Beyond the standard glosses of QM (the realistic clock interpretation)

[marcus]

We've been watching this development taking shape ever since the tentative Gambini Pullin papers about it in 2006. It represents a fundamentally new way to address the problem of interpreting Quantum Mechanics. One person who worked on this back in 2006, with Gambini and Pullin, used to post occasionally here at Beyond forum.

http://arxiv.org/abs/1002.4209
Complete quantum mechanics: an axiomatic formulation of the Montevideo interpretation
Rodolfo Gambini, Luis Pedro Garcia-Pintos, Jorge Pullin
21 pages
(Submitted on 22 Feb 2010)
"We make a first attempt to axiomatically formulate the Montevideo interpretation of quantum mechanics. In this interpretation environmental decoherence is supplemented with loss of coherence due to the use of realistic clocks to measure time to solve the measurement problem. The resulting formulation is framed entirely in terms of quantum objects without having to invoke the existence of measurable classical quantities like the time in ordinary quantum mechanics. The formulation eliminates any privileged role to the measurement process giving an objective definition of when an event occurs in a system."

 

[marcus]

I should mention that Gambini and Pullin are longtime leaders in LQG research. Pullin is currently teaching an undergrad Introduction to LQG course at his university. He also runs the weekly International LQG Seminar, that links researchers in a teleconference that we listen to online. Background independent quantum gravity tends to favor a relational form of QM (there is no privileged time for example). The problem has been to combine realism with relationalism in a way that the universe is completely quantum (does not need a classical island where the observer sits with his classical clock and measuring instruments).
Gambini and Pullin call their new interpretation complete QM.

Basically complete QM is motivated by Quantum Gravity concerns and comes out of QG research. It addresses both the "problem of time" in quantum gravity and the "measurement problem" of QM.

It may also be helpful in the application of QG to cosmology---that is, in a Quantum Cosmology context. In QC there has always been the problem of providing for an "outside observer". If the quantum model comprises the full universe, where is "outside"?

Problems like these have been bugging the QG community for a long time and Gambini Pullin have been gradually working away at a solution---since at least as far back as 2006.
It's nice to see they now have it crystalized in the form of a list of axioms.

 

[Fra]

Marcus, thanks for the posts. This is yet antoher idea that seems to contain very attractive traits. I'll try to skim those papers more later. The undecidability beeing a key distinction between classical and quantum is something that I can relate to and I needt to look into their details.

I associate to how I envision it: simply that "classicality" is simply where further uncertainty is unresolvable or undecidable. Ie. the "classical certainty" is not be be interpreted as a "massive confidence", but rather the "LACK" of distinguishable measure of uncertainty (entropy) as measured from the "inside".

This goes well with "relative entropy" ideas.

The main challange for these ideas I see is how to infer the network of several such interacting systems. Most network inspired ideas postulate constraints that "force" desired structures that one expects semiclassically (ie. local rules + global or network-level constraints) and I haven't yet seen something to my liking. I like to see the constraints removed and instead follow from local rules as the complexity of the local system is increasing.

The risk of removing all constraints is also that one ends up with a landscape without a defined probability measure.

What's the middle road here which keeps the inside view, and makes progress without using ad hoc global consistency constraints, when the global view is non physical? I guess non-decidable inconsistences, are in fact not physical inconsistencies, just mathematical artifacts?

I very much enjoy the recent stream of foundational reflections that have more non-program specific character!

/Fredrik

 

[apeiron]

I like to see the constraints removed and instead follow from local rules as the complexity of the local system is increasing.

The risk of removing all constraints is also that one ends up with a landscape without a defined probability measure.

I like your point that decoherence need not be an exact classical state but instead an average minimum - so inconsistency is minimised rather than actually being zero.

But this then conflicts with your concern over global constraints as what constraints are exactly the kind of mechanism which can minimise, without actually being able to completely control, eradicate, or local degrees of freedom.

An excellent review of such statistics is...
http://www3.interscience.wiley.com/cgi-bin/fulltext/122458566/PDFSTART

However your basic concern could arise out of a misunderstanding of how global constraints are to be thought of in a dynamically self-organised system.

When we talk about the constraints in a thermodynamic system, we usually imagine the box that physically constraints the motions of a collection of particles - the ideal gas model - and so is the kind of deus ex machina imposed boundary you object to.

But emergent constraints, as in a scalefree network, would arise out of collective local actions. So the global constraints would exist everywhere, and nowhere, in the system.

Take a turbulent stream. The emergent attractor would be the vortex. And in a very energetic stream, vortexes arise over all scales. Everywhere water molecule motions are being entrained into whorls that collectively dissipate the maximum energy.

Only an analogy, but in approaches claiming to be background independent, we would be expecting both the local constructive actions (the events) and the global constraints (the context) to emerge together.

 

[Fra]

But emergent constraints, as in a scalefree network, would arise out of collective local actions. So the global constraints would exist everywhere, and nowhere, in the system.
...
Only an analogy, but in approaches claiming to be background independent, we would be expecting both the local constructive actions (the events) and the global constraints (the context) to emerge together.

Philosophically we are quite close, as concluded previously.

No doubt am I convinced that there is a road. My expressed concernt about landscape was mainly to illustrate what can happen, and has happened in some programs, it's not really something I worry about in the program I envision. Instead, we get undecidability. So the predictive power is constrained. This is exactly what the only rational rememdy seems to be to combine these ideas with evolving laws and constraints.

I fully agree that also the constraints must be emergent. But the open problem is still to take what you and med are reasonably in agreement with on the philosophical level, to the complete quantiative prediction level. I have my own pet projects on this, but I'm an amateur and I really have very little time for this so progress is slow. This is what I'm curious about all the recent trends to see if some of the professionals has developed this in a direction that is in line with how I think it must be done.

I've printed a few of Gambinis and Pullins papers to be read, but I fell asleep again last night. So I'll try again today.

/Fredrik

 

[Fra]

An alternative view on ST can illustrate the prolem of missing p-measures:

If we take the string and the string action to represent the elementa of which information is encoded.

Then then problem of emergent spacetime in ST, is what is the structure of the "relations" between several of these units that are "interacting". How can two strings be "consistenct" with each other when they interact?

Obvioulsy ST has a pack of consistency constraints here, that says that the consistencty requirements implies higher dimensional spaces etc. But there is no intrinsic measure of the confidence in these constraints that could be understood by the string itself.

I think this ambigousness makes it not surprised that they end up with a landscape of consistent solutions, but without physical interpretation of the landscape.

I think this should not happen if the constraints are reformulated in terms of intrinsic physics rather than "mathematical level consistencies".

If the "strings" (or more generally whatever microstructure that encodes information) could be understood as also emergent from something simpler (not that a continuum string is anything but simple informationwise) then one should also understand that the emergent spacetime that should be implied from relations between strings might be better thought of as emergent communication channels between observers. And neither the communication channels nor the observers are given, the evolve together. This is why one breaks the idea if one pulls out of nowhere a nontrivial microstructure and postulates that it's fundamental and then requires some kind of "consistency" requirements from this when it is in fact not true that we know that strings are fundamental.

/Fredrik

 

[Fra]

I've been extremely busy lately so I still only made it through two older papers of Gambini & Pullin, covering some interpretational but non-technical implementation issues. So far I like it.

Their reasoning strikes me as very sound, in particular the "undecidability in physical law". This is exactly how I view the reason for "evolving law".

Hopefully I'll get to look into the more critical papers where their ideas are translated into a formalism and see if they loose me, like Rovelli did :)

/Fredrik

 

[Fra]

I made the first skim of the new february paper and some concerns arise to me, which show close similarities to my objection to Rovellis RQM and makes me less optimistic. I will try to read the paper more properly before commenting, to see if it's correct or if it was due to my skimming.

/Fredrik

 

[Fra]

After reading more I can't see I share the continued reasoning.

I certainly think it's sound to acknowledge that there are no "external clocks", where external means (outside of the universe) - this should be obivous, I don't think so either. However, I don't like the way things developed here, the "no external clocks" can be done in several ways.

To mention one thing they seem to leave the physical basis of probability almost like Rovelli does.

I still thinks that it's not wrong to think of the clock as beeing defined external to the *observed system*, it's just that both the observer and the observed system are of course constrained to within the universe. It's rather I think that if we take the "screen analogy", the clock is represented on the observer side of the screen, not the system side.

Edit: I think if we consider real clocks on the system side, then I think technically that is not really measureing observers time. This "clock-time" is something different, and more on par with "rod-readings" than is the observers "cosmological time". AT least it's a clear distinction to me conceptually.

They after all seem to seek observer an independent core? I think the observer indepdendent objectivity can only be emergent. And there is no objective view of this process. Only a set of inside views.

I'm curious to hear if anyone else finds their ideas extraordinary.

/Fredrik

 

[LuisPe]

Hi everyone!
Sorry, Fra, I didn't quite understand when you said "It's rather I think that if we take the "screen analogy", the clock is represented on the observer side of the screen, not the system side.". Why don't you agree with this situation of putting the clock on the observer side?
Sorry I bring this up like a month after the discussion was "hot"...

 

[marcus]

Luis it is a real privilege for us to have someone who knows something about this new interpretation of QM show up here willing to explain and discuss.
I regret to say I don't have specific questions at the moment. I sense that it is in some sense a more realistic and rational interpretation and consequently that it might contribute to the resolving some difficulties with the formulation of QG.

Can you say anything, even in the most general terms, about what might be the consequences of the MV interpretation? Can you anticipate any substantial affect. Imagine the next book that comes out similar to Oriti's "Approaches to Quantum Gravity--towards a new understanding of space time and matter". Suppose a book like that were being written in, say 2011 or 2012. Would there be a chapter developing and presenting the MV interpretation as applied to our basic thinking about space time and matter?

Or is it more of a detached line of investigation, how one interprets QM?

 

[LuisPe]

Well, thank you Marcus! I am not sure if ill be able to explain, but I am definitely in for the discussion! I've been meaning to post for some time now... I am really interested in the critics people have on the ideas.Ok, complicated questions there. I should first say that I know nothing of quantum gravity. My motivation so far has been pure QM and its interpretation puzzles. So I can't answer your question. But as you know Gambini are Pullin are in the QG thing, I guess they see it as a more general thing than I do.
Anyway, I don't think any of these discussions will be even close to being settled by 2012, hehe.

 

[Fra]

Hi everyone!
Sorry, Fra, I didn't quite understand when you said "It's rather I think that if we take the "screen analogy", the clock is represented on the observer side of the screen, not the system side.". Why don't you agree with this situation of putting the clock on the observer side?
Sorry I bring this up like a month after the discussion was "hot"...

Hello Luis, thanks for commenting!

I realize that some of the scentences in my posts are not proper english, I also note some critical typos of mine.

I do think that the clock representing observers time (more closely related to the thermodynamical time, and cosmological time), must be on the observer side (that is EXTERNAL of the observed system). This isn't to be confued though, with me thinking there is a universal Newtonian time. My point is the opposite. Instead of saying there is no time, and point to a timeless symmetries from with time is a gauge choice, I think time is for real, but observer dependent, and instead the symmetries are emergent in time, and evolving. But there is no global time evolution, but I do not see that as a problem.

Clock time of devices beeing part of the system, is a different kind of time, which is more like the non-physical clock time we have in SR and GR, not cosmological time.

I'll expand a little in a while, since I think my objection wasn't clear... it would be very interesting to hear your response to these objections, given that I can convey them...

/Fredrik

 

[Fra]

I do think that the clock representing observers time (more closely related to the thermodynamical time, and cosmological time), must be on the observer side (that is EXTERNAL of the observed system).

Another possible source of confusion is that may the problem isn't on which side the "clock" is, but on which side the observer is? In my meaning of the word here, the observer is by definition on the opposite side of the screen relative to the system. The screen "is" the communication channel. If both observer and obserbed system are on the same side, there is no communication and no "measurement theory". Maybe the measurement problem is solved, by "removing the screen" but at the cost of also killing the core of a inference/measurement model.

/Fredrik

 

[Fra]

Luis, I read your post again and although I see thay my own expressions of my objections may be unreadable, I'm not sure where to expand. Did any of the last two posts make anything clearer?

I'm attraced to the notion of undecidability in that paper, because it's partly I also envision how objectivity is attained/emergent from communicating subjective observers - when due to limiting information(each observer can not hold/process all information) it's not possible to make an inference (to decide) of say a violation of a prior expected symmetry. When this happens the action of the observer will act to stabilise and preserve the symmetry, since it would not be rational to act upon something that's not decided.

But I think there is still no birds view of this entire picture, this is why I think it's not enough to just say that the state of information of the complete system can't be known by an inside observer - I think not even the STATE SPACE can be known.

I have a feeling with this paper, as with rovelli's past reasoning that they are trying to merge some very sound reasoning similar to rovelli's RQM paper (about relational notions, no absolute relations etc) with the idea that the structure of QM, with hilbert spaces etc, is correct and must not be modified. So there seems to take place a compromise here that I find objectionable. I really share some of the relational arguments, but the point is that the QM structure itself (set aside spacetime stuff) is in itself not relational, so I'm more rational and think thta QM itself is emergent. The starting points of timeless hilbert spaces etc, are just very counterintuitive to me since it breakes the inference model. The hilbert spaces must themselves be infered, and this is a evolving cycling processes that taks place everywhere and anytime.

I'll stop there to see if you have feedback, otherwise I'll constrain myself from adding more ramblings to the thread.

/Fredrik

 

[LuisPe]

Hi! I found your comments interesting and clarifying Fredrik.

So, I had been reading some things on models were some internal time is considered, and had some doubts myself. That is why I wanted to come back to your question.

After reading your further comments I believe we think similarly on this point.

This is how I see it, with your screen argument. On one side one has the observer, and on the other the quantum system with the measurement apparatus, like you said. Then there are two cases: in the first the clock is on the observer side and in the second in the system’s side.
This second case would be when one needs the clock to interact with the whole device. For instance, I believe there is somewhere an example where one wants to measure how long some spin points in some direction (the spin is precessing in some magnetic field). In this case, one is asking about some time period, and of course I can’t be looking at the spin and pressing “start/stop” on some clockwatch, so what is needed is some sort of interaction between clock and spin (and probably some more devices). This interaction will produce backaction on the clock, and therefore time uncertainties.
In the case where the clock is on the observer’s side of the screen then there is no interaction, but the time uncertainties just come from the fact that the clock is some quantum system, etc.
So, I think both situations are contemplated on our work, even if we don’t need to distinguish them (we just talk of uncertainties in time).

And then comes our point. When taking into account these errors in time measurement, and writing everything in terms of this “realistic time”, the information that the whole system + measurement apparatus is in a quantum superposition is inaccessible. So even if it is in a superposition, no process will show this.

And then in the last comment you say:
“I have a feeling with this paper, as with rovelli's past reasoning that they are trying to merge some very sound reasoning similar to rovelli's RQM paper (about relational notions, no absolute relations etc) with the idea that the structure of QM, with hilbert spaces etc, is correct and must not be modified. So there seems to take place a compromise here that I find objectionable.”
There I agree with you. We have thought all the process in terms of plain QM, without ever questioning its basics. I guess in this respect I was thinking all the work one step less fundamentally than you. Changing how one sees QM, but not so drastically, hehe. I have no idea how this could be achieved though… are you thinking in something in particular?

I’ll stop here, I’ve written too much already (maybe saying things that were already understood). Hope I haven’t bored anyone. Just in case, I should say that I am just thinking along here, we have not particularly discussed all of these ideas with Gambini or Pullin.

Hope to hear what you guys think…
Luis Pedro

 

[Fra]

And then in the last comment you say:
“I have a feeling with this paper, as with rovelli's past reasoning that they are trying to merge some very sound reasoning similar to rovelli's

RQM paper (about relational notions, no absolute relations etc) with the idea that the structure of QM, with hilbert spaces etc, is correct

and must not be modified. So there seems to take place a compromise here that I find objectionable.”
There I agree with you. We have thought all the process in terms of plain QM, without ever questioning its basics. I guess in this respect I

was thinking all the work one step less fundamentally than you. Changing how one sees QM, but not so drastically, hehe. I have no idea

how this could be achieved though… are you thinking in something in particular?

Thanks for your comments Luis, this clarifies some things for for me. If I "pretend" to accept the premise that QM formalism is perfected, and take as my quest to merge the relational ideas with the QM formalism, then I can appreciate a lot of the way of reasoning better! It's in this light your paper should be seen I think.

But my own thinking has led me to a different starting point for my quest: Seeking an intrinsic inference model, I've come to question the QM formalism itself, so my objections are not so much against your inference, as it is against the premises.

I have a set of personal ideas in mind, how it could be done differently but nothing mature and there is a lot of work left before I would consider fleshing it out in a paper but it's in the plan. There are a few people that I think have presented good arguments that are all building blocks of something new. Part of Rovelli's initial reasoning in his RQM paper, Smolin's evolving law, Ariel Catichas "physics from inference" etc. I also see connections to the gravity as an entropic force, as well as holographic ideas.

Maybe these furher comments are at least indicative of how I see it differently. My way of seeing it feeds new problems, but I think it's problems we have to face and they have physical interpretation.

This is how I see it, with your screen argument. On one side one has the observer, and on the other the quantum system with the

measurement apparatus, like you said.

The way I see it, the "measurement apparatous" IS the observer, and this is always interacting with it's environment. The environment thus is "the system".

But sometimes we consider that we observer only a subsystems of the environment. But IMO, this is only an idealisation, as it's not possible in general. I think the different notions of time, cosmological time vs "clock time" appear when the observer focues on the entire environment vs a subsystem. I also think that the symmetries of a subsystem can relatively speaking be inferred by the observer, to be more stable (~ timeless). The evolution of a subsystem may fit into the timless framework, but the evolution of he entire environment can't.

To me your scenario of observer of one side and the apparatous on the other side, represents in my abstractions, one observer interacting with a second observer, which in turn interacts with another the system, but then "the system" with respect to the first observer, is really then just composite, which systems always tend to be anyway.

So to address what I think is the real problem, the observer IS the apparatous, and the screen is what separates it from the system. And it's over this screen the measurement takes place as I see it, not between the apparatours(observer2) and the system, becayse the observer2 is just part of the system beeing observed by observer1.

From the most general point of view, there is just one system and that is the entire environment. So I think the natural decomposition is an observer, and the screen, beyond there is the environment. The question I ask in my starting point, is what the action is of the observer, as a function of the inferred expectations on it's own environemnt. The action form encoding the action is them, is encoding the _expected_ symmetries of the environment, and is then also evolving due to backreaction from the environment. Since the environment produces a back-reaction for each action of the system. This means that the observer, can instrinsically only "decide" or infer an expected evolution, which I think of more as a differential evolution.

Then there are two cases: in the first the clock is on the observer side and in the second in the system’s side.

"
Yes, but the two casess represent different things. The case where the clock is "in the environment" so to speak, is not the observers intrisic time. It's more like a "clock time".

With intrinsic time, I mean a parameterisation of the expected flow of changes. This is entagled with the production of the "expectation" which in turns I see related to an subjective entropic flow on the observer side. This way of thinking requires that the "clock" is on the observer side.

To me, even in the case where the clock is on the observer side, there IS interactions, because I seek the action of the observer, and it's evolution due to back-reactions for the environment. But thta's not fully decidable, tht's what I think in terms of evolution, not determinisitc dynamics. Even if there was a determinisitc dynamics in some silly sense, this predictive power is inaccessible to the observer. I think this is closely related to your point as well, it's just tht maybe you have a little different view. But my impression is that conceptually the idea behind it, is the same, and THIS I share, and i one form or of the other, I think this may be a key. Although I think me might need to be more radical.

/Fredrik

 

[LuisPe]

So to address what I think is the real problem, the observer IS the apparatous, and the screen is what separates it from the system. And it's over this screen the measurement takes place as I see it, not between the apparatours(observer2) and the system, becayse the observer2 is just part of the system beeing observed by observer1.

/Fredrik

OK. But, for example, we are also thinking that the idea of isolated events are also included. By isolated events I mean just some system interacting with some environment (no other apparatus, and no interaction with any sort of observer). So, rewritting evolution in terms of real time, and in certain cases, the information of whether it is in a quantum superposition or not is not accesible. Then we say an event happens (a kind of "measurement")
The cases in which this would occur is when the system is energetic enough, and the interaction with the environment is not too small, so that the effect of measuring time with real clocks is not tiny.
So we are thinking about events happening all around us, without need of some sort of apparatus or observer.

Do you agree with this? Am I understanding correctly what you were saying...?

 

[Fra]

So we are thinking about events happening all around us, without need of some sort of apparatus or observer.

Do you agree with this? Am I understanding correctly what you were saying...?

My hunch is we are disagree about something since I don't follow what's the notion of an event, when there is no observer. It sounds like using notions/formalisms that are usually tied to an observer (events, eventspace etc), when there is no observer and giving it the status of some mathematical elements with unclear physical basis. This is what I'm trying to avoid.

This critic I have also to rovelli's RQM - he (IMHO) rightly argues that the only way for two observer to compare their experiences of reality, is by communication=interaction. So far so good. But then he just says, the structure of this communication is supplied by QM and thus assigns this "relation" a status of structural realism, when he previously said there are no absolute relations. But this is indirectly what QM is in his usage, as I see it. I think if his spirit of no absolute relations are to be taken seriously, QM structure itself should be emergent as a negotiated CONSEQUENCE of interactions after equilibrations, following from underlying principles of ractional actions upon backreactions.

But since you take your time to respond, which I really appreciate! I'll try to read your paper again and think another round to try to be more precise. I was just responding now based on the stores impressions in my memory of a previous read about a month ago.

I'll try to respond again when I re-read the paper.

/Fredrik

 

[John86]

Hello Fra,
Yesteday i printed this paper by volovik a few years ago i readed the book "universe in a helium droplet" by Volovik. He also mentioned the emergence of QM.

http://arxiv.org/abs/1004.0597

The Superfluid Universe
G.E. Volovik
(Submitted on 5 Apr 2010)
We discuss phenomenology of quantum vacuum. Phenomenology of macroscopic systems has three sources: thermodynamics, topology and symmetry. Thermodynamics of the self-sustained vacuum allows us to treat the problems related to the vacuum energy: the cosmological constant problems. The natural value of the energy density of the equilibrium the self-sustained vacuum is zero. Cosmology is discussed as the process of relaxation of vacuum towards the equilibrium state. The present value of the cosmological constant is very small compared to the Planck scale, because the present Universe is very old and thus is close to equilibrium. momentum space topology determines the universality classes of fermionic vacua. The Standard Model vacuum both in its massless and massive states is topological medium. The vacuum in its massless state shares the properties of superfluid 3He-A, which is topological superfluid. It belongs to the Fermi-point universality class, which has topologically protected fermionic quasiparticles. At low energy they behave as relativistic massless Weyl fermions. Gauge fields and gravity emerge together with Weyl fermions at low energy. This allows us to treat the hierarchy problem in Standard Model: the masses of elementary particles are very small compared to the Planck scale because the natural value of the quark and lepton masses is zero. The small nonzero masses appear in the infrared region, where the quantum vacuum acquires the properties of another topological superfluid, 3He-B, and 3+1 topological insulators. The other topological media in dimensions 2+1 and 3+1 are also discussed. In most cases, topology is supported by discrete symmetry of the underlying microscopic system, which indicates the important role of discrete symmetry in Standard Model.

 

[Fra]

I've been traveling and not had time to respond. I'll be back shortly where I left off.

Thanks for that link John.

/Fredrik

 

[Fra]

Hello Luis, there are a lot of premises in the paper that I do not accept as irrreducidle starting points, these are essentially several of the QM axioms, for example the notion of timeless hilbertspaces (I assume you think of them as timeless, right? My question is for example, how can anyone _decide_ if they are timless? and if these decisions are physical processes, doesn't the decision process itself take time? I think they do. So for me, the evolving structures are the only ones really possible. it's just that we idealized and think of structures where we can not decide that they are evolving, as timeless, when in fact that is nothing but an expectations - _maybe_ this is another sort of way to implement your decision argument, but I still think I have a quite different angle, but I could be mistaken about yours. To me the difference is important.).

I mean just some system interacting with some environment (no other apparatus, and no interaction with any sort of observer).

In my picture it doesn't make sense to do away with the observer, since even if we picture as you say "isolated interactions" where say two subsystems, or one subsystem and it's immediate environment are communicating "in isolation", it does not make sense to speak about this, unless there is a second observer that is indirectly observing this by means of how the action of the total system evolves; in this sense the "isolated interactions" are still indirectly observed (in the abstract sense that some limited but still incompelte inference of information about them takes place).

In the intrinsic information and inference perspective Ithink is necessary, not only is an observer needed for communication/interaction, an observer is also needed to encode and store/hold information. So to make the inference complete, I think the measurement process needs to be combined with a model for sourcing and sinking the code. This is where I see the link to a kind of holographic perspective.

So if I understand you right, you picture say a state space of an isolated system. But if it was properly isolated we would not be able to speak of it, and make no preparations. I think the entire history (preparation included) must be accounted for as this should yield the effective inferred state space of the almost isolated systems.

These things are to me more basic than the clock issue.

So if we picture an "almost" isolated system, there must still be an observer to formulate this representation, and encode information about the "hidden state space". A _completely isolated_ system clearly makes no sense, as it would be completely detached to anything that makes a difference. So we are discussing I think "almost isolated" or say "weakly interacting" observers right? (ie where we can imagine the isolated-interactions to be stronly interacting, but the mandatory observer may be weakly interacting with this isolated complex) But then the history or the interactins are I think crucial and some analysis is still missing.

/Fredrik

 

[Fra]

From page 4 of the paper is an expression of a point of view that I find hard to digest.

"The resulting description will be strongly objective in the sense indicated above without referring any time to observers or measurements."

As I see it, there is a paradox between try to "do away" with external items, such as clocks or observers, and at the same time insist on the "structural realism" that is implicit in the strong objectivity, because the objectivity is then itself, in the structural realism sense - also an "an external view".

What's your opinon of this? Is this not disturbing?

I think the rational argument before seeing a structural realist view is that it's somehow connected to predictability. Without solid objectivity, there is no solid predictions. But I think solid predictions are not possible. I doubt it's not the nature works. Nature is more inductions made up on always incomplete information, and this includes the inference structure, and physical law itself.

So relative to my own position, this Montevideo intepretation or view, seems so conceptually closely related to Rovelli's RQM view that I tend to group them. Although there are variations in the group.

Does that sound fair? or how you see RQM?

I do like like the sound of the undecidability idea, but I also like the sound to Rovelli's "no absolute relations". But then I feel that the spirit that I read into those phasings are broken as progress is made. Rovelli's uses the axiomatic structure of QM, more or less as an element of strucutral realism that its not questioned. I find this to be in contradiction to the generalised spirit contained in several of his introductory arguments (which I like a lot and feel are very well formulated).

/Fredrik

 

[LuisPe]

Hi everyone, sorry I took so long to answer, I've been busy.
I believe I have like I million questions / critics left unanswered... I'll go slow.

First about what we mean by event. Event is just one we can say that some observable takes a definite value (so it's basically a measurement). When you have a quantum superposition (in the observables eigenbasis) there is no definite value.
What we say is that since the evolution when there is an environment and taken the effect of time into account makes it undecidable if there has been a collapse or not (predictions are exactly the same in every conceivable sense), then you might as well think there has been a collapse. This is when we say an event occurs.

And in the sense of what I just mentioned is that we believe that "The resulting description will be strongly objective in the sense indicated above without referring any time to observers or measurements." like you quoted in your last post.
The basic idea I'm thinking about is this: the evolution of systems, even when there is no observer, leeds to undecidability. So basically the information of whether the system is in a superposition or not dissappears. I don't need to come in contact with the system to check if there has been some "event". This would be complicated, because then events (measurements) would only occur in certain situations. Most systems are not in contact with observers, just in contact with environments, and I prefer to think that events can happen everywhere without the need for us. So, IF the observer wanted to try to check if some system is in a superposition (of course, he would have to prepare states and measure and all that), he would not be able to because of how the evolution goes. But even if he didn't, evolution would lead to the loss of the information, so observer is not neccessary.

Do you see this as wrong from a phylosophical point of view, or you are just not convinced about the way we are putting it?

About the notion of timeless hilbert spaces. Yes, we assume that I believe; we left the background of QM intact. In what sense are you thinking about non-timeless hilbert spaces?


I don't think I answered any of your critics after re-reading, but let me know what you think, and I'll keep posting anyway...

 

[LuisPe]

So if I understand you right, you picture say a state space of an isolated system. But if it was properly isolated we would not be able to speak of it, and make no preparations. /Fredrik

Of course, if I wanted to make the experiment some preparation would be needed, but I don't think that to speak about some system and it's evolution I need to make a preparation to do the whole experiment.

I find the evolution of the density matrix given an initial state, and see that the information of whether it is in a superposition is lost. Then an event takes place, I conclude. If i wanted to check if what I think is correct (maybe some other weird affect we haven't considered is going on and I do have a superposition ) I could for once do the experiment and see. But then I don't need to repeat it, the event takes place anyway.

 

[Fra]

About the notion of timeless hilbert spaces. Yes, we assume that I believe; we left the background of QM intact.

In a certain sense, I see this position of yours somehow is at the root of all several of my other questions too. It explains why the questions are not address by your paper I think, since they appear only when to you question the structure of QM - which is a premise in your paper, not brought up for discussion.

But to just leave it at that would be too easy and not make for any discussion I guess :) So I'll try to respond more later, for the sake of discussion.

/Fredrik

 

[Fra]

Do you see this as wrong from a phylosophical point of view, or you are just not convinced about the way we are putting it?

That's what I'm trying to understand, but my current understanding is that even though there are attractive parts, I think some premises seem "philosophically wrong" relative to how I see things.

Here is another thing that focues on parts I personally think is as you say "philosophically wrong"...

The basic idea I'm thinking about is this: the evolution of systems, even when there is no observer, leeds to undecidability.
...
Most systems are not in contact with observers, just in contact with environments, and I prefer to think that events can happen everywhere without the need for us. So,
...
so observer is not neccessary.

I think we have different views of what an observer is, you distinguish between environment and observer. I am not using the word observer as a "classical observer" like the original copenhagen interpretation, with observer I just mean any physical system.

observation ~ interaction ~ communication
observer ~ system

So in my picture, we must treat on the same footing

1. two communicating observer
2. two interacting physical systems

After all, an observer is nothing but a physical system. To me an observer can be an atom, it could be any subsystem.

I think of notions of "predictions" or "decisions" are attached to observers.

As I see it, the starting point for me, is an observer, that is interacting with it's own environment. Now in order to survive and not det destabilised, the observer needs to somehow have an action that is somehow in tune with the expected future evolution. So the expectations of the environment, is implicit in the action, that is physically encoded in the observer.

EDIT: The emphasis here is that no brain or mind is necessary to make sense out of "expectations" or "actions". You can indirectly infer the "expectations" an atom has on it's own environment, but means of it's actions. Does that make sense?

So in my view, the state space is an evolved truncated version of the "mathematically infinite" statespace what one might imagine, and unitary evolution _in this space_ is just an EXPECTED evolution conditional on the prior state of the observer. So the physical basis of the unitary evolution is in my vision in the microstructure of the observer. now, if the observer is in a certain sense in equilibrium with it's environment, then this unitaryt evolution will match the "actual evolution", but in general this can not be decided to be the general case.

So in my view, all "predictions of the theory" are actually expectations. The expectations can be correct as in "rational", even if the future shows to be different. The corroboration of this different way of thinking is different, the corroboration would then be made by using this scheme by construction of expected actions of subsystems (which implies that we would CONSTRUCT the "hamiltonians"), and if this matches the actions of the stnadard model and predicts the same particles we see, the scheme would be strongly corroborated. So as I see it, in my view, the structure of QM (with hilbert spaces, unitary evolutions tec, measurements) can not be postulated in isolation from the actions or hamiltoninans, they evolve togther.

I'm not saying I've solved this puzzle yet, but I'm just tryign to illustrate the visions and how this views, has clear objections to how I understand your view.

So what I suggest is a fundamental reconstruction, where BOTH the actions/langrangians or hamiltonians of the structure of space and matter as well as the structure of the framework itlsef evolve/emerge together. This should not be too surprising as already now, a lot of the standrad model are up to various coupling constants and parameters a "consequence" of the structure of the framework, including expected symmetries. I'm saying I think there is a deeper view of this, where symmetries are evolving. We no longer have the distinction between timeless state spaces, inital conditions and eternal laws. All three things qare treated on a similar footing - as required by my suggested "philosophy".

/Fredrik

 

[Fra]

Some interestings things where I do agree are these things:

Gambini & Pullin writes in an older paper "The Montevideo interpretation of quantum mechanics: frequently asked questions" (http://arxiv.org/abs/0905.4402) writes about their view of physical law.

"The presence of the undecidability we point out suggests strongly that the “regularity theory” point of view is more satisfactory since the laws do not dictate entirely the behavior of nature."

This view of physical law, is then to be constrasted against the view where physical law are hard constraints on nature that nature must obey.

This is in line with how I see it too. But again it's just words, so the question what implications one would draw from this? I draw the implications that physical law - as seen by a given observer, is basically "observed regularities" this observer has inferred from it's own interaction history with it's environment, and these regularities are the best expectations of how "nature" (ie. it's environment) behaves, and the tuned observers action are thus consistent with there "laws".

This is a regularist type of view, but in addition to that, my conclusion is that physical law is observer dependent, and that it's generally always evovling. Objective physical laws, only have meaning, in the context of a group of communicatin/interacting systems, which by a selective press will be mutually driven towards an agreement of a locally objective regularities.

Part of this, to me, also means that state spaces and event spaces, are also observer dependent and evolving.

I picture an entropic connection between the state and event space structure and physical law, where by just defining the event and state space, and the evolved internal relations, a default statistical flow is present - this is what I'd identify with time. And in the differential sense, I expect this to the unitary. But I don't think there is a global unitary evolution, simply because that information can't be captured by an inside observer.

So in a sense undecidability is also something I think is a key, but I guess your starting point of timeless hilbert sturctures confuses me.

I could accept a starting point going like this...

Consider an observer, this observer at some moment of time, "sees" or as inferred a microstructure system with an event space. At this moment of time there is an effective hilbert space, etc etc.

*but* in my picture, as time actually flows, in the generla case, this hilbert space can be deformed, in a way that is a priori undecidable. But I think the observes action, in a moment of time, is invariant with respect to this undecidable future, since like in a decision making process, it is rational to base your decision on available information only. It's a form of "locality", in the sense that the predictable part of the "probabilistic action" of the observer, depends only on what's at hand. Apart from that, there is i think also a fluctuating component.

So in my picture, the flow of time, has a kind of entropic origin. Clocks are just small devices that served to parameterize this flow for book keeping. But not a global entropy, it's just differential entropy. This is why entropic flow can still be consistent with relativity, since the local code of the entropy can transform as to make the flow itself "relative".

/Fredrik

 

[Fra]

I prefer to think that events can happen everywhere without the need for us. So, IF the observer wanted to try to check if some system is in a superposition

I think I see what you mean here, and I sort of fully agree that events sort of happen everywhere, independent of ME (~human observers). I fully share this. When I talk about observer, I don't mean humans or biological systems.

Any system, say an atom or a glass of water, are "observing" it's own environment all the time.

If I understand you right, you could probably agree with this, is that correct?

Thus one can imagine that there is a kind of class of observers, which is pretty much the equivalence class of all subsystems in the universe.

But whatl I'm insisting on, and where I think we disagree is that there can not exist any decidable objective description of this class. Thus, only an actual inside observer can describe this class from the inside, which unavoidably makes in complete. But again there is no observer indepdent way of establishing the uncertainty or probability of this incomplentess. It's more like an genuine uncertainty, not an uncertainty that can be captured by a timeless probability measure.

Since what I suggest admittedly makes things werid, the idea must be complemented by en evolutionary picture, darwinian style. Thus "time evolution" are partly decidable, and partly genuinely unpredictable as it contains a evolutionary component.

In what sense are you thinking about non-timeless hilbert spaces?

I'm thinking that the _structure of the statespace_ implicitly contains information, evolved information, and thus need to be put on similar footing as the information about the statevector. In intrinsic inference perspective, can not, in a fundamental sense as I see it, in a fundamental way distinguish between "information" that specifies the state vector, IN a given space, or "information" that specifies the state space. The difference is more as I picture it, that state space represents evolved information whose uncertainty is indistinguishable from the inside perspective. This is why, it sort of appears timeless, but only for infinitesimal evolutions! What I say is that the inside observer, can not predict how it's own state space evolves! But this must not be conceptually mistaken with (and I think it is often) that the statespace IS fixed and eternal. It's just that the immediate action of the system, is AS IF, it was fixed. But with finite evolutions and the general case, I can't make any sense in the idea that it's fixed.

Some more philosophical arguments on this are present in Smolins idea on evolution of law.
http://pirsa.org/08100049/

I may not agree fully with smolin, but there general argument against timeless statespaces is there. But in despite of his title, I do not think there is a global objective time of course.

/Fredrik

 

[LuisPe]

I think I see what you mean here, and I sort of fully agree that events sort of happen everywhere, independent of ME (~human observers). I fully share this. When I talk about observer, I don't mean humans or biological systems.

...

If I understand you right, you could probably agree with this, is that correct?

/Fredrik

Exactly, I agree with this, and I see now the confusion. Now, by observer you mean an environment then?
So we agree in what we expect the physical theory to be like in this point I believe.

*but* in my picture, as time actually flows, in the generla case, this hilbert space can be deformed, in a way that is a priori undecidable.

...

I'm thinking that the _structure of the statespace_ implicitly contains information, evolved information, and thus need to be put on similar footing as the information about the statevector

/Fredrik

Just to be sure, are thinking in the Schrodinger picture?

So you propose that one cannot fully know what is the hilbert space of some system, and that it might also change in time, ie evolve. I am having a hard time picturing it in some concrete example (probably because I am sort of used to thinking in the ortodox way, the one that is the basis of our work). For instance, say I consider some spin interacting with a bunch of other spins. There I believe there is no problem with assuming that the state space is known.

I’m just asking to try to understand better your point of view, which I find interesting, and I had never thought of (although I still don't grasp the whole idea...)

 

[LuisPe]

I have a more concrete question.

My motivation for the work we've done is that I see a very basic and problematic problem in QM (apart from all this thing of merging it with GR, and QFT problems): the measurement problem. Schrodingers cat and all that. Decoherence is not a fundamental answer.

My question is in what sense do you find it necessary to deny the existence of timeless hilbert spaces? Is it sort of a philosophical argument because you do not like making that assumption, or do see something wrong in QM that makes you look in this direction?

 

[LukeD]

Luis Pedro,

After reading through some of Gambini & Pullin's work, I have some questions.

What kind of scope does this have? In particular, what does it mean to measure time with a clock, and what sorts of things do I necessarily need a clock for? Do I need clocks to determine if 2 events separated in space are simultaneous? (something tells me I do) If that's the case, am I using a clock whenever I declare that 2 events are happening at the same time? But I usually just say that they take place at the same "ideal time" t. Can I no longer get away with that?

Or am I only using a clock when I make an interaction with my system at some time as measured by my watch?

To calculate the effects of a real clock, we still have to use the ideal time t. The entire theory is still formulated in terms of an ideal time. If I turn off GR, it's ok because I can still measure time as accurately as I please, so I can say that t exists in non-relativistic Quantum Mechanics. However, in the case of GR, where I use space-time separation, this is an idealization that does not exist at all (since time cannot be measured arbitrarily accurately), so I am uncomfortable with using the ideal space-time separation in calculations.
Can the theory be formulated without needing to make reference to an ideal time?
the FAQ seems to indicate that the ideal time drops out in the end. Does this mean it's unnecessary?

 

[Fra]

I think the questions we now start to discuss are good ones, so I probably will complement my answers later when I've formulated the better answers, but here are some quick ones.

Now, by observer you mean an environment then?

Yes it could be, but more often it's just a part of the environment, not necessarily the entire environment.

Also, conceptually I think of physical law as a tool used by each observer, to interact with its environment. In this abstaction I flip the notions, the "environment" is "the system under observation", and the observer is what "interfaces" to the environment.

But the key in my view, is that one must account for the action of the observer on the system, as well as the backreaction from the system on the observer.

I don't have all answers here, but to flesh it out a bit as part my starting point I picture that each observer, at each moment in time to to speak, has what I call a system of microstructures which defines or constraints the state space in complexity, and a this structure also has a state, corresponding to the "information state". I picture a entropic action that induces a natural flow on this state space, thus the structure of the statespace encodes the hamiltonian. Once the statespace is set, the hamiltonian flow is basically an entropic flow.

Hilbert spaces and QM state vectors would be a special case, that I expect to be derived from this deeper picture. But I have not been ablt to do so yet, but I'm somehow convinced it's possible.

Just to be sure, are thinking in the Schrodinger picture?

Since I'm picturing a reconstruction, where QM structure eventually would be emergent or induced, it may be confusing to borrow all the usual notions from QM. In the writing I made abover, the schrodinger picture was probably closest, but otoh I don't think it makes any difference to my point if we have a space of evolving state vectors, or we have a space of evolving operators.

So you propose that one cannot fully know what is the hilbert space of some system, and that it might also change in time, ie evolve. I am having a hard time picturing it in some concrete example (probably because I am sort of used to thinking in the ortodox way, the one that is the basis of our work). For instance, say I consider some spin interacting with a bunch of other spins. There I believe there is no problem with assuming that the state space is known.

This is all subtle I guess. First, my own preferred phrasings would not be to say that the hilbert space "evolves IN TIME", it would be rather silly, it's rather that the evolution of the hilbert space, as quantified by a kind of information divergence, IS a kind of time. An incomplete analogy, think about how we used the expansion of our universe to somehow "define" cosmological time. I'm thinking similarly, but in a differeny way.

The example you take, is the type of example where indeed the timeless statespaces make the MOST sense! This is also what Smolin called the case of "subsystems" which is the typical scenario for most particle physics experiments, which after all is WHERE QM as we know it, is confirmed.

The opposite to the "subsystem" scenario, is the "cosmological scenario".

To elaborate: The subsystem scenariou really corresponds in my use of the word, with the entire environment of the observed system (say a system of interacting spin-systems) IS "the observer".

In a particle physics lab, with decectors etc, I think it's fair to say that loosely speaking the ENTIRE environment of the collision domain, is under our control, and here it's fair to think of the ENTIRE environment of the localized events as "the observer". Also the environment is MASSIVE in complexity(and energy) relative to the system. In this example, the usualy logic works very well (but not perfect, but I could expand on that another time since it's a more subtle thing which will only confuse things here). Here I picture that repetivity experiments, and storing large time histories of experimental sequences including preparations in the environment (laboratory) are actually possible, here one can also infer effectively stable "timeless" state spaces. So QM works fine.

But, if we now consider the flip situation, that we sciencetist are the ones stuck inside a some small detector and are making our "observations" not towards a subsytem but out towards our cosmological horizon, into effectively an "open system", then our possibilities to infer, hold and store, histories of experiments are limited simply by _complexity_ or an information bound. For this kind of situation, the inference of a timelss state space of the environemtn just doesn't make any sense to me. As smoling puts it a bit provocative in this talk bout evolving law, it's a "fallacy" to apply the logic of subsystems to the cosomological situation. And I agree with him.

So, I am basically consider that the physical law, and theory itself, LIVES or is encoded, in the microstructure of the observer - in the above examples it's either encoded in the lab-environment, which is relative to the microscopic particles "infinite", or in the other scenario, which we can also call the "inside perspective" corresponding to how the subatomic particles "see" physical law, they must encode the laws themselves! And of course, this is a different situation, but I also think thta this is the reason why the interactions are bound to be unified as we consider less and less (complex) "observers" (read subatomic fragments) which is what happens in High energy experiments and we try to break matter into smaller fragments, then the interactions between the fragments are bound to have simpler and simpler "logic".

This is something I think we need to systemize and take seriously, and it's a natural part in the intrinsic model to me.

About event spaces, I distinguish between expected, and unexpected events. To any observer, the expected evolution in the knowns event space is always "information preserving" (to use a more neutral notion) for obvious reasons, but the undecidability makes it impossible to predict the full evolution. Now my exploit is that I think this will have observable effects to a second observer. The system will have an action, that reveals that it can not predict everything! This is a key exploit, and how I envision that the hamiltonian or action eventually follows and evolves along with the state spaces.

anothre thing is that I've come to the conclusion that the state spaces is rather more like a system of state spaces, that corresponds to "memory compartments" having different compression codings, and that THIS eventually is the origin of non-commuative structures, and QM. But there is a lot of work left here. I have reasonable ideas on all this but progress is snail-speed.

More later, let me know if any of this makes sense to you.

/Fredrik

 

[Fra]

I have a more concrete question.

My motivation for the work we've done is that I see a very basic and problematic problem in QM (apart from all this thing of merging it with GR, and QFT problems): the measurement problem. Schrodingers cat and all that. Decoherence is not a fundamental answer.

I also find motivation in issue with QM as it stands, in the sense of there beeing things that doesn't quite make sense even prior to trying to mix it with GR. I don't find decoherence a satisfactory solution either. But I suspect my issues with it, may be slightly different than yours.

In short: to me the "solution" to the "measurement problem" is to account for the action of the observer on the system, and the backreaction from the system. But I do not mean it in the silly sense of just picturing a new system with the old system + "apparatous". That doesn't solve the problem, it IMO misses the crucial point, by repeating the same flawed logic once more trying to hide it.

Instead, in the schrödingers cat example, the ACTION of the observer, that finds the macroscopic object in superpostion, even though another observer (the apparatous) does not, is simply implying that the ACTION of the observer reflects this. There is not objectivity in the collapse IMO, but again that is not necessary. Instead the "deviation from objectivity" as some would interpret as an "inconsistency" to me implies physical interactions, acting in between the observers that doesn't see the same collapse, the effect produces backreactions on all observers serving to eventually equilibrate them, producing somehow at equilibrium an objective consensus. So in practice, the lack of objectivity, is transient only. Somehow in line with the short decoherence times etc. Here I see also connections to inertia, not too unlike penrose gravity-decoherence connection, it's just that I don't share his vision to find a objective collpase. Penrose tries to use gravity to show that there by consistency has to be an objective collapse in some sort of unclear sense. I think that the SUBJECTIVITY of the collapse, and the evolution of observers IMPLIES the gravitational interaction.

That's the vision - but the details are not on the table of course.

My issue with QM, though is that it is not a measurement theory designed or built from an intrinsic perspective. It's really constructed for the case where we study a subsystem which we can control, manipulate (prepare), and repeat. This is in my view, a special case. The logic valid for this special case, fails in my view when we consider the general case of not having controlled subsystems - cosmological open systems are here the opposite. So the structures of QM, IMO, simply does not match what seems to be forcing traits of an intrinsic measurement theory - that's my basic motivation.

/Fredrik

 

[Fra]

My question is in what sense do you find it necessary to deny the existence of timeless hilbert spaces? Is it sort of a philosophical argument because you do not like making that assumption, or do see something wrong in QM that makes you look in this direction?

As I've tried to elaborate above, "timeless hilbert spaces" or "state spaces" in general, are to me a non-physical realist constructs.

In my picture, the physical state space is related to the state history, so that in a sense the truncated, compressed(datawise) state history sort of "spans" that statespace. In this construct, this space is in general constantly evolving, and the statespace is "encoed" implictly in the microstate of the observer. So the evolving state spaces are just mirroring the evolution of observers.

So from a more abstract view of intrinsic inferece, the information of the state spacestructure and that it's immutable and timeless, is a proposition that is not "constructible" or "decidable".

I am not saying I think that statespaces always has to change and can not be stable, I'm just saying that a intrinsic inference can not deduce with certainty that it does not, and that in some cases it's obvious that it fails, for example when the complexity of the observer grows (increases it mass/energy) then the observable state space will grow.

Another way of seeing it is that I see a "timeless hilbert space" in the cases where it clearly makes decent sense, as an equilibrium condition.

But I think the real benefit of this is when one is trying to understand the action of matter, and the action of a subsystem. Here the "logic" could be that everything looks simple if we could glimpse into the intrinsic perspective, and see an interaction from the point of view of that subatomic observers themselves. And in this view, I think an understanding of the fact that the intrinsic observer "sees" an evolution fo the state space that is unpredictable is the key to understand the construction and unification of action of matter.

But this is admittedly very radical and feeds question, not yet answered. It's just that the questions are a bit different than the questions we get in the current framework.

So the starting point of a timeless state space, that is objective, is I think wrong for an intrinsic measurement theory. But it's still true that my arguments are philosophical. But then there is no good argument the timeless state space either, except it's apparent simplicity.

Part of Lee Smolin's and Roberto Unger's provocation is suggest that we are sometimes trapped by tradition to think in terms of this logic: state space, initial conditions, timeless laws. When in fact there are a range of arguments that gives reasons to dout this.

Instead, a more general scheme should explain WHY, in some cases, the evolving state spaces do reach a steady state? This I think is the better question, and the one I have chosen.

/Fredrik