From the very beginning of the quantum theory it has been controversial what (if anything!) the wavefunction represents: is it a physical characteristic of an individual system, or a statistical description of an ensemble of systems, or a representation of the information that an individual has about a system, or what? It was also controversial how the wavefunction behaves through time: does it always evolve deterministically and linearly (in accord with Schrödinger’s equation) or does it sometimes randomly “collapse”? And it was unclear whether the wavefunction provides a complete physical description of a system or only a partial description.

Why quantum physics needs Asian philosophy

By JAN KRIKKE

Reality is relative in that it depends on the “frame of reference” of the observer.

Albert Einstein, Werner Heisenberg, Erwin Schrödinger and nearly all the other pioneers in quantum physics were captivated by Chinese and Indian thought. 
Einstein praised the Bhagavad Gita and Schrödinger’s work was strongly influenced by the Vedas. Danish physicist Niels Bohr, one of the pioneers of quantum physics, was fascinated by the Chinese notion of Tao. 
Bohr is the father of the Complementarity Principle, a tenet in quantum physics stating that a complete knowledge of phenomena on atomic scale requires a description of both wave and particle properties. When Bohr was knighted for his work, he used the yin-yang symbol in his coat of arms and inscribed it with the words Contraria sunt complementa (opposites are complementary).

What explains the fascination of the quantum physics pioneers with ancient Asian thought? The Asian sages had no way of knowing about electrons, protons, neutrons, and photons. They were aware of magnetism, but they didn’t have electricity, a prerequisite for understanding particle physics. But classic Chinese and Indian texts suggested to the quantum physics pioneers that ancient Asian thinkers had a grasp on the invisible realm that underlies appearances – the realm laid bare by particle physics which showed that matter, whether animate or inanimate, is energy. It seemed as if the Asian thinkers had an understanding of the source of Creation.

In the 100 years since the quantum revolution, the fascination of Asian thought by the founders of quantum physics was largely forgotten and quite often ridiculed. But today’s physicists still struggle to interpret the findings of particle physics, among them the wave-particle duality. And despite a century of trying, physicists have yet to reconcile the standard atomic model with Einstein’s Relativity Theory. The former deals with the micro-cosmos (subatomic particles), the latter deals with the macro-cosmos (gravity). Their integration would ostensibly provide a Theory of Everything.

Space and time

Let’s take a bird’s-eye view of the quantum physics revolution. At the end of the 19th century, German scientists Heinrich Hertz, Ludwig Boltzmann and Max Planck studied the so-called photoelectric effect, and concluded that light not only had wave-like characteristics, as had been commonly assumed, but that it could take on the appearance of discrete particles, or “quanta,” as they called them (hence the name quantum physics). In 1905, Einstein developed a mathematical equation on the behavior of quanta in a paper on the photoelectric, which earned him his only Nobel Prize and would lead him to develop a new theory of gravity.

Legend has it that an apple falling from a tree led Isaac Newton to develop his theory of gravity. Einstein, living at the dawn of the machine age, offered a dynamic variation of Newton’s eureka moment. In his 1916 paper Relativity, he wrote: “I stand at the window of a railway carriage which is traveling uniformly, and drop a stone on the embankment, without throwing it. Then, disregarding the influence of the air resistance, I see the stone descend in a straight line. A pedestrian who observes the misdeed from the footpath notices that the stone falls to earth in a parabolic curve. I now ask: Do the ‘positions’ traversed by the stone lie ‘in reality’ on a straight line or on a parabola?”

Einstein answers his own question. Reality is relative in that it depends on the “frame of reference” of the observer. He wrote: “The stone traverses a straight line relative to a system of coordinates rigidly attached to the carriage, but relative to a system of coordinates rigidly attached to the ground (embankment) it describes a parabola. With the aid of this example, it is clearly seen that there is no such thing as an independently existing trajectory … but only a trajectory relative to a particular body of reference.” In other words, what we observe depends on our position in space.

Using his knowledge of quanta (later commonly referred to as photons), Einstein proposed that light from distant stars behind the sun is deflected or curved by 1.73 arc seconds as it passes the gravitational effect of the sun on its way to Earth. In 1919, scientists photographed a solar eclipse and confirmed Einstein’s calculation to the decimal point. The effect of curved space is typically – and misleadingly – illustrated with the flat surface of a trampoline hit by a ball.

Common sense dictates that curved space is best seen as a metaphor. The trajectory of light (photons) may be curved, and the notion of curved space assumes that light and space are interchangeable phenomena. Space means different things to physicists, astronauts, and architects. But Einstein offered a mathematical construct that fuses the three dimensions of space and the one “dimension” of time into a single four-dimensional continuum. Spacetime diagrams can visualize “relativistic effects” and how our position in space and time determines how we experience a given event.

Chinese space and time – Yu-Zhou

Not widely know is that the Chinese had unified space and time esthetically about 2,000 years before Einstein did so mathematically. It was part of their Tao-inspired method to categorize all natural phenomena in yin and yang. Time was yang, space was yin. Historical records suggest that the ancient Chinese spoke of Yu, meaning space-universe, and Zhou, or time-universe. About 2,000 years ago, these concepts began to appear together: Yu-Zhou.

According to the 20th-century Chinese scholar Feng Youlan, the first known reference to the Chinese character for Yu-Zhou included the following explanation: “What comprises the four points of the compass together with what is above and below: this is called Yu. What comprises past, present and future: this is called Zhou.”

The Yu-Zhou most likely has its origin in feng shui, the Chinese form of an ancient practice known as geomancy. Chinese emperors, who typically constructed entirely new capital cities when they ascended the Dragon Throne, consulted feng shui masters to select the most favorable space (place, location, site) for the new capital. Feng shui masters used a magnetic compass to determine the favorable orientation (typically on the Earth’s magnetic north-south axis) for the new city. Moreover, they selected the favorable astronomical time (the ideal “cosmic moment”) to commence construction, which explains why feng shui experts were also referred to as Masters of Time.

The way the Chinese philosophers defined Yu-Zhou illustrates how they viewed space and time. In one of the Chinese classics, the Mohist Canon expositions, we read: “Duration unites past and present, dawn and dusk. Space embraces east, west, south, and north.” In another classic, the Shizi, we read: “Above, below and the four directions are called space, going from the past to the present is called time.”

The classic Chinese handscroll illustrates how the Chinese esthetically synthesized space and time. While the classic European painting depicts a static, frozen moment in time and uses linear perspective to depict space, the Chinese handscroll, like a movie, is based on a scenario that takes the viewer through space and time. And rather than linear perspective, the Chinese scroll used axonometry, popularly referred to as parallel projection, which conceptually accommodates space and time. Axonometry places the viewer in, rather than in front of, space.

JAN KRIKKE
Jan Krikke is a former Japan correspondent for various media, former managing editor of Asia 2000 in Hong Kong, and author of Quantum Physics and Artificial Intelligence in the 21st Century: Lessons learned from China.