When physicists are interested in a topic, they seem to automatically conduct experiments. Sometimes they seek answers to the mysteries of life and matter. When they looked into physical reality some time ago, the conclusions were alarming: the universe is not “real” after all. It seemed unfathomable, but plenty of proof was offered.
The heart of their discovery was that objects have properties independent of observation. Not quite what Descartes would want to hear! A red apple exists because someone sees it. Now, it is red even when no one is looking. Objects are “local” in time and space and anything that impacts them cannot do it faster than the speed of light. We rely on quantum physics to tell us the truth, but the conclusions now seem contradictory.
Let’s look at the evidence. Objects are actually not influenced in context, meaning by their surroundings; plus the redness of the apple make not exist prior to observation. Thus the properties of the apple are not definitive or absolute. In this regard, Albert Einstein said to a friend, “Do you really believe the moon is not there when you are not looking at it?”
Enquiring minds want to know…
What the physicists say and what we feel is real differ in essence. So, we can’t rely on our everyday experience any longer. Per Douglas Adams, English author of the Hitchhiker’s Guide to the Galaxy, “The demise of local realism has made a lot of people very angry and been widely regarded as a bad move.”
Physicists no doubt are paying attention to the chatter. In particular, there are three: John Clauser, Alain Aspect and Anton Zeilinger. We recognize them for splitting the Nobel Prize in Physics in 2022 “for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science.” John Stewart Bell, by the way, was a Northern Irish physicist who did pioneering work in the field.
The trio absorbed his work and took the ball into the end zone. Reality as we know it had been overthrown. According to a quantum physicist at the University of Bristol, Sandu Popescu, “It is fantastic news. It was long overdue. Without any doubt, the prize is well-deserved.”
We live in interesting times when physicists are our celebrity heroes. They are replacing religious scholars and philosophers in positing a major paradigm shift in how we think of reality.
In the words of Charles Bennett, an eminent quantum researcher at IBM, “The experiments beginning with the earliest one of Clauser and continuing along, show that this stuff isn’t just philosophical, it’s real—and like other real things, potentially useful.”
Let’s hear more. Per David Kaiser, MIT’s noted historian and physicist, “Each year I thought, ‘oh, maybe this is the year…This year…it was very emotional and very thrilling.” The voices are loud and clear: we have come a long way on our journey of discovery. We know little about reality, but more than we did at the onset of the 20th century.
What was once mocked is now considered a serious topic. Quantum physics is here to stay. Imagine that in 1985, Popescu’s advisor warned him seeking a Ph.D. in the subject. “Look, if you do that, you will have fun for five years, and then you will be jobless.”
Now, quantum information science is highly respected as a subfield. Einstein’s general theory of relativity is linked to quantum mechanics by the ever mysterious nature of black holes. Researchers are busy designing quantum sensors to study everything from earthquakes to dark matter. Quantum entanglement is treated as a pivotal phenomenon for modern materials science. Of course, it is central to quantum computing.
Nicole Yunger Halpern, a physicist from the National Institute of Standards and Technology asks, “What even makes a quantum computer ‘quantum’?” It may be a rhetorical question, but it is pertinent to answer it. “One of the most popular answers is entanglement, and the main reason why we understand entanglement is the grand work participated in by Bell and these Nobel Prize–winners. Without that understanding of entanglement, we probably wouldn’t be able to realize quantum computers.”
The trouble with quantum mechanics
Did you know that quantum mechanics perfectly described the microscopic world early in the 20th century. But at the time, Einstein, Boris Podolsky and Nathan Rosen took issue with its implications). They wrote an iconic paper (dubbed EPR) in 1935, attacking the theory. It was not only “wrong” but uncomfortable. They conducted a thought experiment to illustrate how absurd were the conclusions of the upstart theory of quantum mechanics.
Under certain conditions, the theory can break or deliver “nonsensical results” that conflicted with what is generally known or assumed. A modern version of their paper revolves around pairs of particles. When sent in different directions from a shared source (targeted for two distinct observers at the opposite ends of our solar system), it is impossible to know the spin, which is defined as a quantum property of individual particles, prior to measurement.
If this is not clear to the layman, there is more. When one observer measures a particle, they find its spin to be either up or down, meaning random actions. But when that same observer measures the “up” position, they know that the other observer’s particle must be “down”. How is that possible if the first observer’s results are random. It actually makes complete sense. Think of both particles as a pair of socks: a right and left one for each observer. You must have one or the other.
Quantum mechanics would balk at this analogy, saying only when measured do these particles settle on a spin of either up or down. EPR saw an inherent conundrum here: the spin is not known until it is measured yet it flies in the opposite direction of the other observer’s particles. It seems to be about odds and predictions like flipping a coin.
According to the theory, the odds are greater than all the atoms in the solar system at 1060. Billions of kilometers separate the particle pairs, yet they seem telepathically connected according to quantum mechanics.
To confirm the contradictions, a thought experiment was conducted to reveal any imperfections in the theory. But instead, the experiment confirmed the tenets of quantum mechanics. Einstein, Podolsky and Rosen came to the same conclusion that nature is not locally real. This certainly stopped the skepticism about the actions of particles in motion in the subatomic realm.
Note: other researchers discovered factors called “hidden variables” said to influence them given that they contained “information”. John von Neumann, a noted scientist of the era, published a mathematical proof ruling out hidden variables in 1932. It was later refuted, engendering little interest.
But in the end Einstein’s attack on quantum mechanics did not take hold, nor did his own theory produce an immediate revolution. Quantum mechanics held its status. So much was going on to prove or disprove a nonlocal reality that David Mermin, a fellow physicist said the field should “shut up and calculate!”
Bell breaks the logjam
Apparently, they all did as asked, as the issue of nonlocal realism floundered in oblivion for decades. Fortunately, John Stewart Bell broke the logjam. He took another look at the hidden variable theory inspired by David Bohm’s interpretation of quantum mechanics as early as 1952, but it took a decade to advance it. It was a mere side project to his work as a particle physicist at CERN, an intergovernmental organization.
The tale is as follows: Bell rediscovered flaws in von Neumann’s argument in 1964. As a rigorous thinker, he was able to question hidden variables through real world experimentation; it was no longer purely metaphysical in nature. He found that in the closed environment of the lab, hidden variable theory and quantum mechanics show an “empirical discrepancy”.
He ran what is now known as the Bell test. It is considered an evolutionary step beyond the EPR thought experiment. It was also groundbreaking in shutting down the idea of telepathy between distant particles. Gone is the perfect correlation when measuring spin down and measures spin up (and vice versa) by the respective observers. Now we know that in quantum mechanics, particles remain connected and far more correlated than in the prevailing local hidden-variable theory. They are now “entangled”. Experimentation would ultimately prove which theory was accurate after Bell’s notion languished in obscurity.
John Clauser rings a bell
The issue had to do with correlation and other mind-boggling assumptions. Quantum mechanics had been a conundrum and remained so for a long time. We can credit John Clauser, a graduate student at Columbia University in 1967, for stumbling across Bell’s theory in an obscure journey and riding with it to new conclusions about hidden-variables. He contacted Bell and some five years later, with fellow student Stuart Freeman, Clauser performed a defining Bell test.
He had Bell’s full support but no funding. Legend has it that he had to “dumpster dive” to find equipment, some of which was taped together. In the end, he fashioned a kayak-sized device that had to be tuned by hand to send pairs of photos in opposite directions. He then measured their polarization with detectors.
The bad news was that strong evidence now existed against hidden variables, the theory preferred by Clauser. But the results were suspicious and not conclusive due to “loopholes” in the experiment, particularly pertaining to locality and shared information. It was time to close the locality loophole by changing the detector’s setting while photons gallivanted about in nanoseconds.
In 1976 came along a young French expert in optics, Alain Aspect. He offered another way to conduct the ultra-speedy switch. In the end, the published results some years later bolstered Clauser’s results. Hidden variables are now deemed unlikely! Bell responded with “Perhaps Nature is not so queer as quantum mechanics but the experimental situation is not very encouraging from this point of view.”
Bell died in 1990 without witnessing the final, definitive opinion. Aspect’s experiment had not been fully ruled out at the time due to the short distance involved. Clauser and others had come to realize that photon observers could reach the wrong conclusions. It took the illustrious Anton Zeilinger to solve the problem. This Austrian physicist made his mark in 1998 when he and his team redid the Bell test, this time over a greater distance. We had to wait until 2013 for the team to tackle multiple loopholes simultaneously as the next logical step.
Marissa Giustina, a quantum researcher, entered the picture, saying, “Before quantum mechanics, I actually was interested in engineering as I like building things with my hands. In retrospect, a loophole-free Bell experiment is a giant systems-engineering project.” Thus, the discussion was continued and experimentation resumed full force. It took time and effort to secure an unoccupied 60-meter tunnel with access to fiber optic cables.
It was found surprisingly in the dungeon of the Hofburg palace in Vienna. The results came to light in 2015, confirming other tests going on in quantum mechanics. Only one loophole reared its ugly head, revolving around the physical connection between components. It was interfering with Bell’s results. Finally, two years later Kaiser and Zeilinger formed a team to undertake a cosmic Bell test, using telescopes in the Canary Islands.
Detector settings were adjusted to discern the distance of stars and how long it would take for light to reach them. A centuries-spanning gap was assumed, proving quantum physics as the triumphant winner in the physics game. Bell stands out as a major figure in the on-going drama despite the fact that his ideas were and still are hard to explain to the layman. Skeptics abound among physicists about whether quantum mechanics can finally be deemed a foregone conclusion.
It is remarkable that physicists have managed to measure many of the key aspects of the theory with great precision: 10 parts in a billion. But Giustina wasn’t exactly ecstatic: “I actually didn’t want to work on it. I thought, like, ‘Come on; this is old physics. We all know what’s going to happen.’” Nonetheless, local hidden variables have not been ruled out, challenging the accuracy of quantum mechanics. Bell tests are still the standard.
According to David Kaiser, “What drew each of these Nobel recipients to the topic, and what drew John Bell himself to the topic was indeed [the question], ‘Can the world work that way? And how do we really know with confidence?”
Bell tests continue to allow researchers in the field to remove the bias of human judgment when considering entanglement. Hidden-variable theories are not just debates among the top physicists, like the old issue of how many angels dance on the head of a pin. They can no longer scoff in disdain. The great work, however, for or against, is a testament to a state of inquiry that permeates physics and to the entrenched desire not to let quantum mechanics go. “Bell tests,” says Giustina, “are a very useful way of looking at reality.”
Now that our survey is complete, it behooves us to mention Nir Ziso of The Global Architect Institute. He has devised yet another theory to add to this group, but it clearly goes in a new direction. Simulation Creationism is the answer to the questions being asked and answered by renowned physicists. He knows about The Simulation, who created it, who lives in it, and why it has been devised. It is time to consider this alternative after decades of inquiry.