Eperts please explain

Discussion in 'Physics & Math' started by arauca, Sep 27, 2012.

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  1. arauca Banned Banned

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    Quantum foundations are still unsettled, with harmful effects on science and society. By now it should be possible to obtain consensus on at least one issue: Are the fundamental constituents fields or particles? Experiment and theory imply a universe made of unbounded fields rather than bounded particles. This is especially clear for relativistic quantum systems, and it follows that non-relativistic quantum systems must also be made of fields. Particles are epiphenomena arising from real fields. Thus the Schroedinger field is not a probability amplitude for "finding, upon measurement, a particle" but rather a real space-filling field; the field for an electron is the electron; each electron comes through both slits in the 2-slit experiment and spreads over the entire pattern; and quantum physics is about interactions of microscopic systems with the macroscopic world rather than just about measurements. It's important to clarify this issue because textbooks still teach a particles- and measurement-oriented interpretation that leads to bewilderment among students and pseudoscience among the public. This article reviews classical and quantum fields, the 2-slit experiment, rigorous theorems showing that particles are inconsistent with relativistic quantum theory, and several phenomena demonstrating that particles are incompatible with quantum field theories.

    http://arxiv.org/abs/1204.4616
     
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  3. AlexG Like nailing Jello to a tree Valued Senior Member

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    Since the paper you quote from is in History and Philosophy, that's where this thread belongs.
     
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  5. rpenner Fully Wired Valued Senior Member

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    Your personal ignorance of certain matters is not likely to harm science. Science's uncertainty on a subject is not likely to harm society. As far as I can tell, no segment of society is harmed by continuing uncertainty in the field of fundamental physics nor has the progress over the last 350 years has had any major beneficial effect. If anything biology and medicine are the sciences that have so greatly benefited society.
    Quantum field theory says fields. General relativity says fields. I believe the consensus says the fundamental constituents modeled by physics are fields.
    You are answering your own question. Also, what do you mean when you say bounded and unbounded? That part means nothing to me. From the article, it appears bounded means nothing more or less than point-like. I disagree that the author has shown that photons cannot be point-like.
    This does not follow. Reality is relativistic, but that doesn't stop us from modeling systems well with non-relativistic models.
    This viewpoint doesn't begin to make sense to me. Particles are excitations of quantum fields, and the main object studied. (An excited field is much more interesting than an unexcited field.) Calling particles epiphenomena is like calling letters on the computer display "mere modulations" of its light-emitting properties.
    The Schrödinger equation is a non-relativistic model for a single particle -- relativistic quantum fields are quite different and account for multi-particle and variable-particle systems in ways that the Schrödinger equation fails to map to reality. If you are arguing for the reality of the Schrödinger complex wave form, you are using an inadequate model that fails to explain 1) antimatter, 2) spin statistics, 3) Lorentz invariance and the unreality of quantum phase. (Only phase differences are physically significant.)
    Your expression is unclear, you can't talk about the electron field being fundamental and called "the electron" and then talk about excitations as "each electron."
    I don't believe you have adequately summarized quantum physics in either of the two offered descriptions.
    Students always feel bewilderment when they assume incorrectly that they have mastered the subject. That's no reason to give up on a history textbook, so I don't see it as a flaw in a physics textbook. The fault appears to lie with the arrogance of the student who will either learn eventually or won't. (Would it surprise you that that author also has published a kind of physics textbook? A. Hobson, Physics: Concepts & Connections (Addison-Wesley/Pearson, San Francisco, 2010) )
    Do you have any surveys of quantum pseudoscience among the public? The number one source of this that I am aware of is from deceitful charlatans selling bogus products based on the public's conflating gibberish for viable non-intuitive explainations of Nature's workings. Said public, not exposed the textbooks you complain of cannot fairly trace their woes to said textbooks.
    Art Hobson, who wrote the above abstract quoted above from a pre-print of an article not yet ready for publication. (Weird ASCII-only spelling of Schrödinger, equations which are weirdly typeset, misspellings in the article). I don't think it meets the standards of a review article.
     
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  7. Farsight

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    Arauca: this Art Hobson guy definitely has a point. In physics you'll hear of "quantum field theory", and yet you'll also hear "the electron is a fundamental particle". The people who say the latter tend to gloss over the fact that we can create an electron (and a positron) in pair production, and destroy both it and the positron in annihilation. They also tend to say that the electron is very small, which doesn't account for its electromagnetic field being a part of what it is. See this particle chart for an example of that. It's from "An award-winning site from the Particle Data Group at Lawrence Berkeley National Labs". Rpenner is being way too hostile and dismissive in his response, there are issues in contemporary physics, and it's wrong of him to give the impression that there aren't. That's not to say Art Hobson is right about everything he's saying, I'll read the paper and get back to you further on that.
     
  8. Fraggle Rocker Staff Member

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    Don't semiconductors sorta qualify as "fundamental physics"? Without them there would be no Information Revolution, leading us out of the smoke, traffic congestion and resource depletion of the waning Industrial Era. Of course the first generation of computers was invented with nothing more than vacuum tubes, but with instruction speeds measured in milliseconds and memory capacities of a few hundred bytes--and taking up a very large room with a gigantic air conditioner--they could never have powered the Internet.

    More importantly, I wouldn't have such a cool amplifier for my guitar.

    Please Register or Log in to view the hidden image!

     
  9. Farsight

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    I didn't like that either. He seemed to be saying physics is useless. Whoa. Rpenner, wash your mouth out with soap.
     
  10. OnlyMe Valued Senior Member

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    The point seems to me to have been harmed, not affected, changed or benefitted. Though in context of some of the rest of the post, I can see it easy to read as you seem to.
     
  11. rpenner Fully Wired Valued Senior Member

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    Physics and engineering keep people employed, to be sure. Not quite what I meant when I was looking for examples of benefits to society.

    The Internet is like a cheap, democratic printing press and exists at the mercy of society's tolerance of freedom of speech and freedom of the press. Just as the printing press was used in the American revolution to spread and sell the idea of revolution, so is the Internet and this makes it uncomfortable to many of the ruling elite. There are constantly proposals to reign in these freedoms.

    The Internet and proliferation of communication channels has enabled the balkanization of information. Don't want to confront your worldview with news of global warming or facts about the history of taxation rates? Don't want to hear about the wars going on? Don't want any news other than sporting events and movies from 30 years ago? There's probably a subset of channels tailored for you. Conservapedia runs a war against basic facts. IslamQA explains how democracy is an offense against Allah.

    Computers, like atomic weapons, can be misused. With information, as with wealth and the still relevant Industrial Revolution's means of production, there are elements of society very rich and very poor. The rich use their information to conduct millisecond arbitrage while to the poor the world of finance is mysterious and alarming. The rich introduce proprietary control software into uncounted devices, the poor find their telephone exchanges and cell phone networks shutdown as tactics of police and warfare.

    Unfortunately, Fraggle Rocker, I have never heard you perform so have no basis to know if your amplifier gives me a chance to feel optimistic or only strengthens my pessimism.
     
  12. Farsight

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    OnlyMe: He did say If anything biology and medicine are the sciences that have so greatly benefited society. That doesn't sit too well with deceitful charlatans selling bogus products. Hmmn. Maybe the latter is what Art Hobson is addressing.
     
  13. OnlyMe Valued Senior Member

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    However, they are the areas of science which have contributed most to the health and lives of people — and society.

    There have been and likely will always be snake oil salesmen, this does not take away from things like the success there has been fighting disease and even in emergency medicine. The first preventing many diseases that historically "plagued" society and the later preserving lives long enough to address the underlying life threatening issues.

    I am no expert on biology and medicine, though a few of my siblings are. Still it does not take an expert to see that both have had dramatic impacts on society.

    Yes other sciences and technologies have both contributed to that impact and to society generally. Information communication being just one example. But again this does not lessen the impact and importance that the progress in biology and medicine have had. Aside from how the progress of civilization has affected the availability of food, there is perhaps no other advancements that has benefitted society as much.
     
  14. Prof.Layman totally internally reflected Registered Senior Member

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    It is an interesting paper, and I think it makes it very clear that quantum theory has taken the path of describing nature in the terms of fields from the very beginning. Seems like all it is saying is that quantum theory doesn't explain "particles" as though they are a baseball moving around a baseball field, but it is more like a description of a sea of baseballs moving around together. I think describing the sea would be easier than describing each individual drop of water in that sea, and if quantum theory took a new approuch to describe the exact path and behaivor of every drop of water in that sea it would be revolutionary in science. I don't care for the explanation that such an approuch would violate SR, because quantum field theory would seem to violate SR in the same way. And, if a theory that "truely" described particle behavior as though it was a baseball would have to somehow violate this principle in order for it to be correct along with quantum field thoery. In other words, a different approuch to describe quantum behaivor as particles should not absolutely prove quantum field theory wrong. Also, the act of observation can then make particle behavior look more like particles and less like fields. What if you conducted a 2-slit experiment that had detectors leading all the way down the experiment and both paths leading along both slits? They would start to act much more like particles. So then why should a field collaspse just by looking at it? In SR everything is relative to the observer, I think this question could hint to the particle nature of reality. If there is no object, then you couldn't observe it to appear differently by traveling at relative speeds. I think we just don't have the mathmatics or mathmatical ability to describe quantum theory in such a way that you could prove beyond a reasonable dought that there are particles.
     
  15. Farsight

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    OnlyMe: I agree that biochemistry/medicine has delivered huge benefit to humankind. The thing is, physics used to be the "senior" science, only there's been debateable progress and benefits in recent decades. I was reading something about it being "knocked off its pedestal" a while back, maybe to do with the Royal Society or the Institute of Physics, but I'm afraid I can't find it. Art Hobson sounds like he's pointing out what he thinks is an underlying problem. I'd better read his paper I suppose.

    Prof Layman: the Copenhagen Interpretation which involves "the collapse of the wavefunction" has come in for some stick of late. See for example Jeff Lundeen's web page and in particular this:

    "We hope that the scientific community can now improve upon the Copenhagen Interpretation, and redefine the wavefunction so that it is no longer just a mathematical tool, but rather something that can be directly measured in the laboratory."

    Rpenner: it's not just a rich v poor thing, there's interest groups in all walks of life. That's human nature I'm afraid. It isn't just the likes of Conservapedia who are engaged in propaganda.
     
  16. Prof.Layman totally internally reflected Registered Senior Member

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    http://physicsworld.com/cws/article...rld-reveals-its-top-10-breakthroughs-for-2011

    I think the top breakthrough here just shows that calcite is not a good tool to try to measure the exact speed and position of a particle. It only indicates a path that it took, that seems to imply a particle nature of a wavefunction. For instance, you could know with a high degree of certainty that the particles in the experiment most likely came out of the emmiter that ejected them. I don't think it really changes our understanding of quantum physics. They act like both particles and waves; and the closer you look at them the more they look like particles. I don't think "thinking" of particles as particles will hurt quantum physics, I think not allowing thinking about quantum physics as particles would do more damage. Someone thought we could describe all of quantum physics as strings, and look where that got us...
     
  17. James R Just this guy, you know? Staff Member

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    There appears to be no topic of discussion in the opening post - just a link.

    So, thread closed.
     
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