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Schrödinger's cat. What is this cat in a box theory suggesting? What does it teach? Do you agree with it?

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Erwin Schroedinger introduced the cat thought experiment in 1935 as a reductio ad absurdum of applying the quantum rulebook (superposition of states) directly to macroscopic objects. The point is conceptual: when a microscopic quantum event is coupled to a macroscopic outcome, the formalism yields an entangled state that, taken literally, implies a superposed macroscopic result until something causes a transition to a definite outcome. That tension is what people mean by "the measurement problem."

There are several mainstream ways to resolve or reframe that tension. The Copenhagen-style view treats measurement or "observation" as the point where the wavefunction's probabilities convert to a single outcome. The Many-Worlds (Everett) view removes collapse entirely and says all outcomes occur in branching worlds. Decoherence shows why macroscopic superpositions rapidly lose observable interference by entangling with the environment, making them behave like classical mixtures (but it does not itself posit a physical collapse). Bohmian mechanics restores definite particle trajectories guided by a wavefunction. Objective-collapse proposals modify the dynamics so that superpositions of sufficiently large systems spontaneously localize. Each approach answers a different metaphysical question—what ontology you accept—while agreeing on standard laboratory predictions in most cases.

For everyday practice and experiments, environment-induced decoherence is the most useful concept: it explains why quantum effects vanish at the macroscopic scale unless a system is extremely isolated (the reason quantum computing is so hard). There are laboratory demonstrations of progressively larger coherent systems, so the boundary between quantum and classical is experimental and not a mystical divide.

As asked about interpretation, note that differences are philosophical as much as physical: interpretations disagree on "what is really happening" rather than on routine calculation. offered a programming analogy that is pedagogically useful for thinking about observer effects, but its limit is that classical ignorance or reordering is not the same as quantum coherence and interference. For a compact technical handle, the density-matrix / partial-trace treatment is the standard way to show how coherence is lost to the environment.

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Member Avatar for pritaeas

What is this cat in a box theory suggesting?

That observing an experiment may have consequences for it's outcome.

Member Avatar for mike_2000_17

I encountered a nice programming example of Schrödinger's cat. If you have this code:

int main() {
  int a, b, c;
  a = 1;
  b = 2;
  c = a + b;
  cout << "value of c is " << c << endl;
};

Then, the compiler is allowed to re-order the operations in any way such that the result is the same. So, technically, you don't know (without looking at the assembly code) for sure in what order the operations will be performed (because the value-assignment of a and b could be reversed without any difference in the outcome). But, if you wanted to check that the order was indeed the way it was written in the code, you'd have to add some print-outs:

int main() {
  int a, b, c;
  a = 1;
  cout << "value of a is " << a << endl;
  b = 2;
  cout << "value of b is " << b << endl;
  c = a + b;
  cout << "value of c is " << c << endl;
};

But the problem now is that because you have added those print-outs, the compiler is now obligated to perform the value assignment of a before the first print-out, and then do the assignment of b before the second print-out. Which means that you won't be able to answer the question about the order of operations from the first program, because you've now modified the thing you were trying to observe.

So, the whole point of this "cat in the box" analogy is just to state the reality that some things cannot be observed without affecting the conditions of the experiment to the point that the phenomenon you were trying to observe disappears. This does have some implications on fundamental theories too, but it is mostly a matter of technical problems with experiments. Another example is the problem of observing experiments on zero-point energy, which is characterized by a complete absence of electro-magnetic radiation (i.e., light), how would you go about "shining a light" on what goes on there?

More practically though, it is just a reminder of the fact that you always have to be careful about the consequences of making an observation on the experiment itself. This can be as simple as making sure that the instruments you use do not have contaminant on them, like having some organic residues on a probe that extracts samples of martian soil for detecting traces of life on Mars.

Edited by mike_2000_17 because: typo
Member Avatar for BigPaw

I suppose this goes out to others then, would you say that these are the only interpretations? If there are further interpretations, how do they harmonise or contradict? What is it that makes your interpretation, or the interpretation you have learned, believable?

Member Avatar for pritaeas

Here's another interpretation on 9gag.

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