An exploration of Quantum Theory and the Philosophies of Spiritual Traditions
An Introduction to Quantum Physics & Spirituality
At the beginning of the twentieth century, physicists were deeply puzzled by discoveries they had made in their experiments and shook in their scientific worldview: light waves suddenly behaved like particles, particles behaved like waves and measurement outcomes happened randomly. After many years of further research and theoretical development, quantum theory emerged out of a collective effort of scientists, and it was able to predict all observed phenomena with incredible mathematical precision. Up to this day quantum theory has virtually withstood all experimental tests and led to amazing technology that is used by billions of people every day. However, its counter-intuitive predictions continue to divide communities of physicists and philosophers. The convergence of quantum physics and spirituality may help shed light on the problem.
Modern science is far from having reached consensus on how to interpret quantum physics and make sense of its seemingly strange nature. Philosophical debates are probably as heated as they were one hundred years ago and the number of physical theories offering different interpretations of quantum physics is still growing. As the world grew closer together through globalisation and the exchange of knowledge among different cultures increased, scientists, as well as spiritual practitioners, have pointed out common features of certain spiritual philosophies and attempted to interpret the findings of quantum physics.
For example, a topic that pops up a lot in quantum physics is the dependence of the outcome of an experiment on what is observed. What exactly does modern physics mean when it talks about observers and could this be connected to consciousness in any way? Do we require consciousness, intelligent life or even scientists with a PhD to speak of observers in the first place?
In this article, we will explore such questions and we will be focusing on a concept which is described by various spiritual and philosophical traditions and considered of unique importance in Buddhism: emptiness. We will look at some of the strange effects taking place in quantum physics and investigate ideas on how the notions of emptiness and interdependence can be reconciled with them.
Quantum Weirdness
Historically, quantum theory emerged from a series of experiments that yielded quite strange and unexpected results which could not be explained by the existing scientific theories used in physics at the time. It is safe to assume that no scientist would have ever been able to come up with some of these outcomes had it not been for the clear experimental evidence. Even though quantum physics has considerably changed our lives and, together with Einstein’s theory of general relativity, provides all knowledge of physics, it is generally not agreed upon how to interpret it. In other words, scientists do not really understand what, and if at all, it can teach us about the nature of reality.
As of now, there are many different interpretations of the theory that come to the same experimental predictions, however, they differ greatly in their interpretation of the reality that gives rise to those physical phenomena we observe. When the physical understanding and experimental techniques of the previous century had advanced enough, there came a point where it became possible to probe the nature of light and atomic particles with unprecedented precision.
Wave-Particle Duality
As scientists set out to answer all their questions and complete the human knowledge about the physical world, they were instead confronted with one strange phenomenon after another which led to more questions than ever before. As an example, some experiments with light, which had been previously understood like waves, could only be explained by describing them as coming in discrete and tiny packages, or quanta, of energy that could not be divided further – thus resembling more the behaviour of particles. On the other hand, in some situations, subatomic particles like electrons behaved more like waves than particles.
It turned out that the appearance of a wave-like or particle-like character depends on what is measured in an experiment thus influencing its outcome, as the famous double-slit experiment illustrates:
An elementary particle, for example an electron, is shot at a wall with two slits that can be opened or closed, respectively. Behind the wall with the slits, there is a detector screen which catches all incoming electrons and measures where they land at the end. When one of the slits on the wall is open, while the other one is closed, nothing strange happens: Some electrons make it through the slit and land on the detector screen, thereby forming a rectangular shape of “spots” cast by the form of the slit, as one would expect. If we open the other slit as well, it is natural to assume that we would just see two stripes instead of one on the detector screen – imagine shooting footballs at goals with a wall with two slits in between.
Now, the strange thing that happens is that we do not observe this at all. What happens is that we see more than two strips in different places than before – something that physicists call an interference pattern. This alone is very surprising, but the best is yet to come: namely, when we set up devices close to the slits to determine through which of the slits a particle goes, then the interference disappears and what we see is a completely classical picture of two stripes on the detector screen, as in the football analogy. This means that the outcome of the experiment changes depending on the way we observe it and the process of observation. When we stop observing through which of the slits the particle goes, the interference pattern emerges again – even if we just fire one particle at a time.
This fact leads to the bizarre conclusion that, when we don’t know which slit it goes through, it is not enough to just assume that it really went through either the left or the right slit. Mathematically, the situation cannot be described by just assigning a definite path to the electron anymore. In standard quantum theory, we assign probabilities to each possible path that the electron could take, so either left or right. Physicists speak of the state of the electron as being in a so-called superposition of the left and right paths.
Now, the probabilities assigned to the paths behave exactly like waves, meaning they can interact by reinforcing or cancelling each other between the wall and the detector screen, leading to the observed inference pattern. Even though quite stunning, the double-slit experiment is of course not the only instance of strange quantum effects. Another feature of quantum physics is called quantum entanglement and describes how quantum systems like particles can be correlated with each other in ways that could not be imagined in classical physics.
An Analogy from Classical Physics
To give an example of this effect, we will use an analogy from classical physics first. Let’s imagine a scenario, in which there are two balls, one red and one blue, and two boxes. Every day a person puts each ball into a box randomly but doesn’t tell us which ball is in which box. After the balls are put into the boxes, we are allowed to open one of the boxes. When we open box 1 and find the blue ball, we know instantly that box 2 must contain the red ball (and the other way around). Now, leaving the world of classical physics, we can imagine the balls to behave like quantum balls.
In this case, before opening box 1 we cannot describe it as only containing a ball of either blue or red colour – in the same way that we cannot say that the particle in the double-slit experiment went through the left or the right slit when we are not checking. Therefore, when none of the boxes is opened, we must describe the state of the balls as a superposition of “blue ball in box 1, red ball in box 2” and “red ball in box 1, blue ball in box 2” – exactly as for the superposition of the left and right paths in the double-slit experiment.
However, when we proceed to open one of the boxes then one of these possibilities will come true. As with the classical balls, if box 1 shows the blue quantum ball, box 2 will show the red one (and vice versa). In the classical case this is completely acceptable, as opening one box will not affect the ball in the other one. But, since in the quantum case the colour of the ball in each box is not determined before the box is opened, it follows that opening box 1, for example, and observing the blue ball will instantly affect box 2 and fix the colour of that ball to be red.
This instantaneous effect even happens when the two boxes are placed arbitrarily far apart and was termed “spooky action at a distance” by Einstein, as it seems to be an interaction clearly faster than light.
Interpreting Quantum Physics
It is important to discuss the different assumptions we make when trying to interpret quantum theory. When we talk about the state of a quantum system, mathematically this means that we assign a probability between 0 and 1 to each possible outcome that can take place when the system is observed.
In the example above the possibilities are “blue ball in box 1, red ball in box 2” and “red ball in box 1, blue ball in box 2”, and each of them gets assigned a probability of 0.5 (or 50%). When an observation or measurement is made on the system, the outcome that gets observed is assigned the value 1 (or 100%, as it happened with certainty).
Now, when we write down such a state for a system, does it mean that the system is truly in that state? And if it is, does it mean that its state truly changes when we observe it? And does it change objectively or only in relation to the observer?
Various interpretations of quantum theory answer these questions in different ways and therefore do not agree on what seems paradoxical. Some assert that the quantum state exists physically but either does not describe all there is to know about the system (DeBroglie-Bohm interpretation) or it doesn’t change at all when a measurement is made and it is the entire universe itself that splits into different realities (Many-Worlds interpretation).
Other interpretations, however, assert that the quantum state is an epistemological feature of the theory – it can only describe our state of knowledge about the given system and should not be mistaken for the system itself. The widely spread and earliest Copenhagen interpretation falls into that category while viewing the observing system as entirely classical. The interpretation that came to be known as QBism does not make claims about the nature of the world and views the quantum state as a subjective tool that agents can use to make decisions, and which gets updated by performing observations.
While the Von Neumann-Wigner interpretation argues that consciousness plays an active role in an observation (the conscious observer), none of the other interpretations elicit an important role of consciousness itself. Carlo Rovelli’s relational interpretation, for example, treats all systems on the same footing and emphasises the relational character of quantum states: A quantum state is only defined by the relation between two systems, like the observer and the observed, and does not represent an absolute quality of the systems themselves. It attributes no special role to an observer – in fact, any physical system can take the role of an observing system.
For a deeper understanding of the different quantum interpretations presented by quantum physicists and how they relate to Buddhist interpretations of ultimate reality, take a look at our online course: Buddhism and Quantum Physics.
Emptiness And Quantum Effects
What does Buddhism mean by emptiness and how can this play a fundamental role in developing our understanding of reality? The Buddhist teaching of emptiness asserts that all phenomena, whether they are considered physical or mental, lack an intrinsic, independent and unchanging nature. The word “emptiness” does not refer to objects being literally empty, but it is understood that they are empty of an inherent existence in and of themselves. This means that the existence of every object depends entirely on the existence of other objects, which, in turn, are completely dependent on others again.
Since there is no preferred object that can be identified as a starting cause or final effect, the quality of this network of mutual dependencies is referred to as interdependence. Moreover, since no thing exists entirely by itself, no object is free from interacting with another, therefore, the existence of every object is never unchanging and thus impermanent. According to the Buddhist perspective, all beings perceive objects as independently existing and with an unchanging nature, and it is this misperception of reality that leads to their suffering.
Now, might there be a way to think about quantum effects differently, once we have the notion of emptiness in mind? Would they perhaps lose their strange and paradoxical flavour once we stop treating physical systems, such as particles and measurement devices, as intrinsically existing with intrinsic properties and once we give up the assumption that quantum physics describes an objective and independently existing world “out there”?
If we accept that physical objects and the quantum systems that make them up are empty of intrinsic being and properties then quantum theory itself would not necessarily have to point to a hidden, underlying and more fundamental nature. Instead of revealing an incomplete and cryptic account of a deeper reality, it could just be viewed as a framework that makes it possible to formalise our expectations in experiments. By assuming the emptiness of intrinsic existence, the way in which quantum systems appear depends entirely on how they are interacted with. Properties such as position, momentum and spin would only emerge in an interaction between an observing and an observed system. The existence of a property would depend on the existence of the relation between the systems – instead of being an unchanging and intrinsic quality.
Inherent Nature vs Quantum Nature
When we look at the wave-particle duality in the double-slit experiment, what is observed depends on the experimental context, in other words, the questions we ask – whether we ask where the particle lands on the screen or which slit it goes through, in this case. From this point of view, the observed interference behaviour would not imply an intrinsic wave-particle nature of microscopic systems but rather indicate the lack of their inherent nature by itself.
In other words, the observed “nature” of a system is revealed relative to the way the system is interacted with, and it can therefore only be seen as a relative, dependent nature. In our scenario describing the entangled quantum balls with their property of colour, the difference from a classical scenario was that, before any of the boxes are opened and a measurement is performed, the property “colour” of each quantum ball does not have an intrinsic existence. It is only when an observation is made that the colour of ball 1 exists, albeit only relative to the colour of ball 2, and vice versa.
Therefore, in such an entangled system, it is only meaningful to talk about correlated properties of the subsystems (the correlated colours blue/red and red/blue exist), instead of properties of the isolated ones (the isolated colours red and blue for each ball do not exist). Since we cannot separate the properties in a meaningful way, we can think of an entangled system as non-separable. However, assigning intrinsic existence to the correlation itself seems dubious, as even the correlation, or relation, between the subsystems is relative to the experimental set-up and the questions we want it to answer.
In the same way that in Buddhist philosophy emptiness of inherent existence is itself empty of inherent existence, in quantum physics relational existence is itself relative. From a relational perspective, there is also no need to assert the existence of a “spooky action at a distance” from one particle to the other in order to explain the correlation of colours between them. This is because any such correlation can also only exist relative to other systems. However, the only way to relate the correlation to another system would be to send conventional signals from the subsystems to that system, which do not exceed the speed of light.
Conclusion
The aim of this article is neither to explain the nature of reality in terms of quantum physics and the concept of emptiness nor to provide or emphasise concrete physical and conceptual explanations for quantum phenomena. Instead, it merely presents some of the strange effects happening in quantum physics and attempts to highlight the assumptions that might be connected to labelling them as “strange” in the first place.
By aligning the assumptions with those of the philosophical school of emptiness, readers are invited to investigate their perceived notion of “strangeness” of the quantum world. Whatever that might lead to, it should not imply that the analogies between quantum physics and Buddhist philosophy point towards the same underlying nature of reality. However, the intention is to show that what these two traditions say about what reality is not, might be similar.
We hope you enjoyed this article as much as we did. A huge thank you to Manuel, one of our Online Learning Volunteers for writing this thought-provoking article! We plan on writing more of these in depth articles on topics like the nature of consciousness and quantum entanglement. If there are any other topics you’d like to see covered, please get in touch and send your suggestion to hello@sciwizlive.com!
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