This blog post explores how the uncertainty principle of quantum mechanics and the concept of wu-wei (non-action) in Eastern philosophy bridge science and philosophy. It offers new insights through the connection points between these two fields.
Quantum mechanics is both the culmination of highly developed modern physics and a new starting point. The discovery of quantum mechanics was a revolutionary event on par with Darwin’s theory of evolution or Copernicus’s heliocentric theory, triggering another major paradigm shift in modern science. Yet, intriguingly, quantum mechanics—pushing the very frontiers of modern science—shares a curious connection with Eastern philosophy dating back over a millennium. This fact is, in a way, highly paradoxical. The temporal gap is obvious, but it’s also difficult to readily accept that scientific theories developed in the West share common ground with Eastern philosophy.
The points of convergence between quantum mechanics and Eastern philosophy can be found in concepts such as quantum uncertainty, the role of the observer, and the superposition of wave functions. These concepts bear a striking resemblance to the ‘ambiguity’, ‘complementarity’, and ‘holistic perspective’ long emphasized by Eastern philosophy. Eastern philosophy has long understood the world not as fixed entities, but as an ever-changing, interacting process. For example, Daoism views all beings and phenomena in the universe as changing within the flow of the ‘Dao’ rather than existing in fixed states. Similarly, quantum mechanics posits that a particle’s position or momentum is not fixed but can change depending on observation.
After the 19th century, China collapsed under the Western powers, and subsequently, a wave of Westernization rapidly began under the guise of modernization. During this process, a trend of Sadaejuism—rejecting Eastern culture and diverse philosophical thought as outdated while venerating Western ideas—became widespread, and current societal attitudes are not significantly different. Yet, Eastern philosophy, long disregarded, is now gaining attention as a new paradigm for understanding the universe, alongside the development of quantum mechanics. So, what exactly is quantum mechanics, how has it developed, and what are its origins? Let’s explore these questions and trace the similarities between quantum mechanics and Eastern philosophy.
In 1900, German physicist Max Planck analyzed the conclusions drawn from his experiments on blackbody radiation and realized that the existing concepts of statistical mechanics needed revision. Until then, physics had considered energy to be a continuous quantity proportional to temperature. However, Planck proposed the hypothesis that energy is proportional to frequency and possesses discrete, non-continuous values, stating that “energy is quantized.” In this quantum theory, a quantum refers to a discrete unit of energy. Five years later, Einstein formulated the photon theory to explain the photoelectric effect. The photoelectric effect refers to the phenomenon where electrons are emitted from a metal surface when light of a certain frequency or higher is shone upon it. This phenomenon could not be explained solely by the wave nature of light. Einstein, drawing on Planck’s quantum theory, defined light energy as being composed of discrete energy units, which he termed light quanta or photons, thereby explaining the photoelectric effect.
Subsequent research into quantum theory intensified, culminating in Niels Bohr’s proposal of a new hydrogen atom model based on these quantum properties. The hydrogen atom model proposed by Rutherford before Bohr could not be explained by classical mechanics. According to electromagnetic theory, electrons orbiting the nucleus should lose energy due to accelerated motion, causing their radius to gradually shrink until they collide with the nucleus, leading to the collapse of the hydrogen atom. However, in reality, hydrogen atoms do not collapse, and their energy appears in discrete, characteristic bands rather than continuously. To resolve this, Bohr proposed that electrons move in ‘specific orbits’ around the nucleus, calling these orbits ‘stalk orbits’. The hypothesis was that electrons do not lose energy within these normal orbits. When moving from one orbit to another, they emit or absorb light with a frequency proportional to the energy level change.
While classical quantum theory achieved great success in atomic and molecular optics, it remained confined within the limitations of classical mechanics and could not explain phenomena like collisions or scattering. A prime example of this limitation is the dual nature of light.
Thomas Young’s interference experiment with light through a double slit clearly demonstrated that light possesses wave properties. However, as seen through the photoelectric effect, it is equally clear that light also exhibits particle properties. Even more intriguing is the fact that if experimental apparatus is used to determine which of the two slits a photon enters in the double-slit experiment, the light no longer produces an interference pattern. That is, light behaves entirely as a particle. The moment the experimental apparatus is removed, and it becomes impossible to know which slit the photon passes through, light once again exhibits wave properties. In other words, the act of observation fixes light into one state—either particle or wave—and the moment observation ceases, it exists in an ambiguous state where both states coexist. To explain this phenomenon, in 1927, Born defined the wave function of a particle as a ‘state function’ and proposed the hypothesis that the intensity of the wave obtainable from this state function could be considered probability, allowing the derivation of the particle’s probability distribution. The particle’s wave function, which is a superposition of multiple state functions interfering with each other, ‘collapses’ into a single state at the moment of observation. Building on this, Heisenberg discovered the famous ‘Uncertainty Principle’. The Uncertainty Principle states that it is impossible to simultaneously reduce the uncertainty in both a particle’s position and momentum. Precisely knowing the position means one cannot obtain information about the momentum, and conversely, precisely knowing the momentum means the uncertainty in position becomes very large.
When I took a quantum mechanics class last summer, Professor Ham Don-hee explained this phenomenon by saying, “Nature knows.” The ‘nature’ he referred to carries a more philosophical meaning. Laozi, the founder of Daoist thought during China’s Spring and Autumn period, adopted the philosophy of ‘non-action and naturalness’ (無爲自然) as a political ideology, rejecting artificial norms like those of Confucianism. The wuwei ziran advocated by Laozi here is precisely the same concept as the ‘nature’ mentioned by Professor Ham Don-hee. Wuwei ziran refers to nature as it is, unadulterated by human intervention. From the perspective of classical mechanics, nature can be viewed as an artificial space divided by humans into a single system. Therefore, from the viewpoint of classical mechanics, this phenomenon cannot be understood or explained. However, in the state of wuwei ziran advocated by Laozi, the dual nature of light poses no problem whatsoever.
Prior to quantum mechanics, Newtonian classical mechanics understood physics through deterministic thinking, based on the premise that “if all conditions at any point in the past are known, the future can be determined or fixed in a single way.” Yet this way of thinking could not explain quantum phenomena at all. Consequently, the Copenhagen school, led by Niels Bohr, proposed the ‘principle of complementarity’ as a fundamental premise of quantum mechanics: that a quantum particle simultaneously possesses both particle and wave properties; that the state and position of a quantum particle are determined only at the moment of observation; and that prior to observation, these properties exist in a superimposed state.
While this perspective of quantum mechanics enabled the explanation of various phenomena, it also created another paradoxical situation. This is precisely the Schrödinger’s Cat theory. Schrödinger proposed a thought experiment: imagine placing radioactive material, a device with a hammer, a vial of poison, and a cat inside a sealed box. If particles emitted by the radioactive material meet specific conditions, the device activates, causing the hammer to shatter the poison vial, killing the cat. The key point of this experiment is that if the particle is not emitted, the bottle remains unbroken and the cat survives. Since opening the box is the only way to determine whether the particle was emitted, the cat exists in a state of simultaneous death and survival. The act of opening the box corresponds to ‘observation,’ which determines the particle’s position and state.
Quantum mechanics has developed by embracing all this uncertainty. While this uncertainty reveals the limits of human epistemology, it simultaneously unveils laws of nature previously unknown to us. Quantum mechanics offers a new perspective on nature, enabling us to transcend fixed, conventional thinking. This resonates with the state of ‘wu-wei’ (non-action) pursued in Eastern philosophy.
