Lately I have been obsessed with quantum physics. I've been reading books and Web articles on the subject, trying to understand paradoxes like the two-slit experiment and the delayed choice experiment, in the hope that I can find some theory of the universe that will tie it all together. But it's not working! Nothing makes sense.
The key question is how the quantum wave function collapses - how a quantum object like a photon can make the transition from a wave to a particle. As a wave, it exists as a set of possibilities. As a particle, it exists as a distinct entity. When it makes the transition from wave to article, it becomes "real." If everything existed only as quantum waves, there would be no reality, only infinite possibilities. Reality enters the picture only when the wave collapses. But how does it collapse? How does reality become real?
Most physicists seem to think that the observer is the key ingredient in the puzzle. When no one is watching the photon, it is a wave function. When someone does watch, it is a particle. The observer somehow brings reality into existence. The simple act of observation converts possibility into actuality. But by what means?
At first I thought some form of interactionist dualism would work. Mind works directly on matter - say, by affecting the flow of electrochemical impulses in the brain. This idea is popular in some circles right now. But while this might explain the collapse of the wave function with regard to thoughts - with various possible thoughts collapsing into one actual thought - it doesn't explain the collapse of the wave function with regard to outside events. It doesn't get us very far.
Unless we assume that there are no outside events. Maybe everything that happens is purely mental. Make the universe subjective; say it's all an idea in the mind of God or a consensus in the collective consciousness of humanity. That's called monistic idealism, and it's popular, too.
But (sigh) there are problems. If the transcendent mind (God or Cosmic Consciousness or what have you) collapses the wave function, then the wave function should collapse instantly at every moment, because there's never a moment when God isn't looking. So we have to say that only the mind mediated by the physical brain can cause the collapse. But the brain is a material object. If no material objects can exist until the brain actualizes them, and if the brain itself is a material object, then how did the whole process get started? It's possible to talk about "tangled hierarchies," but this doesn't seem very clear.
Also there's the problem of cosmogenesis. If a physical brain is necessary to create the material world, and if for the first 15 billion years of the history of the universe there were no creatures with brains, then how did all of that history happen? We have to say that the universe didn't actually exist until the possibility of a brain became immanent, and then the whole 15 billion year past just snapped into existence. This stretches credibility, don't you think?
And what about near death experiences? Some people may not take them seriously, but I do. If someone can still perceive physical reality while having an NDE, then reality can be perceived without the mediation of the brain. But in this case the brain isn't necessary to collapse the wave function, right?
So then I heard about decoherence theory, which says that the observer isn't really necessary to collapse the wave function, after all. The photon simply becomes "entangled" with its environment, and as a result of this entanglement, the wave function collapses automatically. No one has to be watching. This interested me because it seemed to be a way out of my difficulties. I was so excited that I got up in the middle if the night and started Googling "quantum decoherence." I was reading about this stuff on my computer at 4:30 in the morning!
But the more I read, the more depressed I became. Because it turns out that quantum decoherence theory doesn't really explain how the wave function collapses. It can't explain how a set of possibilities (the wave function) becomes an actuality (the particle). It doesn't explain reality at all!
It sure seems as if the mind of an observer is necessary to create reality as we know it. But how? Is reality subjective, or is it independent of the mind but influenced by it? Or is there some other explanation? I'm at the end of my string, Abby. Please help!
Freaked Out By Physics
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The effort you've made to understand ultimate reality is honorable, but it is doomed to fail. Essentially you are trying to reduce reality to an explanation that can be grasped and communicated in words. This means reducing it to terms that the left hemisphere of your brain can handle. But reality is too big and complex and mysterious to be reducible to the dimensions of the limited mind-brain.
Even quantum physicists don't understand reality - they only know how to do the math and carry out the experiments. They leave the philosophizing to others, or they come up with the philosophical approaches you mentioned, all of which are deficient in some respect.
The only people who can make some claim to understand reality are very advanced mystics who have transcended the mind-brain and grasped the nature of existence directly. But even they can't reduce their discoveries to words in any satisfactory way.
What, then, is the solution? Forget theory, and experience reality directly. Shut off the stream of words in your mind and just be.
And practice patience. All will be clear eventually, but it may take many lifetimes and many stages of personal evolution. Everything is on schedule and cannot be rushed.
Now get some sleep.