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Cryptizard t1_ixcw0gj wrote

Reply to comment by ArgentStonecutter in Expert Proposes a Method For Telling if We All Live in a Computer Program by garden_frog

If you could answer that question you would win a Nobel prize.

Edit: sorry, I think I was attributing more to your question than you intended. The direct answer to how a particle “knows” it is observed is that it interacts with another particle. So observation is another way of saying that you are putting up guard rails on the system so it is forced into a smaller number of states. Whether that is a wave function collapse or whatever, it still makes it easier to compute.

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ArgentStonecutter t1_ixcxq42 wrote

My answer is to unask the question. Mu.

Look, consider the cat in the box thought-experiment. Everyone gets all hung up on the cat being in two states, and doesn't stop to think "what if the cat is also an observer". When the vial breaks the cat collapses the system. Or "what if the mechanism that breaks the vial of poison is also an observer". And that's just the lowest level of confusion. I'm saying, what if the experimenter isn't an observer?

They open the box and are now in a superposition, their wave function has two peaks in the states "looking at a live cat" and "looking at a dead cat".

The device, the cat, the experimenter, they're all just collections of particles. You can't meaningfully point to any of these collections and claim that the privileged role of the observer stops there.

And you can't go the other way, and say it's observed when it interacts with another particle, because quantum mechanical devices have been used to keep entangled states functioning as qbits while in a sea of particles, or even transmitted them over fiber optic cables made of zillions of particles.

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Cryptizard t1_ixcya3n wrote

There is no such thing as an entangle macro state, so everything you have written here is based on an incorrect assumption. Nobody actually thinks the cat is dead and alive, it is reduction ad absurdism to illustrate the limitations of schroedingers equation. Read a book on quantum mechanics.

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ArgentStonecutter t1_ixczyvr wrote

You say that with such insulted seriousness.

And yet there are many respected physicists treating the many-worlds interpretation entirely seriously. Here's a fairly recent paper arguing that it's actually required for conservation of energy in QM.

https://www.preposterousuniverse.com/blog/2021/01/28/energy-conservation-and-non-conservation-in-quantum-mechanics/

> What you and I think of as a “measurement” is just when a quantum system in a superposition becomes entangled with some macroscopic object (the “measuring apparatus”), which in turn becomes entangled with its environment (“decoherence”).

Edit: Oh, you blocked me? Well, bye bye.

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red75prime t1_ixd0u7u wrote

Correction. Whether the cat can be in a dead-alive superposition is an open question. The enormous technical difficulties of keeping and detecting such a state make its experimental testing a very distant prospect (if we won't find the definite line between quantum micro and classical macro before that).

I'm not sure what is the largest object that was kept in a superposition. Wikipedia mentions piezoelectric resonator which comprises about 10 trillion atoms.

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