Wanna learn some basic principles of quantum physics? I got ya!
I love and adore quantum physics and I hope I'll make a job out of this hobby I have. And I want people to see the beauty of quantum mechanics even though this shit doesn't make any se...
The state of a particle can let us define its position in space-time, its speed, and its energy. In quantum physics, we use the symbol |ψ⟩ to define the quantum state of a quantum system like an atom, an electron or a photon... Superposition states that it can be in two or more states at the same time.
To explain this better, we know that in quantum physics a particle, let's say for example an electron, can be in some levels of energy, but can’t be in levels of energy in between. This picture here shows better what I’m trying to say.
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I’m not good at explaining anyway.
So you can see in this image that we denoted the authorized energies from 1 to 4. Well simply put, in superposition, our electron can be in a state of |1⟩+|2⟩. Or, in terms that would make more sense to us humans, in the states |1⟩ and |2⟩ at the same time. The particle will then settle for one of the states when it’s measured. Mind blowing right? Well I’m not finished.
Have you ever heard of Schrodinger's cat? It’s a thought experiment made by our dear Schrodinger, an Austrian physicist, to prove that the principle of superposition is wrong. Principle that saw the day thanks to his OWN mathematical equation. I told you I’m not finished :D Physicists and scientists all around the world were trying to find this one universal mathematical equation that would explain everything about the universe and us to answer all our philosophical questions. Some of them did get close to it like Einstein with his theories of special and general relativity E = mc2 , Newtons’ law of gravitation F = G(m1m2)/R2 and many others. And Schrodinger was one of them. While in his trip on vacation, he finally found this equation
∇2ψ+8π2 m(E – U)ψ/h 2=0
where ψ is the wave function, ∇2 the Laplace operator, h the Planck constant, m the particle's mass, E its total energy, and U its potential energy.
It’s the fundamental equation in quantum mechanics like Newton’s is in classical physics. Only, this equation led to this principle we’re talking about here, and Schrodinger was totally not okay with this. So he proposed this thought experiment that is now known as “Schrodinger’s cat”.
Now imagine that you have an atom, ok? This atom is in superposition. Let’s say for example that it’s radioactive and normal at the same time (the more appropriate way to say it would be “ in a state of radioactive + normal” but let’s put it like that to make it more simple to understand. Not like it is but anyway) When an atom is radioactive it becomes really unstable, and starts falling apart sending particles.
So let’s say we put that atom in a box, and with it we put a detector that if activated will knock down a hammer, we also put a poison bottle, and finally, a cat.
If the atom sends a particle the detector would detect it (no shit sherlock) and activate the hammer that would break the poison bottle that would instantly kill the cat.
Now if the atom is in a state of superposition, that means it will send a particle PLUS not send a particle. Which means that the detector and the hammer will also be in a state of activated plus unactivated, the poison bottle in a state of broken plus not broken, and the cat in a state of dead plus alive. (We can’t say that the cat is alive and dead at the same time. That would be quite false but people tend to phrase it that way to give it more sense. I mean hearing that a cat is alive PLUS dead doesn’t really make sense right? In fact, quantum physics doesn't make sense. Now that we’re talking about it, LIFE doesn’t make sense- anyways)
So, I said that this thought experiment was imagined to prove that superposition is wrong right? And I mean Schrodinger is not totally wrong. We don’t often see cats like this in our everyday life. But I wouldn't say that he is totally right either.
Remember what I said earlier? That since the atom is in superposition the detector would also be in superposition? well that’s theoretically impossible. Since the detector is also made of atoms, that means that the atom in superposition is dealing with a bunch of other atoms. And the idea here is basically that the superposition principle would disappear, evaporate, vanish, fade, go, and many other synonyms.
So superposition, and in fact, any principle in quantum mechanics, totally stops working when coming in contact with our macroscopic world. I mean superposition stops working just because we observed it. We didn't even touch it or make it go in contact with anything else we just measured it.
But then, if a particle in superposition, when measured, settles for one state or the other, what proof do we have of the existence of something called superposition?
Well, you can go back to the first chapter, with the double slit experiment made by Thomas Young in 1801. We have a proof of quantum superposition thanks to this experiment. It played a big role in proving that superposition, at quantum scales, exists.
