Thursday, May 26, 2016

Cranks denying local causality

I criticize mainstream professors a lot, but I am the one defending mainstream textbook science.

Philosopher Massimo Pigliucci claims to be an expert on pseudoscience, and is writing a book bragging about how much progress philosophers have made. Much of it has appeared in a series of blog posts.

One example of progress is that he says that philosophers have discovered that causality plays no role in fundamental physics:
Moreover, some critics (e.g., Chakravartty 2003) argue that ontic structural realism cannot account for causality, which notoriously plays little or no role in fundamental physics, and yet is crucial in every other science. For supporters like Ladyman causality is a concept pragmatically deployed by the “special” sciences (i.e., everything but fundamental physics), yet not ontologically fundamental.
I do not know how he could be so clueless. Causality plays a crucial role in every physics book I have.

A Quanta mag article explains:
New Support for Alternative Quantum View

An experiment claims to have invalidated a decades-old criticism against pilot-wave theory, an alternative formulation of quantum mechanics that avoids the most baffling features of the subatomic universe.

Of the many counterintuitive features of quantum mechanics, perhaps the most challenging to our notions of common sense is that particles do not have locations until they are observed. This is exactly what the standard view of quantum mechanics, often called the Copenhagen interpretation, asks us to believe. Instead of the clear-cut positions and movements of Newtonian physics, we have a cloud of probabilities described by a mathematical structure known as a wave function. The wave function, meanwhile, evolves over time, its evolution governed by precise rules codified in something called the Schrödinger equation. The mathematics are clear enough; the actual whereabouts of particles, less so. ...

For some theorists, the Bohmian interpretation holds an irresistible appeal. “All you have to do to make sense of quantum mechanics is to say to yourself: When we talk about particles, we really mean particles. Then all the problems go away,” said Goldstein. “Things have positions. They are somewhere. If you take that idea seriously, you’re led almost immediately to Bohm. It’s a far simpler version of quantum mechanics than what you find in the textbooks.” Howard Wiseman, a physicist at Griffith University in Brisbane, Australia, said that the Bohmian view “gives you a pretty straightforward account of how the world is…. You don’t have to tie yourself into any sort of philosophical knots to say how things really are.”
This is foolish.

The double-slit experiment shows that electrons and photons are not particles. Not classical particles, anyway.

Bohm lets you pretend that they are really particles, but you have to believe that they are attached to ghostly pilot waves that interact nonlocally with the particles and the rest of the universe.

Bohm also lets you believe in determinism, altho it is a very odd sort of determinism because there is no local causality.

Just what is appealing about that?

Yes, you can say that the electrons have positions, but those position are inextricably tied up with unobservable pilot waves, so what is satisfying about that?

Contrary to what the philosophers say, local causality is essential to physics and to our understanding of the world. If some experiment proves it wrong, then I would have to revise my opinion. But that has never been done, and there is no hope of doing it.

Belief in action-at-a-distance is just a mystical pipe dream.

So Bohm is much more contrary to intuition that ordinary Copenhagen quantum mechanics. And Bohm is only known to work in simple cases, as far as I know, and no one has ever used it to do anything new.


  1. Roger,
    Yes there are particles, not knowing how they are physically structured does not change that there is something interacting with something. All actions and interactions require 'something' interacting with a 'something' else. Something and nothing do not interact. Nothing and nothing do not interact, logically, how could they?

    Please stop metaphorically/logically/scientifically conflating verbs with nouns. Causality requires a noun to perform or produce an action. Sans noun, you can have no action. There are no waves/movement/change sans object. Ever. A man can run. A man is running. A man has run. Never does the action of running produce a man or any object in any tense, or anything else for that matter. Never does running occur without something doing the running.

    As to quantum nonsense,

    When you can't find your left sock, it has not turned into a probability through magical hypostatization, or reified into a wave without object, or miraculously doubled its mass/energy by splitting in two. When you stop thinking about your missing sock it also does not disappear, or translocate by itself. When you remember your sock is missing, it does not then pop into existence retroactively. The reality is, you simply do not know where it is, and no matter how many calculations you perform or fantasies you evoke over your uncertainty, it will have no effect whatsoever on the unknown location of your missing left sock.

    When you lose something, or can't account for it, don't then lose your mind as well. A better approach might bet to start thinking like a grown up who has been to a magic show. If you are being rational, You know the magician isn't teleporting objects or pulling them from the void, you know what you think you saw happen, but logically and rationally understand that you CAN be deceived, so you have to apply other methods that do not involve giving in to magic or delusion.

    When the magician had one golf ball, and now has two in his hands, instead of blathering on about how the other ball is not a ball at all, but a 'wave' of piffle, why don't you instead ask yourself, 'where did the other ball come from?' and work your way out from there? With the full understanding that balls do not pop into and out of existence for the caprice of children at magic shows, an answer might be found.

  2. Anyone interested should also read up on Feynman's 'shrink and turn method'. The fact that this 'method' actually works proves there is a mechanical, not purely mathematical underpinning to QED. Despite Feynman saying you couldn't visualize such processes, he did so with his students anyway. Just because Niels Bohr didn't believe there was anything to visualize does not mean anyone else should agree to his lack of visualization. Men who can not visualize are not usually the best resources as to how things look. When someone in a position of any kind of authority tells me not to look behind the curtain, as a rule, I take a good look.

    When actual motions are removed from physics, there is no physics anymore. We know particles move and spin (see Roger's Bubble Chamber tracks picture to the right), as do planets, as do solar systems, as do star systems, as do galaxies, as do galactic clusters, so can we please stop pretending 'point particles' of no size or the capacity to spin are going to functionally serve as a foundation of how particles move and interact? For grief's sake, try modeling the motion of a football or baseball as a non-spinning point and see where that gets you.

  3. "Belief in action-at-a-distance is just a mystical pipe dream."

    Quit saying that there is no action-at-a-distance. There is tons of it! It just propagates with a speed limit.

  4. Matthew,
    Before you entertain spooky action at a distance, consider just about anything else that doesn't involve pixie dust. If one thing affects another thing, there is mediation between the two of some kind, not unknowable mystical magical forces or overblown mathematics that somehow can explain what science can not. The very fact that there is a 'speed limit' to propagation is a big red flag that something you aren't detecting is going on. If you want to know what that is, stay the course with testable discovery, don't mathematically hand wave it away or subscribe to non answers.

    If you want to believe in magical forces, ok, stay cool and don't try to explain things at all, leave that to uptight slightly OCD people who are a little more critical about the details of causation than 'because it just happened.'

  5. "unknowable mystical magical forces"

    That's what a "field" or "force" is. Things do effect things at a distance even if the physics is strictly local. You just need to define what you mean by local first.

  6. "Contrary to what the philosophers say, local causality is essential to physics and to our understanding of the world. If some experiment proves it wrong, then I would have to revise my opinion. But that has never been done, and there is no hope of doing it. "

    What about this: