Thursday, April 16, 2020

How Heisenberg Became Uncertain

I have decided that my YouTube channel lacks a history part because there is so much we can learn from the history of science. So, today I want to tell you a story. It’s the story of how Werner Heisenberg got the uncertainty principle named after him.



Heisenberg was born in 1901 in the German city of Würzburg. He went on to study physics in Munich. In 1923, Heisenberg was scheduled for his final oral examination to obtain his doctorate. He passed mathematics, theoretical physics, and astronomy just fine, but then he run into trouble with experimental physics.

His examination in experimental physics was by Wilhelm Wien. That’s the guy who has Wien’s law named after him. Wien, as an experimentalist, had required that Heisenberg did a “Praktikum” which is a series of exercises in physics experimentation; it’s lab work for beginners, basically. But the university lacked some equipment and Heisenberg was not interested enough to find out where to get it. So he just moved on to other things without looking much into the experiments he was supposed to do. That, as it turned out, was not a good idea.

When Heisenberg’s day of the experimental exam came, it did not go well. In their book “The Historical Development of Quantum Theory”, Mehra and Rechenberg recount:
“Wien was annoyed when he learned in the examination that Heisenberg had done so little in the experimental exercise given to him. He then began to ask [Heisenberg] questions to gauge his familiarity with the experimental setup; for instance, he wanted to know what the resolving power of the Fabry-Perot interferometer was... Wien had explained all this in one of his lectures on optics; besides, Heisenberg was supposed to study it anyway... But he had not done so and now tried to figure it out unsuccessfully in the short time available during the examination. Wien... asked about the resolving power of a microscope; Heisenberg did not know that either. Wien questioned him about the resolving power of telescopes, which [Heisenberg] also did not know.”
What happened next? Well, Wien wanted to fail Heisenberg, but the theoretical physicist Arnold Sommerfeld came to Heisenberg’s help. Heisenberg had excelled in the exam on theoretical physics, and so Sommerfeld put in a strong word in favor of giving Heisenberg his PhD. With that, Heisenberg passed the doctoral examination, though he got the lowest possible grade.

But this was not the end of the story. Heisenberg was so embarrassed about his miserable performance that he sat down to learn everything about telescopes and microscopes that he could find. This was in the early days of quantum mechanics and it led him to wonder if there is a fundamental limit to how well one can resolve structures with a microscope. He went about formulating a thought experiment which is now known as “Heisenberg’s Microscope.”

This thought experiment was about measuring a single electron, something which was actually not possible at the time. The smallest distance you can resolve with a microscope, let us call this Δ x, depends on both the wave-length of the light that you use, I will call that λ, and the opening angle of the microscope, ε. The smallest resolvable distance is proportional to the wave-length, so a smaller wave-length allows you to resolve smaller structures. And it is inversely proportional to the sine of the opening angle. A smaller opening angle makes the resolution worse.

But, said Heisenberg, if light is made of particles, that’s the photons, and I try to measure the position of an electron with light, then the photons will kick the electron. But you need some opening angle for the microscope to work, which means you don’t know exactly where the photon is coming from. Therefore, the act of measuring the position of the electron with a photon actually makes me less certain about where the electron is because I didn’t know where the photon came from.

Heisenberg estimated that the momentum that would be transferred from the photon to the electron to is proportional to the energy of the photon, which means inversely proportional to the wavelength, and proportional to the sine of the opening angle. So if we call that momentum Δ p we have Δ p is proportional to sine ε over λ. And the constant in front of this is Planck’s constant, because that gives you the relation between the energy and the wave-length of the photon.

Now you can see that if you multiply the two uncertainties, the one in position and the one in momentum of the electron, you find that it’s just Planck’s constant. This is Heisenberg’s famous uncertainty principle. The more you know about the position of the particle, the less you know about the momentum and the other way round.

We know today that Heisenberg’s argument for microscopes is not quite correct but, remarkably enough, the conclusion is correct. Indeed, this uncertainty has nothing to do with microscopes in particular. Heisenberg’s uncertainty is far more than that: It’s a general property of nature. And it does not only hold for position and momenta but for many other pairs of quantities.

Many years later Heisenberg wrote about his insight: “So one might even assume, that in the work on the gamma-ray microscope and the uncertainty relation I used the knowledge which I had acquired by this poor examination.”

I like this story because it tells us that if there is something you don’t understand, then don’t be ashamed and run away from it, but dig into it. Maybe you will find that no one really understands it and leave your mark in science.

152 comments:

  1. I believe someone (I think from memory it was Bohr) corrected Heisenberg at the time about the argument not being correct, even if the outcome was.

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  2. OK, something I don't understand, or at least am curious about:

    Neutrino oscillations tell us that neutrinos travel at less than c, contrary to what was previously believed. So they have a rest frame into which we could place ourselves, though it might present some engineering challenges, no? If we were to do that and examine a neutrino at rest or moving at low speeds, what would we expect to see?

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    1. My blog is not a forum for random physics questions. Please read the comment rules. Having said that, the answer to your question is, the same thing, boosted.

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    2. Egad,

      This might be one of those questions that are worth looking into if you fail them on a PhD exam :) There is a paradox there, since all neutrinos are created left-handed, yet, if we were to observe a neutrino while traveling even closer to the speed of light and in the same direction, we would have to see it right-handed. Or not. This is a good popular description of the situation: https://www.forbes.com/sites/startswithabang/2019/09/17/this-is-why-neutrinos-are-the-standard-models-greatest-puzzle/#1eb15b76453f

      In short, answering your question might lead to an insight similar in importance to the Heisenberg's Uncertainty Principle :)

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    3. Sergei wrote:
      > There is a paradox there, since all neutrinos are created left-handed, yet, if we were to observe a neutrino while traveling even closer to the speed of light and in the same direction, we would have to see it right-handed.
      ...
      >In short, answering your question might lead to an insight similar in importance to the Heisenberg's Uncertainty Principle.

      No, this is just an issue of "helicity" vs. "chirality": anyone who passed a course on QFT is supposed to know how to calculate this -- it's just elementary manipulation with spinors and gamma matrices.

      There are various interesting questions concerning the possibility of Majorana neutrinos, etc., but the issue of what the spin would look like in different frames of reference is trivial. As Sabine implies, you just apply the appropriate "boost."

      By the way, the simple answer is that a neutrino at rest has neither left-handed nor right-handed spin intrinsically, since there is no non-zero velocity vector to single out a privileged direction along which to measure spin. Whether it is left-handed or right-handed will then depend on the arbitrary direction you choose to count as "up."

      Exactly the same as for electrons, which no one thinks is a deep physical issue.

      There are serious issues concerning neutrinos, but no competent physicist would fall for thinking this is one of them.

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  3. I've often heard the Uncertainty Principle described this way, as having to do with the fact that a measurement unavoidably involves disturbing that which is measured. But when I studied QM, what I learned was that it's just a feature of the Fourier Transform. You get the same phenomenon with musical tones: you can't localize a tone to arbitrary precision in both time and frequency. A very pure tone must have sufficient duration; a very short tone must have a broad range of frequencies. And none of this has anything to do with the process of measurement disturbing a system.

    So does this business of measurement disturbing the system being measured really have any fundamental connection to the Uncertainty Principle, beyond a historical footnote explaining what led Heisenberg to investigate the idea?

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    1. Kevin,

      Yes, that's right, it's a property of Fourier transformations. It has to do with quantum mechanics because you need the quantization prescription to relate the wave-number with the momentum (they are related by Planck's constant), otherwise you merely have a statement about waves.

      A measurement process always disturbs the system. It's just that for most classical systems you don't notice. If you watch a rock fall down, say, then the photons bouncing off it don't matter much. However, think of measuring the temperature of something. The act of bringing the thermometer in contact with it will actually change the temperature you are trying to measure.

      The business of measurement disturbing the system contributes to the total measurement uncertainty but not to the uncertainty principle.

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    2. Is it possible to have another video on "A measurement process always disturbs the system. It's just that for most classical systems you don't notice." considering that disturbance is an influence. And connecting or linking this to Weizmann institute experimental inference.

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    3. "A measurement process always disturbs the system. It's just that for most classical systems you don't notice." This is very interesting and intriguing. I want to add that sensory perception is also measurement in the sense that there is the biological-program and the senses which receive sense data deliver it to the brain which then processes the data according to the human-program.

      It is also very tempting to add that psychological interpretations like "Muslim", "Hindu", "Christian" and all the prejudices associated with them are also measurement in the psychological field. Let me make myself clear. Right from one's childhood one is programmed or conditioned as a Hindu, for example, and this becomes the background from which one looks at other human beings, say Muslims, for example. When I look at a human being, I not only identify him as a Muslim etc., but all the associated images of bias against Muslims get invoked. My hindu-program influences my looking and translates what I see, just another human being, into a Muslim etc., and the associated prejudices and biases further influence my looking. This is measurement at the psychological level which again is the same mechanism which takes place with regard to sense data.

      The question then is, is it all measurement at the sensory level or the psychological level? Now, the biological program and the psychological Hindu-program and their acts of measurement are classical aren't they?

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    4. My prejudices and biases psychologically color my looking. The coloring is an act of measurement psychologically.

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  4. Hyperlink 1: If sine epsilon/ lambda is large, it means that delta p or momentum is large, which in turn means that the kick is large, therefore, we cannot ascertain the position. Conversely, if Sine Epsilon is small and lambda is large, then the kick is small but we don't know where the photon came from. Correct me if I am wrong. Talking in terms of resolution: if the resolution is good that is delta p is large the kick is large. Then, talking in terms of influence: if resolution is good then the influence of measurement is large and the kick is large. Finally, talking in terms of disturbance, if the resolution is good, the influence (of measurement) is large and the disturbance is large and the kick is large. Through high resolution or influence of measurement there is greater certainty momentum but uncertainty about position. Let us consider the certainty of one thing as a function of measurement influence.

    Hyperlink 2: Weizmann institute of science experiment. From this experiment, we learn that when the observer influence is large, then the interference pattern is weak or the particulate behavior is more defined. Again, when the resolution is large the measurement influence is large and the particulate nature is more manifest. With resolution and measurement influence the definition increases, that is, the greater the observer influence the better the definition.

    Now hyperlinking from 1 to 2, we see that with resolution and measurement influence the certainty increases, and increase in certainty weakens the interference pattern. The observer apparatus is influencing the observed in the act of measurement. Any alteration in the observer apparatus's influence correspondingly alters the observed. This means that it is measurement that is producing certainty and clear definition. If I play with measurement specifications then the observed dances to the tuning. The observed is the virtue of the measurement.

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    1. The sinε is a result of optics for ε the angle of a cone of light after passing through a convex lens. The spread in the resolution Δx = λ/sinε means the best resolution possible is where the angle of this focused cone of light (not a light cone in relativity) is 90 degrees or π/2.Of course, optics being what it is the lens glass will have chromatic aberration due to dispersion and so the angle is usually not this sharp. Heisenberg made the ansatz for the spread of momentum Δp = h sinε/λ. Heisenberg employed Bohr’s idea of discrete energy steps E = hν = hc/λ, wrote an analogue for momentum, and then said the momentum transfer is modified by the angle.

      If I recall the history, the following year the German economy went completely into the tank with various issues of the French intervening in the Ruhr. Heisenberg spent this time at a family property in Heligoland where during the year of down time, sounds like today, he developed the matrix formalism of quantum mechanics.

      His situation with the Nazi party later on was rather murky. After the meeting with Bohr in Copenhagen in 1941, as I recall the date, Bohr expressed some horror at Heisenberg’s opinions.

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  5. With reference to my previous comment, if momentum and position are considered as a superposition, then measurement as an influence resolves the superposition, and clearly defines with certainty one thing based on the strength of influence or measurement. Only one of the things in superposition because the specifications of the measurement dictate the outcome, a single outcome, and which outcome, in that, the measurement setup, which is the observer, dictates the outcome and which outcome. The measurement-program dictates the outcome and the clarity of its definition. Now, what happens if the measurement stops? That is the question. It is all undefined, uncertain isn't it? To put it differently, what happens if I remove the measurement apparatus, the observer, the measurer? Where is the definition? Can I define? The observer is the definition.

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  6. With reference to my previous comments, if we have come thus far, then we can ask what is reality? Is reality the virtue of the observer? Then what is actuality?

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    1. Since this is also about history of science. Niels Bohr and Werner Heisenberg among others were very much inspired by Idealism - we create the things when we messure - there is no objective reality. The Copenhagen interpretation of QM that came out of that is still what is accepted by most scientist, although almost not discussed. QM is mathematical formalism, a recipe that gives very good predictions, it has indeed been successful. But it is not a physical theory, which physically describes for example the measurement process. Here you are told to shut up and calculate and sing „nothing is real“. Let us work hard and find the real quantum theory, where the observer is not that important and independent.

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    2. In one of Lyall Watson's books, Dr. Watson quotes a scientist who said that "there is something out there . . . the actual . . . odorless, tasteless, colorless" this is not the exact quote, rather something close to it. I am using that word "actual" and therefore "actuality" in the sense in which that scientist quoted by Lyall Watson is using it. By "reality" I mean "of the observer", and by actuality I mean "what is" in the absence of the observer.

      Let us take two high level observers: fly and human, or more accurately, the fly-eye and the human-eye. We know that the fly-eye is a compound eye. Then let us take Quantum Darwinism. From Philip Ball's article we have:

      "When you see an object, for example, that information is delivered to your retina by the photons scattering off it. They carry information to you in the form of a partial replica of certain aspects of the object, saying something about its position, shape and color. Lots of replicas are needed if many observers are to agree on a measured value — a hallmark of classicality. Thus, as Zurek argued in the 2000s, our ability to observe some property depends not only on whether it is selected as a pointer state, but also on how substantial a footprint it makes in the environment. The states that are best at creating replicas in the environment — the “fittest,” you might say — are the only ones accessible to measurement. That’s why Zurek calls the idea quantum Darwinism."

      From the above para let us zero in on the sentence "Lots of replicas are needed if many observers are to agree on a measured value — a hallmark of classicality."

      Now, the catch is "if many observers are to agree on a measured value". If it is the human-eye-program then all the human observers will measure the same value or see the same thing. What if it is the fly-eye-program? What will it look like to the fly? What a thing(the replicas) "really" look like to us will not "really" look like to the fly-eye-program. Both programs, the fly and the human, process the thing or replicas differently and present two different realities. How can the same thing or replicas present two different realities? This means, doesn't it, that reality is the virtue of the program. Reality is dependent on the program. Reality is the interpretation of the program. Reality is a description of a thing or replicas--whatever they are--according to the program.

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    3. . . . what that thing or replicas "actually" are we dont know. We or the fly interpret those replicas according to our respective programs. . . so what is "actuality"?

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    4. . . . what those replicas "actually" are may be colorless, odorless, tasteless . . . like the scientist quoted by Lyall Watson said. What is it that gives color, odor, taste? Isn't it the fly-program or the human-program or what ever the program?

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    5. The moment something is definitive it is the product of measurement.

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    6. Again QD, "What’s special mathematically about pointer states is that the decoherence-inducing interactions with the environment don’t scramble them: Either the pointer state is preserved, or it is simply transformed into a state that looks nearly identical. This implies that the environment doesn’t squash quantumness indiscriminately but selects some states while trashing others. A particle’s position is resilient to decoherence, for example."

      Because replicas have been made and there is selection and super selection, the environment makes the measurement, in that, the environment is measurer or observer.

      The replicas themselves have passed one level of measurement. They themselves are interpretations because they belong to the world of decoherence. Since they passed one level of interpretation, I call them the least interpreted primordial; and there is the uninterpreted primordial which is not of the world of decoherence.

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    7. John, I think you are right: we messure! :)

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    8. Realism in quantum mechanics is hard to identify. Realism appears to be a manifestation of the type of quantum interpretation one works with. Bohr’s Copenhagen interpretation is ψ-epistemic, in that all the wave function or ψ does is to predict what and where measurement outcomes will obtain. The wave function is not anything real. The QuBism interpretation is also ψ-epistemic. In contrast, the many worlds interpretation (MWI) is ψ-ontological, in that it works with ψ being real. The de Broglie-Bohm interpretation is also ψ-ontological. It is no clear which perspective is right.

      I did some analysis with hidden variables, also using a parameter that varied from 0 to 1 as to how local they were. This leads to a sort of uncertainty whether QM is ψ-epistemic or ψ-ontic. There is nothing in QM that constrains it either way. This had some problems with spin or angular momentum. I also could not make it work for 2-state systems. Of course, Gleason’s theorem has a similar hole in it. I have had this on ice for several years now. Maybe if I get the time and temerity, I will resurrect this.

      The one thing in physics that is real, or real enough for all practical purposes, is the classical world. The Copenhagen interpretation (CI) would concur with this, though there is an ambiguity with where the classical and quantum worlds separate. Zurek does work with the idea of classicality as einselected states that are with large N, or number of states or action, are stable under environmental quantum noise. The CI does admit a reality to classical systems, and the classical world sits by itself as all that is fundamentally real. In this setting Bohr and Heisenberg were not complete idealists, they were only so with respect to quantum measurements. Further, the outcome of a quantum measurement is not predictable beyond the probabilities given by P_i = ⟨ψ_i|ψ_i⟩ = |ψ_i|^2.

      One of the funny issues with QM and probability can be seen with QuBism. There is a hole in this interpretation, just as there are holes in all of them, is that QM is fundamentally about states and amplitudes, and probabilities are the modulus square of states. Even if we work with density operators, also matrices as Heisenberg showed, ρ = |ψ⟩⟨ψ| the probabilities occur as a summation given by the trace 1 = Tr(ρ) = sum_iP_i. This is from an integration perspective an L^2 measure with Tr(ρ). A strict classical probability measure is just L^1 as seen on the right. The second equal sign is then in a way “funny,” where it is assumed from the Born rule with a “unit observable.” This connects QuBism with the Born rule, or the Born rule fills in a hole, where in the opposite end Carroll and Sebens have found connections between MWI and the Born rule, but really again the Born rule fills in a hole. I find myself thinking about this stuff often.

      Reality in physics is not as easy to identify. Remember, the Bell inequality demonstrates a dualism between nonlocality and realism. The Frauchiger and Renner result shows that in a Wigner’s friend set up reality can be the choice sacrificed in favor of a locality of measured outcomes. We have in a sense run into the problem of identifying reality that existentialists pointed to.

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    9. John Bihl wrote:

      >Since this is also about history of science. Niels Bohr and Werner Heisenberg among others were very much inspired by Idealism - we create the things when we messure - there is no objective reality. The Copenhagen interpretation of QM that came out of that is still what is accepted by most scientist, although almost not discussed.

      I think historians of philosophy and historians of physics would argue that Bohr and Heisenberg were influenced by "positivism," which is widely viewed as a revolt against "idealism."

      That being said, I actually think you are on to something here. It has always seemed to me that positivism is simply idealism with all the pretty Victorian ornaments stripped away. Both philosophies focus on our own thoughts and sensations rather than on the idea of a physical world existing independent from us.

      To be sure, it would hardly be the first time that would-be revolutionaries ended up looking remarkably similar to the Establishment they replaced! Almost a law of history.

      Anyone know if any philosopher has made this point?

      I think you are too pessimistic, however, in claiming that the Copenhagen interpretation still reigns supreme. The problems with the foundations of quantum mechanics is now quite a hot topic: Sabine discussed it in her book and has also discussed it here in her blog.

      Steve Weinberg, about as senior and respected a figure as there is in physics today (and a former prof of mine), has been clear and forceful in laying out the problems.

      No one yet has a fully adequate solution, but I think there are few physicists today who are unaware that there is a problem.

      Dave

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    10. Lawrence Crowell, I propose a classic experiment, I will try to describe it as well as possible. Suppose we have an elevation with two planes inclined to both sides with the same slope; we also have two balls, both have a blue hemisphere and the other hemisphere red; Suppose the two balls are at the top of the elevation connected by the pole of the blue hemisphere of one with the pole of the red hemisphere of the other; then we break the connection between both balls and one will roll on the right side and the other on the left side; At the same distance from the top we placed a photographic camera that would photograph each ball from above (to make the experiment more explicit); every time you have a blue ball in one photo, the other is red; each situation is inverse of each other however you measure it; no one in their right mind would say that one measurement interferes with the other; all would assume that the symmetry of the space covered is responsible for the result. In both the classical and the quantum example, the symmetry of space must be responsible for the result, it seems to me; if the symmetry of space is broken, the synchronization of the results is broken. I would like to know what you think.

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    11. I guess I am not sure what this has to do with Heisenberg uncertainty principle. Yes if the symmetry of space is broken something as you state might occur. The hardest might be a violation of Newton's third law, which is about the isotropy of space.

      There is though a sort of breaking of a space symmetry. It is parity violation, found by Mdm Wu. This is a chirality to the weak interactions, which has a basis in why the Kaon and anti-Kaon have slightly different decay channels. The B-factor has been working to probe deeper into this.

      Does this have to do with some breaking of the symmetry of space or spacetime. Maybe, but I will not now go into my thoughts on this.

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    12. PhysicistDave wrote:
      “I Think you are too pessimistic, however, in claiming that the Copenhagen interpretation still reigns supreme. The problems with the foundations of quantum mechanics is now quite a hot topic: Sabine discussed it in her book and has also discussed it here in her blog.”
      I wish you were right but you are unfortunately not. The foundation of physics/QM is not a hot topic.QM is used by most scientists as a calculator and few if any questions are asked. When directly asked there is often a reference to the discussions between Einstein and Bohr - and that Bohr answered properly in 1935. Bohr did not.. and then came the Second World War and shut up and calculate. Now we are in the middle of a crisis in physics where string theory and inflation and multiverse/many worlds dominate. If you as a student realise that these theories are the way to go if you want a job and a career in physics, no wonder that only few choose another path, namely to go back and study the physical description of the measurement process. I think that is the way to go to get real progress in physics.

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    13. John Bihl wrote to me:
      >If you as a student realise...

      John, I am not a student: I took QM from Richard Feynman in the '74-'75 academic year and tried to get him interested in the foundations of QM, without any apparent success. (I had written a paper that year on Bell's theorem for another class, so I knew something about then-recent work on the subject.)

      On the other hand, Peter Shor, who knew Feynman a few years later, seems to think Feynman did eventually become interested in the topic. So, perhaps I had some effect after all.

      I also took QFT from Steve Weinberg when he was visiting Stanford in the late '70s while I was doing my doctoral degree. Again, Steve showed little interest in foundational issues back then, but his recent book on QM takes such issues quite seriously.

      What certainly is hot today is quantum computation, which, historically, is largely an offshoot of the work in foundations, especially Bell's work.

      It really is progress compared to what I saw back in the '70s.

      John also wrote:
      > I think that is the way to go to get real progress in physics.

      Well, Sabine and Tim Palmer and 't Hooft and, lest of all, I myself are all working on it -- that makes at least four physicists! If you look at the arXiv, it's really quite a few people. Even a few intrepid philosophers try to seriously wrestle with the physics: I have in mind, in particular, Tim Maudlin, who has commented here.

      You think we don't have much to show for our work? Well, it's hard: it flummoxed Einstein, after all.

      But we're trying.

      All the best,

      Dave

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    14. Lawrence Crowell, Thank you very much for your kind response; but I think I did not make myself understood; I was talking about the EPR experiment; I see no reason to believe that measurement in one particle will collapse the measurement in the other; there are many situations with classic objects that give correlated results like the example I gave and nobody in their right mind would say that one object influences the other instantly; if as it is said on this page, the Schrodinger equation is dominant even in the classical world; Why do they have to have different interpretations? Is it not better to consider space as a system that imposes a certain symmetry? Excuse me for asking questions that may seem silly to you. I don't know why you remind me of Penrose, hahaha, it would be for his patient style

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    15. Sigh …, I was going to ignore this. I will still punt in a way, for your question illustrates a huge gap in understanding. I will then say you need to read some text for book on this. A fairly recent and I think very readable popular text is by Aczel titled Entanglement.

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    16. Lawrence Crowell ,You have made me laugh a lot, "Sigh", hahaha, I am also glad that you have taken my comments for what they really are, questions from a neophyte; I don't promise you anything about reading the book that I recommend, I have already read lots of articles on the subject, that use formulas, using letters, using colors and a lot of logical tricks and I always think that if space does not play any role here; then I will never understand the phenomenon. Have a good day.

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  7. From quantum measurement there emerged sensing in the biological world. Sensing or sensory perception is an act of measurement. Again from sensing in the biological world there emerged psychological measurement as identifying and coloring human beings based on prejudices and biases. It is all the evolution of measurement. This is plausible, isn't it?

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  8. ... Quantum Biology is teaching us so many things about the quantum behavior at deep levels in living things, for example, photosynthesis.

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  9. ... as long as the observer is active whether at the level of the observer apparatus in the double slit experiment or at the psychological level as a Hindu-program measurement takes place.

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  10. Sensing must preclude recording. From experiments that prove aspects of the theory of Quantum Darwinism, we now know that recording goes on at the quantum level. And since sensing precludes recording, must there be "Quantum sensing"?

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    1. correction: must there not be "Quantum Sensing".

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    2. Gokul Gopisetti

      Please stop. Your random nonsense musings are for your own blog

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    3. Sir, John Bihl was a little encouraging. Just a few comments for his sake, and I will stop. You are not the only person Mike, who has asked me to stop, but many others have. We will take a decision once for all, fine. I will ask Prof. Sabine her honest opinion. Is that fine? Just a few comments for Mr.Bihl, that's all.

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  11. 17-APR-2020

    What if -- by similar chance that led to a gifted physicist finding and
    formalizing quantum uncertainty -- it had been Heibergsen, ne'r-do-well
    son of a chartered public accountant? Nice kid, but lazy. Not the
    sharpest chisel in the toolshed, but fairly bright and easily motivated
    by a good puzzle. Had a high school diploma and could read, write and do
    simple arithmetic. A tenured pedestrian.

    Having found this seemingly significant bit of physics while doodling
    in the margins of the local classified ads, young Heibergsen felt genuinely
    moved to communicate his discovery to a credible authority. A bit of a
    loner, he couldn't immediately think of anyone to ask for guidance, so he
    went first to the old man.

    Heibergsen the elder was immutable in defending the agenda conceived
    with his progeny. In response to the half-baked "so, whaddya think I should
    do pop?" hurled by his son from out in left field, Heibergsen senior said
    only this:

    "You'll be an accountant. . . Stay away from science; it's dangerous and
    you'll get cancer."

    "Thanks pop."

    From a former public school teacher, in response to a letter from a forgotten
    student, Heibergsen jr. received only a corrected and poorly graded copy of
    the original letter and a terse note reminding the young thinker that, had
    he thought of this in school when he should have, he'd know exactly what to
    do now.

    Letters to physicists and mathematicians at colleges in near-by towns went
    unanswered; except one, from whom Heibergsen received an admissions package and a handwritten note of thanks for showing interest in their school.

    Defeated, the young Heibergsen came to the conclusion that people can learn the pleasure of finding things out for themselves (who needs them), and he became a painter of ambiguous pictures of uncertain or possibly trivial meaning and value. Struggling appropriately, Heibergsen the painter wrote to other artists who invited him to exhibit, for a fee.

    I like this story because it probably happens more often than you'd think.

    cheers,
    mj horn

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  12. In the beginning of sensing are the beginnings of consciousness. So, so, so, very interestingly, is there quantum sensing.

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  13. I enjoyed reading that historical insight for the uncertainty principle, thank you.

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  14. In the following article in Quanta Magazine,
    https://www.quantamagazine.org/quantum-darwinism-an-idea-to-explain-objective-reality-passes-first-tests-20190722/

    Philp Ball asks

    The vexing question then becomes: How do quantum probabilities coalesce into the sharp focus of the classical world? Isn't it "recording".

    ReplyDelete
    Replies
    1. Isn't it "recording" is my answer to Philip Ball's question.

      Delete
    2. Eienstien was looking at the roof tops of the buildings outside his patent office. He then asked what if I fell of the roof? Would I feel my weight? These were some of the questions that triggered the idea behind gravity.

      He was travelling in a bus. He turned back and looked at the tower clock. He asked if he was travelling at the velocity of light would the image of the clock reach him?

      He asked if a person travels in a accelerating space ship, and if the acceleration was sufficiently large, then the person can walk about inside the space ship and carry out activities like on earth.

      Initially, when these ideas cropped up, there was no mathematical framework. The mathematical framework came later, and was built around these ideas. Also, what prompted Eienstien to say that imagination is more important than knowledge? One might have all the mathematical knowledge but if one lacks that critical, tipping component imagination then one cannot go very far.

      Delete
  15. Fascinating bit of science history. By conceiving a profound thought experiment, Heisenberg ultimately uncovered a key aspect of nature. His determination to make up for his poor showing in an exam paid off handsomely.

    ReplyDelete
  16. Sabine,

    Interesting article.

    Does the HEP mean that the non-commuting observable that is not measured just cannot be determined, or that it is meaningless?

    I ask because I have heard the HEP explained something like: "a person is in a room with the doors closed. You can ask them where they are standing OR what they have in their lap, and the person will immediately give you an answer. Obviously, once your question is answered the other question becomes meaningless".

    If the non-commuting observable becomes meaningless, I wonder what that implies as we go back towards the Big Bang, localizing time closer and closer to t=0. Is energy (since time and energy don't commute) an observable that can't be known, or is the concept of energy there meaningless?

    ReplyDelete
    Replies
    1. i aM wh asked:

      >I ask because I have heard the HEP explained something like: "a person is in a room with the doors closed. You can ask them where they are standing OR what they have in their lap, and the person will immediately give you an answer. Obviously, once your question is answered the other question becomes meaningless".

      When I started learning QM back in the 1960s, the Heisenberg style of thinking about uncertainty was still widespread and was often interpreted as you say.

      A lot of us younger physicists found this sort of thinking awfully muddy and found the mathematical proof discussed above by Sabine and Kevin S. Van Horn a lot more convincing.

      Probably the best way of understanding all this nowadays is the "decoherence program," the point of which is not so much the magnitude of the semi-classical effects of measurement but rather the breakdown of quantum interference (basically the fact that quantum probabilities do not add as one would naively expect).

      However, if you get a dozen physicists together to try to hash this out in detail, even today, my guess is that you might get a dozen different explanations as to what is "really" happening.

      Delete
    2. @PhysicistDave

      "Probably the best way of understanding all this nowadays is the "decoherence program," the point of which is not so much the magnitude of the semi-classical effects of measurement but rather the breakdown of quantum interference (basically the fact that quantum probabilities do not add as one would naively expect)."

      The "decoherence program" is a quite interesting alternative indeed. The decoherence phenomenon seems to be related with a loss of information. If these ideas are true, one should think about, that the total probability of all predicted observations can't be normalized to one any more.

      Delete
    3. A former LEP expermentalist wrote to me:
      > The "decoherence program" is a quite interesting alternative indeed. The decoherence phenomenon seems to be related with a loss of information. If these ideas are true, one should think about, that the total probability of all predicted observations can't be normalized to one any more.

      Hey, Sieg!

      While information is certainly, for all practical purposes, lost, no, the probabilities still sum to one, as of course they must. Basically, what we usually call the "interference terms" get averaged out, but they average to zero, so it does not change the sum of probabilities. If the probabilities did not sum to one, after all, the odds of anything at all happening would not be 100 %!

      If you want to look into this, the best source is probably Max Schlosshauer's Decoherence and the Quantum-To-Classical Transition.

      Schlosshauer is sensibly cautious in claiming any large philosophical implications for decoherence, whether in terms of the quantum measurement problem, the mind-body problem or anything else.

      He does have a very good and very measured discussion of the "quantum mind," the "von Neumann cut," etc. in his Chapter 9: this is all highly relevant to the mind-brain problem.

      In any case, Schlosshauer makes very clear that this effective "smearing out" of the interference terms really does and must occur and that we know now how to get good quantitative estimates of how this occurs.

      As to the "grand issues" of QM, well, the best Schlosshauer offers (and I concur) is that understanding decoherence will help to clarify the questions.

      By the way, I think it was Peter Woit who made me aware of Schlosshauer's work: Peter is, I think, like me, a fan.

      Dave

      Delete
    4. Dove!

      "While information is certainly, for all practical purposes, lost, no, the probabilities still sum to one, as of course they must. Basically, what we usually call the "interference terms" get averaged out, but they average to zero, so it does not change the sum of probabilities. If the probabilities did not sum to one, after all, the odds of anything at all happening would not be 100 %!"

      I understand quite well what you mean. But anyway, there is an information loss, which is not correctly accounted for! Do you have any idea, how to measure it?

      Delete
    5. PhysicistCave wrote to me:

      "Hey, Sieg!

      While information is certainly, for all practical purposes, lost, no, the probabilities still sum to one, as of course they must. Basically, what we usually call the "interference terms" get averaged out, but they average to zero, so it does not change the sum of probabilities. If the probabilities did not sum to one, after all, the odds of anything at all happening would not be 100 %!"

      Dove!

      I understand quite well what you mean! That does not change the fact, that there is an information loss! IMHO, this information loss is not taken correctly into account, if you want to talk about Decoherence. Do you have any idea, how the information loss could be taken correctly into account, if we are talking about macroscopic objects like viruses, bacteria or Schrödingers cats?

      Delete
    6. @PhysicistCave

      Hey Dove!

      Just to be a little more precise with my question:
      Once I have learned, that QFT processes are invariant under CPT symmetry. Could you pls. explain to me if this still holds under the assumption of decoherence phenomena which are occurring e.g. when trying to predict the behavior of amoeba?

      Delete
    7. A former LEP expermentalist asked me:
      >I understand quite well what you mean! That does not change the fact, that there is an information loss! IMHO, this information loss is not taken correctly into account, if you want to talk about Decoherence. Do you have any idea, how the information loss could be taken correctly into account, if we are talking about macroscopic objects like viruses, bacteria or Schrödingers cats?

      Hi, Sieg!

      Well, the short answer is the information is not really lost -- it just becomes imperceptible to us humans. I assume you are familiar with the two-slit experiment. Imagine that you look at the output of the two-slit experiment but with blurry vision: the interference pattern will just blur out and you will just see the average classical result.

      And, of course, that is what will really happen if you do the two-slit experiment without carefully arranging slit sizes, spacing, wavelength of the incoming particles, etc. -- it is actually hard to create a two-slit experiment such that we can see the interference pattern with our naked eyes.

      In terms of the standard decoherence program, as discussed in Schlosshauer's book, that is just the end of it: even ameobas show interference effects, but we will probably never have the instrumentation to detect those effects (experimentalists have in fact shown interference effects with larger and larger objects -- I do not know what the current limit is, though of course a lot smaller than an amoeba!).

      Now, I know you'd like an "in principle" answer as to some physical process that, in principle, limits observation of interference effects.

      As far as I know, no such answer is currently known by experts in the field.

      Ultimately, I think this boils down to the famous quantum measurement problem, which is, of course, unsolved.

      I know your intuition is that quantum interference must break down before you reach an amoeba. Perhaps. Certainly, most people who have thought about this believe that quantum interference must break down at or before you reach human minds: otherwise, you end up with the many-worlds interpretation, which most of us reject for various reasons.

      But no one knows the true answer.

      By the way, the point on which you were arguing earlier with Sabine and me is that we were pointing out that as natural science exists today, the weirdness of QM is supposed to continues through macromolecules, amoebas, and up and beyond.

      I (and also, I think, Sabine) recognize that this is a problem: the point is not that cats really can be in a quantum superposition but rather that current physics seems to say that cats can be in a superposition, and that therefore physics has a problem.

      This of course was also Schrödinger's point with the (in)famous cat gedankenexperiment: Schrödinger did not think cats could really be in a quantum superposition. He merely thought that the gedankenexperiment showed there was a real problem with quantum mechanics.

      And he was right: hence the quantum measurement problem.

      All the best,

      Dave

      Delete
    8. Hey Dave,

      "Well, the short answer is the information is not really lost -- it just becomes imperceptible to us humans. I assume you are familiar with the two-slit experiment. Imagine that you look at the output of the two-slit experiment but with blurry vision: the interference pattern will just blur out and you will just see the average classical result."

      You may be right, you may be wrong.
      Whether the information is getting lost or becomes imperceptible doesn't make any difference. This is not related to any possible physical observation for very principal reasons. Thus it has no relation to physical science, which is meant to understand and describe our real world observations.

      It's nothing more but a religious consideration. May be it could be also seen as a philosophical question and one could try to publish these considerations within a journal concerning the foundations of mathematics.

      Delete
    9. A former LEP expermentalist [sic] wrote to me:
      >Whether the information is getting lost or becomes imperceptible doesn't make any difference. This is not related to any possible physical observation for very principal reasons. Thus it has no relation to physical science, which is meant to understand and describe our real world observations.

      Well... as it happens, I was born with a serious vision impairment (i.e., not correctable with glasses), so that what is clear to your vision is very blurry to mine.

      So, there will be many cases in which you can see an interference pattern from the two-slit experiment and I cannot see it at all. (This has been a really serious problem for me in life, by the way: for example,, I could not read the whiteboard in school -- I learned to listen very carefully! I was "legally blind" as a child.)

      Anyway, if we take your extreme empiricist approach seriously, the laws of physics will differ for you with your good vision vs. me with my congenitally lousy vision.

      That would be a weird sort of science!

      More broadly, of course, every time experimentalists mange to increase their ability to detect interference effects, the laws of physics would change!

      What we are seeing here is why naive empiricism is an absurd approach to science.

      What I think we are also seeing is the rather dramatic difference between successful theorists and unimgiantive experimentalists.

      Progress in physics has not usually occurred by experimentalists just stumbling upon new phenomena. Rather, it has progressed by theorists taking existing theories, pushing them to their logical limit beyond what current experiments have observed, noticing some problems with these gednakenexperiments, and proposing a resolution.

      Then you Johnny-come-lately experimentalists come along and check whether the proposed theory works.

      This is what happened with Planck's work on black-body radiation, Einstein's work on both special and general relativity, de Broglie's work, and, skipping ahead a few decades, Feynman's work on QED, Weinberg et al.'s work on electroweak unification, gravitational waves, and pretty much everything I can think of in terms of progress in fundamental physics for over a hundred years.

      A former LEP expermentalist [sic] also wrote:
      >It's nothing more but a religious consideration. May be it could be also seen as a philosophical question and one could try to publish these considerations within a journal concerning the foundations of mathematics.

      Well, I guess there is a reason no one ever heard about or cared about the experiment you worked on at LEP. You guys were just losers who viewed actual work that led to advances in physics as "religion."

      Fortunately, everyone from Einstein to Weinberg to John Bell spent their time puzzling over problems that were not presented by then existing experimental data.

      And so you guys were losers, and they got the Nobel prizes.

      Sometimes, life is fair, after all.

      Delete
  17. Dr. Hossenfelder,

    You are so right in your assessment of needing to know and understand history. Most importantly, your last paragraph was what readers should be looking at. Digging into things and thinking critically as you learn so that you can ask questions is what I believe physics is all about.

    However, critical thinking and thinking outside of the box and asking too many questions is not always looked upon favorably. An example, How do we know that Dark Matter follows the uncertainty principle? The follow up question would be if we look at dark matter under the rules and constraints that we have in place doesn't this create the possibility of not discovering what dark matter and maybe dark energy are?

    There are many more examples associated with today's physics where questioning the dogma is not acceptable. Do not worship what is known, question it.

    ReplyDelete
  18. @mj horn,

    Heibergsen could have written a letter to Einstein after the physics journal rejected his paper, like Bose did. Or drifted off into obscurity, like Lunn.

    "In 1921, prior to de Broglie, Arthur C. Lunn at the University of Chicago had used the same argument based on the completion of the relativistic energy–momentum 4-vector to derive what we now call the de Broglie relation.[14][15] Unlike de Broglie, Lunn went on to formulate the differential equation now known as the Schrödinger equation, and solve for its energy eigenvalues for the hydrogen atom. Unfortunately the paper was rejected by the Physical Review, as recounted by Kamen.[16]"

    ReplyDelete
  19. “ ... Indeed, this uncertainty has nothing to do with microscopes in particular. Heisenberg’s uncertainty is far more than that: It’s a general property of nature.”

    Well, this is one way to interpret this result. The other, less spectacular way is: It is a standard property of waves of any kind.
    The following relation is standard knowledge for every RF engineer:
    Δf * Δt >= 1/2.

    It explains with which precision Δf the frequency f is defined for a wave of the limited length Δt. (Some engineers call this relation the “Nyquist theorem”, but I am not sure if this is the right term.)

    We can now use the knowledge that in an elementary particle we have the relation
    E = h * f .

    If we insert this formula into the former equation, we end up with
    Δf * Δt >= 1/2*h
    which is the famous relation published by Heisenberg.

    It is assumed by the different particle models that a particle is either represented by a wave or it is guided by a wave, which means in any case a wave package of a limited length. For both versions this relation explains why Heisenberg’s relation (why “principle”?) works.

    This is a more technical explanation than the portentous statement of the blog. But it tells us more about the details of particles and their reactions and so may help to better understand the physics behind.

    ReplyDelete
    Replies
    1. antooneo,

      It is related to the so-called Nyquist sampling theorem, though it is not quite the same.

      What you are pointing to is the same thing Kevin S. Van Horn and Sabine discussed above.

      antooneo also wrote:
      >This is a more technical explanation than the portentous statement of the blog.

      In English, "portentous" means "done in a pompously or overly solemn manner so as to impress," to quote from an online dictionary. I hope that is not what you intended!

      Delete
    2. The Nyquist theorem or rule is related to the quantum uncertainty in much the same way Heisenberg's optical argument works. This though gives the energy-time uncertainty, not the momentum-position uncertainty.

      Delete
    3. Dave,

      My dictionary says it a bit differently, but basically this wording says what I mean. The statement: ”It’s a general property of nature” sounds very heavy, like a basic rule of this world declared by the Pope.

      My intention was to show that this uncertainty rule is in contrast a quite trivial property of waves. And to use this knowledge helps to guide physics back to a reductionist understanding which I feel to be overdue.

      Yes, Kevin S. van Horn and Sabine discussed this by use of the Fourier function, which is of course correct. I was aware of that. But I wanted to show that not even a formalism like Fourier is necessary to understand this basic logical fact.

      Delete
    4. Lawrence Crowell,

      Energy-time can be converted into momentum-position:

      According to Newton, energy is defined as
      dE = F * dx = (dp/dt)*dx (F is force and p is momentum)

      Now dt to the other side:
      dE*dt = dp*dx

      If we now replace the differentials by the Δ - differences we get
      ΔE* Δt = Δp* Δx
      and so we have the other pairing.

      Delete
    5. Lawrence Crowell,

      For once antooneo is right. Frequency/time vs. wave-number/momentum is the same math: both Fourier transforms.

      antooneo does have me scratching my head, though, on one point: while Nyquist and the uncertainty principle are making similar points -- resolution in one domain is inversely related to resolution in the Fourier-transform domain -- they are mathematically different statements.

      It seems to me that there ought to be a mathematically simple way to prove one from the other, but I don't see it.

      By the way, the Nyquist principle applies to position/momentum space when you are doing QFT on a lattice, so there is a concrete reason that physicists need to know this.

      Now the real exercise for the student is to explain why when one does fermions on a lattice this works a wee bit differently: you get so-called fermion doubling.

      All of us who have worked in this sorta feel that we see why it is happening, but no one really has a clean way of dealing with it. Personally, I think none of us is viewing it in quite the right way.

      Hence, I scratch my head.

      Dave

      Delete
    6. There is the 2π vs 4π issue and the Pauli exclusion.

      The two are Fourier transforms, but there is a funny asymmetry. With space we have negative and positive momenta, but we do not have negative frequency. There is in part with this no shifting between energy and time representations. We do not then have a time operator in the sense of T = i∂/∂E.

      As a result relativistic quantum mechanics is not seamless, and the bolts between special relativity and QM are visible. Arguments with the uncertainty principle in the momentum-position domain and energy-time domain are somewhat heuristic. Even with classical mechanics we have conjugate variables between position and momentum, but not time and energy.

      Is there a resolution to this? Maybe, but for me to discuss these possibilities would take up a lot of my time and space here.

      Delete
    7. Lawrence Crowell wrote:
      >There is the 2π vs 4π issue and the Pauli exclusion.

      Well, at some level, that is the answer to all of the mysterious behavior of fermions. Much of it is laid out of course in Streater and Wightman's PCT, Spin and Statistics, and All That. Of course the little secret is that the book is quite impenetrable! (By the way, years ago, I had an exchange of letters with Wightman, who was a very helpful fellow, even if his book is a bit challenging.) This really bugged Feynman: he was a bit obsessed with the "plate trick" that shows how SO(3) is doubly connected, and he mentioned in our QM class that he was sure there was a simpler way than Streater and Wightman to show how it all fit together.

      Lawrence also wrote:
      > Arguments with the uncertainty principle in the momentum-position domain and energy-time domain are somewhat heuristic.

      Well, as Sabine said, the mathematics is actually quite rigorous.

      Lawrence also wrote:
      >With space we have negative and positive momenta, but we do not have negative frequency.

      Well, we do: you see it quite explicitly in the Feynman propagator. The fact that forward in time in one frame is backward in time in another... but it is all saved by antiparticles -- that's what makes the whole thing work.

      As to time as an operator... well there are states that are stationary in time (energy eigenstates), and there are states that are stationary in space (momentum eigenstates). Given special relativity, the two are obviously connected. I'm afraid the issue of a "time operator" just seems irrelevant to me -- just work with the wave-functions directly, and life is good!

      Dave

      Delete
    8. Lawrence Crowell,

      You say:
      “With space we have negative and positive momenta, but we do not have negative frequency.“

      Indeed, we do not have negative frequency. Because how could that be? We count periods in a time interval and the count is <0 ? That is physically meaningless.

      This is a good point to remember that we are doing physics and not mathematics. A mathematical formalism normally allows to insert also parameters which are physically senseless. So the result cannot be physical. This is also a case for a formula which contains the parameter “time”. Here we are formally able insert a negative run of time which is also not physical.

      It is, however, to some extent practice in present physics to redefine notions or to stretch the theory in a weird way, which is said to be necessary. That is something known from history. The epicycle formalism to describe planetary motion was a similar case. - Why are we willing to accept theories which require assumptions of this kind? Can such theories reflect the physical reality? We should urgently look for better ways.

      Delete
    9. When you do Fourier transforms from frequency to time domain the integration is for frequency 0 to ∞. The integration from the momentum to position domain is -∞ to ∞.

      I could go into this issue as some depth, but it would be fairly speculative. As a result I will avoid do this. A part of the issue is the unidirectionality of time and why physics has dynamical equations that are time reversal invariant, but what we observe in general is not.

      Delete
  20. Hi SABINE !!!

    First, I hope you and 'all yours' are doing well.
    Secondly, all apologies
    - for not communicating
    sooner.
    My personal situations/ circumstances ( of course)
    take priority.
    This concept or 'tool'
    known as reductionism
    is a basic tenant of
    empirical science.

    That being said,it is something
    to be guarded.

    Ultimately, a POV ( or point of view) determines whether we should
    'take something apart'
    - or merely observe it
    to understand it's mechanism.

    Wishing I had more time,
    at the moment.

    Love you,
    and
    Love Your Work.

    ( please feel free to not publish)

    ReplyDelete
  21. Prof. Hossenfelder,

    Many people have asked me to stop commenting on this blog. What is your honest opinion? (1) Stay, (2) Leave, (3) Take a long break. You can just type 1, 2, or 3 and nothing else. Also, 1,2, and 3 are just numbers; they have no double meaning or hidden meaning. Thank you. Eagerly waiting for your answer.

    Other commentators can also vote. Thank you. Eagerly, waiting for the other commentators vote.

    ReplyDelete
    Replies
    1. Gokul,

      You have been writing very long posts with very little information and you seem very ill-informed about what you are talking about.

      To the degree anyone has replied, you seem not to learn from their replies.

      You seem like a nice enough fellow, and I won't tell you to stay or leave -- that is between you and Sabine.

      But you might consider trying to learn more and ask questions of those who know more than you rather than posting such long comments on matters of which you know very little.

      Delete
    2. This comment has been removed by the author.

      Delete
    3. Hi Gokul,

      Since my spare time is quite limited, I have read your comments only occasionally but I want to tell you, that they are quite inspiring for me and are stimulating me to think my own thoughts.

      It is a pity that there is no real discussion with other blog participants thinking differently.

      Personally, i would appreciate to have your reflections presented in a somewhat more closed form, such as a series of articles or within the context of a book.

      Delete
    4. Dear Gokul,

      maybe it would also be a good idea to set up your own wordpress blog.

      Delete
    5. @PhysicistDave

      "To the degree anyone has replied, you seem not to learn from their replies."

      The same also holds the other way round.

      Delete
    6. A former LEP expermentalist [sic] wrote to me:
      >The same also holds the other way round.

      Well, it is indeed true that you seem unable to learn from others' replies. But it is a good sign that you are coming to realize it.

      Delete
    7. One Last reply to Mr. LEP experimentalist. The Indians (Asia) have turned me into an open book and have made a laughing stock out of me. That is why I turned to the West. They mostly write into the book. Today or Tomorrow they will say that the West and the rest of world is reading a book they the Indian greats have written into. Mind you if the book is right. What if the book is all wrong? What will the Indians say? It is anybody's guess. Thank you all. Bye Bye.

      Delete
    8. I just ask you to be precise and concise

      Delete
    9. @Physicist Dave

      "Well, it is indeed true that you seem unable to learn from others' replies. But it is a good sign that you are coming to realize it."

      My idea was that you yourself are unable to learn from other replies. However, I can't see that you are starting to realize it"

      So far I have received very few significant responses to my comments about my concerns regarding current state of the art physical theories. It seems that not too many people want to think about such topics. IMHO, this can easily be explained psychologically considering the mechanisms of "group think".

      Delete
    10. This comment has been removed by the author.

      Delete
    11. This comment has been removed by the author.

      Delete
    12. @Gokul

      Sorry to hear that. You should be quite careful when you allow people to write into your open book. I am quite sure that you should better start writing by yourself! Good Luck and hope to see you again.

      Delete
    13. A former LEP expermentalist wrote to me:

      >So far I have received very few significant responses to my comments about my concerns regarding current state of the art physical theories. It seems that not too many people want to think about such topics. IMHO, this can easily be explained psychologically considering the mechanisms of "group think".

      Hey, Sieg!

      Ummm.... that is probably the biggest single topic that Sabine blogs about, and, heaven knows, there has been plenty of interest on that topic in the comments, some well-informed, some nor so well-informed.

      If you have concrete issues you wish to raise about the current state of physics, I do not think you will have trouble getting responses. Whether you will agree with those responses is, of course, another issue.

      One thing to keep in mind: if Sabine or Peter Woit or you or I or any other physicist actually knew the right way to make a major leap forward in physics, we would pursue that approach, it would succeed, and we would be much more famous than any of us is today!

      In short, the problems that physics faces today are unsolved because they are really, really hard.

      That does not negate the point that Sabine and Peter and others have made that many physicists pursuing failed or patently pointless approaches is wasting resources and reducing the prospect of solving important problems.

      Still... Einstein working in the Swiss Patent Office came up with three major breakthroughs in one year.

      If you or I or Sabine has the key brilliant insight, nothing is stopping us from pursuing it.

      Dave

      Delete
    14. Hi Dave!

      "In short, the problems that physics faces today are unsolved because they are really, really hard."

      I am glad to hear you saying this. I couldn't agree more.
      However, I got the impression, that too many physicists are somewhat over-confident, that they are asking the right questions and doing the right things. This observation does not specifically related to what you are commenting on this blog, but also e.g. to some M-Theory genius from CERN or Harvard University, not to mention some physicists of minor importance from the Czech Republik.

      Delete
  22. 18-APR-2020

    @i AM wh

    Hi i -

    Lunn's obscurity at least appears to have been documented.
    Someone knew Lunn.

    But Heibergsen, unlike Lunn, had no university experience.
    Heibergsen isn't an unknown, lost or forgotten colleague
    of anyone. No academic with a job is going to reach out and
    touch that sort of uncertainty. If Heibergsen isn't some kind of
    freak, then why didn't he go to university like everyone else?

    mj horn

    ReplyDelete
  23. ...”Heisenberg’s uncertainty is far more than that: It’s a general property of nature.”
    Not really... It is a general property of quantum mechanics, which is a common theory about nature.

    QM-uncertainties on closer inspection,
    what one should know about the use of such “uncertainties”...
    A »time-energy uncertainty (principle)« is often mentioned lightly in connection with the »position-momentum uncertainty principle«. In quantum mechanics, time is not an observable, but a number that parameterizes the chronological sequence of the quantum processes. So there is no* time operator with a unique universal exchange relation that could be investigated... (see for instance *How to Introduce Time Operator Zhi-Yong Wang, Cai-Dong Xiong https://arxiv.org/ftp/quant-ph/papers/0609/0609211.pdf )

    Feynman-Stückelberg interpretation for "inexplicable" negative energy values of the Dirac equation

    In the picture of quantum mechanics, this problem was supposedly "solved" with the help of Heisenberg's uncertainty principle, by arbitrarily interpreting the corresponding solutions as entities with positive energy that move backwards in time. The negative sign of energy is transferred to time (Feynman-Stückelberg interpretation). But this is from an epistemologically point of view frankly speaking “nonsense” and leads to a far more controversial aspect, the time-reversible Lagrangian (field theory), which is not observed in real physics. Break your teacup and try to restore it...On closer inspection one has to “bridge” microscopic interactive atoms and macroscopic teacups with a formalizable model, this model would be certainly not based on time reversal.

    The calculation of ground state energies is based neither on quantum mechanics nor on quantum electrodynamics. Because a significantly decisive part is determined by the ratio of the interacting masses. This ratio is neither QM and certainly not QED based (see Bethe-Salpeter equation from Green’s function, Dyson equation). "Look" at the reduced mass term in muonic hydrogen to get an impression how "bad" the situation is. The reduced mass [mred = mA / (1 + mA / mB)] is - whether you want it to be true or not – (historically) derived from "Newtonian celestial mechanics" within the framework of standard physics. In plain language, this means that in terms of atomic interactions ground state energies are neither QM nor QED based.This is one of those touchy issues which are completely out of focus because there is not even a hint how to solve this in the QM framework.

    ReplyDelete
  24. In principle, we can see that uncertainty is an emergent phenomenon of interactions. If physics could be modelled only as the patterns of waves, maybe it would be certain and exact.

    But that was matter of belief because we as emergent measurers would have nothing existent without interactions. :)

    ReplyDelete
  25. Dirk Freyling wrote:
    >"Look" at the reduced mass term in muonic hydrogen to get an impression how "bad" the situation is. The reduced mass [mred = mA / (1 + mA / mB)] is - whether you want it to be true or not – (historically) derived from "Newtonian celestial mechanics" within the framework of standard physics.

    You have no idea what you are talking about at all, do you?

    I can assure you, as a PhD physicist, that no one who has a legitimate degree in physics could write as you do. Dealing with the reduced mass in QM is on completely solid ground: no, we are not just naively pulling in something from classical physics.

    You have soiled yourself in public. You should be deeply embarrassed. You should refrain from posting comments for a few years --- or a few decades.

    But people like you know so little that you do not even know how to be embarrassed, do you?

    ReplyDelete
  26. Dirk,Although I cannot explain it mathematically, I feel that the uncertainty principle is a consequence of the fact that the nature of a particle cannot be measured by dividing into discrete spaces or smaller time intervals; the very existence of the particle is a complete space-time package; in the classical world we do not need time to define the existence of a stone, only its dimensions and its coordinates; But how do you define the existence of a dynamic phenomenon without time?; it's just a question , not statement.

    ReplyDelete

  27. Sabine, your story is wonderful, and I think I know the reason why Heisenberg did not do his experimental task; people who are enthusiastic about the mysteries are not motivated by what is already known. Have a good Sunday

    ReplyDelete
  28. »PhysicistDave«,
    Sabine Hossenfelder’s blog is mainly about theoretical physics. Once in a while she sings and places her song-videos here too. Does she use the alias »physicistSabine« or »singingphycisistSabine«? Does she have to? Obviously the writes about physics and she sings. Let us see if you get my point about you on a personal level...
    I guess it is a pretty fair assumption that someone who uses the alias »Physicist-first name« that this is related - psycollogically speaking - to some sort of insecurity about his skills in that field. I also guess that this is the reason why you are so impolite. Also interesting, the fact that you think you “speak” here for all physicists. However I can’t and I won’t solve your personal problems. My advice: “Some” emotional restraint what be appropiate. Good luck with anger management.

    Down to business...
    I suspect that you don’t understand the fundamental problems which exist if one tries to describe the mass-mass-interaction of charged-entities*. Don’t assure me “whatever comes” to your mind...Prove it. Just show how QM and/or QED describe the interaction of two charged mass-particles from a phenomenologically point of view using a formalism. I’m not talking about the math [mred = mA / (1 + mA / mB)], which, I pointed out, is historically based on gravity-observations, my advice, before you try to lecture me again, put your feelings aside and start to think like a physicist, how the math-term [mred = mA / (1 + mA / mB)] got into the world of physics. “Simply” show how mass interact phenomenologically with charge. I’m curious.

    *Entity is also hard to figure if you want to understand more than “math” ...remember the SM-postulated “leptonic” electron and the proton as a SM-postulated composite particle...You migth read Sabine Hossenfelder’s book »Lost in math« or Brigitte Falkenburg’s book »Metaphysics: A Critical Account of Subatomic Reality (2007)«, amongst a lot of useful aspects Falkenburg pointed out that...

    „It must be made transparent step by step what physicists themselves consider to be the empirical basis for current knowledge of particle physics. And it must be transparent what the mean in detail when the talk about subatomic particles and fields. The continued use of these terms in quantum physics gives rise to serious semantic problems. Modern particle physics is indeed the hardest case for incommensurability in Kuhn’s sense.“...

    ReplyDelete
    Replies
    1. Fwiw, I think the likely reason Dave calls himself "PhysicistDave" has very little to do with insecurity and very much to do with the fact that, in the English-speaking part of the world, Dave is a very common name and blogger is probably full with Daves. And let me add that this is a good idea because a lot of comments that come from common-first-name-only-accounts are junk and the exceptions therefore are likely to accidentally also end up in the junk.

      Delete
    2. Sabine,

      It is even simpler than that: when I first started commenting on your blog, my "PhysicistDave" account was the only account I could get to work to log me in! I have a "Dave Miller" account, but I could not get it to work here: "Dave Miller" is the name I have tended to use on physics blogs (such as Peter Woit's).

      Of course, there are also so many "Dave Millers" in the world (and indeed in physics!) that that is not very distinctive either.

      All the best,

      Dave

      Delete
    3. Dirk Freyling wrote to me:
      >I’m not talking about the math [mred = mA / (1 + mA / mB)], which, I pointed out, is historically based on gravity-observations, my advice, before you try to lecture me again, put your feelings aside and start to think like a physicist, how the math-term [mred = mA / (1 + mA / mB)] got into the world of physics. “Simply” show how mass interact phenomenologically with charge. I’m curious.

      Well... I am talking about the math, Dirk, m'boy.

      Physics is kinda mathy, you know.

      And the math in question here is very straightforward undergrad math.

      And, no, Dirk, it does not come from "gravity-observations"! It comes from algebra, Dirk m'boy, plain and simple algebra, which, alas, is beyond your capabilities.

      You can't grasp and accept this math, and therefore you cannot grasp physics.

      Dirk also wrote:
      >*Entity is also hard to figure if you want to understand more than “math” ...remember the SM-postulated “leptonic” electron and the proton as a SM-postulated composite particle...

      What kind of gobbledygook are you spouting?

      Utter nonsense.

      Look: for some reason, blogs like this are magnets for crackpots who are sure they have a wonderful new theory that overthrows well-proven and established physics, even though they themselves do not actually understand established physics at all.

      I've googled you: I know the game you are playing. Why don't you just come clean about what your goofy little hobby-horse is and how that explains your weirdly incoherent attacks on real physics?

      Dirk also wrote:
      >You migth read Sabine Hossenfelder’s book »Lost in math« or Brigitte Falkenburg’s book »Metaphysics: A Critical Account of Subatomic Reality (2007)«, amongst a lot of useful aspects Falkenburg pointed out that...

      I've read Saine's book: it is very good and has nothing to do with what you are talking about.

      As to the other book, I tend not to follow book recommendations from people who are running some sort of game.

      Delete
    4. I am apparently a junk-man here, please, let me know, if I am not wanted on this blog. I am from history with, among other things, an interest in the history of physics. Many things about QM can be learned from the history of QM, actually I think the crisis of physics the last 40 years (not many new theories with predictions that can be tested are seen) can be explained from the way the Copenhagen interpretation were accepted, the historic context is very important here. I think it is very urgent in physics to study the competing old theories (de Broglie, Bohm) and newer ones (Sabine Hossenfelder and Tim Palmers December 2019 paper on superdeterminism was a very good Christmas present).
      To PhysicistDave: I have not suggested that you are a student, I addressed the big problem in physics, that it is very difficult to get a job, if you do not sign up to the present mainstream dead ends in theoretical physics. I think you are right, that quantum computation could be a „back door“ for new insights to the foundation of physics. But you must admit that you almost mentioned all the few scientists, who try to find „another path“.

      Delete
    5. John Bihl wrote (I think to me):
      >I am from history with, among other things, an interest in the history of physics. Many things about QM can be learned from the history of QM, actually I think the crisis of physics the last 40 years (not many new theories with predictions that can be tested are seen) can be explained from the way the Copenhagen interpretation were accepted, the historic context is very important here.

      Oh, I agree, John, and I think Sabine does also -- hence this post. There is, incidentally, a lot of other interesting aspects historically to Heisenberg's discoveries: my own feeling is that Max Born deserves a lot of the credit for Heisenberg's work.

      John also wrote:
      > I have not suggested that you are a student...

      I wasn't sure if you meant that to be directed to me or just hypothetically.

      John also wrote:
      >it is very difficult to get a job, if you do not sign up to the present mainstream dead ends in theoretical physics.

      Yeah, Sabine has addressed this in detail in many posts, and the issue is complicated: the sociological structure of the academic world, economic incentives, the financing of research, and a lot more.

      Is it any better in history?

      I remember discussing this with some of my fellow grad students at SLAC back around 1980: our conclusion was that maybe Einstein had been wise to work at the Swiss Patent Office! (To be sure, that was not exactly his first choice.)

      John also wrote:
      >But you must admit that you almost mentioned all the few scientists, who try to find „another path“.

      Well... I think there are quite a few others, admittedly often not at the most famous research centers. Sabine's closer to the job market than I am; I'd be interested in her take. I think work in foundations is more accepted than it was fifty years ago, but no doubt still not the best way to get a tenured position at Princeton, Stanford, etc.!

      All the best,

      Dave

      Delete
    6. PhysicistDave wrote:
      Is it any better in history?
      I think you can find the same pattern everywhere in the academic world, but in physics I find it very extreme.

      Delete
  29. I am going away for sure. Just one last question to PhysicistDave:

    There is a fly, a human, and some rotten stuff. The human finds the stuff offensive, while the fly finds it attractive.

    The question is this:
    Where is the offensiveness or attraction
    (1) In the stuff
    (2) In the air
    (3) Neither
    (4) Elsewhere

    Choose an answer: either 1,2,3, or 4 and explain. Don't look up my previous comment for an answer; as you know, I may be wrong.

    ReplyDelete
    Replies
    1. The offensiveness is in the stuff and the human.

      The attractiveness is in the stuff and the fly.

      Those answers aren't allowed by the choices you gave.

      Delete
    2. @I aM wh

      Are you from India too?

      Your answer to Gokul seems to be quite clever, it is however not just the kind of humor, that a large number of physicists may understand! ;-)

      I personally can hardly imagine, that the information exchanged between Gokuls question and your answer will ever be understood by any AI software proposed to solve the Turing Test. Whoever understands this joke is definitely human!

      A computer may calculate on this problem for a very large number of years and its answer may be 42. ;-)

      IMHO, it even reveals, that physical information theory is definitely incomplete.

      Delete
  30. »PhysicistDave«,
    there is a German expression: Der Argumentationslose möchte, daß Kritiker “Über ein Stöckchen springen”, it means that someone tries to avoid a clear answer by keeping critics busy to react to insults. This concept does not work if the critic is aware of this.
    I read a few of your past comments to various blog-articles. Obviously you stage yourself as a kind of guardian to protect common views of modern physics and you tend to insult commentators, if they don’t agree with your interpretations. I’m pretty sure that it is useless to argue with you; because you don’t have arguments...To make a long story short...You still have no answer. Try again...

    ReplyDelete
    Replies
    1. What you call "common views" should be called "widely accepted facts" and what you call "people who don't agree with your interpretations" are "people who do not understand the facts (or think that facts are interpretations)".

      Delete
    2. Dirk Freyling wrote to me:

      >To make a long story short...You still have no answer. Try again...

      Mope.

      You see, my friend, I am under zero obligation to answer your questions. Now, if someone around here who is polite were to ask me a question -- Sabine, JeanTate, Lawrence, Phil, even my friend Steven Evans -- then I might feel an obligation to answer their question.

      But you?

      Nope.

      You barged in here and said some remarkably outrageous and rude things about physicists and made your ignorance obvious by what you said about "reduced mass." I exposed you for what you are.

      I am content with the result.

      Look at John Bihl: he and I had a (minor) disagreement, he replied courteously and we clarified our views, and I like the guy -- if he ever gets to Sacramento, we can go out to Starbucks.

      You... not so much.

      Look, if you want to talk politely about the reduced-mass issue, I will consider it: I actually do understand what is going on with "reduced mass," thought I am under no obligation to explain it to your satisfaction..

      But if you continue to act as if you are the master of a subject you do not understand at all and to express contempt for those of us who do understand it, no, we are not obligated to treat you as anything except what you are.

      In short: grow up and understand that the rest of the human race does not exist to play the role you assign to us in your fantasies and con games.

      Delete
  31. @PhysicistDave there is no hidden or double meaning in my question. It is straight forward question. I am going away. . . . can you answer my 1:27 AM, April 20, 2020 question

    ReplyDelete
  32. @PhysicistDave I know you like difficult questions. So, lets leave the biological realm. In the psychological realm, here is a question:

    You are there, there is also another human, and the human is a Muslim.
    The question is this:
    Where is the Muslim?
    (1) In the human
    (2) In the mosque
    (3) Neither in the human nor in the mosque
    (4) Elsewhere

    The answer is either 1,2,3, or 4. Choose and explain. I am going away for sure . . .

    ReplyDelete
  33. In the previous comment you are looking at the Muslim.

    ReplyDelete
  34. I repeat the last question:
    You are there, there is a human, and the human is a Muslim.
    You are looking at the Muslim.
    The question is this:
    Where is the Muslim?
    (1) In the human
    (2) In the mosque
    (3) Neither in the human nor in the mosque
    (4) Elsewhere

    choose one answer and explain.

    ReplyDelete
    Replies
    1. Gokul Gopisetti:

      You keep saying you are going away and then coming back and insisting that I answer some remarkably silly questions!

      You are not a prosecutor and I am not a defendant: I do not have to answer your dumb questions.

      I don't mean to be rude, but if you are going away, why not just go away?

      Delete
    2. When you say the human is a Muslim, you meant that he belongs to a category of people who identify themselves as Muslim.(Or group if you like, implying a a sense of belonging.) If you ask: 'where is THE Muslimn', you talk about specific member of this category or group. Where that person is depends on who you mean. If you mean the same you are looking at, than he stands in front of you. However, being a Muslim is only one attribute of that person, he could also be the scientiest, the father, the one with spectacles etc. etc.

      Delete
  35. For what it's worth, here's a link to a recent paper by researchers from MIT who claim a breakthrough on the rigorous understanding of fundamental limits on the resolution of an optical system: https://arxiv.org/pdf/2004.07659.pdf
    Disclaimer: this may not be related to Heisenberg's uncertainty principle (but they do have lots of Fourier transforms in their paper!)

    ReplyDelete
  36. Gorkul,
    This is a question that boarders on dogma. The some total of any religious experience is not resident in dogma.

    ReplyDelete
  37. Sabine,

    I've noticed a significant decline of the comment quality at least in this post. Gokul Gopisetti keeps spamming, PhysicistDave gets downright insulting. Not sure how much you care, just thought I'd mention it.

    ReplyDelete
    Replies
    1. Sergei wrote:
      >PhysicistDave gets downright insulting

      No, Sergei, I am not "downright insulting." I am just telling the truth about some very annoying and very dishonest people, and you misinterpret the truth as insults.

      Do some googling and find Dirk Greyling's website. What I said about him was very, very restrained. You try to figure out what game he is playing!

      In fact, as far as I can figure out, Greyling's whole website (and oh is he prolific!) is one paragraph of incoherent insults against all physicists followed by another. It is hard to find a sentence that truly makes sense.

      He is not a normal person -- he has some very, very serious issues.

      Delete
  38. Gokul,

    To help your decision, I will no longer publish comments from you, good bye.

    ReplyDelete
  39. Gokul,

    your last question is surely worth to think about. The answer seems to be quite obvious. But within the context of this blog it is off topic.

    ReplyDelete
  40. "Study hard what interests you the most in the most undisciplined, irreverent and original manner possible" (Richard P. Feynman)

    ReplyDelete
  41. This blog of yours, Sabine, is certainly about the core of nature and science. I would wish a common platform for physicists to intensely discuss only the foundation of physics. The crisis of physics really calls for that. I think the weak point is QM.

    ReplyDelete
  42. Dr. Sabine :-) I know you don't think Wolfram's recent stuff is 'interesting' but it could still be instructive to many of us if you were to give a brief write-up of why not on your website.

    To me, it is 100% smoke and mirrors, with nothing actually at the core, but I don't claim to be a physicist, nor do I claim to always be able to tell when something is, in fact, just smoke and mirrors and a desperate (failed) attempt to appear smart and be relevant. (To begin with I don't see how you could get Bell inequality violations from cellular automata.)

    Indeed it might do us good if you were to indicate the signs that a paper/idea/book is just hubris, even if it is 800 pages long or 1200 pages long and full of big words. For example, perhaps crackpots could evaluate their own stuff better.

    Best

    ReplyDelete
    Replies
    1. I am sure that it would do YOU good. But would it do ME good? That's what you should ask. Also have a close look at the "donate" button in the top right corner.

      Delete
    2. I have on my stack of things to read or study Wolfram's latest presentation. I though am not exactly jumping up and down with excitement though. Remember 20 years ago or so Wolfram brought a big announcement about A New Kind of Science, which had some interesting aspects to it. I bought his book and read it. However, the claims that this would completely upend science and how we thought were a bit overblown. Plus ca change, plus ce le meme chose, or deja vu all over again? We shall see.

      Delete
  43. Sabine,

    Yours is a very interesting blog, and the ability for anyone to comment or ask a question is valuable too, but I fear it has attracted a clutch of trolls.

    I have witnessed how disruptive such people can be, I beg of you to implement a policy whereby anyone who writes junk or completely off-topic gets censored immediately and blocked from future attempts at posting.

    ReplyDelete
    Replies
    1. David,

      I hear what you say, but I have such a policy already. The problem is that to actually be consistent about it, I'd have to read all comments which are submitted to begin with. And I don't always have the time. That is to say I partly rely on someone telling me that something is going wrong. (Also, give me some credit for all the crap that you do not have to read because I never approve it in the first place.)

      Delete
    2. Sabine,

      I was wondering how could you possibly have the time for your job, research, family , travels, writing this blog, and reading all these comments for approval; which have grown considerably over the years. Now that I know you can't read every single comment I can no longer think of you as super woman.

      Delete
    3. Thanks for that reply Sabine. The ideal solution would be if there was a report button which would enable people to report responses that they felt were unreasonable.This is common on internet forums. Obviously the report would come to you to respond as you saw fit.

      That way your readers would shoulder some of the burden - because I agree, you can't really read the whole lot.

      Delete
    4. Louis,

      Sorry to have shattered your illusions ;) It's even worse, I can't fly either.

      Delete
    5. David,

      I have nothing to do with the software underlying this site. Blogger is hosted by Google. You should take complaints about the website functionality to the Google forums, not to me.

      Having said that, I usually do read comments that are directly addressed to me. So, short of a report-button, just leave a comment saying "Sabine, commenter XYZ is trolling, please cut them out." or similar, and I'll look into the matter.

      Delete
    6. David Bailey5:46 PM, April 21, 2020

      As you are interested in stopping trolling, did you write to Brian Schmidt, Physics Nobel Prize winner, to ask why he wrote a preface for Fortunate Universe, a trolling book written by professional astrophysicists claiming ludicrously that there is evidence for fine tuning of the universe and that this could be explained by a multiverse or the Creator father of Jesus Christ? Gods and demi-gods are the subject of Physics now - backed up by a Nobel laureate.

      Also, have you written to the editor of Physics Today to ask why he published a trolling, nonsensical review of the above book by another professional physicist with a delusional agenda, Marcelo Gleiser?

      Maybe the clean-up job should begin by ensuring that Physics Nobel laureates and the editor of Physics Today know what Physics actually is. These are influential positions in your field as a I understand it.

      " anyone who writes junk .. gets censored immediately"
      Excellent idea. So Philip Helbig and Luke Barnes no longer get to claim that the universe is finely tuned. Philip Goff no longer gets to claim that panpsychism is a thing.

      Again though, the priority should be to remove this junk from University departments first, then the comments section of a blog. How about introducing a minimum level of quality to University Physics departments - like, not being delusionally insane and understanding that Physics is an empirical subject?

      Delete
    7. Sabine, I think Steven Evans is trolling - please consider cutting him out.

      Delete
    8. David Bailey7:55 AM, April 23, 2020

      Do you think Philip Helbig and Luke Barnes are trolling when they claim without evidence that the universe is fine-tuned and refuse to provide evidence when asked to do so repeatedly?

      Should we not point out when physicists are being cranks or frauds because we might upset them?

      Delete
    9. David Bailey7:55 AM, April 23, 2020

      Just to ensure you are not being biased, can you disclose your positions on the following points?
      1) Do you think there is any evidence that the universe is fine-tuned?
      2) Do you believe baby Jesus' father or some "god" "made" the universe?

      Delete
    10. Steven Evans,

      I like your questions well enough I will give my answers:

      Steve: Do you think Philip Helbig and Luke Barnes are trolling when they claim without evidence that the universe is fine-tuned and refuse to provide evidence when asked to do so repeatedly?

      Dave: No, Phil, at least is smart and seems to be honest.

      Steve: Should we not point out when physicists are being cranks or frauds because we might upset them?

      Dave: We should point out cranks and frauds, but that is not the same thing as being mistaken.

      Steve: 1) Do you think there is any evidence that the universe is fine-tuned?

      Dave: No, but I am willing to change my mind if given good reasons or evidence.

      Steve: 2) Do you believe baby Jesus' father or some "god" "made" the universe?

      Dave: No, though I can imagine evidence causing me to change my mind (not so much about Jesus: I know too much about the New Testament).

      So, at least you got someone to answer!

      All the best,

      Dave

      Delete
    11. Dave, I see. I can see David Bailey's point to some extent. I wouldn't hold your breath on evidence of gods - it is an idea very specific to primitive humans - there's no reason to think it has any connection with reality. Philip Helbig has promised to publish a paper on fine-tuning - so we have that to look forward to during the lockdown.

      Delete
  44. PhysicistDave, You wrote:"In short, the problems that physics faces today are unsolved because they are really, really hard."

    This reminds me of a little anecdote from my physics studies:
    At the end of the first year we had an intermediate math exam.
    One of my fellow students was supposed to have a curve discussion in two dimensions
    and failed. The examiner was not very amused.
    And then the fellow student said: "But I could have done it in 3 dimensions."
    This ended the exam.

    30 years later I believe the following:
    1. The student really believed that he could explain something complicated, even if he couldn't do the basics.
    2. I think it's always the basics that someone didn't understand.

    With the standard model, I still lack an explanation of the double-slit experiment.
    I believe that objects like electrons and photons really exist.
    And I believe that these objects have a certain appearance and certain rules.
    And I would like to know these rules.

    Unfortunately, the standard model only has rules for humans.
    The results are very impressive, but they're all just rules that humans use to predict the outcome of experiments.
    There are no simple rules for the objects themselves.

    I think the mistake is in the beginning with wrong assumptions.
    Two things at the end:
    1. Ptolemy assumed that the planets move in circles around the earth. That is wrong.
    Nevertheless, he got very good results.
    2. In mathematics it is easy to start from something wrong and get something true after some transformations.
    For example, it is easy to start from 1 = 2, which is wrong, and come to 2 = 2, which is true.

    Best wishes
    Stefan

    ReplyDelete
    Replies
    1. Stefan Freundt wrote to me:
      >With the standard model, I still lack an explanation of the double-slit experiment.
      >I believe that objects like electrons and photons really exist.
      >And I believe that these objects have a certain appearance and certain rules.
      >And I would like to know these rules.

      Well, Stefan, so would I. So would I.

      But, you know, you are not exactly the first guy to have noticed that quantum mechanics gives simply phenomenological predictions of experimental results without telling us anything about the objects of study in and of themselves.

      Everyone has noticed this, including Bohr, who tried, rather unconvincingly, to make a virtue of it.

      Stefan also wrote:
      >Unfortunately, the standard model only has rules for humans.
      >The results are very impressive, but they're all just rules that humans use to predict the outcome of experiments.
      >There are no simple rules for the objects themselves.

      Indeed, and an awful lot of very, very bright people have spent a lot of time trying to figure out what is really happening, starting with geniuses like Schrödinger, de Broglie, and Einstein himself through to one of the creators of the Standard Model today, Steve Weinberg, and including a lot of us who are perhaps not quite that brilliant, indeed including Sabine and me.

      And no one has been able to come up with those simple rules you (and we) want. And it is not that we lack a desire for simplicity.

      The biggest leap forward we have made is a mathematical proof that any simple rules that reproduce the empirical observations cannot be that simple. I'm referring, of course, to Bell's theorem: I will not try to rehash that here, except to say that any attempt to get around the assumptions of Bell's theorem is not going to be that simple!

      There are in fact several comparatively simple models -- notably Bohm / de Broglie theory -- that do predict all of the experimental results of quantum mechanics.

      But the way that Bohm / de Broglie theory and these other models fit in with special relativity is very strange: basically, they maximally break special relativity in a way that can never be detected at all. I think you might agree that this is not that simple!

      So, there you have it: quite a few truly brilliant people and a swarm of us who are at least pretty smart and we cannot figure this out. And we have a mathematical proof that the simplest sorts of models will fail.

      I'm afraid that just telling us to think more simply is not much help. Believe me, we have tried that.

      Of course, if you want to learn the relevant physics and give it a shot yourself, go for it! The more the merrier.

      All the best,

      Dave

      Delete
  45. About the prehistory of Heisenberg's uncertainty principle
    part I
    The double-slit experiment has become a classic thought experiment, for its clarity in expressing the central puzzle of quantum mechanics – wave-particle complementarity. Such wave-particle duality continues to be challenged and investigated in a broad range of entities with electrons, neutrons, helium atoms, C60 fullerenes, Bose-Einstein condensates and biological molecules.[5]

    If one refers, interprets or reminds of the Heisenberg’s uncertainty principle in terms of »Modern Phycics« it might help to be aware of the prehistory...This documented history started with Grimaldi.

    As Fresnel and Newton noted, the proportions of the diffraction that contribute to the interference originate primarily from the slit edges. Grimaldi [1] was the first to report about diffraction and also about the glowing edge that can be seen when a light source is covered by a half-plane.
    [1] F. M. Grimaldi, Physico-mathesis de lumine, coloribus et iride 1665.

    Fresnel [2] explicitly confirmed in his first work on diffraction that he had convinced himself that diffracted light only came from the edges, which he never considered later. The existence of a luminous edge as a physical phenomenon was generally recognized at the time. The conclusion that diffracted light does not come from the entire slit was self-evident, it did not need to be particularly emphasized.
    [2] A. J. Fresnel, Oeuvres Complétes I. Paris 1866; Abhandlungen über die Beugung des Lichtes. Ostwalds Klassiker Nr. 215, Engelmann, Leipzig 1926.

    Fresnel was able to calculate limit cases of diffraction. He only shared his measurement results if they corresponded sufficiently with his theory. If not, he didn’t communicate the discrepancies.

    Newton [3] reported in the III. Book of his "opticks" comprehensive about diffraction. The 5th observation is of interest here, where he proves that diffracted light only comes from the narrow surroundings of the edge (in the order of a few 1/100 mm); and observation 10, where he demonstrates at the triangular slit that at short distances and large slit widths only the inner diffraction stripes of the slit which correspond to the diffraction of the edges as half-planes (within the shadow boundary diffraction stripes with uneven spacing, outside continuous decay). The outer diffraction stripes (outside the shadow boundaries), which have been described in textbooks as the only diffraction stripes at the slit since about 1850, only develop at great distances or with small widths. Not only did Newton make the claim, but he also demonstrated with the above observations that light can never be a wave. However, he could not bring up any theory of diffraction, because Newtonian mechanics could not give a reason for the deflection perpendicular to the direction of propagation for point-shaped light particles. Newton's diffraction experiments showed what characterized diffraction outside of Fresnel's theory, but this did not fit Fresnel's ideas. Therefore, the textbook authors simply left out Newton's diffraction experiment, they were embezzled and ignored; one extrapolated over this area inadmissible and wrong. An incomplete and therefore misleading diffraction theory was propagated.

    [3] Newton, Opticks 1704; Opera quae exstant omnis, Tom. IV, London 1782; Optik II + III. Übers. W Abendroth, Ostwald’s Klassiker Nr. 97, Engelmann, Leipzig 1898; NeuaufIage Bd. 96/97, Vieweg, Braunschweig 1983; Optique. Trac. J. P. Marat 1787; Bourgois 1989

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    1. Sabine, I suspect Dirk Freyling is trolling, please consider cutting him out

      Delete
    2. Sorry for not being able to expound further, Sabine, but the same goes for Lorraine Ford. None of what she states has any validity and the differences and similarities between "representation" and "being" are irretrievably lost on her: completely invisible. She is not trying to eat a steak in one bite, she is trying to eat a whole bull.

      Delete
    3. Folks,

      If I were to cut out everyone who I think is posting nonsense here, I might as well save myself the effort of having a comment section to begin with. I am merely trying to avoid or at least discourage commenters who are disruptive in one way or the other, either by insulting others or by clogging the thread with off-topic remarks or being a nuisance in other ways, eg by repeating the same nonsense over and over again. If you think someone is just wrong on something but otherwise they're not much of a bother, I recommend you ignore them. The exception is if them being wrong is actively harmful (climate deniers, anti-vaxxers, general conspiracy theories and so on).

      In any case, thanks for your support. And I will have an eye on the commenters you mention.

      Delete
    4. Ivan from Union,

      Lorraine is no crazier than most people here or most human beings. (I can't judge whether she is saner or crazier than me: a man ought not to be a judge in his own case!)

      She has a distinctive view that certain types of logical thought can only be a product of minds rather than inanimate objects, though we can build objects that mechanically imitate some of our logical thought.

      Many (I suspect most) philosophers share her view as do many people who actually understand the nitty-gritty details of how "thinking machines" actually work.

      Might she be wrong? Of course. But, as I keep insisting to Steve Evans, "wrong" is not the same thing as "crazy." And she is not making up crack-pot nonsense about physics or math: she has opinions on matters that are deeply contested by thoughtful people.

      You wrote:
      >the differences and similarities between "representation" and "being" are irretrievably lost on her: completely invisible.

      The funny thing is that I think you and she may be trying to make similar points but with very different vocabularies!

      Dave

      Delete
  46. About the prehistory of Heisenberg's uncertainty principle
    part II
    Conclusion
    Fresnel's alleged proof of light as a wave, based on an inadmissible and incorrect extrapolation of the formula for zero-distance diffraction. Around 1850, Fresnel diffraction with waves was the only option presented in textbooks. Newton's diffraction experiments, on the other hand, were embezzled, thus manifesting a simplified and misleading theory. Even later after the discovery of the photoelectric effect, nothing had changed in the "manifested" theory, and only a dualism of wave and body was inferred. Even Bohr built his quantum theory with the Copenhagen interpretation on the dualism of wave and corpuscle, which he combined with indeterminism in quantum theory, from which the lack of clarity in quantum processes was inferred. Einstein objected to this, but could not justify his view.

    {Side note
    On closer inspection, diffraction experiments only confirm the periodicity of the light but do not confirm the “wave nature” of light. Ernst Mach [4] already showed that all diffraction and interference experiments do not prove the wave, but only the periodicity of light. Think about it, if you disagree with Mach, it would be necessary to prove it, »links« to scientific papers would be great...
    [4] Ernst Mach, Die Prinzipien der physikalischen Optik. Barth, Leipzig 1921; The Principles of Physical Optics. New York 1926.]

    Heisenberg used the dualism of wave and corpuscle on the basis of the "Copenhagen interpretation of quantum theory", he accepted inadmissible and incorrect extrapolation with the wave quoted as "a general mathematical proposition" with which one can build up a wave packet of any shape, namely any piecewise monotonous function. Since every experimental result is monotonous “piece by piece”, Heisenberg thought that this is a correct approach. But taking diffraction experiments as above mentioned into account the general application of the Fourier theorem loses its universal justification. Phenomenologically, particles with structure cannot be labeled with two “details” such as location and momentum or – generally speaking - a pair of canonically conjugated variables. However, the Heisenberg uncertainty principle is only applicable for point-shaped particles. In this sense, how would one interpret the double slit experiments with protons, neutrons or atoms phenomenologically? See for example: Quantum Theory Approach for Neutron Single and Double-Slit Diffraction[5] https://arxiv.org/pdf/0910.3027.pdf

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    1. I don't want to waste a lot of time on crackpottery, but in case anyone is in doubt, yes, our friend Dirk Freyling's claims are utter nonsense.

      As to his question:
      >However, the Heisenberg uncertainty principle is only applicable for point-shaped particles. In this sense, how would one interpret the double slit experiments with protons, neutrons or atoms phenomenologically?

      The answer is: by using quantum mechanics.

      If anyone thinks I am being unfair to Kirk, by all means google his website and judge for yourself. (Google translate works fine if you do not have much German.)

      And, no, Kirk, I am not going to debate it with you: I already tried to get you to take seriously your errors re "reduced mass," and you declined. I only debate with honest people.

      Delete
  47. One doesn't know anything about the color yellow unless one has read The Potters of Firsk by Jack Vance.

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  48. An interesting document for perusal is a 1927 article by Heisenberg "Physical Content of Quantum kinematics and Mechanics," which can be located in the 1983 Wheeler/Zurek compendium, or pdf file online (at NASA technical reports server). Heisenberg concludes: "quantum mechanics establishes the final failure of causality."

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  49. Steve Evans,
    I don't think if does much good on this blog to rant about fine tuning. There are not that many here who support that idea. But if you wanted try your hand on a blog somewhat more supportive of that idea, here is some ammunition:

    In the February 3rd issue of Nature there is an article by an experimenter at Tokyo University who calculated the likely hood of the emergence of self replicating RNA as essentially non existent with only 10^22 sun like stars in the observable universe. However, if you add a bit of inflation which suggests that there are upwards of 10^100 sun like stars in the entire universe, why then you can get self replicated RNA and etc. Like I have written before, not especially "fine" tuning.

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    1. Steve Bullfox6:09 PM, April 24, 2020

      " Like I have written before, not especially "fine" tuning. "
      Fine-tuning includes the idea of a fine-tuning mechanism (a la piano tuner) and the idea of a large number of trials leading to an outcome which is low probability per trial (a la lottery win). Obviously, there may be fine-tuning within the universe (e.g. piano tuners and lottery winners), but there is *zero* evidence that the universe itself is fine-tuned. The RNA example would be of fine-tuning within the universe not of the universe, but as I wrote, the probability calculation is obviously incorrect.

      Delete
  50. Steve Bullfox6:09 PM, April 24, 2020

    "I don't think if does much good on this blog to rant about fine tuning."
    Fortunate, then, that I haven't. I have written mostly comments relevant to the OP against thinking concepts in the mind or artefacts in models are real without empirical evidence (the fundamental point of natural science) e.g. fine-tuning, inflation, MWI, panpsychism, religion not being refuted by science, conscious thought possibly not being instantiated in matter, Hoyle's discovery of the C12-resonance being Anthropic (even post-factum), gods and demi-gods. Quite bizarrely, often the wrong side of the non-argument has been taken up by professional physicists or other academics paid actual money.

    "the likely hood of the emergence of self replicating RNA as essentially non existent with only 10^22 sun like stars in the observable universe."

    Sounds like a clearly false claim Fred Hoyle used to make about protein folding and blind men solving Rubik's cubes. The probability calculation in the "Nature" article is incorrect with probability 1. Self-replicating RNA didn't come about randomly, it came about driven by evolution. Therefore, it's practically impossible to calculate what the probability is that it came about. It's incredible that "Nature" would publish such cr@p. It's a primary school level misunderstanding of probability. If the die isn't fair, then the probabilities for throwing each number aren't all 1 in 6. Strange that a Tokyo University researcher wouldn't know that.

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  51. Steve Evans,
    Probably the best argument against fine tuning is simply to ask where is everybody? My relative, who does not believe in evolution also believes the earth is 6,000 years old which if it were true would make evolution problematic.

    I think people who don't believe in evolution don't much consider how old the earth is. Likewise, people look at the one example we have of life in the universe and see fine tuning with out much consideration of how big the universe is. They way over estimate the probability for life.

    Clearly, estimating the odds for life in the universe requires a lot of assumptions. The researcher in the Nature article was just looking at data on the random assembly of strands of RNA. He concluded that random assembly of strands long enough to self replicate is highly unlikely.

    My whole point is considering the very long odds for life in the universe completely wipes away the religious implications of fine tuning. I don't see much point in continuing the discussion since among other things you and I seem to be basically in agreement.

    ReplyDelete
    Replies
    1. Steve Bullfox1:31 PM, April 25, 2020

      "Probably the best argument against fine tuning is simply to ask where is everybody? "
      This isn't an argument against fine-tuning - fine-tuning apologists would just say if you tweak the fundamental constants "a little" we wouldn't be here. There is zero evidence of fine-tuning of the universe because (i) there is no evidence of a fine-tuning mechanism, and (ii) nobody knows the probability distribution for the fundamental constants and laws; it's not known whether it is possible for the universe to be any different than it is. So there is *zero* evidence of either kind of fine-tuning (piano tuner or lottery winner).

      "people look at the one example we have of life in the universe and see fine tuning with out much consideration of how big the universe is. They way over estimate the probability for life."

      I see what you're saying - people in general don't realise how vast the universe is and how insignificant humans are, so they think the universe must have been created for humans. But nobody knows the probability for life existing in the universe, so we can't actually say whether they are over-estimating or not. Considered in the correct context the probability of life must be reasonably high or it wouldn't have happened. But whatever the context (universe, multiverse, bouncing universes), the probability is high due to nature not design, which is where these people are going wrong.

      "Clearly, estimating the odds for life in the universe requires a lot of assumptions. "
      Even if we knew how life started on Earth, which we don't, it would be impossible to estimate these odds. If random assembly is assumed then the "estimate" at best gives only a lower bound on the probability, which apparently is essentially zero if some number of Sun-like stars are assumed. OK, but I already know probabilities are between 0 and 1. What is the point of such a calculation? The mind boggles.

      "The researcher in the Nature article was just looking at data on the random assembly of strands of RNA. He concluded that random assembly of strands long enough to self replicate is highly unlikely."
      Of course. And this is the same as what Fred Hoyle did for protein folding - assumed random assembly. But it's completely wrong, because life on Earth has been driven by the processes of evolution. It's not random.

      "My whole point is considering the very long odds for life in the universe completely wipes away the religious implications of fine tuning."
      We have no idea what the odds for life are in the universe, because the process by which life on Earth came about is too complex to calculate probabilities for, and despite the recent exoplanet discoveries, we have no idea whether there is a lot of life or not in the universe in general. It's a complete mystery.

      Religions are fairy tales believed by the mentally deluded and sold to them by criminal fraudsters. Religion is not a scientific issue but a mental health issue, and should be a matter for CID. They investigate all other scams and frauds on the vulnerable, why not this one, the biggest of the lot?

      Delete
  52. The Heisenberg argument you describe uses the old QT and justifies the existence of incompatible observables. In the new QT (post 1926) one has a similar looking expression whose meaning is entirely different! Namely, a relation between the standard deviations of two observables given any particular quantum state.

    ReplyDelete

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