I don’t understand..
When we observe it, we can define it’s state right? But it was never in both states. It was only in one, we just didn’t know which one it is. It’s not like if I go back in time and open the box at a different time, that the outcome will be different. It is one of the 2 outcomes, we just don’t know which one until we look. And when we look we discover which one it was, it was never the 2 at the same time. This is what’s been bugging me. Can anyone help explain it? Or am I thinking about it wrong?
In: Physics
You are taking it too literal. Schrödingers cat is just a thought experiment to help you understand the concept of superposition of wave functions. No one is saying that it actually applies to anything bigger than subatomic particles, let alone macroscopic entities like animals. Think about it this way: You may not know if the cat is dead or alive without looking, but the cat does.
You need to think about it quantum mechanically. Superposition exists. We know this because of experiments like the double-slit experiment. We have also been able to out whole atoms into superposition.
Put the cat in the box with the poison and the radioactive isotope and detector. Seal the box off from the rest of the universe (which is practically impossible). The box and everything in it is in superposition. It’s not a superposition of alive and dead. It’s a superposition of all possible quantum states.
When you open the box, the superposition collapses to one of those states, the most likely being a cat that is alive or dead.
I think the basic point of Schrödinger’s cat is that you can’t in any way, **predict** what’s going to happen to the cat **until you open the box**. Even if you knew the state of every atom inside the box and knew the cat on a cellular level, you wouldn’t know if it would live or die until you **experienced** it. This is because “the cat dying” is tied to a quantum event that isn’t really defined until we perceive it, which is the point of the parable.
Flip a coin. While it’s in the air is it heads or tails? Or both? Or neither? You can’t know until it lands.
Trying to ELI5 as it’s a complicated thing.
In superposition particles can be in more than one state. For example, a qubit in quantum computing is both 1 and 0 at the same time.
It’s only when you measure it – observe it – that it will have a clear state: 1 or 0.
The thought experiment includes an atom that can decay at any point – send out a radioactive particle. But as long as you don’t measure it, it’s both decayed and not decayed. Moving further, it means the bottle with the poison is broken and not broken at the same time, and this the cat is alive and dead at the same time. Only when measuring- observing by opening the box, you force the atom to be in one of the two states, and thus also the bottle, and thus also the cat.
Since it sounds as nonsense – how could a cat be dead and alive at the same time, Schrödinger wanted to show the superposition thing was ridiculous.
Take the example of a die. It has a value between 1 and 6. As long as don’t look, all numbers have an equal chance to face up. When you look, the state will be one of those numbers. In QM, you’d say that before observing, the die _has all numbers facing up at the same time_, until you look which will cause it to have only one value. That’s obviously not true.
Fun fact: Einstein was the first to come up with a thought experiment to show it was nonsense to him. Instead of a cat, it was a barrel of gunpowder that was both exploded and not exploded at the time. But somehow the cat became famous, and not the gunpowder.
It’s not an actual cat. It’s a thought experiment. It was never done as an actual experiment. A thought experiment is a sort of metaphor that smart people use to entertain themselves.
So the cat is a metaphor, the box is a metaphor and the whole thing is a metaphor.
The goal of the whole metaphor is like this: “hey, look at the electrons how weird, they are in a state that can be A or B but we never know which one they choose until we know”. And that’s it.
It’s a joke he made to show how a lot of people misinterpret quantum theory.
Your confusion is EXACTLY what he was going for!
Sometimes people put things down on paper that seem to add up, but don’t actually make any sense in the real world.
So, the idea is – I can imagine different outcomes for the same event before it happens (superposition) and prepare for them (mathematically), then when I find out which one it actually is (state collapse) I am ready for it!
Back in the day when people were first learning this they thought it meant “all the things were really happening all at once until someone looked at it, then somehow magically just the one thing would become real” like we have super powers or something. So Schrodinger made his ridiculous “cat thought experiment” to show them how silly that would be.
>It is one of the 2 outcomes
Incorrect. It is one of infinite outcomes, with some outcomes more likely than others. The problem is we don’t know which outcome occurred without measuring/observing. With enough information, you can guess without observing, but the problem is that no matter what variables you include and no matter how finely you measure you won’t know for certain what the outcome is with observing because there will always be errors in your measurements.
The point of the thought experiment was an attempt to use a simple allegory to explain the observation that the universe isn’t “fixed”. At the quantum level, the universe is a mass of probabilities that don’t resolve until there is an interaction that forces resolution.
I am not a physicist, but here is my limited knowledge and understanding of the thought experiment.
It seems like you are taking the experiment literally; I open the box now, the cat is alive, I go back in time and open it, the cat is alive, how can this be?
Schrödinger’s cat is a thought experiment regarding quantum superposition. Basically, he uses the cat as an analogy of determining the position of quantum particles. This is his interpretation of quantum particles being a wave function, existing over a select volume of space with a probability of being in any one point of said space.
How this then relates to the cat is that you can only confirm/determine the exact position of the particle at the moment a photon bounces of it and hits your eye; the act of observing the particle.
So, bringing this back to the cat, the live status of the cat simply represents the position of the quantum particle. It is a probability of live or dead, but only when you open the box and directly observe it, you will get the exact status of the cat.
I have left out the bottle of toxins and the hair trigger set to release the toxin out as I think that may complicate my demonstration to you.
It’s a metaphor, you’re not supposed to take it literally. “Aliveness” and “Deadness” of cats are not eigenfunctions of the Hamiltonian. The cat does not exist in a superposition of states until you look at it.
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