Quantum mechanics, the measurement problem, and the nature of reality
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4.0 You've had yours, now it's my turn.
It is not surprising that the aspect of quantum mechanics that has triggered most controversy (apart from the counter common sense parts such as non-locality) is when the wavefunction collapses. Although physically this doesn't make much difference since it is an unobservable quantity changing at some time while we necessarily aren't looking at it, the philosophical implications are immense.
To begin with, look at the 'nonsensical' Schrodinger's cat thought experiment. Now consider instead of a cat a man inside the box, observing - the Wigner's Friend paradox. Now we have something which we know will collapse the wavefunction inside the box. Does that mean that the wavefunction has collapsed long before we look in the box, or does the wavefunction appear differently according to the knowledge of the person looking at it? Wigner believed that this was where 'consciousness enters the theory unavoidably and unalterably'.
If it were not a man but a simple measuring device we would have no problem in saying that the device had joined the quantum system and the entire system was now in a state of superposition - but what if the device were smart, intelligent even. Perhaps as intelligent as a man. This is where things start to get a little more difficult and we venture from the realms of physics into the the realm of physical reality - what is actually out there?
In all of this, we mustn't forget that quantum theory is just a theory; a model to predict the universe around us with. Now important are statements it makes outside the mandate of its theory?
I would say that quantum theory could give us valuable insights into the nature of information and observation. In the same way that the Copenhagen interpretation is a way of looking at quantum mechanics, then QM is a metaphor for the universe - a kind of kaleidoscope that rearranges reality into patterns that we can understand more from.
QM predicts that the universe is blurred. More than saying that these are the probabilities of finding particles, it states that superpositions occur, and we have experimentally verified this. If so, this is a fundamental difference in what 'is' and what we perceive 'is'.
Humans necessarily perceive in a discrete manner: either something is or it isn't. Perhaps this is because we are macroscopic, or perhaps there is an alternative way of viewing the universe that lets in alternative realities, but we force the universe to be discrete because we can't perceive it any other way.
Perhaps, because of this, we have become entangled into the quantum system. The universe is indefinite, but by looking at it we force it into discreteness.
Consider a two-slit experiment where instead of measuring which slit the particle has gone through we instead measure the particle's position in a non-discrete way across the whole plane of the slits. Whereas measuring which slit the particle has passed through destroys the pattern, this method of measuring obviously would not - we'd just obtain the particle positions as if we'd placed the viewing screen infinitely close to the slits.
It's only when we demand that either one thing happens or another that the pattern disappears. It isn't the measuring device in place doing the measuring that has destroyed the pattern. It's that we have implicitly said to the system that it has to have a 100% or 0% chance of passing through a slit, nothing in between. It's not the act of measurement, it's the demand of discreteness.
Possibly, in a way that we are entangled into a quantum system and collapse wavefunction when demand values, we could given credence to Rupert Sheldrake's (somewhat bizarre) ideas about a scientific basis for telepathy and influencing experiments as they occur simply by wanting a particular result. Then again, possibly now. I wouldn't want to give Sheldrake too much ammunition.
Then again, this would be almost consistent with Penrose's ideas that what we term 'free will' is a macroscopic amplification of quantum events taking place inside brain cells. I would have to agree with his critics in this case however and say that we need a mechanism for connecting consciousness to the structure of the brain before we start saying that if consciousness was connected in such-and-such a way, then this is a possible way that it could come about. It is difficult to regard anything said about a subject we know so little even about the simple aspects of, let alone the causes of, as anything other than pure speculation.
The unknown nature of quantum mechanics has drawn in large numbers of often odd interpretations. QM continues the process of overlapping philosophy and physics as it brings greater insights into our place in the universe. It is no bad thing to reduce the universe to its simplest formulation, as long as understanding is gained and not lost along the way.
It seems that with every greater advance in science we have been displaced one more step: the Copernican shift to a heliocentric system, the discoveries in astronomy that place us at just another location in a vast universe. The next step seems to displace our very consciousness, or demand of us that we find what is so special about ourselves that we earn the title of 'Observer'.
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