I’m not as pleased with this paper as I have been with previous ones. I procrastinated and rushed this one at the last minute. And it’s the same problem as before: these are big, big topics, and it’s hard for me to compress them down without making leaps and assumptions or feeling like I’m leaving important stuff out. So long as I get a pass, I’m not too bothered.
Could Quantum Mechanics Have Any Metaphysical Implications?
Coursework submitted in accordance with the requirements for
Science and Religion
Birkbeck, University of London
22 March 2007
Metaphysical questions have always been a part of philosophical and theological inquiry. This is not surprising since these studies involve thinking about the world, and are not traditionally grounded in the testable, scientific physical realm that we experience. We are capable of wondering and of extrapolation, and these capabilities have always led us to ask big questions: What is the nature of the universe? How did it begin? Why does it exist at all? Is our experience of the world a real one?
Natural philosophy has been categorised as “science” from the 19th century. Since that time, metaphysics has – consistently, albeit at variable rates – diverged from scientific enquiry and focused on the big questions. In the last hundred years, however, we have encountered a realm of science that not only seems exceedingly strange in light of our experience and our common sense, but also forces scientists to look at the big questions again: that of quantum mechanics.
The predictions and phenomena of quantum mechanics seem to be at odds with much of what we previously regarded as laws about how the universe works. As I will show, quantum mechanics implies that our thoughts affect states of affairs in the physical world. It may support the idea that the world is non-deterministic, and this has implications for free will. It creates the possibility that parallel universes exist. Questions that we would previously have encountered only as philosophical ponderings are suddenly popping up in the laboratory. It seems as if our ability to be analytic, scientific enquirers has caught up with our ability to speculate about some of the grand questions that have only relatively recently been separated out as metaphysics.
In this paper, I will outline – to avoid the considerable mathematical rigour required to demonstrate the physical phenomena – why I believe quantum mechanics not only adds new perspective on some metaphysical questions, but also stands poised to answer them and thereby push back the boundaries of metaphysics.
What is metaphysics?
The word metaphysics is sometimes used in a very broad sense to mean all philosophical enquiries. It has also recently been used (quite incorrectly, I feel) to mean ideas which are clearly supernatural and outside any current scientific explanation. I will use the definition that metaphysics is that branch of philosophy that inquires after the nature of reality – particularly its first principles, including the ontology and cosmology of the universe. In this sense, I do not take metaphysics to include the natural sciences. Moreover, in the case where a metaphysical question receives a generally-agreed answer, that answer becomes part of physical science and the question is removed from the realm of metaphysics.
What is quantum mechanics?
Quantum mechanics was born – quite accidentally – in the period between 1900 and 1905, when German physicist Max Planck developed a mathematical model that would marry earlier models of black-body radiation with experimental data of that phenomenon.[i] In 1911, Austrian physicist Paul Ehrenfest demonstrated that Planck’s model and statistical methods for developing it necessarily implied that electromagnetic energy came in discretely-sized packets, or quanta. This result troubled the vast majority of the scientific community,[ii]since physicists previously believed that energy was continuously variable. Apart from this majority, Albert Einstein accepted the idea of these quanta and went on to develop fundamental and famous mechanical and electromagnetic theories around them.[iii]
I will not describe the experimental and thought methods by which these theories were developed, nor will I describe them in mathematical terms. I will instead focus on the well-established consequences and behaviours of quantum mechanics, as developed by Einstein (who won a Nobel Prize[iv] for his work on the theory). In addition to the quantisation of some physical quantities, quantum mechanics has, generally, three other outcomes that seem at odds with our classical knowledge: wave-particle duality, the uncertainty principle, and entanglement. Combined, these phenomena provide significant challenges to previously held views of how the universe works.
Even Einstein had problems accepting these outcomes, despite his being instrumental in their discovery. Prior to quantum mechanics, physicists believed that the motions of bodies could be described deterministically by Newton’s Laws. The uncertainty principle, however, showed that there is an intrinsic imprecision in measuring exactly any particle’s momentum and position. The motions of bodies therefore became a probabilistic process:
The uncertainty principle signalled an end to…a model of the universe that would be completely deterministic…quantum mechanics does not predict a single definite result for an observation. Instead, it predicts a number of different outcomes and tells us how likely each one of these is.[v]
Suddenly, we found that we were never able to predict exactly how things will move, and Newton’s “laws” of motion are clearly only approximations. How then does this probabilistic multiple-outcome process actually work? There are several views, but the most popular is the Copenhagen interpretation;[vi] some of its consequences are discussed in the next section.
Wave-particle duality implies that some physical quantities seem to display characteristics of both particles and waves, sometimes at the same time. The famous photon-slit experiments demonstrate this.[vii] This behaviour challenged the notion that we could draw clear lines of distinction between particles of matter and waves of non-material energy.
Entanglement is a very difficult concept, given our classical understanding of the universe. Entanglement implies that some properties of particles that are created from splitting a single larger particle seem to retain some relationship with each other. Changes to one particle’s properties can effect changes in its entangled partner, even though we do not understand any mechanism by which such entanglement could happen (so-called “spooky action at a distance”). Moreover, that entanglement happens instantly over any distance, which seems to contravene the understanding we have from the theory of relativity (that no signal could be travelling between the particles faster than the speed of light). Entanglement, in conjunction with the uncertainty principle, also means that we – as conscious observers – seem to become part of the systems we are measuring, and outcomes in quantum mechanics appear to be influenced by whether we are observing or not.
Metaphysics and the weirdness of quantum mechanics
The Copenhagen interpretation of quantum mechanics says that we have superimposed states of probability when we actually measure any state of affairs. For example, if we have a system that could be in one of two states with equal likelihood (say, red or green) then the system simultaneously exists in a superposition of both states (i.e., is both red and green) until such time as we actually measure it (at which stage it will be either red or green). This interpretation implies that we will have an infinite regress of states unless we can identify a mechanism that somehow “collapses” the set of superimposed states to the one that we detect when we do measure it.[viii]
How do we decide at what point of the process this collapse happens? Von Neumann was the first to propose that the collapse of the wave function happens when the signal reaches the brain.[ix] The question then becomes: at what stage does the signal reach the brain? More precisely: at what point does consciousness of sense data from the outside world occur? How do we separate the consciousness – presumably in or at least resulting from the brain matter – from the signal that is received in the eye or transmitted through the optic nerve? In his Discourse on Method, Descartes said that the thinking “substance” of his mind was separate from the unthinking “machinery” of his body, and that this mind-body duality was made possible by interactions in the pineal gland.[x] Modern science tends to think less of this duality, and more of “mind” as the complex conglomerate of all the machinery of the brain. Quantum mechanics re-opens the debate of the philosophy of mind, because consciousness appears to impinge on physical reality external to the body.
There are other interpretations of how quantum states of being translate into the universe we perceive. Some maintain that the brain exists in a superimposed state as part of the measurement system, and that we somehow arrive at a result not by a collapse to one of the possible outcomes, but by some sort of statistical evaluation of the most likely outcome.[xi]This is a consequence of the difficulty in demarking where the signal of light to the eye, through the optic nerve, and into the brain becomes consciousness, and thus where the system under examination ends and the mind begins. Even if that line were clear, it is still unclear how this evaluation of an outcome might happen. No matter where we draw the line for what constitutes our measuring system, quantum mechanics seems to require we understand the distinction between the world and our own minds.
The displacement of the Newtonian view (which, as previously stated, is at best an approximation and which we could now claim to be essentially reductionist) does influence two other longstanding metaphysical questions: that of a cosmological first cause and that of human free will. Since there is no clear causality line in a world of quantum mechanics, the view that the universe required a single first cause for its being appears to be made weaker.[xii] Also, the lack of determinism in the way that the world works – that nothing, including human beings, is a clockwork mechanism that must produce predictable results given certain conditions, and that outcomes are in some way contingent on our involvement – suggests that there may be an opportunity for at least some level of free will.[xiii]
Most scientists believe – as Einstein did – that our understanding of quantum mechanics is still incomplete. Many are working to introduce determinism to the theory.[xiv] One result of this is the “many-worlds” interpretation:[xv] that every act of measurement splits the entire universe into a number of different, non-interacting branches. There is no collapse or evaluation of probabilities, and the end result is a complex product of vector states of each possible quantum outcome and the observer. This interpretation then becomes deterministic. However, it also means that every possible outcome actually occurs, and we are left with the somewhat difficult notion of a branching universe, where new – but presumably isolated – realities are created at every point of measurement or interaction. If this has been happening since the Big Bang (say 15 billion years ago) then it has been estimated that 10100 universes might now exist.[xvi] A development of this idea is of parallel universes: that quantum options happen in pre-existing (but still non-contacting) universes, and they are not created by branching at each new measurement point.[xvii] Again, these interpretations are describing phenomena that are, in some sense, real enough that quantum computing (complex computing that uses quantum states of 0, 1 or a superimposed state of both) is a serious area of scientific enquiry.[xviii]
The ontology of physical objects is yet another concept that is affected by quantum mechanics. Einstein’s theories of general relativity show us that space and time are inextricably linked, and that time is a dimension not very different from the three spatial ones we perceive (i.e., space-time). Objects may therefore properly be thought of as four-dimensional hunks of matter.[xix] That is, we should conceive of matter as taking up four-dimensional space-time, not just three-dimensional space with time somehow happening separately. Defining separate objects therefore means defining them as objects that do not occupy the same 4-D space. As I have described, however, the uncertainty principle of quantum mechanics says that we may not specify objects precisely in this way, and our ability to be precise about what occupies what space-time – and what is therefore an “object” – is, like Newtonian motion, limited to approximation.
In the last 60 years, scientific enquiry has tried to focus on distinguishing what we can scientifically measure and what we should relegate to mysticism. The logical positivism of the Vienna Circle (and, to a lesser degree, Karl Popper) was the most significant attempt to remove everything non-analytical – mind, being, metaphysics, God, et cetera – from philosophy and place them with the arts and religion.[xx] Whether or not one agrees that positivism ever truly removed metaphysical questions from science, the discussion above shows that quantum physics would certainly have brought at least some of those questions back.
The degree to which quantum mechanics has re-opened questions of metaphysics is made clear by the degree to which pseudoscientific proponents have attached themselves to the theory. This tendency has sometimes been called quantum mysticism.[xxi]As an example, in a paper called Quantum Metaphysics, Stenger says:
In some sense, the wave function of the universe is an etheric cosmic mind spread throughout the universe that acts to collapse itself in some unknown way. The human mind (spirit, soul) is, of course, holistically linked to the cosmic mind and so exists in all space and time. Once again we have and example of what Paul Kurtz calls the “transcendental temptation.”[xxii]
These sorts of views are not useful from either scientific or philosophical points of view. They exist because quantum mechanics is scientific, but its phenomena look similar to those predicted by certain pre-existing unorthodox views. Concepts of entanglement, action at a distance, and outcomes influenced by our conscious states are irresistible to many of those who seek validation of New Age ideas of cosmic unity or powers of mind over matter. We should take care to exclude these views from serious inquiry into how quantum mechanics affects our metaphysical ideas.
The methods of positivism and the future of quantum mechanics
The behaviour of quantum mechanics seems to be in opposition to realism, the view that there exists a reality independent of us as conscious observers. If it truly is the case that a non-deterministic collapse of probabilities only occurs when observed, then what does it mean to talk about a reality independent of any observers? Similarly, if the many-worlds interpretation is true and there are many universes, either created or pre-existing, what does it mean to be a realist?
Even if we subscribe to realism, however, we should not discount current interpretations of quantum mechanics simply because we have not found a view that squares with it. Quantum mechanics is one of the most successfully predictive theories ever developed, and is obviously correct in some very significant way.[xxiii] It is part of the progressive mathematisation of the physical sciences that began with Galileo and continues today, using the methods – if not the entire philosophy – of the positivists:
Most Western scientists actually learn to use themethods of the positivists during their formal education…They learn to adopt a pragmatic, sceptical approach to science in which philosophy – and particularly metaphysics – appears to play no part.
However, for many scientists the stuff of their theories – atoms, electrons, photons, etc. – are quite ‘real’. Many assume these objects to have an existence independent of the instruments used to produce the effects their theories are supposed to explain…A modern scientist might typically adopt the methods of the positivist but the outlook of the realist.[xxiv]
There are also consequences of quantum mechanics that – while being at odds with previous theories – seem to make our universe more understandable, at least in some limited respects. For example, the relativistic space-time model of the universe leaves cosmologists with a gravitational singularity at the instant of the Big Bang: that is, a point where the mathematics of how we know space and time to work break down into meaninglessness. However, some scientists maintain that when quantum effects are included in the model this singularity disappears, and we get a definable and more consistent model of the universe that includes the moment of the Big Bang[xxv].
It may be that quantum mechanics – or whatever follows it – holds many more surprises for us. Albert speculates about future humans who might have artificial means of objectively analysing their own brain states (either through other observers, or cybernetic devices in their brains).[xxvi] He extends these capabilities to hypothesize – with some very complicated vector mathematics – that these future humans might be able to bypass the uncertainty principle, or have knowledge of what occurs in parallel universes, or even in the future. In the end, we might find that there is a deterministic interpretation of quantum mechanics – like that of parallel universes – after all, but that interpretation would almost certainly contain phenomena we find exceedingly strange.
It is clear that whatever our interpretation of it, our understanding of quantum mechanics is incomplete. There is no reason to assume, however, that we will not improve our level of understanding. Some philosophers of science have speculated that our current comprehension of the theory is roughly equivalent to the understanding of the atomic-molecular model in the mid-19th century.[xxvii] If this is true, we are certainly extrapolating some distance beyond our current abilities to accurately understand how quantum mechanics works, and this has the consequence of results which appear quite unrealistic.
Quantum mechanics seems certain to do as much damage to our ideas of the nature of the universe as did the Copernican revolution. I have shown that investigations into quantum mechanics are forcing us to ask questions about the nature of free will and determinism; about cause-and-effect; about where reality stops and our consciousness starts; and about whether our reality is the only one that exists. The fact that quantum theory has caused us to revisit areas of metaphysics is an indicator that we are grasping for straws to explain physical behaviour that is currently at odds with much of our previous experience. When we find explanations for these questions, some of these metaphysical questions will certainly be answered, and answered quite concretely. As we come to understand more about quantum mechanics, analytical knowledge will come forward to claim the ground that metaphysics has abandoned.
[i] Baggott, J. (1992), The Meaning of Quantum Theory, 6.
[ii] Baggott, 9.
[iii] Hawking, S.W. (1988), A Brief History of Time: From the Big Bang to Black Holes, 56.
[iv] Hawking, 56.
[v] Hawking, 55.
[vi] Baggott, 81-83.
[vii] Hawking, 56-60.
[viii] Baggott, 186.
[ix] Baggott, 186.
[x] Baggott, 189.
[xi] Baggott, 191.
[xii] Baggott, 204-206.
[xiii] Baggott, 192-194.
[xiv] Baggott, 159.
[xv] Baggott, 194.
[xvi] Baggott, 199.
[xvii] Baggott, 200-201.
[xix] Heller, M. (2001), “Temporal Parts of Four-Dimensional Objects” from Metaphysics: Contemporary Readings (M. J. Loux, ed.), 333.
[xx] Hamlyn, D.W. (1987), The Penguin History of Western Philosophy, 306-310.
[xxii] Stenger, V.J. (1995), paper presented at the Conference on New Spiritualities,Westminster College, Oxford, England, March. Published in Modern Spiritualities, Laurence Brown, Bernard C. Farr, and R, Joseph Hoffmann (eds.), 1997. Also published in The Scientific Review of Alternative Medicine 1(1), 26-30, 1997. Viewable on the internet at:http://www.colorado.edu/philosophy/vstenger/Quantum/qmeta.html
[xxiii] Norris, C. (2000), “Quantum theory and the logic of anti-realism” from Quantum Theory and the Flight from Realism, 66.
[xxiv] Baggott, 79-80.
[xxv] Hawking, 133-141.
[xxvi] Albert, David Z. (1992), Quantum Mechanics and Experience, 180-189.
[xxvii] Norris, C. (2000), “Is it possible to be a realist about quantum mechanics?” fromQuantum Theory and the Flight from Realism, 35.