susu.exp wrote:

SpeedOfSound wrote: No! Not what I am saying at all. Local realist theory? What the hell is that?

It is a theory, which is local and realist.

SpeedOfSound wrote:You just told me what you think realism means to you. Not necessarily what it means.

I've told you what it means in the context of Bells inequality. It has a precise technical meaning in physics.
...

Ok. Now I am really confused and we are flying further apart. Realism has a precise technical meaning in physics? You are going to have to cite some reliable sources for me here.

SpeedOfSound wrote:

susu.exp wrote:

SpeedOfSound wrote: No! Not what I am saying at all. Local realist theory? What the hell is that?

It is a theory, which is local and realist.

SpeedOfSound wrote:You just told me what you think realism means to you. Not necessarily what it means.

I've told you what it means in the context of Bells inequality. It has a precise technical meaning in physics.
...

Ok. Now I am really confused and we are flying further apart. Realism has a precise technical meaning in physics? You are going to have to cite some reliable sources for me here.

I don't agree with conclusion of this passage but it does define terms:

http://www.galilean-library.org/site/in ... l-realism/

Local realism is a two-pronged thesis: 'Local' means that objects can only be influenced by their immediate surroundings; this idea is well supported by relativity theory, in that influences are shown to propagate finitely: at a maximum, the speed of light. So there can be no instantaneous influences across space.

Realism is implicit in the scientific enterprise, and in daily life; it seems just to be common sense: It is the idea that there is a real, objective world out there independent of our minds and senses. It means that things out there have real values and properties independent of our measurements or observations of them, and would retain those values and properties even if no observers existed at all.

Yet, local realism is false. This has been known since the 1980s. The experimental demonstration of the violation of the Bell Inequalities not only provided strong support for quantum theory (refuting Einstein's criticism of it) it did something even stronger: These experiments showed that even if quantum theory eventually is shown to be false, local realism cannot be true; there is no competing theory that ever can be formulated which makes the violation of Bell inequalities compatible with local

I really think physics needs to use another word besides 'realism'. WTF?

DrWho wrote:

SpeedOfSound wrote:

susu.exp wrote:

SpeedOfSound wrote: No! Not what I am saying at all. Local realist theory? What the hell is that?

It is a theory, which is local and realist.

SpeedOfSound wrote:You just told me what you think realism means to you. Not necessarily what it means.

I've told you what it means in the context of Bells inequality. It has a precise technical meaning in physics.
...

Ok. Now I am really confused and we are flying further apart. Realism has a precise technical meaning in physics? You are going to have to cite some reliable sources for me here.

I don't agree with conclusion of this passage but it does define terms:

http://www.galilean-library.org/site/in ... l-realism/

Local realism is a two-pronged thesis: 'Local' means that objects can only be influenced by their immediate surroundings; this idea is well supported by relativity theory, in that influences are shown to propagate finitely: at a maximum, the speed of light. So there can be no instantaneous influences across space.

Realism is implicit in the scientific enterprise, and in daily life; it seems just to be common sense: It is the idea that there is a real, objective world out there independent of our minds and senses. It means that things out there have real values and properties independent of our measurements or observations of them, and would retain those values and properties even if no observers existed at all.

Yet, local realism is false. This has been known since the 1980s. The experimental demonstration of the violation of the Bell Inequalities not only provided strong support for quantum theory (refuting Einstein's criticism of it) it did something even stronger: These experiments showed that even if quantum theory eventually is shown to be false, local realism cannot be true; there is no competing theory that ever can be formulated which makes the violation of Bell inequalities compatible with local

In the colored portion we can see that what I was saying to susu about the mind being involved in the semantics is most certainly true. The confused issues of 'mind and senses' with 'observation'. This is where physics and some really ignorant physicists come off the rails end up fodder for the woo mills. Calling it local realism fans the flames. I would prefer something like 'proximal causality' but still I would complain about using 'causality'. Proximal relation would be better.

susu.exp wrote:...

SpeedOfSound wrote:Line two is gibberish. It is all the rage to think that there really are realists who think like this though. But read it a few times out loud and you'll see how ridiculous this is.

See above. We measure the spin of a particle in one direction. Does it make sense to say that the particle has a spin in another direction? Consider that we could have measured it in that direction.

Okay. I get all that.

Now look at the last bit. You are willing to give up the local relationship because experiments are sort of leaning that way. Why are you still using 'particle' when experiments have long been leaning away from that?

The problem here is in making assumptions about human-concerns and trying to carry them into physics. Human-concerns are such things as objects that we can manipulate with our hands at the spacial and temporal resolutions of our ordinary biological realities.

Now a realist knows, as I do know, that these biological realities are most certainly present and act in such a way that I could model them as having persistent properties and identity. But the realist also knows that he is an animal, with a fallible brain, and things we find to be real at other resolutions most certainly will have a more interesting and surprising geometry.

Now compare a tree to a hypothesis about a subatomic particle. Can you do that without laughing? If the 'particle concept' turns out to be nothing at all like the tree in your yard are you then going to claim that the tree should behave with quantum statistics? That would be naive realism somewhat in reverse.

DrWho wrote:...

http://www.galilean-library.org/site/in ... l-realism/
...

The post right after that one is someone who I can get behind.

http://www.galilean-library.org/site/in ... l-realism/

Posted 09 October 2009 - 01:18 AM
You say that the local aspect of local realism is well-supported by relativity theory. If quantum entanglement is non-local, then we have a bona-fide contradiction. But it seems to me that localism isn't purely empirical, it must be metaphysical to some degree, as contained in it are propositions about causality. So the metaphysics already contained in localism would be where you would want to pay attention.

I'm really ignorant about the whole subject. Just, that's where I would inquire.

If you want to grapple with realism, personally I think we've become too hung up on the mind-dependent/mind-independent and objective/subjective distinctions. Perhaps these opposing ideas are more like opposite sides of a graduating continuum? On one side, the mind simply submits to every perception where observation can only be a purely passive activity. On the other side, observation is purely active, and every perception is a bona-fide reification. The trouble is that there is no "world". Maybe my trouble with anti-realism is that it complicates things enormously. Without a world all we can do is dream. But what is the point of that when we are already dreaming? All our points lose their edge. Maybe if we can find sense between the two sides of continuum we'll still find reason to believe there is yet a world.

SpeedOfSound wrote:I really think physics needs to use another word besides 'realism'. WTF?

It has conterfactual-definedness, which is used synonymously. But it is quite a mouthfull and using realism in this sense preserves trees and keeps talks within the allotted time frame. Another alternative is hidden-variables. So you could say local hidden variables rather than local realism, but again, that's quite a bit more to type or say.

On Dr.Whos 3 links: 2 of those discuss Bohmian mechanics. Which is non-local and has causal loops. Not a good counterpoint to "you either have non-realism or causal loops". The third one is weirder (2nd link). It discusses some non-Kolmogorovian approaches to probability. Now, standard probability theory is build upon Kolmogorovs axioms and there's an issue when you try to combine this with relativity - there are some sets that probability theory doesn't assign probabilities to, because they lead to contradictions otherwise, and combining GR with QM in a straightforward way asks you to assign probabilities to precisely these sets. So some people have taken approaches that do not use Kolmogorovs axioms (generally weakening them in some way). The article argues that QM is Kolmogorovian, i.e. it uses probabilities in the way standard probability theory does, rather than in these non-standard alternatives. It then states that this allows determinism - no further argument is provided here and it basically boils down to: These are ordinary random variables, rather than these weird alternative random variables, so they aren't random variables. I leave it to the reader to find the problem with that (in addition a key part of the argument are correlations between variables - but deterministic variables are uncorrelated).

SpeedOfSound wrote:Now compare a tree to a hypothesis about a subatomic particle. Can you do that without laughing? If the 'particle concept' turns out to be nothing at all like the tree in your yard are you then going to claim that the tree should behave with quantum statistics? That would be naive realism somewhat in reverse.

Well, naive realism is realism in a philosophical sense, not in the sense of counterfactual definedness. Naive scientific realism asserts that the theoretical objects of scientific theories are ontologically real. That's something different from the physical notion. To say that the universe is not counterfactually defined means to state that if we measure the spin on one axis, it is pointless to argue about the spin on other axes, because there is no such thing. A scientific realist can still make ontological assertions about this - the theory only talks about spin in one spatial directions, well then that is real...

SpeedOfSound wrote:In the colored portion we can see that what I was saying to susu about the mind being involved in the semantics is most certainly true. The confused issues of 'mind and senses' with 'observation'. This is where physics and some really ignorant physicists come off the rails end up fodder for the woo mills. Calling it local realism fans the flames. I would prefer something like 'proximal causality' but still I would complain about using 'causality'. Proximal relation would be better.

Well, counterfactual definedness has nothing to with minds. It does have something to do with measurements however and here's where I should probably hand things off to @hackenslash.

Okay. we are getting to the same page. Just not that my rant a few pages back is what happens when you grab a hot potato from philosophy, like the word 'realism', and put it in a physics paper. I'm sure you can see how all of this has turned into grist for the woo-mills.

Now back to trees. I like trees. Trees can easily and effectively be modeled as having identity and persistent local properties. Realism follows the model. What is real is what is the model. Same with cat's in boxes. They are dead or alive. No experiment with actual cats in actual boxes will ever find one to be in both states. So we should leave the fucking cat at home when talking about QM. Along with the word 'realism'.

SpeedOfSound wrote:I really think physics needs to use another word besides 'realism'. WTF?

There may well be a case for that, except for about 80 years of historical usage. It isn't a metaphysical term in physics. In other words, and to put it in terms that we have agreed upon previously, it's realism, not RealismTM, and has to do with whether particular measurable properties of particles such as position, velocity, spin about a given axis, etc, have any meaning prior to measurement. This is a less-than-robust way to express it, but it's a layman's version of a more precise, technical term as applied in QM.

The historical usage stems from the arguments Einstein had with Bohr about QM's ability to fully describe nature. Einstein insisted that, for example, a particle always has a 'real' velocity regardless of whether we were actually measuring it or not, while Bohr, in line with the Copenhagen interpretation, said that it didn't have such a property until measured or, in the language of QFT, that our observation caused the field to behave in a particular way.

SpeedOfSound wrote:In the colored portion we can see that what I was saying to susu about the mind being involved in the semantics is most certainly true. The confused issues of 'mind and senses' with 'observation'. This is where physics and some really ignorant physicists come off the rails end up fodder for the woo mills. Calling it local realism fans the flames. I would prefer something like 'proximal causality' but still I would complain about using 'causality'. Proximal relation would be better.

Indeed, though problems would still arise, simply because we have to keep 'mind and senses' and 'observation' entirely separate, because confusion reigns there, for the simple reason that observers aren't required to be conscious.

This all comes back to some of the deep problems in theoretical physics, namely that it's limited in some ways by the language we use. We use everyday terms like 'real', 'observe', etc, because we don't have better words. Our language is often insufficient to deal with the entities and processes in question when transcribing to lay terms, but the mathematical formulations are robust and tell us what we need to know.

I am enjoying the conversation

And I like this quote from John Bell

It would seem that the theory [quantum mechanics] is exclusively concerned about "results of measurement", and has nothing to say about anything else. What exactly qualifies some physical systems to play the role of "measurer"? Was the wavefunction of the world waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer, for some better qualified system ... with a Ph.D.? If the theory is to apply to anything but highly idealized laboratory operations, are we not obliged to admit that more or less "measurement-like" processes are going on more or less all the time, more or less everywhere. Do we not have jumping then all the time?

Spooky quantum mechanics therefore no determinism smells, looks, feels and generally marches around like bullshit.

romansh wrote:I am enjoying the conversation

And I like this quote from John Bell

It would seem that the theory [quantum mechanics] is exclusively concerned about "results of measurement", and has nothing to say about anything else. What exactly qualifies some physical systems to play the role of "measurer"? Was the wavefunction of the world waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer, for some better qualified system ... with a Ph.D.? If the theory is to apply to anything but highly idealized laboratory operations, are we not obliged to admit that more or less "measurement-like" processes are going on more or less all the time, more or less everywhere. Do we not have jumping then all the time?

You couldn't make the necessary measurement.

hackenslash wrote:

SpeedOfSound wrote:I really think physics needs to use another word besides 'realism'. WTF?

There may well be a case for that, except for about 80 years of historical usage. It isn't a metaphysical term in physics. In other words, and to put it in terms that we have agreed upon previously, it's realism, not RealismTM, and has to do with whether particular measurable properties of particles such as position, velocity, spin about a given axis, etc, have any meaning prior to measurement. This is a less-than-robust way to express it, but it's a layman's version of a more precise, technical term as applied in QM.

The historical usage stems from the arguments Einstein had with Bohr about QM's ability to fully describe nature. Einstein insisted that, for example, a particle always has a 'real' velocity regardless of whether we were actually measuring it or not, while Bohr, in line with the Copenhagen interpretation, said that it didn't have such a property until measured or, in the language of QFT, that our observation caused the field to behave in a particular way.

Very well then. I was not familiar with that usage. Learn something new every day. But you can see how this has caused issues right?

However. I am on this campaign to steal all the good words back from the woo so I should be all for this. Physicalism for instance is no longer a woo-filled metaphysical word for me.

hackenslash wrote:

SpeedOfSound wrote:In the colored portion we can see that what I was saying to susu about the mind being involved in the semantics is most certainly true. The confused issues of 'mind and senses' with 'observation'. This is where physics and some really ignorant physicists come off the rails end up fodder for the woo mills. Calling it local realism fans the flames. I would prefer something like 'proximal causality' but still I would complain about using 'causality'. Proximal relation would be better.

Indeed, though problems would still arise, simply because we have to keep 'mind and senses' and 'observation' entirely separate, because confusion reigns there, for the simple reason that observers aren't required to be conscious.

This all comes back to some of the deep problems in theoretical physics, namely that it's limited in some ways by the language we use. We use everyday terms like 'real', 'observe', etc, because we don't have better words. Our language is often insufficient to deal with the entities and processes in question when transcribing to lay terms, but the mathematical formulations are robust and tell us what we need to know.

The approach that I like is to model things in minimal structures and then see what certain things like properties and identity might mean. I quickly understood that things like locality, properties, and identity were not requirements but rather they were could-be or maybes. The linear space model was a big maybe though a requirement of most models. So I had to imagine there may be a stranger real geometry underlying my linear model.

Then a cool intuition hit me upside the head. That the particles or little identities themselves could be shadows cast by the geometry itself. With these things in mind non-locality and matter without property ownership seem, not surprising, but likely.

As long as we are stealing words back, how about metaphysics to represent the kind of modeling I mentioned above? It certainly isn't physics. It tries to reach beyond physics to find new models.

Then a cool intuition hit me upside the head. That the particles or little identities themselves could be shadows cast by the geometry itself. With these things in mind non-locality and matter without property ownership seem, not surprising, but likely.

That's close to a good intuition about QM itself, namely the the particle is a shadow, not of the geometry, but of the interaction of observation.

Always good because useful intuitions about QM are hard to come by.

hackenslash wrote:

Then a cool intuition hit me upside the head. That the particles or little identities themselves could be shadows cast by the geometry itself. With these things in mind non-locality and matter without property ownership seem, not surprising, but likely.

That's close to a good intuition about QM itself, namely the the particle is a shadow, not of the geometry, but of the interaction of observation.

Always good because useful intuitions about QM are hard to come by.

hmm....shadows of interactions....sounds like good poetry...how about 'the ghost of the observation'

better yet...

The particle is the ghost of not of geometry, but of the shadow of the interaction of the observation.

Keep It Real wrote:Spooky quantum mechanics therefore no determinism smells, looks, feels and generally marches around like bullshit.

Not being able to find a cause is treated as evidence that there is no such thing - even though it is assumed and useful in all non-QM science.