I enjoy reading and thinking about quantum mechanics. Yes, it’s a weird and quirky branch of science, and scientists seem to agree that it’s valid, even though it doesn’t seem to make sense at our level of being and thinking.
I’ve read about this thought experiment for years, and here I’ve found the best explanation that works – for me.
I hope it explains things a bit better for you too.
Enjoy. Please feel free to comment.
Thanks,
JML
“Have you ever heard of the many-worlds interpretation of quantum mechanics?”
“Only in cocktail party discourse that would make you roll your eyes and heave deep sighs.”
“Well, there are certain experiments where the results only make sense if the system that’s being observed actually exists in more than one state (italics in original) until the moment when the scientist makes the observation.”
“Is this Schrodinger’s cat? Because even I have heard of that.”
“That’s the classic example. It’s just a thought experiment, by the way. No one ever actually did it.”
“That’s good. PETA would be all over them.”
“Do you know what it is?… You put a cat in a sealed box. There’s a device inside the box that is capable of killing the cat, by breaking open a vial of poison gas or something. That device is triggered by some random event generator, like a sample of some radioactive material that either decays – producing a bit of radiation – or doesn’t. You close the lid. The cat and the poison gas and the radioactive sample become a sealed system – you cannot predict or know what has happened.”
“You don’t know if the cat is alive or dead.”
“It’s not just that you don’t. You can’t. (italics in original) There is literally no way of knowing… Now, in a classical physics way of thinking, it’s either one or the other. The cat is either alive or dead for real. You just don’t happen to know which. But in a quantum physics way of thinking, the cat really is both alive and dead. (italics in original) It exists in two mutually incompatible states at the same time. Not until you open the lid and look inside does the wave function collapse.”
“Whoa, whoa, you had me until the very end!… When did we start talking about – what did you call it? A wave function? And how does that – whatever it is – collapse?”
“My bad… It’s just physicist lingo for what I was saying. If you were to express the Schrodinger’s cat experiment mathematically, you’d write down an equation that is called a wave function. That function has multiple terms that are superimposed – it’s not just one thing… A term here means a fragment of math – it is to an equation what a phrase is to a sentence.”
“…there is one term for “cat is alive” and another for “cat is dead”? Is that what you mean in this usage?”
“Yes.”…
“And when you say they are superimposed –”
“Mathematically it just means that they are sort of added to each other to make a combined picture of the system.”
“Until it “collapses” or whatever.”
He nodded. “Multiple terms superimposed is a quantum thing. It is the essence of quantum mechanics. (italics added) But there is this interesting fact, which is that that kind of math only works – it only provides an accurate picture of the system – until you open the lid and look inside. At that point, you see a live cat or a dead cat. Period. It has become a classical system.”
…“that’s what you mean by the collapse of the wave function.”
“Yes, it’s just physicist-speak for the thing that happens when all of the superimposed terms – the descriptions of different possible realities – resolve into a single, classical outcome that our brains can understand.”
“Our scientific, rational brains, you mean…”
“Exactly.”
…“If you buy the many-worlds interpretation of quantum mechanics, it means that all possible outcomes are really happening somewhere.” (italics original)
“There’s one world with a live cat and another with a dead cat.”
“…fully independent realities that are the same except that in one of them, the cat’s dead, and in the other, it’s alive. And the quantum superposition? That just means that the scientist standing there with his hand on the lid of the box is at a fork in the road. Both paths – both worlds – are open to him. He could shunt into one, or the other. And when he hauls the lid open, the decision gets made. He is now in one world or the other and there’s no going back.”
From “The Rise and Fall of D.O.D.O.” HarperCollins 2017. Stephenson, Neal; Galland, Nicole. Pp 32-34.