Quantum Mechanics, Determinism & Free will
Abstract
In the following discussion I address the role of quantum mechanics with regards to a deterministic universe set in the context of free will. The constraints placed on us by our current understanding of the universe set out the limits of what we can know about free will and indeed any other aspect of nature of this kind. These arguments are used as a basis for my own direction in pursuit of a truer understanding of the universe.
Reality and measurement
It seems that there can be a lack of distinction between the nature of measurement or observation and the nature of what is real (reality), amongst scientists and philosophers alike.
Our understanding of the universe is largely based on the construct of quantum mechanics and since its conception has revealed many surprising aspects about the laws of nature, but non as important to us as Heisenberg’s uncertainty principle. Briefly put, HUP states that so called conjugate variables of a quantum system cannot be know simultaneously e.g. the momentum and position of an electron. By considering the universe as a collection of quantum mechanical systems, which we believe it to be, the HUP can be expanded to encompass all aspects of nature. There is nothing surprising about this. The universe is in a sense unknown to us, we can predict its behaviour with some probablility, but can never determine exactly how things will pan out. However, this is not to suggest that the universe itself plays out in a random fashion. The key to understanding this point is to grasp the meaning of what reality is, and how it may be different in its nature to the restrictions of measurement.
Quantum mechanics can be fun.
What we measure is of course different to reality, we know this to be a consequence of HUP, but this is not the point of the discussion. Because measurements of reality are limited by HUP, and turn out to be probabilistic, does not necessarily mean reality itself is probabilistic. It is important to draw the line between the nature of observation and that of reality
The HUP is a limitation on measurement and therefore we cannot claim that reality is indeed probabilistic. This distinction forms the premise of this argument.
What is reality?
The laws that govern our universe restrict the information we can obtain from any system and so we can only predict with uncertainty in any ‘billiard ball’ model how it will evolve. Reality could be different however, it can never be deterministic in the sense that we could predict it, but it may be internally deterministic. By this is meant that nature herself could ‘know’ precisely what reality is. This in turn destroys the notion of free will. On the other hand, nature may not know what reality is, and reality itself may be subject to constraints similar (or perhaps identical) to those of measurement (HUP).
Are we free?
This question has been of great interest to many great philosophers throughout history. There is a huge desire as an intelligent species to provide a solid answer to this conundrum. But how could we ever know if the universe affords us free will? Unfortunately with our current understanding of the universe, and in particular that of quantum mechanics, we can not know anything of this sort, and so in philosophy it shall remain.
Remarking on our understanding
Quantum mechanics undermines determinism, however, it is not an argument for free will. Since free will, if we believe it to exist, must form part of reality which we can never know with complete certainty.
Scientific direction
What has been said up to now is completely factual and is based on our current understanding of the universe. My own opinion is the following. I believe free will does exist, it is something I can only believe in, I suppose it is a faith. Quantum mechanics (along with evolution) is one of the most proven scientific theories in existence and for this reason I believe also in the HUP. So I have three options, either to accept reality to be internally deterministic, indeterministic or that it has some other nature I have not explored yet. Any way, if I knew which one it was, I would form an argument in favour of my belief in free will. Being as I have no choice but to remain ignorant of reality, I see no point in forming arguments of this kind.
This way
It is my view that questions concerning free will, the existence of god and our very own conscious existence (cogito ergo sum) can be futile endeavours if not tackled from the correct angles. In particular, the quest for a better understanding of consciousness. Although philosophy can be a rewarding and worthwhile exercise, I believe it will fall short in providing a true understanding of consciousness. One flaw with using philosophically grounded arguments for proofs concerning consciousness is that it uses consciousness to unravel the very mystery of consciousness (Prof. Robert Winston). Perhaps for this reason it is bounded by limitations we are unable to address as possibly conscious beings. I believe this aspect of human endeavour will be fruitful if explored in a scientific context based on theory and experiment. We may never arrive at a full understanding, but it may bring us a little closer.
Matthew Broome 21st October 2008
Links
Chris Crawford - Free Will & Determinism
Christian Neuroscience Society - Quantum Mechanics & Free Will
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Just a few points to make.
1) That quantum mechanics only describes probability in measurement and not reality:
Just a few points to make:
1) That quantum mechanics only describes probability in measurement and not reality - I don’t think this is so. diffraction patterns are observed in Young’s slits experiment even for single photon emission and, even here, there is only a probability of a single photon being emitted. It is intrinsic in nature - the event is not just probabilistic at the display screen where we observe the diffraction pattern but is probabilistic at the site of the 2 slits as well, where no observation is taking place. When detectors are placed such that one knows whether a photon has gone through either one slit or the other, only then does the diffraction pattern disappear as we have collapsed the photon’s wavefunction upon observation.
2) When you say that “quantum mechanics undermines determinsim”, I presume by this you mean making deterministic predictions based on measurement, otherwise this would go against your saying that “reality” may be deterministic even if we cannot measure it to be so. Either way, with regard to my first point, I think QM undermines determinism in its entirity.
3) I totally agree that we will never know the true reality of being. Nonetheless, we can make very informative proclomations based on inference using a set of coherent ideas. Sure, we cannot claim that this proves anything but such a proclomation could be extremely difficult to refute and thus can provide great help in our deeper exploration of being (NB: it may also prove to be very misleading!)
4) As for free will, I think my point is made in my blog “Consciousness: behind the scenes of survival”:
http://www.quantumbrain.info/blog1/?p=24
In summary, it states that the notion of free will is ann emotion that has arrived from evolution to minimise apathy and promote survival instincts in a species.
The point is, we don’t know if reality is random and non-deterministic in nature, and we can never hope to know the full picture given the constraints placed on us by QM.
When I say ‘reality may be deterministic’ I mean to say that it may have no choice but to progress in a particular manner and thus not lending itself to notions like free will or human choice.
Ok, I see what you’re saying. You are right in that we can never know, at least I think you are (can I possibly know?!…). Whether we measured something deterministic or something random, it would still have a random element in our observation.
BUT….I think that this would verge on absolute skeptism in that we could say “how can we know anything?” We would have to say that there is only a probability of observing the diffraction pattern in Young’s slits experiment - it could be a freak random event. This it is but only significantly so at the slits themselves - the photon interacts with itself because of its probabilistic nature. The interaction of the reflected photons with our retinas is also a probabilistic event but when we observe so many as to reliably observe a diffraction pattern then we must infer that something fundamentally significant is going on, this being the intrinsicly probabilistic nature of the photon.
On a side, I think that the use of the word “random” is misleading. Nature is probabilistic - intrinsicly. On large scales, this approximates to determinism but determinism with a twist!
I get the feeling that after much discussion, we’ll end up realising that we were trying to argue exactly the same point! Language is a bugger sometimes.
Thanks for good post