Do particles have well-defined positions at all times?

  • Thread starter Thread starter Fredrik
  • Start date Start date
  • Tags Tags
    Particles
Click For Summary
The discussion centers on the interpretation of quantum mechanics (QM) regarding whether particles have well-defined positions at all times. A quote from Ballentine's 1970 article suggests that particles can be considered to have definite positions, realized with relative frequency in an ensemble, although he later admits uncertainty about this claim. The conversation explores the implications of the Aspect experiments, which challenge local hidden variable theories and suggest non-locality in quantum correlations. Participants debate the nature of measurements, asserting that all measurements ultimately reveal position, and discuss the statistical interpretation of QM, which may rely on hidden variables. The thread concludes with a recognition that the statistical interpretation does not necessarily conflict with the idea of particles having well-defined positions, but the nuances of these interpretations remain contentious.
  • #61
Fra said:
Correct. This is why I said several times that I'm not doing pure interpretations. However, this "program" I'm into, implies a certain "interpretation". But the ultimate reason for preferring the interpretation is the success of the program.

But in fact, this is why it's worth considering. The pure interpretations, end up beeing the same mathematical formalism we have, and it provides NO further insights into unification and QG issues. So the "problems" you mentions, are just proving that this is non-trivial.

To excercise some lentght "interpretations" that in the end makes no further predictions than the current shut up and calculate formulation; then what is the point?

Yes but this is IMO a VERY poor excuse for not doing ones own thinking :) Without the right attitude we will never succeed.

So I think I can do better than everyone else? Apparently. Yes I know I'm probably crazy, but sometimes you need to be a little bit crazy to try.

Every successful novel progress in the history of science has been backed up by a history of failures; this is entirely normal. It should not be seen as discouraging at all. Anyone who thinks he/she can't succeed just because everyone else failed probably doesn't have the right mindest for this undertaking in the first place.

This should not be confused with naivety though.

That's exactly what I'm trying to do of course.

But before I make any bold proposals for new frameworks I have a lot more work to do.

But in short; the SE is most certainly correct as it stands, when you consider that it is a limiting case. Conceptually I've tried to explain it rouglhy, but the exact framework is in progress.

The whole point of conceptual view is a guide to finding the new framework. So I am constructive here.

This is in large contrast to those who try to find an interpretation of the existing already known! framework? What is the point?

I think we should focus on solving OPEN problems, an not ONLY make up interpretations to theories in domains where they are absolutely excellent, and where the interpretations makes no difference.

Please give some example how the MWI aspires to add any insight to an open problems to physics?

/Fredrik

You make a lot of sense in this message! I found myself being limited by current interpretations that don't have enough degrees of freedom. They are too rigid. Can you cite other mainstream physicists who are working along the lines you mentioned? Like maybe Carlo Rivelli(?) or even Lee Smolin? Who else? What important papers did they publish along this line?
 
Physics news on Phys.org
  • #62
Unfortunately there is to my knowledge none that has published anything that is completely in the direction what I think needs to be done, but there are several peoples and programs that have fragments that point to this direction.

But the general direction I'm favouring is an inference perspective to physics, where the ultimate idea is that the laws of physics are nothing but natures own "rational infernece". Then this is combined by physical constraints on the inference system (hosted by the observing system).

Some ideas that at least RELATE to this (but which develops different later) you find here.

1) Ariel Caticha
http://www.albany.edu/physics/ariel_caticha.htm
His main idea is that the laws of nature are derivable from the rules of rational inference. Ie. that information about physical interactions between two systems in nature, can be understood as a rational inference on their behaviour. In his view rational inference = probability theory, and for the extension to non-commutative cases quantum theory.

How this relates to my view: the main idea that the laws of physical are "rational expectations" is right in line with I envision, but I think we Need to start the analysi much deeper. In particular to I reject the too naive usage of continuum based probability. I think we need to start at the discrete levels and not just jump into the limits. This is why the causal set program may have bigger potential. But the idea is that these programs might meed somewhere.

2) Lee Smolin (Roberto Unger angle)

Smolin is very scattered and writes about almost everything, but the part I like the most is his collaboration with R Unger (expert in social theory) where he argues that the idea of eternal and timless laws of physica is wrong. The laws of the universe are evolving. I won't repeat the argument here, but this is also in line with my thinking, and it merges well with the reconstruction of ratinal inference from discrete ordered and partitioned sets of sets. It ultimately means that the laws of physics are also the result of a rational inference. But I find that Smoling isn't radical enough, he doesn't go all the way.

3) Kevin Knuth
Foundations of Physical Law
http://knuthlab.rit.albany.edu/index.php/Program/Foundations

His idea is that natural law derives from ordering relations. The idea could be that order is naturally present in the chain of events that defines the observers knowledge. This is an abstract idea that aims to ultimatley infer the laws of nature, from ordering relations of set, combining them also with equivalence relations of sets. This is an abstract reasoning that takes place long before spacetime is defined.

This kind of research is important and may relate to what I have in mind. But what he does is very basic structures, I can not answer for what Knuth's vision of the more elaborated things are.

How this relates to my view: This reminds of some of basic structure I'm working with. The basic abstractions are sets of distinguishable events, as well as counter states, that represents memory structure (where information is encoded). Then I have sets of such sets, that are related by different encodings (fourier transform is just an example). This entire set is constrained by a complexity. A time history is ordered, but a reencoded history has a different order. This is why networks of order create complex sturcutres that can be interpreted as multidimensional. Then this entire set of sets is subjct to random walks as the networks of sets develop in different directions entirely depending on the data stream fed into it. But this research is so abstract that on first sight, I have to admit that it's hard to see how it connects to physics. This is why I thin that IF someone is working on this, and publish parts of it, it may be in mathematical papers.

4) String theory
While I do not like string theory as such, it may be interesting to associate to it since it's after all one of the main BTSM reasearch programs.

In string theory, the idea is to deduce the action of the system, from some form of string action, and different state of the string. But ultimately the origin of the string action is just a silyl association to the string as a mechanical litteral string, oscillating. Then you quantize etc.

My generic view is to infer the action of a system from the rational action of the system, where the rational action is what follows from a random system just subject to the acquired self-constraints (such as ordering and equivalence relations of historical events). No classical action is needed. Also the "quantum" should be emergent as the structure of the system evolves from a single set to several non-commuting sets.

It is possible that string theory, may be a continuum limit of a deeper theory (without strings or more specifically without continuum objects at all; just sets of sets with inter-relations). The idea is that all interrelations would be understood from rational inference (almost the same as entropic reasoning).

5) Rovelli's LQG is not at all what I have in mind. When I started to read his book, during some of the first parts it started to converge to a picture I had where the networks would correspond to the observers information state; and that we would consider interacting networks. This would have been interesting to me, it could also connect at some point to te more abstract causal set views... but I later learning this is NOT Rovelli's vision.

Rovelli's RQM paper contains grains of excellent thinking, but again I find that because he wants to be conservative, he does not fully acknowledge his "no absolute relations" mantra. Because at some point he claims that communication is govergned by QM, and this is exactly the point where I find his reasoning looses coherence. But this is also because rovelli wants to find a "good interpretation" of QM, without changing it! But the outcome is not a good compromise IMO.

See http://arxiv.org/abs/quant-ph/9609002

--

My starting point, is a set of sets, that can be though of as (in constrast to classical statmech) a set of interacting microstructures, with a complexity conservation constraint. The microstructurs are related by different data encoding algorithms. When this structure is subject to new data, the data favours reallocations in this structure that can be understood as en entropic flow. New microstructures can be branched off at any time is situation demands. So there is NO static state space. The state space is always chancing. This is why expected changes are only relative to current state space. This is also why it's unitary (in the instant state space); there is simply no way to EXPECT the unexecpted. So unitarity is simpled to understand. It's no conicidene, or not magic tricks is needed to secure it. This is like when you move in a curved space; your tangent space is still always linear. There is an analogy here. Except that the structure of the embedding curved environment is unpredictable from the inside view; this is whay it's a true random walk, one step at a time.

But the difficulties start when these systems are interacting, then a selection will take place as there is a mutual interaction causing an evolution where at some point there may be a nash type equlibrium where systems maintain status quo (or approximately so). The task is to mathematically identify these equilibrium points, and the hope is obviously that the equilibrium points will prove to have a structure exactly fitting the standard model + of course include gravity and provide a GUT.

So in this view, there are no classical hamiltonian or lagrangians that are manually "quantized"! All there is are the logic of rationality (effectively serving as a selecting mechanics) then the effective hamiltonians will correspond to equilibrium points in this "game". Quantum logic automatically emerges out of this scheme as rational inference applied not to a single microstructure, but to sets of them (where they are related by information recodings), and constrained by "information capacity conservation".

/Fredrik
 
Last edited by a moderator:
  • #63
Thanks Fra for all the info. I'll take a look at them. Hope you won't be like Einstein spending half of his life chasing and solving and gaining nothing. This is because he lacked theoretical guiding principle in the latter half of his life. At least with GR, there is Equivalence Principle and this thought experiment of riding in a light wave in SR. So unless you have guiding principle (I don't know if this a right term). You may get nowhere. Lee Smolin mentioned that in String Theory they don't have guiding principle so it's possible they may face blank wall in later years turning it into a Theory of Nothing.
 
  • #64
Varon said:
Lee Smolin mentioned that in String Theory they don't have guiding principle

I agree the guidind principles are essental indeed.

The key issue - from MY perspective - is that the meaning of the strings and the various string actions, lacks justification from the point of view of rational inference.

It's pretty much originating from the classical picture of a litteral string, blindly which you then quantize mechanically checking just for mathematical consistency. Then one found that there are several different theories, lots of dualities, but still there is no proper understanding what this is, beyond mathematical realtions. This is also I think the reason why there is no selection principle among the possible string backgrounds, there is even discussion of wether such a principle is needed or not. I find this highly confused, and it can't be covered up just by elegant mathematics.

IMHO, the string action and the string background, should be understood as a rational action, and definining the microstructure of the observer. So the "interacting observers" is what should provide the selection mechanism; the "moduli space" of backgrounds is then to be understood as the external picture; of a set of interacting strings (ie. strings observing each other), but that would suggest that not every point in the landscape is "populated" in the observer cluster; this the big size of the landscape is an illusion due to confusing mathematical possibilties with physical ones. But without this guide, the difference is not there. All there is are mathematical possibilities which isn't understood.

But in order to make sense out of it, one needs to do a complete reconstruction. The starting points of a classical string, has no justification at all in this picture.

/Fredrik
 
  • #65
Fredrik said:
Right, but then we can at least conclude that the wavefunction doesn't just describe the statistical distribution of particles with well-defined positions. It has some other significance as well.

I think we're closing in on an answer to my original question: There is no known argument or experiment that can completely rule out the possibility that particles have well-defined positions at all times, but we can rule out the possibility that the only significance of the wavefunction is to describe the statistical distribution of particles with well-defined positions.

This makes me wonder if I've been thinking about Bohmian mechanics in the wrong way. I've been thinking that it's a different theory that makes the same predictions as QM, but this makes me think that it should (or at least can) be viewed as a genuine interpretation of QM. It seems that you can add some Bohmian assumptions on top of QM to turn the theory into something that might be a description of what actually happens, without changing the theory's predictions. It might be a description of a purely fictional universe, but at least it's a description of something. This is exactly what I think an "interpretation of QM" should do.
Perhaps now this can also be reconsidered from the point of view of a recent experiment already discussed here:
https://www.physicsforums.com/showthread.php?t=503861
https://www.physicsforums.com/blog.php?b=3077
 
Last edited by a moderator:

Similar threads

Replies
4
Views
2K
  • · Replies 13 ·
Replies
13
Views
2K
  • · Replies 12 ·
Replies
12
Views
2K
  • · Replies 309 ·
11
Replies
309
Views
15K
  • · Replies 64 ·
3
Replies
64
Views
10K
  • · Replies 23 ·
Replies
23
Views
6K
  • · Replies 30 ·
2
Replies
30
Views
5K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
5
Views
1K