yes, that's the Pilot Wave alternative. Or we can suppose object has no properties at all before observation. I would say any relaxation of the original assumption violates SMOR.

Assumption "future is uncertain and doesn't yet exist" is related to assumption that we have "free will".

SMOR does, indeed, assume free will. But physics works without it; we can use Block Universe and still get the right answers.

I'm beginning to see where our confusion lies. I could say this: All the assumptions are necessary for SMOR; none are necessary for physics.

BTW this illustrates an important general lesson. These concepts are original philosophy (not science) so we don't yet have a common language for them. Therefore statements will inevitably be misunderstood. It's necessary to keep talking, even when - especially when - the other guy seems to make no sense. After a while the terminological mismatch is bound to come out. But if you just give up, (as so many do), it never will.

We need a firmer foundation. I should define SMOR more. But my main point is more general: how to analyze physics considering SMOR. I'll try to give a clearer, high-level, statement of my overall approach. If you lose interest, and no one else cares either, that's alright: you win a few, you lose a few.

 

[secur]

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. 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.

Physical Reality (PR)

PR is the model of reality derived from science, physics. It's always being updated as new physics happens. It's much more detailed than APR. It matches all experimental results.

APR doesn't match PR (the so-called "real world") in a number of ways, like relativity. Conversely, the physicist's model fails to match some human experience. Both models are valid in their own domain.

Relation between APR and PR

At first glance you may think APR has nothing to do with science. We can simply experiment and build our PR model. Who cares about APR which, after all, is something even cats understand. But science definitely can't ignore APR, nor does it. APR dominates (one way or another) half of science.

Most advances in physics involve rejecting one or another assumption hidden in APR. Simple physics accords with a priori intuition but before too long, with more refined experimental technique, it doesn't. It's very useful to categorize theories according to which APR assumption they invalidate, and what they replace it with. One example, from dozens: relativity proves APR's Euclidean space is wrong; actually it's Minkowskian or Riemannian. "Wrong" in this context means: doesn't match the "real" universe we live in.

But APR plays another, even more important, role in science and physics. The key fact you may not realize is: we can think only in terms of APR. Nothing else can or ever will make sense to us - until the brain itself gets modified. That means all physics must ultimately be expressed in terms of APR, else it's gibberish.

Of course good physics already follows this rule. One example, GR violates APR in a few ways, like curved space. But GR calculations are more-or-less always done on a tangent plane, with a time axis - which does match APR. We tame the curved Riemannian space, which can't make sense to us, by envisioning an APR-compliant space tangent at each space and time point. Etc. A lot of physics reasoning, and intuition, involves expressing a non-APR aspect of the PR model in terms of APR.

Experiments are the best example. All facts of physics no matter how non-intuitive must ultimately be demonstrated and proved by experiments (or, observations). As we all know, we understand experiments from the point of view of our macro, classical world. We read a pointer on a dial, or something equivalent. Thus all facts are grounded in the APR. APR doesn't know about relativity, atoms, EM fields, wavefunctions, or even a rotating Earth orbiting the sun. APR thinks the Earth is flat, and holds still. The proof of such effects must be, and is, understood in simple APR terms that even a monkey can appreciate. The dial points here, not there. That's the only way we know about quantum spin. The Foucault pendulum plane is seen to rotate during 24 hours. That's the closest we get to sensing Earth's spin.

Theoretical APR Analysis

Here's how to analyze a physics theory to ensure it's "APR-legal". First find where it violates APR. (Note, even in advanced topics a lot of it is intuitive as it stands.) Wherever it's non-APR, you have to translate the non-APR concept to APR. For example, for GR, Einstein (actually, Riemann, or originally Gauss) translated the non-intuitive concept of curved space into APR via tangent planes linked via Christoffel connections.

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.

 

[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.
''
''
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.