Submitted by garden_frog t3_z1n43x in singularity
ArgentStonecutter t1_ixci0kq wrote
Reply to comment by Cryptizard in Expert Proposes a Method For Telling if We All Live in a Computer Program by garden_frog
This only applies if you treat the collapse of the wave function as a thing that actually happens.
Cryptizard t1_ixciea1 wrote
Which interpretation of the measurement problem allows for quantum mechanics to be easily simulated? Whether you believe the wave function is real or not doesn’t change the math that governs quantum states.
ArgentStonecutter t1_ixcneis wrote
I didn't suggest any of them did.
Cryptizard t1_ixcokv8 wrote
Cool so you have no point then. Thanks for contributing.
ArgentStonecutter t1_ixct4mf wrote
You said that something is harder to compute if it’s not observed. That’s only true if the collapse of the wave function is a real thing, and is one of the reasons for postulating the collapse in the first place.
Cryptizard t1_ixctiy1 wrote
No, it’s not only true if the wave function collapses. If you believe in an interpretation where the wave function doesn’t collapse, then the observation still puts constraints on the possible states that a particle/system can be in and it is still easier to simulate.
ArgentStonecutter t1_ixcvoes wrote
Now you're the one that's claiming some interpretations make it easier. Instead of being an actual thing that happens, observation is now a performance hack.
How does the system know "observation" has occurred?
Cryptizard t1_ixcw0gj wrote
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.
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.
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.
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.
> 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.
[deleted] t1_ixdqwt9 wrote
[deleted]
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.
PIPPIPPIPPIPPIP555 t1_ixh2ner wrote
No if the Collapse of the wavefunction is not a real thing decoherence have to be a part of the nature of the wavefunction that we do not know how to describe right now and then when we say that we measure a particle we are just interacting with it in a maner that the decoherense in the wavefunction constraints it to a smaler space of possible states and the wavefunction is exactly as complex and difficult to simulate is it was when it was in a superposition state
PIPPIPPIPPIPPIP555 t1_ixh3prl wrote
But the wavefunction does have to collapse or decohere at some point because too large objects can not be in an entangeled superposition so if a macroscopic measuring device decoeheres and meauser a small quantum state that can collapse into 2 possible states the timeline of the universe either splits into 2 separete timelines that will not interact with each other because they are too different on the macro scale because of the measurement on the quantum nano scale. If the people that are using the measuring device to detect one of 2 possible states in the quantum state becomes entangled with the quantum state when they measure it the 2 different sates with the scientists can not interact with each other and will be separeted into 2 different timelines that will not interact with each other so if you believe that the wavefunction does not collapse it does either decohere in a deterministic maner and follows a skngle timeline or it separetes into 2 distinct and separeted timelines that will not interact and the wavefunction is not easier to calculate than classical macrosciopic physics in neither of these cases
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