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Einstein and Schrodinger's Quest for a Unified Theory led to a Titanic Clash
StartsWithABang writes When it comes to the very nature of quantum mechanics — about the inherent uncertainty and indeterminism to reality — it's one of the most difficult things to accept. Perhaps, you imagine, there's some underlying cause, some hidden reality beneath what's visible that actually is deterministic. After all, a cat can't simultaneously be dead and alive until someone looks can it? That's one of the problems that both Einstein and Schrödinger wrestled with during their lives. An investigation of that story, their work on that front, and their friendship that ensued as both pursued that same end is thoroughly investigated here by physicist Paul Halpern.
1. if detecting a particle *determines* its state vs *observes* it state, (the main point of conflict) then:
2. There is no perfect isolation, a vacuum is not perfect, and does not shield magnetic fields or other effects.
3. Interactions with other stuff *IS* detection. That other stuff does get influenced depending on the state of the particle. The magnetic field does influence the world around it.
4. Your photon has a magnetic field, and that influences the matter around it, depending on its wave function.
5. And thus it is detected ALL THE TIME BY EVERYTHING AROUND IT, long before you put it through a diffraction grating, or whatever test you dream up.
6. Thus your Quantum uncertainty theory can never work, the particle/photon/whatever's state MUST be determined BEFORE *you* detect it by its interactions with other matter.
Interesting argument, but I'm not sure that I agree on point 3. We've got a number of very subtle experiments that have tried to tease out exactly where the observer effect starts and ends. Bell's Theorem and EPR prove that no hidden variables exist, so these properties are not things that are stored and just discovered when we check - the behavior that's observed can only be explained if they "decide" what to be when we make a measurement.
Also, consider things like the quantum eraser, and delayed-choice quantum eraser - it seems like the universe is keeping track of what we are looking for and how, such that we can "detect" a particle, destroying the wave-nature and interference pattern, but then "erase" our knowledge of the detection, and see the wave-nature restored.
Finally, with your point about the bricks, you seem to be saying that maybe half-particles exist but we can't detect them because of limitations of our instruments - but discrete, quantum-mechanical behavior extends to far more than just particle counts and even positions. The Stern-Gerlach apparatus being a clear counterexample to your point. The behavior observed there doesn't depend on dealing with any particular number of particles - it just shows that particle spin is entirely quantized, since the particles passing through are deflected entirely one direction or another. We could readily detect particles which were deflected partially, according to continuous, classical behavior - if they existed.
Ultimately, you've got a good argument if all your suppositions are true, but we've got experiments that prove quantum uncertainty as well as anything has ever been proven. In the words of Feynman: "It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong."