Epistemic status: A quick rejection of the quantum consciousness woo. If you have already read the sequences, there's nothing new in here. If your new to the site, or need a single page to point people to, here it is.
Real Quantum mechanics looks like pages of abstract maths, after which you have deduced the results of a physics experiment. Given how hard the maths is, most of the systems that we use quantum mechanics to predict are quite simple. One common experiment is to take a glass tube full of a particular element and run lots of electricity through it. The element will produce coloured light, like sodium producing orange, or neon producing red. So take a prism and split that light to see what colours are being produced. Quantum physisists will do lots of tricky maths about how the electrons move between energy levels to work out what colour different elements will produce.
There have been no quantum mechanics experiments that show consciousness to have any relevance to particle physics. The laws of physics do not say what is or is not conscious, in much the same way that they don't say what is or is not a work of art. Of course, consciousness is a property of human brains, and human brains, like everything else in the universe, are made of electrons and quarks playing by quantum laws. The point is that human brains are not singled out for special treatment, they get the same rules as everything else.
For the writers among you, think of a word processor feature that takes some text, and turns it into ALL CAPS. You can put a great novel into this feature if you want. The point is that the rule its self acts the same way whether or not it's given great literature. You can't use the rule to tell what is great literature, you have to read it and decide yourself. Consciousness, like literature, is a high level view that's hard to pin down precisely, and is largely a matter of how we choose to define it. Quantum mechanics is a simple, mechanistic rule.
Yes I know that some of you are thinking of the double slit experiment. You make a screen with two slits, shine light through and get an interference pattern. Put a detector at one slit, attach a dial to the detector, and have a scientist watching the dial so they can see which slit the photon went through, and the interference pattern disappears. Perhaps, thought some of the early scientists, consciousness causes the quantum wave function to collapse, the universe doesn't like us knowing which slit the photon goes through.
However, lets do a few more experiments. Repeat the previous one, except that the scientist is sleeping in front of the dial. No interference pattern. Turn the dial to face the wall, remove the scientist entirely. Still no interference pattern. Unplug the dial from the detector, so electrical impulses run up the wire and then can't go anywhere. Again, no interference. Whatever is stopping interference patterns, it looks like detectors, not consciousness.
It turns out that any interaction with any other particles, such that the position the other particle ends up in depends on which slit a photon went through, creates entanglement between the photon and the other particle, which destroys interference. And the atoms in the dial, the electrons in the wire, and particles in the detector its self, all have there position depend on where the photon went.
In general, the way to get rid of mysteries is to break them up into smaller mysteries, until your left with loads of tiny mysteries. How life worked used to be one big mystery. But thanks to modern biology, we now have thousands of tiny mysteries about how yeast metabolism can tolerate high levels of alcohol, or how protozoa DNA doesn't get tangled when they replicate. And these are surrounded by large amounts of well understood science. (I'm not a biologist, so these particular things might be solved by now, but you get the Idea) Big mysteries get broken down into a pile of fact, and several smaller ones.
Gluing the "mystery" of quantum mechanics, to the "mystery" of consciousness to make a bigger and more mysterious mystery, would be a mistake even if both of these things were actually mysteries to humanity. Mystery is a blank textbook, not a feature of the world, and in this case, there is a clear picture of quantum mechanics, and a rough sketch of consciousness in the textbooks.
If you take the multiverse explanation there is one possibility. In the multiverse view, the observer also proliferates along with the rest of reality as the present diverges into multiple futures and so the "collapse" is really just a clarification - the observer finding more precisely among possible observers which one they are. If this is the case, consciousness is part of the wave function and thus certain thoughts might influence the future wave function as holding particular thoughts bar certain futures from happening. This already occurs indirectly as the scientist consciously decides to run a slit experiment instead of something else, which has definite impact as thought cascades into action. More directly Universities and research groups are doing studies along these lines with random number generators and consciousness. http://noosphere.princeton.edu/ It is less mysterious as it sounds once you realize consciousness is a derived property of molecular/electro chemical structure or "shape" of the quantum fields and as such part of the quantum waveform.
Epistemic status: A quick rejection of the quantum consciousness woo. If you have already read the sequences, there's nothing new in here. If your new to the site, or need a single page to point people to, here it is.
Real Quantum mechanics looks like pages of abstract maths, after which you have deduced the results of a physics experiment. Given how hard the maths is, most of the systems that we use quantum mechanics to predict are quite simple. One common experiment is to take a glass tube full of a particular element and run lots of electricity through it. The element will produce coloured light, like sodium producing orange, or neon producing red. So take a prism and split that light to see what colours are being produced. Quantum physisists will do lots of tricky maths about how the electrons move between energy levels to work out what colour different elements will produce.
There have been no quantum mechanics experiments that show consciousness to have any relevance to particle physics. The laws of physics do not say what is or is not conscious, in much the same way that they don't say what is or is not a work of art. Of course, consciousness is a property of human brains, and human brains, like everything else in the universe, are made of electrons and quarks playing by quantum laws. The point is that human brains are not singled out for special treatment, they get the same rules as everything else.
For the writers among you, think of a word processor feature that takes some text, and turns it into ALL CAPS. You can put a great novel into this feature if you want. The point is that the rule its self acts the same way whether or not it's given great literature. You can't use the rule to tell what is great literature, you have to read it and decide yourself. Consciousness, like literature, is a high level view that's hard to pin down precisely, and is largely a matter of how we choose to define it. Quantum mechanics is a simple, mechanistic rule.
Yes I know that some of you are thinking of the double slit experiment. You make a screen with two slits, shine light through and get an interference pattern. Put a detector at one slit, attach a dial to the detector, and have a scientist watching the dial so they can see which slit the photon went through, and the interference pattern disappears. Perhaps, thought some of the early scientists, consciousness causes the quantum wave function to collapse, the universe doesn't like us knowing which slit the photon goes through.
However, lets do a few more experiments. Repeat the previous one, except that the scientist is sleeping in front of the dial. No interference pattern. Turn the dial to face the wall, remove the scientist entirely. Still no interference pattern. Unplug the dial from the detector, so electrical impulses run up the wire and then can't go anywhere. Again, no interference. Whatever is stopping interference patterns, it looks like detectors, not consciousness.
It turns out that any interaction with any other particles, such that the position the other particle ends up in depends on which slit a photon went through, creates entanglement between the photon and the other particle, which destroys interference. And the atoms in the dial, the electrons in the wire, and particles in the detector its self, all have there position depend on where the photon went.
In general, the way to get rid of mysteries is to break them up into smaller mysteries, until your left with loads of tiny mysteries. How life worked used to be one big mystery. But thanks to modern biology, we now have thousands of tiny mysteries about how yeast metabolism can tolerate high levels of alcohol, or how protozoa DNA doesn't get tangled when they replicate. And these are surrounded by large amounts of well understood science. (I'm not a biologist, so these particular things might be solved by now, but you get the Idea) Big mysteries get broken down into a pile of fact, and several smaller ones.
Gluing the "mystery" of quantum mechanics, to the "mystery" of consciousness to make a bigger and more mysterious mystery, would be a mistake even if both of these things were actually mysteries to humanity. Mystery is a blank textbook, not a feature of the world, and in this case, there is a clear picture of quantum mechanics, and a rough sketch of consciousness in the textbooks.