Comments

  1. Kevin Lewis says:

    Hello, Dr. Brooks. Thank you for your magnificent book. I feel like I now have a secret decoder ring to better understand other writings on the subject. I wish I had been aware of it sooner. Thank you for spending your precious time on this work.

    My question is about the role of the observer. I’m not completely sure I understand why you say there is no role for the observer in field collapse. What about the double-slit experiment? Hasn’t it been shown that field collapse occurs when a human observer detects “which slit” a “particle” goes through? Isn’t it true that field collapse does not occur without an observer even if the detector remains on, but does not record the data? What about the “quantum eraser” experiment that seems to show that field collapse can even seem to occur retroactively based upon observation.

    Forgive me if I’m showing a lack of understanding of your excellent work. It would not be due to your writing, but rather the many other sources of information that may have confused me on the topic.

    • Rodney says:

      No, as I understand QFT, it doesn’t require an observer. After all, don’t things happen the same way on Mars, even though there are no observers there (yet)?
      You’re right about “other sources of information”. Many physicists take the view that collapse doesn’t occur until someone looks. This is the
      point of view that Schrodinger lampooned with his cat experiment, calling it “ridiculous”, and that Einstein lampooned when he asked “Do you think the moon is there only when I look?”
      A field quantum collapses when it interacts with an atom (according to the field equations) and “decides” to collapse into that atom. We may not know which one until we look, but that’s when the collapse occurs. And remember, it’s a physical collapse, not a collapse of probabilities.

  2. Kavan says:

    Hello Dr. Brooks,
    My name is Kavan. I purchased your book on Amazon (kindle version). I have some true beginner questions I would like to pose, for clarification purposes.
    Would that be ok?
    thanks,
    Kavan

  3. Howard Green says:

    Great Book!nn1nn1

  4. Robert A. Robinson says:

    I am only trying to buy this book. I will buy from Amazon, Scientific American Book Club or any other source which has this book in hardcover.

    • Rodney says:

      The print version is available in paperback from amazon.com. The ebook can be bought from Kindle, Nook or iTunes. See “Buy Now” on the home page

  5. David says:

    This may sound like quibbling but I observed in one of your videos an overhead in which it was stated that “…equations determine…” I am unaware of any equations that are causal in nature. Wouldn’t it be more accurate to say “…equations describe…”?

    • Rodney says:

      I could settle for either “determine” or “describe”. Most physics equations, starting with Newton’s Laws of Motion, are causal in the sense that they tell you how the quantities in question change with time. The equations of Quantum Field Theory, for example, tell you how the field intensities change with time. It is only the infamous Schrodinger’s equation of quantum mechanics that deals with probabilities, and therefore might be termed acausal. This is one of the reasons why I prefer the QFT description of reality to the particle description of QM. Yes, there is an acausal event in QFT and it is field collapse, but this is a separate event from the deterministic evolution of the fields.

  6. Mike Wells says:

    Finally! An explanation that makes sense. I am creating a “reality scorecard” to distinguish between all of the major theories past and present (for my own edification). I don’t have a hard and fast definition of reality. I just rely upon the proponents of each theory to posit what is real. On the “reality” axis, I put ether, wave, particle, string, force, field, time, 3D space, multi-D space, event, causality, law, energy, and universe. I may have missed some, but I hope not. Then I subdivide each reality candidate into 4 sub-categories: single instance, multiple instances, single form, and multiple forms. For example, in the Standard Model, particles take multiple forms and of course have multiple instances of each form. When I analyze QFT, the only real things I find are fields (multiple instances and multiple forms), causality (multiple instances and a single form), and finally the universe (single instance and single form). Please let me know if my interpretation is correct for QFT.

    • Mike Wells says:

      Thank you for the reply. I just happened to check for your reply after you posted it. The instance and form sub-categories were just a way for me to further classify theories. For example, some theories have a single instance of “universe” and others have multiple instances (“multiverse”). I don’t know of any theories that posit different forms of universes like there are different forms of quarks. Sometimes the sub-categories don’t apply, and sometimes the line between what constitutes an instance and what constitutes a form is blurry. It is just interesting to see what each theory calls real and what forms each real thing can take. For example in Gibbin’s “Schrodinger’s Kittens and the Search for Reality: Solving the Quantum Mysteries” there are two forms of causality: one forward in time and one backward in time. I would have never thought two forms of causality were possible, but, hey, there is a theory for it. It kind of makes me wonder what other combinations of real things will be proposed and explored to create a “theory of everything”. Perhaps it isn’t fair to expect physicists to label what is real and what is not, but most theories make these types of assumptions anyways. Since I doubt I will ever be able to understand the intricacies of most theories, I might as well find some way to understand and distinguish them. Thanks again for clarifying what QFT considers real.

      Just a couple more follow-up questions. Why doesn’t QFT consider space real? Do the properties of space emerge from fields? -Mike

      • Mike Wells says:

        In reading the book a second time, it seems that I missed a real entity. It appears that field quanta are also real. Is the relationship between fields and field quanta the same as the relationship between a dog and its component atoms? Both are equally real, it is just that one is composed of the other. I am not one to make the distinction between “more real” and “less real” as some are wont to. It keeps things simple.

        • Rodney says:

          Field quanta are nothing more than bumps, or excitations, in the underlying (vacuum) field that is always present. If we must use the dog analogy, you might say that quanta are like the ears, or perhaps tail, of the dog – especially if it’s wagging.

    • Rodney says:

      I don’t understand about the multiple instances and forms, but yes, in QFT fields are the only real things and yes, there is causality (except for field collapse, which is not covered by the theory). And there is just one universe. Rodney Brooks

  7. Russ Abbott says:

    I enjoyed your book very much. I have a question that I would appreciate your considering. Is there, for example, a single matter-lepton field or does each electron, muon, etc. have its own matter field? Or could one say it either way?

    Also, if there is a single field, and all electrons are excitations in that one field, what distinguishes one electron from another so that a negative force can exist between them?

    Thanks.

    • Rodney says:

      Those are good questions, Russ, and I’ll try to answer them. First, I don’t know if any particle-oriented physicists have “confirmed the scientific validity” of my book. But I’m not sure what there is to validate. Quantum Field Theory is a theory, and as I say in the book, the choice is up to you. I admit that my picture of QFT is oversimplified, and I’m sure a purist could object to that, but I think this is necessary to make it understandable at a lay level.

      As to your question about the lepton field, yes there is a single lepton field that permeates space – even in what we call a vacuum. In addition there are “excitations” in that field that we call quanta, or perhaps electrons. The creation and existence of these quanta are very elegantly described by the math of QFT, even if it’s not included in the book. Although the quanta are, in a sense, part of the overall electron field, each one has its own identity and acts as a unit.

      So how do we explain the repulsion between two electrons? By the electric field that each one creates. Surrounding each electron (which we visualize as a blob of “yellowness”) is a “green” EM field that extends into space following the 1/r-squared law. Thus each electron experiences three different “green” fields: the underlying vacuum field, its own “self-field”, and the EM field of the other electron. Now its interaction with its own self-field is problematic, and is solved by the process called renormalization (p. 117 in my book). Or, as Richard Feynman suggested, maybe there is no such effect (p. 103). It is the EM field set up by the other electron that causes the repulsion. And vice versa.

  8. Russ Abbott says:

    Have any particle-oriented physicists looked at the book and confirmed it’s scientific validity — even though they may disagree with it’s perspective?

  9. Tina Lucas says:

    Just think that energy and mass can be exhausted. Time is, however, unexplainable.

    • Rodney says:

      Sorry, but I can’t agree with this. Energy and mass cannot be exhausted; while interchangeable, their total sum is constant. Time, on the other hand, can be explained as simply a measure of change or movement. As Lucretius wrote in 60 BC (quoted in my book): “Time by itself does not exist; but from things themselves there results a sense of what has already taken place, what is now going on and what is to ensue. It must not be claimed that anyone can sense time by itself apart from the movement of things.”

  10. Paul says:

    Wonderful book! I’ve found it looking for further QFT explanation after watching several Sean Carroll public lectures (talk at the Ri for example, in which he’s explicitly saying that “Everything is Field”).

  11. Art Hobson says:

    Rodney – I haven’t yet read the second edition of “Fields of Color,” but I understand that you have incorporated into it many of Frank Wilczek’s insights as stated in his book “The Lightness of Being.” Wilczek’s book is excellent. His title refers to the pure field nature of reality. It is very much a field-oriented account of contemporary physics. I cannot understand why my fellow physicists balk at the notion, expressed so clearly in both your and Wilczek’s book, that there are no particles, there are only fields. – Art

    • Rodney says:

      I fully agree (except, with all due honor and respect to Wilczek, I think my book is easier to understand than his). I think the main problem physicists have with the “only fields” view is that field collapse is non-local. That is, if fields are real then a field quantum (or even two entangled quanta) can disappear or change its (their) polarization instantaneously, no matter how spread-out it (they) may be. My response (see Chap. 8 of my book) is that we must accept nature as she is, not as we would like her to be. Instantaneous field collapse may be surprising, but there is nothing inconsistent about it, Einstein notwithstanding. In fact, if we accept the quantum nature of fields – that each quantum must live and die as a unit – it is essential. However with Wilczek now publicly on board the “fields only” train, I think this view will ultimately prevail.

  12. Lawrence Reiner says:

    I can undersand this writing. Now I have trouble with all the uninformed minds spouting old wornout drivel. This should be television special on the Discovery channel.