Schrödinger's Cat: Difference between revisions
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{{Useful Notes|wppage=Schrödinger's cat in popular culture}}
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{{quote|"Do you know that thought experiment with the cat in the box with the poison? Theory requires the cat be both alive and dead until observed. Well, I actually performed the experiment. Dozens of times. The bad news is that reality doesn't exist. The good news is we have a new cat graveyard."|'''[[GLaDOS]]''', ''[[Portal 2]]: Lab Rat''}}
The {{w|Schrödinger's Cat}} thought experiment is an increasingly popular [[Motif]] in fiction. Erwin Schrödinger originally presented it to demonstrate how the {{w|Copenhagen interpretation}}, the classic interpretation of quantum mechanics, was utterly idiotic. It has since been appropriated by the general public; the pop-culture version of the experiment now serves as a metaphor for uncertainty of the [[Truth and Lies|truth]], [[Sliding Scale of Fate vs. Free Will|fate]], Quantum Physics, [[Quantum Mechanics Can Do Anything|how quantum physics can do anything]], and whatever the hell is inside that box. Schrödinger's name has itself become a byword to invoke these ideas, among the general public, and on [[This Very Wiki]]. When used in a work of fiction, it can either show off the [[Author Appeal|writer's]] [[Genius Bonus|cleverness]], or [[Did Not Do the Research|lack of research]]. (Possibly both at the same time.)
In quantum mechanics, things like subatomic particles routinely exist in superpositions of states, and correct predictions of the outcomes of certain experiments can only be made by taking these effects into account.<ref>A classical example is the double-slit experiment for electrons where the resulting interference pattern is only expected if you assume the electron is in a superposition of states</ref> In this case, we're dealing with radioactive nuclei; a nucleus is at the center of an atom, and some nuclei are radioactive, so they undergo something called "radioactive decay". Heisenberg's {{w|Uncertainty Principle}} shows that it's impossible to directly observe this decay; we're dealing with particles so small that any equipment we have to monitor them would interfere with what they're doing. Even using the smallest equipment available to us, such as photons and electrons), it is impossible to get a complete picture on the state of an electron at any given moment; we can get reliable results about an electron's position, or we can get reliable results about its momentum, but we can't get reliable results of ''both''. Therefore, the best we can say about any particular radioactive nucleus is that, at any given moment, it [[Captain Obvious|may either be decayed or undecayed]]; that much isn't controversial.
The thought experiment was originally a critique of the [[wikipedia:Copenhagen interpretation|Copenhagen interpretation]] of Quantum Physics, where the cat can be [[Mind Screw|living and dead at the same time]] as a superposition of "realities". <ref>According to the Copenhagen equation, the cat is 50% alive and 50% dead.</ref> The paradox should be obvious. Note that the paradox only exists in the Copenhagen interpretation, the classic interpretation of quantum mechanics. According to the many-worlds interpretation, what actually happens is that ''the entire world'' splits into a superposition of worlds where the cat is alive, and those where it is dead.▼
The Copenhagen interpretation says that, because of this, each particle is both decayed and undecayed ''[[Mind Screw|at the same time]]'', in a superposition of "realities".<ref>According to the Copenhagen equation, the particle is 50% decayed and 50% undecayed.</ref> Schrödinger, however, thought that this idea was [[Insane Troll Logic|obviously flawed]]. So, he presented the following thought experiment:
* Imagine a cat sealed inside a box. There is a Geiger counter attached to the box, which itself is hooked up to a device primed to break open a vial of toxic gas inside the box, killing the cat inside.
* Inside the Geiger counter is a small amount of radioactive substance. The toxic gas device will only go off when the radioactive substance decays.
* The box is secure; until it is opened, there is no way to conclusively determine whether the cat is alive or dead.
* The cat is left in this box for an hour.
▲
The Schrödinger's Cat experiment thus posits that if we can accept that small particles (like the radioactive trigger) can routinely be in these kinds of states, then we have to accept that large objects (like the cat) can also be in these kinds of states, raising the question of why we don't routinely observe that.
{{tropenamer}}
* [[Schrödinger's Butterfly]]: The story is both real and [[All Just a Dream]] simultaneously.
* [[Schrödinger's Cast]]: A character is both alive and dead simultaneously, in different versions of the story.
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