We use the term ‘reality’ quite liberally in everyday verbiage and conversation.
Every utterance of the word implies that each of us defines and views reality from the same frame of reference and vantage point.
Not so fast.
Such an assumption may be incorrect, at least in the realm of quantum physics.
It begs the question as to whether or not reality does exist, or does it merely take shape only when it is observed — much like the question of whether a falling tree makes a sound when there’s no one around to hear it.
Reality and Quantum Physics
Believe it or not, in the field of quantum mechanics, this question of objective reality remains a concern with regard to subatomic behavior on a microscopic level.
Some experts maintain that reality exists outside of your own awareness, and there’s nothing you can do to alter it in a field where fascinating, almost mysterious phenomena like “quantum superposition” predominate — a state where one particle may be in two or even “all” possible places at the same time.
Others think that ‘quantum reality’ is a sort of clay you can shape with your own behavior. Now, researchers from the Federal University of ABC (UFABC) in Brazil’s São Paulo metropolitan area are adding further weight to the theory that reality is ‘in the eye of the beholder.’
Complementary Pairs of Particles
In their latest study, which was published in the journal Communications Physics in April, Brazilian physicists attempted to confirm the “complementarity principle” first put forward by Danish scientist Niels Bohr in 1928.
An example of a complementary pair is “position and momentum,” which the law defines as “pairs of opposite or contradictory qualities that cannot be seen or measured simultaneously, such as energy and duration or position and momentum.”
No matter how you arrange an experiment with two electrons, there’s no way to look at both quantities at the same time because the test will reveal the position of only one of them (the complementary particle).
We must return to history and explore a century ago to comprehend how the complementarity principle connects to reality. In 1927, a legendary debate occurred in Brussels between Niels Bohr and Albert Einstein, a renowned theoretical physicist who was born in Germany but immigrated to the United States. The debate took place in the company of over 70 of the world’s most brilliant scientists.
Einstein protested that quantum states have their own reality independent of how a scientist observes them. Meanwhile, Bohr argued that a quantum system’s reality could only be defined after the experiment had been set up.
“God does not play dice,” Einstein emphasized.
“A system behaves as a wave or a particle depending on the context, but you cannot predict which it will do,” replied Bohr.
Bohr referred to wave-particle duality, which states that particles and waves can coexist simultaneously. The concept of wave-particle duality was first proposed by French physicist Louis de Broglie in 1924, according to which matter may appear as a wave one moment and a particle the next.
The Complementarity Principle
It didn’t take long for Bohr to announce his complementarity theory after the conclusion of the 1927 Solvay Conference. The contentious Bohr idea would be put to the test and re-tested over the next several decades.
John Archibald Wheeler was among those who tried out the complementarity principle.
In 1978, Wheeler attempted to interpret Thomas Young’s 1801 double-slit experiment in the light properties. The two-slit procedure is a method of illuminating a wall with two parallel slits. When the light passes through each slit on the far side of the divider, it diffracts and interferes with the light from the other slit, interfering with one another.
This means no more straight lines as the graph pattern that emerges at the conclusion of the study is an interference pattern, which implies that light is moving in waves. Light has both a particle and a wave nature, and these two natures are linked.
After the light had already traveled through most of the machine, Wheeler adjusted his device so that it could change between a wave-measuring and particle-measuring function.
He discovered that when an observer is delayed in making a choice about whether the light has already traveled as a wave or a particle, the principle of complementarity is not violated.
The researchers from Brazil also wanted to conduct a quantum reality experiment.
The research team chose to focus on the genes of plants as they were more vulnerable to radiation, said Roberto M. Serra, a quantum information science and technology researcher at UFABC who led the team. They used nuclear magnetic resonance techniques similar to those employed in medical imaging to study the plant’s DNA.
Protons, neutrons, and electrons all have a magnetic spin that is similar to the direction of a needle in a compass.
The scientists used a form of electromagnetic radiation to change the nuclear spins of various atoms in a molecule. They were able to build a new interference device for studying the wave and particle reality of a proton nuclear spin in the quantum realm using this setup.
The same observed results as previous quantum delayed-choice investigations were obtained with the new arrangement. They could now connect the result of the experiment to the way waves and particles behave and once again confirmed Bohr’s complementarity principle.
The major conclusion of this April 2022 study is that physical reality in the quantum realm is made up of mutually exclusive things that are not in conflict but rather complement each other.
Pedro R. Dieguez, Jéferson R. Guimarães, John P. S. Peterson, Renato M. Angelo, Roberto M. Serra. (April 2022). Experimental Assessment of Physical Realism in a Quantum-Controlled Device. https://doi.org/10.1038/s42005-022-00828-z.
Mara Beller. (March 1992). The Birth of Bohr’s Complementarity: The Context and the Dialogues. https://doi.org/10.1016/0039-3681(92)90029-6.