Comments by "Lepi Doptera" (@lepidoptera9337) on "Does the Many Worlds Interpretation make sense?" video.

  1. Your first sentence was already completely wrong and it got only worse from there. ;-)
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  2. Physics is all about reality. We simply compartmentalize reality into smaller, easier to describe pieces. That's why we are the most successful intellectual discipline of all times. ;-)
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  3. ​ @moskitoh2651 My first theoretical physics teacher said this in the first few minutes of the first lecture: "Gentlemen. Physics is the art of approximation. Those of you who are not comfortable with the fact that physics uses increasingly more refined and accurate models of reality should leave this lecture now. The philosophy department is across campus. There you will learn the absolute truths about the universe... and they will all be completely false.". Big laughs, nobody got up to become a philosopher. You would, obviously, have been the exception. If you are looking for absolutes, that's philosophy and religion. Both are absolute bullshit. ;-)
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  4. Because a measurement is an irreversible energy transfer and an ideal beam splitter is reversible. A real beam splitter does absorb a little energy (because it has finite mass), but in practice that's very hard to measure and for most cases irrelevant.
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  5. There is nothing interesting about MWI. Everett simply didn't understand what quantum mechanics is. He mistook the (admittedly misleading language) for gospel and created a piece of poetry in motion.
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  6. Yes, and all of that goes away instantly once you use less weed and focus on studying undergrad physics. ;-)
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  7. Do you say that about everything you don't understand?
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  8. In the purest form MWI is total nonsense. :-)
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  9. Wave function collapse doesn't exist, so why would it lead to better anything?
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  10. One can easily make a source that can only emit a single photon: trap one atom in a Penning trap. Excite it to one of its optically unstable states and let it decay into the ground state. Voila. Exactly one photon. Having said that, your problem is that you simply don't understand why the number of photons in such an experiment is completely irrelevant (because of linearity).
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  11. It sounds like complete nonsense because it is complete nonsense. Everett simply didn't understand that quantum mechanics is an ensemble theory, i.e. it describes frequentist averages of infinite repetitions of the same experiment. In practice there are no ensembles. All our measurements are finite. Moreover, we usually do not build more than one copy of the same experiment. We simply reuse the same setup over and over, again, hoping that it shows no "memory" effect, which would require the use of different formulas than those in quantum mechanics.
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  12. @ If it looks like that it doesn't make sense then it is because it doesn't make sense. The universe does not have a wave function and there is only one universe. The wave function is a mathematical abstract that gets created by a divide and conquer methodology that assumes that experiments are infinitely repeatable AND that all of the repeats are independent. That assumption simply does not hold for the universe. It's actually worse than that: the universe is not even a system, so almost none of the assumptions used in physics are valid.
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  13. Yes.
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  14. Yes, it would mean that, except that there are no such things as particles and MWI is simple nonsense. :-)
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  15. We don't even need Bell. That there can be no local hidden variables follows directly from relativity.
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  16.  @vitulus_  You can find Everett's mistake in the second sentence of his thesis. He simply didn't understand quantum mechanics. Oh, wait, you never read it and you don't understand quantum mechanics, either. ;-) Where did you get the idea from that nature is deterministic in the first place? It's a trivial fact that anybody can tell you last week's lottery numbers but nobody (including Everett) can tell you next week's. That alone rules out that nature is deterministic. This is a kindergarten level science observation, so I have to ask: why did you stop paying attention in kindergarten? ;-)
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  17.  @vitulus_  The modern interpretation makes exactly the same mistake. Can you name it? I can. :-) Copenhagen doesn't contain that mistake. Copenhagen tells you exactly what happens in nature. All you have to do is to listen. ;-)
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  18.  @vitulus_  There are no beliefs in Copenhagen. It consists of two self-explanatory formulas. Can you explain them to me? If you can't, then you simply don't understand Copenhagen. ;-)
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  19.  @vitulus_  It is obvious that you can't even give an inaccurate description of Copenhagen. Dude, stop pretending that you understand physics. You don't. End of story. ;-)
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  20.  @vitulus_  Awh, you are so cute when you are feeling sorry for yourself. Here, let me give you some more attention on your way out. ;-)
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  21. Except that a good philosopher would know that this is not a theory. It's not even a hypothesis. You just gave a really good example for WHY serious scientists don't think much of philosophers. You guys can't even the primary school science right. ;-)
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  22. There is no such thing as a collapse. They are only people who don't understand physics and who can't tell the difference between reversible and irreversible systems.
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  23. The curious thing is that there is no such thing as collapse of the wave function in physics. You won't even find that terminology in well written quantum mechanics textbooks like Sakurai. The book is online. Do a search, see if you can find it. I couldn't. ;-)
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  24.  @ИльяАнфимов-ъ7н  It means that Dirac had the wrong intuition about quantum mechanics, or that he was using problematic language, at the very least. The individual system does not have a state before measured, which means it can't "jump into it" as consequence of the measurement. All the quantities in your math are ensemble quantities. They aren't making ANY statement about individual systems. It is not the math that is wrong here, but the interpretation of the math. We know what quantum mechanics is. It is a geometric partition of unity that happens to satisfy relativity. The "unit" in this partition is the unitary totality of all events in the quantum mechanical ensemble. That is how the theory was constructed from day one. It differs in nothing from probability theory in that regard.
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  25. So just like Einstein you don't understand the most trivial theory in all of physics. ;-)
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  26.  @gsmollin2  Why would quantum mechanics require that? MWI is simply the proof that Everett didn't understand quantum mechanics, either. So that makes three of you now: Einstein, Everett and now you. ;-) Of course the strange state of public understanding of quantum mechanics enrages me. We are teaching in high school that "quanta are small amounts of energy", which is basically all you need to know to derive the theory from, but nobody seems to be paying any attention. Are these six words a joke to you guys? :-)
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  27.  @gsmollin2  Except that Einstein didn't believe his own explanation. Read his paper and you will find a sentence in there in which he immediately identifies those quanta of energy with Newtonian corpuscles that have position and path. That sentence is 100% wrong. It is also 100% unmotivated by the actual experimental evidence. Most importantly it is unnecessary. Nowhere does the photoelectric effect require that photons have position and path properties. It's complete intellectual nonsense but Einstein never managed to get rid of this unnecessary assumption in his own mental models as far as I can tell. Every time he talks about quanta he refers to them as if they were Newtonian corpuscles. To this day most people can't let go of that nonsense. MWI doesn't follow from Copenhagen. It's a complete misunderstanding of Copenhagen. Copenhagen simply tells you the facts on the ground: quantum mechanics is a theory of independent ensembles (because individual experimental outcomes are not predictable) and it requires two of those: the ensemble of the free quantum system and the ensemble of the quantum system plus the measurement system because the actual physically measured outcomes depend on the spectral absorption function of the measurement system. Everett didn't understand either of those statements. Einstein may have come close to understanding the ensemble character, but I kind of doubt he ever understood where that came from (hint: it comes from special relativity!). End of story. ;-)
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  28. The only way you get from the SE to MWI is by not understanding the SE. Everett for sure didn't. He made a major mistake in the second sentence of his thesis. ;-)
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  29. Congrats. You just passed your oral undergrad QM exam. Or at least you got one of the questions right. :-)
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  30. The universe can not have a wave function. A wave function requires an ensemble of quantum systems. One can not make copies of the universe and it's not even a system. Wheeler was peddling the "wave function of the universe" idea without actually thinking about the implications. I suggest you try to do better.
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  31.  @philweight3480  That Wheeler was a big fan of the "universal wave function" can be checked easily in his papers about it. Why are you telling me that you don't know the literature? I don't care about all the things that you don't know about. :-) That we don't have a means to recreate infinite copies of the universe is about as hard a fact as they come. ;-) That the universe is not a system follows from the definition that physical systems can exchange energy, momentum, angular momentum and charges between each other. The universe can, also by definition, not do any of that. OK, kindergarten science is over. Please report to Mommy for feeding, bathing and bedtime. ;-)
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  32.  @philweight3480  And now you are just feeling sorry for yourself, kid. Don't. It makes you look insanely immature. ;-)
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  33. Bad taste is not a crime.
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  34. Not even particles exist. Quantum mechanics is a theory of the behavior of quanta of energy, momentum, angular momentum and charge. All of these quantities are system properties. They are not tied to some mythical tiny pieces of matter.
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  35. You have been told wrong. :-)
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  36.  @moskitoh2651  The part about physics not talking about reality. What else would it be talking about? Caspar the ghost? ;-)
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  37.  @moskitoh2651  My teacher knew that science is not religion. Having said that, the mathematical structure of quantum mechanics is inescapable. It's based on the same assumptions (independence) that probability theory is based on. Independence of measurements can be tested. If an experiment violates it, then it will show up in the data, so we can tell empirically if the formalism of quantum mechanics is applicable or not. In many cases it is not and then we can use arguments that deviate from the formalism but are still returning the correct answer. An important, albeit virtually unknown problem of this kind is the Mott problem. Your problem is that you don't know any of this. You are currently just waving a giant foam hand around that has absolutely nothing to do with either physics in general or quantum mechanics specifically. I call that "the poetry of intellectual laziness". ;-)
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  38. It's worse than that. Hidden variables were never alive. The tragedy is that what looks like "hidden variables" is an obvious consequence or relativity and Einstein himself couldn't see it. He should have been the first one to point out that the structure of QM follows immediately from the causality structure of relativistic space-time. Worse, Nathan Rosen was a young but very advanced relativist. Even if Einstein didn't notice because of his age and emotional closeness with the matter, Rosen should have seen it in a split second.
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  39. What makes you believe in all of this nonsense? ;-)
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  40.  @GeorgesDupont-do8pe  Science is not a poetry in motion contest. Time is simply that which the clocks show. We try to teach that to the five year old kids... of course if you weren't paying attention to that piece of trivia, then whatever came next certainly must have overwhelmed you. Don't tell anybody, but Sabine doesn't know that time is that which the clocks show, either. :-)
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  41.  @GeorgesDupont-do8pe  Yes, we know exactly that time is that which the clocks show. We made the clocks and we defined the word "time" that way. The only problem here is that you and Sabine weren't paying attention in your early lives. ;-)
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  42.  @GeorgesDupont-do8pe What does that have to do with the definition of time? It is still what the clocks show, whether they are moving or not. ;-)
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  43.  @GeorgesDupont-do8pe  The clock isn't wrong. The clock is the clock. You are simply looking at a delayed signal from the clock. The delay depends on your position and relative motion. So why is it important to know that time is that which the clocks show? Because a clock is, BY DEFINTION, a local energy reservoir that emits that energy in a controlled manner into the physical vacuum. The relativistic effects on clocks are therefor actually effects of spacetime on the flow of energy. See how much you can deduce just by knowing the basic definitions? ;-) I am a physics PhD, by the way. You are preaching to the wrong man. This was my profession. ;-)
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  44.  @GeorgesDupont-do8pe  Literal? Physics doesn't run on allegories. It runs on comparisons. F=ma compares three phenomena, acceleration, inertia and force, and defines a strict relationship between them. The only way to truly measure a force is to let it act on a test mass and then to measure the acceleration of that mass. My high school physics teacher told me once that if a science teacher introduces force using a spring balance, then students will remember that for the rest of their lives as the definition of force: force is that which elongates a spring. That is a completely unworkable definition in physics. It's completely false, but that is what "sticks" in the layman's mind. The imagery of the spring is stronger than the words of the actual definition. This phenomenon of "learning the wrong lesson" is unfortunately fairly universal. I am trying to correct some of the misconceptions in people's minds (which is a fool's errand, I know) by giving them the correct definitions. Much of the ontology of physics is like lawyering: every single word and their relative position to each other matter. Not everybody is cut out to be a lawyer (I am not) and similarly not everybody can make peace with this property of physics. Not even the theorists (like Sabine), who are so focused on the math that they often forget what it means: behind every one of our formulas there is an experiment.
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  45.  @GeorgesDupont-do8pe  It's all based on four things: energy E, momentum p, angular momentum L, charge Q. That's it. That's all physics ever cared about. If you can't explain it in simple terms, then you don't understand it. As you can see, there are a lot of content creators on YouTube who don't understand it. Cheers! I drink to that! ;-)
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  46. From my experience nobody in physics proper ever talks about Schroedinger's cat. It doesn't solve any problems that real physicists are trying to solve.
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  47.  @papalaz4444244  Schroedinger simply didn't get that quantum mechanics is not about objects. It's about energy exchange. Since energy is a system property it doesn't have a size. That's why QM is valid at any scale. It's not even true that quantum effects are not detectable at large scales. The Planck spectrum of the sun is quantum mechanics at work at the scale of a star. The photoelectric effect can be detected with a macroscopic piece of metal connected to a macroscopic mechanical electrometer. magnetism is a quantum effect. So is superconductivity. There are simply smart ways of thinking about nature and there are not so smart ways. Schroedinger's cat is one of the least smart ones.
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  48.  @papalaz4444244  Schroedinger was obviously both educated and intelligent, but being smart about something is different. It translates into useful and working strategies of dealing with a problem. Schroedinger's approach does not satisfy those criteria. His argument doesn't address physical reality properly and it doesn't solve the issue of how quantum mechanics actually translates into the macroscopic world. He was too late, anyway. Both Heisenberg and Mott had solved it before him, already.
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  49. I did read his thesis. The major mistake is in the second sentence. He never recovers from it.
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  50.  @udolehmann5432  Why are you telling me that you didn't read it yourself? I don't care about all the things you didn't do. ;-)
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  51. Oh, no, it's far, far, far more than that. You don't understand, grasshopper. The number of possibilities grows exponentially with the number of quanta. Well, actually, it grows exponentially with the exponential. You are, however, totally right about the idiots part. MW is really nothing but a total misunderstanding of trivial physics. :-)
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  52.  @ljvanstone876  If you want to see the technical mistake, it's in Everett's paper, second sentence. He simply mistook the description of the quantum mechanical ensemble (which is an infinite number of HYPOTHETICAL copies of the experiment) for the description of the single system. It's about as stupid as identifying an entire forest with each single tree.
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  53. The only way an observer ever splits is if you take an axe to him or her... which our legal system does not condone. ;-)
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  54. It doesn't come from philosophy. It came from a trivial counting problem: Everett couldn't tell the difference between one and infinity.
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  55. There are no other universes. This is like a really boring physics version of Harry Potter. It's a completely made up fairytale.
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  56. Introduces ghosts and solves nothing. At most it gets you further away from the correct solution.
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  57. What is the alternative to what? Paying attention to the details of the Copenhagen interpretation would help.
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  58.  @erikals  Interpretations don't differ. They are either physically correct like Copenhagen or they are just intellectual nonsense. Copenhagen tells you exactly what is happening in nature. Did you listen? No, of course not. Your own confused thoughts are still drowning out any and all rational analysis. Hint: Copenhagen gives you two formulas. Why does it do that?
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  59.  @erikals  Let me know when you are ready to learn real physics. Not yet, it seems.
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  60.  @erikals  It's just the facts. I am all about the facts. ;-)
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  61.  @erikals  You sound rather annoyed. Why is that? Am I not giving good attention to you right now?
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  62. Of course there would be way more universes without you then with you. That's why comic book style travel between universes would be absolutely suicidal. ;-)
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  63. Awh, you are so cute when your lack of education is showing. ;-)
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  64. Nothing ever branches. MWI simply doesn't understand that quantum mechanics is an ensemble theory.
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  65. There are no multiple interpretations, there is just a lot of confusion about Copenhagen. In terms of physics Copenhagen tells you the facts unfiltered, you just have to listen carefully what it says. Most people don't and Everettians in particular are covering their ears whole singing "Lalalalalalala...". ;-)
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  66. The world you live in is perfectly local, but it contains a lot of people who call it non-local because they don't understand physics. ;-)
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  67. Yes, that was a lot of nonsense. :-)
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  68. @ A physicist would have read Everett's thesis and found the problem in his second sentence. No philosophy needed. Everett simply didn't understand quantum mechanics. I bet you don't understand it, either. ;-)
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  69. @ You are correct. They gave me my PhD in physics because I was intellectually lazy and that's also why I actually read Everett's thesis and you didn't. ;-)
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  70. @ Everett thought that the wave function is the description of an individual quantum system. That is nonsense. It's the description of the isolated quantum mechanical ensemble. :-)
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  71. @ Copenhagen tells you exactly what happens in the quantum lab and why. Everett's nonsense tells you nothing. ;-)
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  72. @ Copenhagen tells you how the isolated quantum mechanical ensemble evolves and then it tells you how that ensemble transfers energy to a second ensemble called "the measurement system". :-)
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  73. @ Bro, what have you been consuming? I never said that Copenhagen describes a single system. I said that it tells you what happens in the lab. Are you high like a kite right now? :-)
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  74.  @frosted1030  Yes, all of that was total nonsense. We taught you everything that you need to know about this in high school science class. You simply weren't listening, so you don't know how to use that knowledge to understand what is going in. ;-)
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  75.  @frosted1030  Yes, I get it that you are a genius in your own mind. That's the only place, though. Out here, in the real world, you are merely desperate for attention. ;-)
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  76.  @frosted1030 Nobody is confused about you. We simply don't like you. ;-)
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  77. If you can't handle quantum mechanics, then you are simply not very intelligent. It's one of the, if not the, most simply of all physical theories. :-)
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  78.  @WayOfAges  A quantum is a small amount of energy, momentum, angular momentum and charge. More precisely, it's the smallest amount of angular momentum and charge that physical systems can exchange. A quantum process consists of the irreversible emission or absorption of one of these quanta by a source or detector system. If quantum processes are independent of each other (i.e. none of them can be predicted based on the results of all the others), then their statistics can be described by two formulas which are usually called "the Schroedinger equation" and "the Born rule". Both are based on either matrices or linear operators and they can be derived from Kolmogorov's axioms and a few assumptions about the physical interpretation of the linear algebra. That's it. The remainder is basically just math that uses linear algebra and linear operators. For the purposes of physics it's not much more complicated than what we are teaching in high school.
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  79.  @WayOfAges  I am calling the people who can't explain quantum mechanics this easily unintelligent. A better phrase would be "intellectually lazy". These facts about quantum mechanics have been known for a long time. OK, the derivation directly from Kolmogorov might be only thirty years old, or something. I don't remember the earliest paper in which I saw it being done. Maybe it was from the 1980s, which would put it into the 40 year category, but I wouldn't rule out that there are much earlier papers that I simply haven't seen, yet. I am not a science historian and I won't spend weeks or months in the library to dig up some obscure paper from the 1940s that only three people have ever read. So, yeah, my own QM 101 professor was in that category of "intellectually lazy teacher". He didn't care to explain what it was that we were doing there. He just threw the linear algebra at us without any physical connection to the real world. He could have known better, IF he had read the literature that existed at the time. This problem is endemic in the physics community. Professors who are being tasked with teaching a subject are usually very good at their specialties and crap at everything else (as you might expect). Quantum mechanics is not even a specialty. It's a general framework that is being used in many actual physical disciplines like atomic and molecular spectroscopy, nuclear physics and solid state physics. Everybody knows how to use it but almost nobody knows WHY it works and WHY it works the way it works. That almost nobody knows, however, has nothing to do with it being unknown. It's known extremely well because it is extremely trivial. It just happens that nobody teaches these trivialities and the language that we are teaching, even in university, is basically 100% false. The math is all correct, but the way we are talking about the math is about as misleading as one can make it. That's a phenomenon of science history.
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  80.  @WayOfAges  It is a fact that there is no complexity here. There are only bad teaching habits. Quantum field theory and general relativity, those have serious complexities. QM doesn't have any of that. We could teach it in high school and one day we will. Nobody in physics profits from any of this, either. Most physicists just don't care to explain it correctly. I just did. It's up to you whether you actually want to listen or not. My guess is you won't. And that, my friend, is YOUR intellectual laziness at work. ;-)
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  81.  @WayOfAges  "Quanta are small amounts of energy.". It doesn't need much superiority to remember that. You just have to actually listen to what you are being told in high school. So, yeah, if you can't do that, then my initial comment was spot on, wasn't it? The difference between you and me are six words that I can retain and you couldn't. :-)
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  82.  @WayOfAges The problem here isn't that I can't teach. The problem here was always that you can't learn. :-)
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  83.  @WayOfAges  I am not talking down to people who are ASKING honest questions. I am talking down to people who are suffering from Dunning-Kruger and who simply don't know what they don't know. I gave you the correct answer in my second reply without talking down. You weren't listening and gave me some p*ssed off reply. That's a fact that only you can change. I can't change it for you. If you have a question I will try to give the correct physical answer. If I don't know the answer then I will tell you. I do have an answer for most of the trivial questions people are asking. That does not mean I have all the answers. The most simple question about quantum mechanics that I can not answer as of today is this: "Why is angular momentum quantized?". I honestly don't know. I suspect that it's something non-trivial in special relativity but I can't give a simple intuitive argument why it has to be this way. I am still searching for a way how one can understand it from first principles. Maye I need to read a few more quantum field theory books. Maybe there is a paper that I haven't seen, yet, but it is a fact that as of right now that's still a bare spot in MY knowledge about the world. See how easy it is to admit that you don't know something? I can do it. Please try to learn this technique yourself. It will make science far more enjoyable for you.
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  84. Most of it is solid state physics, actually. You guys are just too lazy to learn solid state physics. It's also boring like hell if you are not into it. ;-)
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  85. Pilot waves tells you exactly the same as standard quantum mechanics but it invokes an invisible ghost field that does not have any back-reaction and a hard ball that nobody has ever seen. If you are into strange forms of the occult, it might be for you. As a physical model it's pointless. What it mostly does, though, is to take your eye off the facts. Copenhagen tells you exactly what is happening, IF you care to listen to it. Bohm's nonsense tells you absolutely nothing. :-)
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  86. The robustness of quantum systems like superconductors and superfluids is caused by an energy gap that is greater than kT. That's why these systems have critical temperature at which they lose these properties.
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  87.  @GennadyKarvitsky I gave you the answer. These systems have an energy gap. That the difference between quantum/classical depends on size is simply bullshit. It was never true, John Q Public just doesn't want to understand how quantum systems really work because it is... complicated. John Q Public doesn't do complicated. He likes to do "utterly false", though, as long as it's simple.
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  88. You make a billion in this one. That's your one and only chance. Get going. ;-)
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  89. There is no randomness in nature. Random numbers don't satisfy any of the conservation laws. The world is, indeed, non-deterministic, but that's trivial. It's experimentally easy to verify (I can tell you last week's lottery numbers, but you can't tell me next week's) and it follows trivially from relativity.
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  90.  @mskiptr  I am using the proper definitions. You are simply mistaking randomness for statistical independence, which is the actual technical criterion for the validity of quantum mechanics. That, however, follows trivially from relativity.
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  91. Everett multiplied the universe by at least Aleph_2 because he didn't know how quantum mechanics works. There is no math here. It's simply a guy who didn't understand physics talking nonsense. ;-)
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  92.  @curiouskoala411  Have you been drinking just now? ;-)
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  93. Everett was shunned by people who understand quantum mechanics because he made a serious mistake in the second sentence of his thesis. His argument never recovers from that mistake. Anybody who can't spot that mistake is simply not qualified to talk about the topic.
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  94.  @sat25940  Dude, in the second sentence of his thesis Everett assigns the wave function to the state of the individual physical system. That is complete bullshit. The wave function is, by definition and design, a description of the quantum mechanical ensemble. A single system does not and can not have a wave function. In other words: a quantity that describes an infinite repetition of the same experiment is falsely assigned the role of describing the behavior of an individual system. THAT is what multiplies the number of worlds in MWI by an infinity. It's a trivial counting mistake. Wheeler did one worse, by the way. He assigned a wave function to the universe, which is not even a system (and it sure as heck can not become a repeatable experiment). These are trivial undergrad mistakes.
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  95.  @sat25940  That wave functions describe ensemble averages follows immediately from the unitarity requirement. Where else would it come from? From god's toe fungus? Please, at least try to THINK about this rationally for a little while. And of course it is "canonical". The probability that drops out of the Born rule is an ensemble property. Single events don't have probabilities. If you don't believe me, try this: I measure a single quantum of 1.63eV at the position x=-14.3mm and y=28.5mm. What was its wave function? :-)
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  96.  @sat25940  YOU need to tell me what the wave function was because this is science. It's not religion. I don't take things on faith. If YOU can't tell me the wave function based on a single event, then the single event does not have a wave function. The only information we are getting from YOU not telling me the wave function is that YOU don't understand basic physics. Not that that's new information, anyway. That was obvious right from the beginning. :-) How do you know that the atom is in the ground state without observing it for a long time, by the way? Is god's toe fungus telling you that there won't be any energy coming out, even if you don't look? Dude, you are making a total fool of yourself here. Stop it. My sides are hurting from rolling around on the floor laughing. ;-)
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  97. There is nothing to understand here. If you read Everett's thesis, then you can find his logical mistake in the second sentence. Everything that follows after that is trivially false.
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  98. I don't know any physicists who are taking drugs. Why are you projecting, though? ;-)
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  99. The simple explanation is that you aren't thinking clearly and you weren't paying any attention in school. We show the double slit with water waves in high school. Where do you see photons in water waves? We also demonstrate that interference is the absence of self-interaction in linear waves. Interference is NOT a physical effect. It's the absence of a physical effect. ;-)
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  100.  @Qichar  The pattern with water waves is also aligned perpendicular to the slits. This has nothing to do with the detailed nature of the waves. It holds for scalar, vector and tensor waves. Why? Because it is a feature of the geometry of the double slit. We even derive the result for you in Frauenhofer approximation in school and all it needs is a little bit of geometry. Nowhere does it need Planck's constant or even angular momentum quantization. Light is not a wave at the quantum level. It is the excitation of a quantum field, but the double slit does NOT demonstrate the quantum level. It demonstrates only the mean field theory and the mean field theory of light IS a wave theory. At the level of de Broglie you are still talking about waves because you are still not exploring the full consequences of angular momentum conservation. At least Planck's constant shows up, already, but it already did that in the Planck spectrum. The fully quantized theory only becomes visible in things like the hydrogen spectrum.
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  101.  @Qichar  Photons are small amounts of energy. They are not objects that the field is made of. These amounts of energy also depend on the measurement system, so they do not already "exist" in the field before the actual measurement is made. The field has some energy, but it is not atomistically made out of these bits and pieces that we just pick up at the end. Instead the measurement process itself selects how much energy it absorbs and where and when that absorption happens. Intuitively that's probably the hardest part to get used to. If you want a game of luck analogy, imagine a game of roulette, but the player decides which kind of wheel he wants to play with. He can get a wheel with 37 positions like in the standard version or he can pick one with just four, or another one with 19 possible outcomes. In quantum mechanics the choice of measurement is equivalent to the wheel the player would pick in the roulette example. You also have to let go of the idea that photons interact. They don't. Quantum mechanics is a theory of statistically independent ensembles in which every single outcome is completely independent of all other outcomes. There are physical systems for which this assumption holds (like the free electromagnetic field) and then there are systems for which it does not hold (and that's experimentally testable!). In the latter case the formulas of standard quantum mechanics do not apply. One can construct formulas even for that case and the first example of such a system that I am aware of was given by Mott in the year 1929. The problem with the way we teach quantum mechanics is that we do not mention these very important assumptions about the theory, which leads people to speculate about completely irrelevant things like "single photon interference". There is simply no such thing. The theory rules it out explicitly in the way it is constructed and the reason why this works is because the electromagnetic field does not interact with itself measurably at optical wavelengths.
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  102. We are never finding "particles" anywhere. We are only detecting quanta of energy. Quanta of energy are always being detected where the detector is. Their "position" is not "their position". It's the position of the detector.
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  103. The Copenhagen interpretation gives you two formulas: the first one is a reversible ensemble dynamics formula for a single, completely isolated system. The second one is a formula for the likelihood of irreversible energy transfer between the first system and an irreversible second system once a spectral function mitigates the interaction between the two. How in the world can you get away with "fewer" than two formulas when you are describing exactly one system with one and two with the other???? Can anybody around here count to two? Seriously?
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  104. They are only in the minds of people who don't understand quantum mechanics. ;-)
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  105. There is no such thing as "the original" photon. A photon is just a small amount of energy. Energy isn't labeled as "this is energy 1", "this is energy 2".... "this is energy 10^78" etc..
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  106. Did you pull this nonsense out of your own rear? ;-)
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  107. All of quantum mechanics is based on observations... you were just too lazy to learn about them. ;-)
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  108. Systems are never in superposition. Only an abstract mathematical quantity that does not exist in nature is.
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  109. It isn't. It's related to the question why people aren't paying attention in school when we explain physics to them. ;-)
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  110. There is no such thing as a "collapse postulate" in standard quantum mechanics. You won't even find the word "collapse" mentioned in well written introductory QM textbooks like Sakurai. It serves no purpose and it doesn't have a workable definition in physics. It has established itself as a meme because it has been repeated endlessly by people who don't understand quantum mechanics.
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  111. The main error of MWI is in the second sentence of Everett's thesis. The main error in the bible is in the first sentence. The bible wins this context by one sentence. ;-)
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  112. Quantum systems aren't in superposition. They are uncertain. The mathematical object that we use to describe that uncertainty has the properties of a vector space. That's what we mean by "superposition". It's not a physical property but merely an abstract mathematical one.
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  113.  @camdenwhite4657  Such a value does not exist and can not exist. Nature is just as "uncertain" about the outcome of a measurement as we are. Wave functions do not make statements about individual measurements. They only make statements about ensemble averages. The theory is completely clear about that. The entire formalism is designed to be an ensemble theory. That's why its living in a vector space with a unitary evolution to begin with. We do, unfortunately, not teach how the theory was designed when we teach how to calculate with it. Some people call that "shut up and calculate", but in reality it's just very, very poor academic teaching habits.
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  114.  @camdenwhite4657  The wave function doesn't even contain enough information to get an ensemble average. We have to specify the measurement in addition to get any physics out of it. The only actual measurements that we can perform physically are energy, momentum, angular momentum and charge measurements. Why? Because these are the only conserved quantities that stay unchanged between the quantum system and the measurement system. Everything else are just histograms over these individual quanta of energy. Don't mistake von Neuman's math for physics. One has virtually nothing to do with the other. Wave functions are not even the right way of looking at nature. Scattering cross sections are.
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  115.  @camdenwhite4657  I give you the wave function. How do I calculate when my detector makes the next click? What's the formula for that?
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  116. Yes, and it sounds like total nonsense because it is total nonsense. :-)
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  117. Yes, it can be easily confirmed that it is nonsense. All you have to do is to read Everett's dissertation. He clearly demonstrates that he doesn't understand physics. ;-)
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  118. MWI doesn't even work in this universe. ;-)
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  119.  @curiouskoala411  The mistake is in the second sentence of Everett's thesis. He didn't know how quantum mechanics works. ;-)
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  120.  @curiouskoala411  Feynman's path integral is basically just the (formal) Green's function for the Schroedinger, Dirac etc. equation. It describes the time evolution of an ensemble average. You still have to make exactly the same mistake that Everett made and mistake an ensemble of systems for a single system to get to MWI. Boring. ;-)
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  121.  @curiouskoala411  An ensemble is, BY DEFINITION, non-interacting. Dude, you are failing the basic here. OK, then. I will give you as much attention as you need to get your failed education trauma out of your system. Why don't we start with you throwing flat Earth and creationism at me, as well. You are halfway there, already. ;-)
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  122.  @curiouskoala411  An ensemble is, BY DEFINITION, non-interacting. Dude, you are failing the basic here. OK, then. I will give you as much attention as you need to get your failed education trauma out of your system. Why don't we start with you throwing flat Earth and creationism at me, as well. You are halfway there, already. ;-)
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  123.  @curiouskoala411  Science is the rational description of the observed. It's not the bullshit detector against the occult. ;-)
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  124. Observers are not local. That the theory has to be is enforced by relativity.
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  125. Sounds good... until you read von Neumann's book from 1932 and it's all in there. Oh, wait, you never read any of the old papers, either. :-)
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  126. Sean Carroll is a sell-out who is making money with this idiocy.
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  127. There are no objects in quantum mechanics. There are only systems. In non-relativistic quantum mechanics the observer (better "the detector") is a system. In relativistic field theory even that has been eliminated and replaced with much more simple asymptotic states.
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  128.  @killers31337  Systems are arbitrary partitions of the universe. Did you pay attention in high school physics? It doesn't sound like you did. ;-)
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  129.  @killers31337  What makes you believe that your high school teacher lied to you when he wanted you to learn that "Energy is the ability of a system to perform work on another system."? You won't be able to understand quantum mechanics until you fully understand the meaning of that sentence. Dude, quantum mechanics can be fully understood at the high school science level. It is NOT difficult conceptually, but you have to pay attention to the details. That's just a general requirement in science. :-)
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  130. Why don't you try to get a grant for that and see how much money they will give you. Hint: it will be 0 dollars. ;-)
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  131. Neither are disturbing because neither MWI nor wave function collapse are scientifically correct. You won't even find the term "wave function collapse" in many textbooks (it doesn't have a firm definition and it serves no purpose in the theory) and authors who can't identify the error that underlies MWI should not be writing textbooks in the first place.
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  132. So they are basically replacing the Born rule with a different but equivalent axiom. There is nothing to "recover" here. The Born rule describes physics that is different and not equivalent to the physics of the free (unmeasured) ensemble. Some theorists keep surprising me with their inability to see the obvious. At most one could prove that the Born rule (or any of its equivalents) is the only "additional" axiom that we need for the theory to be complete. In reality, of course, all of this has been made obsolete by quantum field theory.
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  133. An observation is an irreversible energy transfer. We usually teach this in the second year undergrad physics. ;-)
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  134.  @btestware  A photon doesn't have a direction. It only has energy, momentum and angular momentum. Location, direction and timing are emergent phenomena of many quanta. That you can't think beyond them is a limitation of your mind that has been over-trained on Newtonian mechanics, which is 100% false at this level.
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  135.  @btestware  You said we can't shoot ONE PHOTON AT A TIME. Yes, we can. Now, if you had said that we can't give it a proper trajectory, then you would have been correct. That is not what you said, though. You simply don't know enough physics to even chose the proper language. :-)
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  136.  @btestware  What you said was simply nonsense. It still is. ;-)
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  137.  @btestware  Because it doesn't matter. I already told you that you simply don't understand physics. Well, actually, you don't even understand photography. Lowering the light intensity doesn't change an image. It simply makes it darker and the necessary exposure time to get the same signal to noise ratio becomes longer. In other words: you don't have any clue about anything here. ;-)
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  138.  @btestware  Nothing stops you from performing nonsensical experiments. There is no law against wasting your time. ;-)
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  139.  @btestware  Sabine is a troll and so are you. So what? So nothing. ;-)
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  140. Observation isn't considered a special case. The special case is "non-observation" which requires complete isolation. Good luck with that... or, of you don't believe me, just watch how hard the quantum computing folks are struggling NOT to have the environment "observe" their computers. :-)
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  141. It's not a model. It's just a misunderstanding of trivial physics.
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  142. There is nothing to learn here. We are teaching in second year physics that observations are irreversible energy transfers. We gave you an example of those relating to quantum mechanics in high school when we explained the photoelectric effect. All of this is trivial, people are just not paying enough attention in school. :-)
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  143. @ Nope. It's all just in your head. :-)
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  144.  @DaneWheeler-ni2qj  Yes, you weren't paying enough attention in school, either. All of this has been explained to you.
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  145. @DaneWheeler-ni2qj I am simply telling you that we did explain to you what energy is in thirteen words. We also told you that quanta are small amounts of energy in six words. That is all there is to it at the physical level. That you can't remember and apply nineteen words is NOT my problem. I will give you some more attention, though, until your Mom comes home to fix your dinner, if you insist. ;-)
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  146. Everything in physics is about systems that exchange energy. That's just how physics works and that is how we teach physics even at the high school level. Not much of an insight there, I have to say.
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  147. Is something that doesn't exist orthogonal? No, not really. :-)
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