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    There’s this funny history in physics where some of the really well known metaphors were meant to be arguments against a thing by reductio ad absurdem.

    For example, Fred Hoyle used the term “Big Bang” to argue against the idea of an expanding universe with a single point of creation. (He thought it was a religious argument rather than a physical one.)

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      It’s too late now, the cat is already out of the bag.

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        See, I don’t know anything about QM.

        Then why write this blog post? Why add to the confusion?

        It’s challenging even for experts to communicate an understanding of quantum phenomena, and everyone who hasn’t gone through all the math almost certainly has a completely incorrect understanding. Anything that doesn’t involve at least some linear algebra is at best a limited crutch intuition, so it’s pointless to argue too much about off-hand comments by historical figures (who, by the way, didn’t have anything like the level of understanding we have now).

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            Any sense of clarity you got from this article is almost certainly superficial and won’t hold up to consideration. The “correct” solution to schroedinger’s toy problem depends on how collapse works, which we don’t know. I’ve been studying QM for years and I would only claim to have a superficial understanding of the consequences of various popular collapse theories.

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          I liked the link a comment writer (calling themselves spaghetti) gave.

          As mentioned earlier, the supposed paradox relies on a flawed understanding of Quantum Physics. The flaw lies in not knowing what it means to observe something; observation is not the passive thing like in the world of the everyday, but an active process. In the theoretical box (no physicist would actually do this; it’s highly unethical), the observer isn’t the scientist, it’s not even the cat; it’s the Geiger counter, and it keeps the wave function collapsed into either 100% alive or 100% dead, and not 50% both.

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            Be aware it’s bollocks. The state of the cat is entangled with that of the Geiger counter and thereby with that of the particle, but as long as the box remains isolated from the rest of the universe all three remain in a superposition state.

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              The Geiger counter would collapse the wave function though.

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                Not from the perspective of an observer outside the box. Decoherence isn’t magic.

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                  It’s not magic, which is why you don’t need squishy meat cameras to collapse the wave function. Consider what happens if we replace the cat with a grenade: would the box be in a superposition of exploded/not-exploded?

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                    If it was isolated from the rest of the universe? Yes.

                    Let’s do a more realistic example: the dual slit experiment. We understand that electrons (despite being particles) create diffraction patterns (wave-like behavior) due to the probabilistic nature of QM. The electrons travel through both slits (or, more pedantically: the traveling wave of the electron goes through both slits). But we can do the same thing with molecules. The individual atoms in the molecule are interacting with each other, but so long as no atom in the molecule interacts with a particle outside of the molecule before hitting the target, the whole system is in a superposition.

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                      Well, if you want to get technical…

                      The dual slit experiment works with electrons because of wave-particle duality: specifically, a massive particle has a corresponding de Broglie wavelength inversely proportional to its momentum. Diffraction happens with light when the wavelength is less than width of the aperture. The same thing happens with particles. If an electron is moving at, say, .1c (low enough we can roughly ignore relativistic equations), the de Broglie wavelength would be about 25 picometers. That’s large enough demonstrate diffraction of the wavelength. On the other hand, a 1 gram object moving a 1m/s is less than 1e-18 picometers. That’s several orders of magnitude smaller than the width of a proton. You are not doing to see diffraction this object!

                      That’s why we don’t see QM behavior in our day-to-day lives: macroscopic objects are just too massive to meaningfully experience them. In our box experiment, the same would hold true. The geiger counter is absolutely a macroscopic object regardless of how else the rest of the universe interacts with it, which means it can (furious air quotes) ‘observe’ the radioactive decay just fine.

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                        That’s why we don’t see QM behavior in our day-to-day lives: macroscopic objects are just too massive to meaningfully experience them.

                        This isn’t the case.

                        There’s a thermodynamic argument for why measurables look continuous and smooth with large objects. However, scenarios like schroedinger’s cat are specifically designed to subvert this argument. With nonlinear systems (like Geiger counters, which take a small effect and magnify it many times), you can entangle a macroscopic system with a system that is small enough to obviously exhibit quantum behavior. If unitary physical theories are correct, the large object would also be in a quantum superposition.

                        It’s not entirely clear why/how this doesn’t manifest in obvious ways at large scales. This is part of the measurement problem, and it’s an area of active research.

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                  We don’t actually know how collapse works, but that’s probably wrong. The Geiger counter would, in any unitary theory (which is many of them), enter a superposition state as well.

                  Again, we’re not really sure how collapse works, so at best you’re just speculating.