Comments by "Lepi Doptera" (@lepidoptera9337) on "Understanding Quantum Mechanics: Schrödinger's Cat Experiments" video.

  1. That's the misunderstanding. The box symbolizes the complete isolation of the free quantum system. What's in it is entirely irrelevant. It's still being described by a quantum mechanical equation WITHOUT outcome. The outcome always requires a system that is OPEN to a measurement device. I don't believe Schroedinger understood this and his cat doesn't make it any easier to "grok".
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  2. The decay of a nucleus is described in quantum mechanics by a superposition of states. One state is the intact nucleus times the empty space state. The other states are the decayed nucleus and the ejected photon/electron/alpha state. The latter is a continuum of free particle states that fill the entire volume around the nucleus. If we can make a completely closed, perfectly reflective box around the nucleus (like imagined by Schroedinger's cat), then the decay is never complete, i.e. there is a finite (but small) probability to find the nucleus in its non-decayed state at all times, even long after many decay time constants have elapsed. If we make this shell very close to the nucleus, then it will basically never decay. How could it? The decay energy has nowhere to go. The effective binding energy of the nucleus has been altered by the reflective potential of the box and it is no longer unstable.
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  3. Superposition does not "exist" at all in a physical sense. It's a property of the theory, not a property of nature. You have seen this phenomenon before, by the way. Superposition in quantum mechanics is EXACTLY like the description of vectors as linear combinations of base vectors. What linear combination we need to make a given physical vector depends on the choice of the base (and we can determine the coefficients with a simple "projection" procedure by taking a scalar product between the base vectors and the physical vector). In the exact same way the "superposition" of the wave function is a linear combination of base states. Which base states we chose is irrelevant and nature does not know anything about our choices.
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  4. It wasn't a joke. Schroedinger simply didn't understand quantum mechanics. The solution to it is actually completely classical and it was known since the late 19th century. Look up "Poincare recurrence".
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  5. We know exactly what the math means. At most you don't. ;-)
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  6. Because it is also isolated and therefor the trigger system is also not in a classical state from the viewpoint of an external observer. The "solution" to this was known long before Schroedinger. It's called the "Poincare recurrence theorem". It basically says that an isolated system has a finite phase space and within that phase space the system takes on all possible states if we are willing to wait long enough. This means that no matter how unlikely the initial state was, eventually, after a very, very, very long time the system will return to its initial state. The so called "Poincare recurrence time scale" is insanely long, though. Much, much longer than the lifetime of the universe. And the quantum mechanical recurrence time scale is much longer than that, still. But since Schroedinger didn't perform a time scale separation in his example his argument that we don't know if the cat lives or dies is valid. Eventually the cat will live, again (for a very short amount of time). This doesn't contradict the reality that a cat in a closed box is always dead (because it runs out of oxygen). Reality is simply the short term solution and Schroedinger's choice of superposition is the long term solution. One can calculate this explicitly for an atomic system with an initial state <excited atom| vacuum ground state| that decays into a new state <atom in ground state| single photon in vacuum|. In a completely isolated (mirrored) box the photon emitted by the atom will, eventually, be reabsorbed by the atom and it will get back to its initial excited state again. That is the real solution to Schroedinger's cat. It's trivial and says absolutely nothing about quantum mechanics.
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  7. The nucleus is not in superposition, either. What is in superposition is the wave function that describes the average behavior of an infinite number of copies of the experiment. This is perfectly analogous to the case of classical probabilities. Dice that are still rolling are not in a superposition of the numbers 1 to 6. They are simply in no state that one could describe with 1 to 6 at all (because they have a second set of properties that are not static: momentum and angular momentum). Where quantum mechanics differs from dice is the "readout" mechanics. Dice have one standard readout: it's the friction of the table that brings them to a halt. The equivalent of "friction" in quantum mechanics is the energy transfer to a measurement system, which depends in the internal details of the measurement system. That's the reason why not all measurements are equal and not all of them are interchangeable.
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  8. This was all understood in 1927 and in greater level of detail in 1932. Why are you telling all of us that you didn't read the literature? ;-)
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  9. Don't worry. It doesn't exist. ;-)
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  10. Measurements do have a definite outcome. It's just not 0 and 1. Its an amount of energy, momentum, angular momentum and charge. This combination of physical properties is called "the quantum".
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  11. Yes, you don't understand physics. ;-)
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  12. Yes, and all of that was complete nonsense. ;-)
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  13.  @williamwalker39  There is no rule on the internet that I have to disprove any of the bullshit that you throw at it. :-)
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  14.  @williamwalker39  All you have given us was a huge load of bullshit. I will treat it for what it is and nothing else. ;-)
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  15.  @williamwalker39  Like I said, there is no rule that I have to. I am just here to feed the pigeons. :-)
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  16.  @williamwalker39  Where is my ansible? ;-)
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  17. Yes. That was 100% false. :-)
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  18. We don't need better math. We need students who are paying attention in high school when we are teaching it. ;-)
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  19. It wasn't a joke. It was Schroedinger's polemic against the Copenhagen interpretation or, better, against his misunderstanding of it. If you follow the literature, then you will find that von Neumann had basically cracked all of quantum mechanics in his book published in 1932. Strugglers like Schroedinger and Einstein probably didn't read it or they didn't understand it and they were still fighting with windmills years later (1935 to be precise, that's when both Schroedinger's cat and the EPR paper were published).
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  20. We didn't ask you to waste a lot of bits on bullshit. ;-)
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  21. Why are you telling us that you had a really crappy high school experience? ;-)
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  22. There is no "smooth transition". Why? Because there is no smooth transition between closed, reversible and open, irreversible. These are hard binary choices that we have to make. Either a physical system is completely closed and isolated and then it has fully reversible dynamics or its open and then it has irreversible dynamics. It's already like that in classical physics, we just don't teach this fact very well, so people get confused when it comes to quantum mechanics.
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