Schrödinger’s cat is a famous thought experiment in quantum mechanics that feels quite absurd in a real-life scenario. Austrian-Irish physicist Erwin Schrödinger proposed this thought experiment after observing the problem of Copenhagen Interpretation of quantum mechanics.
What Does Schrödinger’s Cat Experiment State?
Schrödinger’s cat experiment (thought experiment) assumes a hypothetical cat present inside a sealed box.
- Firstly, the sealed box contains a flask of poison and a radioactive source. Secondly, there is also a Geiger counter (one that is used for detecting radioactivity and also used in radiation dosimetry).
- Now, assume you haven’t opened the sealed box yet. So, the experiment states that unless we have opened the box, the cat is both dead and alive (strange! Right?). Yes, it’s quite strange even to consider that the cat is both dead and alive.
What are the interpretations of Schrödinger’s cat experiment?
In this paragraph, we’ll see what this “dead and alive” actually means quantum mechanically.
- The “dead and alive” state of the cat interprets quantum superposition. Well, what is quantum superposition? When two states are added together, and as a result, they produce another valid quantum state, we shall call it quantum superposition.
- In fact, we can represent every quantum state as the sum of two or more various distinct states. Actually, this is what Schrodinger was trying to convey through this thought experiment.
- Unless we open the sealed box and observe the ongoing experiment, we cannot simply predict whether the cat is dead or alive. Until that moment of observation, the cat will be in a superposed state of both dead and alive. At the moment we open the box, we will find it either dead or alive; not both.
What does observation have to do anything with the results of the experiment?
First of all, an observer plays a very important role in quantum mechanics. The simple act of observing the electron moving through a slit can totally change the consequences of the experiment. For instance, double slit experiment beautifully depicts the aforementioned fact. Before observing Young’s double slit experiment by a detector, the electron was giving totally different patterns than that after the placement of a detector. Hence, this is called the observer effect. There occurs a thing called wave function collapse that make this happen. Double slit Experiment of Quantum Mechanincs
What is the collapse of a wave function?
Here, I will try to make you understand this concept using a simple example.
Consider your friend is in her room. And you don’t know exactly where she is inside the room. Is she on the bed watching some series? Is she on her chair studying? Or Is she on the floor practising yoga? You don’t know for sure where she is exactly inside her room. But you know for certain that she is inside the room. The probability of you finding your friend inside her room is equal to one.
Now, we will distribute the probability of you finding on her bed, on the floor or on her chair. Now see carefully. Until if you have opened the door, you have almost a distributed function for all the possibilities. But once you open the door, you come to know where she is exactly. You realize she is on her bed. Therefore, suddenly, your view changes. The distribution function that you did before suddenly becomes one big mountain kind of graph in the bed category. Therefore, this is what you call that the wave function collapsed. Exactly the same occurs in quantum mechanics.
This graph shows three possibilities. They are: your friend on the bed, on the floor, on her chair.
Here the wave function collapsed into a single wave. Ultimately, it shows that you found your friend on the bed only.
Collapse of the wave function in case of the Cat:
When you opened the sealed box, the wave function of the cat being alive or dead collapsed. If the radioactive material had decayed, then the cat would have been dead. If not, the cat would have been alive.
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