The quest to understand quantum mechanics has led to remarkable technological advancements, granting us power and control over the natural world. However, despite these successes, the paradoxes and mysteries surrounding the theory continue to challenge our understanding of reality. This raises the question of whether science, particularly quantum mechanics, provides us with true comprehension of the world or merely equips us with power without deeper understanding, writes John Horgan.
As a science writer, I’ve always felt a little embarrassed by my lack of formal mathematical training. And so three years ago, at the beginning of the Covid pandemic, I set out to learn the math underlying quantum mechanics. My quantum experiment, as I came to call it, has had an unexpected outcome. Instead of enlightening me, it has made me wonder whether we’ll ever really know the world or ourselves.
Let me back up a minute and ask a basic question: What is science for? One obvious end is power. Science helps us manipulate the world so we can live longer, see further, move faster, crush our enemies. I’ve never really been that interested in applied science. I became a science writer 40 years ago because I wanted to understand.
Ideally, these two ends of science—knowledge and power--complement each other. More knowledge leads to more technology leads to more knowledge leads to more technology and so on. This positive feedback effect fueled the explosive growth of science and technology in the 20th century.
Quantum mechanics lies at the heart of these revolutionary developments. Quantum mechanics is, in one sense, science’s greatest achievement. Countless experiments have confirmed its predictions, and it has yielded technologies that help us probe the deepest recesses of matter and farthest reaches of the universe.
Quantum mechanics, discovered a century ago, has spawned more sophisticated theories that describe all of nature’s forces except gravity. These successes inspired physicists like Stephen Hawking to predict that they would soon find a “final” theory, which accounts for all the forces and solves the riddle of existence. This “theory of everything” would tell us how the universe, and we, came to be.
The problem is that quantum theory makes no sense. Unlike Newtonian physics, quantum mechanics does not specify how matter behaves; it presents a range of possible paths for, say, an electron. Only when you actually observe the electron do you determine which path it takes.
This so-called measurement problem subverts the basic premise of scientific objectivity, that the world is what it is regardless of how we perceive it
And what you observe depends on how you observe, that is, how you carry out your measurement of electrons or whatever. This so-called measurement problem subverts the basic premise of scientific objectivity, that the world is what it is regardless of how we perceive it.
For more than a century, experts have tried to interpret quantum mechanics, to say what it means, in ways that resolve the measurement problem and related puzzles. But all interpretations are preposterous. They resemble reductio-ad-absurdum arguments, except adherents want us to believe the absurdum.
The many-worlds interpretation, for example, holds that all the possibilities described by the Schrodinger equation actually happen—in different universes! Superdeterminism says everything happening today—from the outcome of Trump’s trial to the scores of baseball games--was determined at the beginning of time by undetectable “hidden variables.”
Many physicists insist that the true meaning of quantum mechanics is embedded in its underlying mathematics. That is why I decided to study the mathematics underpinning quantum mechanics, including calculus and linear algebra, different equations and matrices, vectors and complex numbers. In this way, I would surely gain some insight into the measurement problem and other riddles.
If I get quantum mechanics now, it’s because of a brilliant little book called Q Is for Quantum. The author, physicist Terry Rudolph, happens to be the grandson of Erwin Schrodinger, of the equation and the cat, but that is not what qualifies him to explain quantum mechanics. Rudolph is, more importantly, the R of the so-called PBR theorem, which has been described as one of the most significant advances in quantum theory of the last half-century.
The PBR theorem proves that before we look at a photon or electron, it lacks specific properties; it exists in a probabilistic haze. Only when we look at the electron does it acquire specific properties. Rudolph is no mere theorist. He is also the co-founder of PsiQuantum, a frontrunner in the race to build commercial quantum computers.
In Q Is for Quantum, Rudolph explains quantum mechanics with a relatively simple system, in which black and white balls fall in and out of boxes that operate according to specific rules. These rules involve plain old algebra, not linear algebra. No vectors or matrices or complex numbers, let alone differential equations, are required.
After studying Rudolph’s system and carrying out many of his book’s exercises, I gradually grasped the principles underlying effects such as superposition, which refers to the blurry, probabilistic state of quantum systems. I also gained some understanding of how quantum computers exploit superposition to do things that ordinary computers can’t.
Rudolph resembles a magician who patiently reveals exactly how he performs his sleights of hand. He shows you that quantum mechanics is not magic; it is just a set of procedures that lead to outcomes that seem magical. Anyone can learn these tricks with practice.
But here’s the irony: After learning Rudolph’s system and practicing solving problems with it, I’m more baffled than ever. Rudolph, in effect, has taught me how to pull a rabbit out of a hat, albeit clumsily. But I don’t know where that rabbit came from; the trick still seems like magic to me.
We will be forced to accept that language, including the language of mathematics, can never truly capture reality, whatever that is
Here’s an even bigger irony: Rudolph is baffled too. Here is a physicist who has mastered the intricacies of quantum mechanics, and who is applying that knowledge to build quantum computers. His firm, PsiQuantum, has raised hundreds of millions of dollars. But he confesses that quantum theory leaves him in a state of “cognitive dissonance.” He can’t believe the conclusion of his own PBR theorem, that the world does not possess precisely defined qualities when we’re not looking at it.
If I wanted to end this essay on an up-note, I’d say: Breakthroughs could be around the corner! After all, corporations and governments are funneling billions of dollars into quantum computing. If quantum computers work, they could help physicists discover a more powerful--and sensible--theory beyond the current theory. Ideally, this new theory won’t be riddled with paradoxes like the measurement problem.
This new theory might take us closer to a theory of everything, which tells us why there is something rather than nothing. The theory might even solve the deepest riddle of all, how matter gives rise to mind--because without mind, there might as well be nothing.
But my guess is that the opposite will happen. My quantum experiment has convinced me that the more deeply we peer into nature, the more befuddled we will become. We will be forced to accept that language, including the language of mathematics, can never truly capture reality, whatever that is.
Science will surely keep giving us more power. If you think ChatGPT is clever, imagine what an AI based on quantum computing can do. But the dream of a final theory, a revelation that makes everything clear, will remain forever just that, a dream, a fantasy with no hope of being fulfilled.