The Beholder’s Quantum Share

Art is subjective, as is the world we observe. The difference between what was and what is perceived is the beholder’s share, but that is built up one quantum at a time.

What makes art art?

A painting is just a surface of woven fiber that has absorbed a mixture of resin, solvent, and additives. Different parts of the surface have different additives, called pigments, that absorb specific wavelengths of light and scatter others. Occasionally, a member of the species Homo sapiens perceives this scattered light and calls it art. The difference between this art and the physical configuration of the atoms on the canvas is what is known as the beholder’s share.

While the idea dates back to the writings of early 20th-century art historians, it was Marcel Duchamp that dared quantify it, saying that an artist only completes 50% of the work. The remaining 50% is done by the perceiver of it. Trying to quantify it exactly is a bit silly, of course, but the point remains — art is a collaboration between the artist and the beholder.

Good art thus requires the beholder’s mind to contribute actively to its completion. But, the work of every beholder need not be the same. Indeed, it is said that great art must be open to interpretation. In other words, the beholder’s share is not objective — each perceiver must complete a different piece of art. Disagreement is often a good proxy for this — is the Mona Lisa smiling, for example?

From beholders to observers

In science, measuring and testing things is often invasive. In medicine, a biopsy is an obvious example of a measurement that alters the organ being tested. Measuring the temperature of a room requires the transfer of heat from the room to the thermometer. Measuring the air pressure in a tire requires letting at least a little bit out. These are examples of what is called the observer effect — the change in the thing observed due to the act of observation.

Scientists understand the observer effect well as it is a small part of the many types of errors that can occur during an experiment. However, most also believe that a scientist acting in good faith is one who is making the best attempt to eliminate all errors. The ideal observer is one who is able to ascertain the “true value” of a measured quantity without any disturbance to the thing being observed. Moreover, it is believed that — at least in principle — such an ideal observer could exist.

Einstein argued that the Moon surely has a definite position in the solar system regardless of whether or not it is being observed. In his view, there is a true objective reality out there, and if we were clever and careful enough, we could know it. Einstein’s vision is that of objective realism — there are definite things in the world that obey the laws of physics. They have done so since the dawn of time and will continue to do so regardless of whether any observer is around to witness them. Unfortunately, Einstein was wrong.

Enter the quantum

An ideal observer would be like an ideal beholder who could ascertain the “true” nature of a work of art. But art necessitates an observer, and each comes with their own experiences and expectations, which shape predictions and interpretations that provide the meaning which defines the concept of art. From the discovery of quantum physics, we now know that — like the impossibility of an ideal beholder — an ideal observer does not exist.

Werner Heisenberg illustrated the point most clearly with a hypothetical experiment now called Heisenberg’s microscope. Like all microscopes, light strikes an object and reflects or refracts such that it is imaged by an eye or a machine. Crucially, the object in question is an electron, one of the smallest known particles. Being so small means being hit by light will significantly affect it. It’s kind of like trying to find a basketball by throwing baseballs at it. In essence, at the level of quantum things, the observer effect is unavoidable.

In the 1960s, John Bell showed that entanglement — the most enigmatic quantum phenomenon — effectively disproved the notion of objective reality altogether. The Moon is not there if nobody is looking at it. While this seems comically preposterous, denying it is simply a misunderstanding of what reality is.

You, me, and the art we see

The Moon is art. Otherwise, like pigment stuck to canvas, it is just another arrangement of molecules. What we typically consider to be part of reality — moons, desks, chairs, cash, and so on — is simply an agreement between observers about the interpretation of our perceptions. The Moon is real because I have expectations about what I will see in the night sky, and those agree with the expectations of (mostly) everyone else. Moreover, in 2022, we also intersect in our mental models of what that object is — a large ball of rock and metal, rather than cheese. The reality of the Moon is tied up in our collective stories that include culture, history, tradition, science, conspiracy, and so on. It’s not the same for everyone. No one holds in their mind the “true nature” of the Moon, and that’s impossible anyway.

In some dimensions, the Moon makes for boring art. Parts of it leave no room for interpretation. Like the Mona Lisa, which we all agree is a portrait of Italian noblewoman Lisa Gherardini, the beholder’s share lies in the details. The smile is like the shape of the Moon’s maria, which appears as a face to some and a cat to others. But even finer details — at the level of atoms — no two people can agree upon. This is because no quantum reality lies beyond our perceptions.

What is essential about art is its relative permanency. The Mona Lisa sits in the Louvre, as it has for the past 200 years, and displays roughly the same set of brush strokes as it always has. This information is copied and replicated for the eyes of the beholders in the gallery but also for the virtual observers of the digitized versions appearing all over the internet. If the brush strokes disappeared as da Vinci painted them, it wouldn’t be art for the now obvious reason that there’d be no beholder’s share.

The beholder’s quantum share

The subtlety of the information contained in atoms is that it cannot be copied and replicated — that’s a law of quantum physics. Once observed, the quantum information is destroyed — an irreversible act. At the level of quantum things, the observations might also differ for each observer. In aggregate, though, they build up to create a seemingly rigid reality, which is where meaning lies.

The fact of the matter is that the real Mona Lisa, the actual painting in the Louvre, will not last forever. This is thanks, in part, to the observer effect. Every time a particle of light strikes the painting, it imparts its effect, eventually leading to the decay of the pigments and fibers. Each particle of light is then taken by an observer, a beholder of the art. Whatever that particle did to the painting can never be recovered.

Each particle — each quantum of light — is the beholder’s quantum share. With each share we take, we destroy a part of the organized world. It is the price we pay to construct an intersubjective reality worthy of the name.

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Chris Ferrie

Chris Ferrie

Quantum theorist by day, father by night. Occasionally moonlighting as a author. csferrie.com