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what would happen if a CC Camera or videocorder is put along with Schrödinger's cat inside the sealed box? Would it influence the outcome?

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  • $\begingroup$ This is the same as when you place a detector by one of the slits in the double slit experiment: the diffraction pattern disappears $\endgroup$ – Beta Decay Jan 29 '18 at 13:43
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    $\begingroup$ Note the following: "Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics.". So Schrödinger never meant to say "This is how it will be in reality". What he meant was: if(!) the Copenhagen Interpretation is accurate, then it leads to this totally absurd situation. Therefore we have a problem with the Copenhagen Interpretation, because we intuitively know the cat is either dead or alive, not both. $\endgroup$ – MichaelK Jan 29 '18 at 14:11
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I assume that the camera in your thought experiment is not a gate out the box i.e. it also doesn't interact with external world until you open the box.

The crucial point about the Schrödinger's cat thought experiment is that it's not the cat who is in the superposition of the macroscopically distinct states. As a matter of fact you can't assign a pure quantum state to the cat alone, only to the whole interior of the box. So what you get is basically a bigger Schrödinger's cat - the cat, the detector, the air, your camera should all be considered a "Cat" that is in the quantum superposition.

If you ask whether the addition of the camera destroys the quantum superposition of the macroscopically distinct states of the interior the answer is no.

However you can ask the following question. If you open the box and measure the interior what is the probability that the cat is found to be dead whereas the recording of the camera shows it to be alive?

If your cat and camera actually consist of several atoms this probability actually may be quite significant. However for macroscopic system for those few degrees of freedom you're actually measure the process of the quantum decoherence happens. In that case this probability may actually be so small that it should be considered zero for all practical purposes.

So while for the external observer the whole interior should be considered to be in the very nonclassical state until you open the box, the camera recording extracted in the end will show the approximately classical behavior. The "collapse" happens for the camera, not for you.

If instead the camera is constantly translating to you through some little hole in the box (and this is the only interaction of the interior with the external) then you will destroy the superposition. To what extent is actually a difficult question to answer without details of your communication with the camera. If it is very weak you may get too little bits and too much noise to distinguish dead cat from alive with high degree of certainty and that will determine how much the superposition inside decoheres.

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  • $\begingroup$ I am puzzled by your assertion that there is some probability (in case of molecular camera and cat) for the recording on the camera to be at at odds with the fate of the cat. Could you point to a specific model or experiment illustrating this point? $\endgroup$ – Stéphane Rollandin Jan 29 '18 at 15:04
  • $\begingroup$ What'd happen if camera is transmitting the live recording wirelessly to server through Wi-Fi/IOT? $\endgroup$ – Aoi. T_015 Feb 4 '18 at 6:33
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Yes obviously, you are observing the system and that collapses the Superposition of wave function to a single wave function giving a specific result. The basic ideology is like this: Suppose you are conducting the experiment and until unless the box is opened or you observe the situation inside the box implicitly there are only two possibilities, the is either dead or alive. Now this either or statement makes a very deep sense in quantum mechanics. If u1 and u2 are the states of a system, then u = u1 + u2 is a state too! Similar analogy is applied here. Both dead and alive are possible states of the system and now applying the probability theory we get the probability of collapsing to each state is 50%. Therefore until unless you observe the cat, it is both dead and alive [At Least 50% alive] but when u open the box you find it is 100%dead [Wave function collapse] so you killed the cat. So the answer to your question is yes!!

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  • $\begingroup$ Putting the camera inside the ideally isolated box is not observing unless you have the connection to the camera. $\endgroup$ – OON Jan 29 '18 at 14:45
  • $\begingroup$ Wow, what is the use of that camera then! By the way, the result depends only on your observation as i said above!! $\endgroup$ – Siddharth Mishra Jan 29 '18 at 15:30
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The unfortunate Schrodinger cat is used as a proxy for a Geiger counter. Since the poison will be released when a nuclear decay happens, a quantum mechanical state, the first level of detecting a decay is a Geiger counter. The thought experiment stresses the quantum mechanical probabilistic behavior of decays. The cat is collateral damage, irrelevant to the real cause of the probability distribution of which one instance will be the deadly decay.The cat is alive until there is a decay. Observing with a camera the cat will show that it is alive or dead, but will not affect the decay from the nucleus. It changes the level of the observer's knowledge, not of the experimental state.

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