June 29, 2023. Some scientists seek to clarify reality, others to mystify it. Physicist David Bohm seemed driven by both impulses. He is renowned for promoting a sensible (according to experts like Einstein, John Bell and philosopher Tim Maudlin) interpretation of quantum mechanics. But Bohm also asserted that science can never fully explain the world, and his 1980 book Wholeness and the Implicate Order veers into spirituality. Bohm’s interpretation of quantum mechanics has attracted increasing attention lately. He is the hero, for example, of Adam Becker’s book What Is Real: The Unfinished Quest for the Meaning of Quantum Mechanics. In The End of Science, I tried to make sense of this paradoxical truth-seeker, who died in 1992 at the age of 74. Below is an edited version of my take on Bohm. –John Horgan

In August 1992, when I visit David Bohm at his home outside London, his skin is alarmingly pale, especially in contrast to his purplish lips and dark, wiry hair. His frame, sinking into a large armchair, seems limp, languorous, and yet suffused with nervous energy. One hand cups the top of his head, the other grips an armrest. His fingers, long and blue-veined, with tapered, yellow nails, are splayed. He is recovering, he says, from a heart attack.

Bohm’s wife brings us tea and biscuits and vanishes. Bohm speaks haltingly at first, then faster and faster, in a low monotone, with ancient-Mariner urgency. His mouth must be dry, because he keeps smacking his lips. Occasionally, he pulls his lips back from his teeth in a grimace-smile. He has the disconcerting habit of pausing every few sentences and asking, “Is that clear?” or simply, “Hmmm?” I am often so hopelessly befuddled that I just smile and nod. But Bohm can be bracingly clear, too. He oscillates in and out of focus, like an exotic quantum particle.

Born (in 1917) and raised in the U.S., Bohm left in 1951, the height of anti-communist hysteria, after refusing to answer a Congressional committee’s questions about his ties to communism. After stays in Brazil and Israel, he settled in England. Bohm was a scientific dissident too. He rebelled against the so-called Copenhagen interpretation of quantum mechanics promulgated by Danish physicist Niels Bohr.

According to the Copenhagen interpretation, a quantum entity such as an electron has no definite existence apart from our observation of it. We cannot say with certainty whether it is a wave or particle. The interpretation also rejects the possibility that the seemingly probabilistic behavior of quantum systems stems from underlying, deterministic mechanisms.

Bohm rejected that view. “The whole idea of science so far has been to say that underlying the phenomenon is some reality which explains things,” he explains to me. “It was not that Bohr denied reality, but he said quantum mechanics implied there was nothing more that could be said about it.” Such a view reduces quantum mechanics to “a system of formulas that we use to make predictions or to control things technologically. I said that's not enough. I don’t think I would be very interested in science if that were all there was.”

In 1952 Bohm proposed a model that builds upon one invented by Louis de Broglie in the 1920s. Particles are particles at all times, not just when observed in a certain way, and their behavior is determined by a force called the “pilot wave.” Any effort to observe a particle alters its behavior by disturbing the pilot wave. Bohm thus gave the uncertainty principle a purely physical rather than metaphysical meaning. Niels Bohr had interpreted the uncertainty principle as meaning “not that there is uncertainty, but that there is an inherent ambiguity” in a quantum system, Bohm says.

Bohm’s interpretation gets rid of one quantum paradox, wave/particle duality, while doubling down on another, nonlocality, the capacity of one particle to influence another instantaneously across vast distances. Einstein drew attention to nonlocality in 1935 in an effort to show that quantum mechanics must be flawed. Together with Boris Podolsky and Nathan Rosen, Einstein proposed a thought experiment involving two particles that spring from a common source and fly in opposite directions.

According to the standard model of quantum mechanics, neither particle has fixed properties, such as spin, before it is measured. Upon measuring one particle’s spin, the physicist instantaneously determines the spin of the other particle, no matter how distant. Deriding this effect as “spooky action at a distance,” Einstein argued that quantum mechanics must be flawed or incomplete. But in 1980 French physicists demonstrated spooky action in a laboratory. Bohm never doubted the experiment’s outcome. “It would have been a terrific surprise to find out otherwise,” he says.

But here is the paradox of Bohm: Although he tries to make the world more sensible with his pilot-wave model, he also argues that complete clarity is impossible. He reached this conclusion after seeing an experiment on television, in which a drop of ink is squeezed onto a cylinder of glycerin. When the cylinder is rotated, the ink diffuses through the glycerin in an apparently irreversible fashion. Its order seems to have disintegrated. But when the direction of rotation is reversed, the ink gathers into a drop again.

The experiment inspired Bohm to write Wholeness and the Implicate Order, published in 1980. Beneath physical appearances, the “explicate order,” he argues in the book, there lies a hidden “implicate order.” Applying this concept to the quantum realm, Bohm conjectures that the implicate order is a field consisting of infinite fluctuating pilot waves. The overlapping of these waves generates what appear to us as particles, which constitute the explicate order. Even space and time might be manifestations of a deeper, implicate order, according to Bohm.

To plumb the implicate order, Bohm says, physicists might need to jettison basic assumptions about nature. During the Enlightenment, thinkers such as Newton and Descartes replaced the ancients’ organic concept of order with a mechanistic view. Even after the advent of relativity and quantum mechanics, “the basic idea is still the same,” Bohm tells me, "a mechanical order described by coordinates.”

Bohm hopes scientists will eventually move beyond mechanistic and even mathematical paradigms. “We have an assumption now that’s getting stronger and stronger that mathematics is the only way to deal with reality,” Bohm says. “Because it’s worked so well for a while, we’ve assumed that it has to be that way.”

Someday, science and art will merge, Bohm predicts. “This division of art and science is temporary,” he observes. “It didn't exist in the past, and there’s no reason why it should go on in the future.” Just as art consists not simply of works of art but of an “attitude, the artistic spirit,” so does science consist not in the accumulation of knowledge but in the creation of fresh modes of perception. “The ability to perceive or think differently is more important than the knowledge gained.”

Bohm rejects the claim of Stephen Hawking and others that physics can achieve a final theory, or “theory of everything,” that explains the world. Science is an infinite, “inexhaustible process,” Bohm says. “The form of knowledge is to have at any moment something essential, and the appearance can be explained. But then when we look deeper at these essential things, they turn out to have some feature of appearances. We're not ever going to get a final essence which isn't also the appearance of something.”

Bohm fears belief in a final theory might become self-fulfilling. “If you have fish in a tank and you put a glass barrier in there, the fish keep away from it,” he says. “And then if you take away the glass barrier, they never cross the barrier, and they think the whole world is that.” He chuckles and shows me his smile-grimace. “So your thought that this is the end could be the barrier to looking further.” Trying to convince me that final knowledge is unattainable, Bohm says the following:

Anything known has to be determined by its limits. And that’s not just quantitative but qualitative. The theory is this and not that. Now it’s consistent to propose that there is the unlimited. You have to notice that if you say there is the unlimited, it cannot be different, because then the unlimited will limit the limited, by saying that the limited is not the unlimited, right? The unlimited must include the limited. We have to say, from the unlimited the limited arises, in a creative process. That’s consistent. Therefore we say that no matter how far we go there is the unlimited. It seems that no matter how far you go, somebody will come up with another point you have to answer. And I don’t see how you could ever settle that.

To my relief, Bohm’s wife enters the room and asks if we want more tea. As she refills my cup, I spot a book on Buddhism in a bookcase and ask if Bohm is interested in spirituality. He nods. He was close to Jiddu Krishnamurti, an Indian sage who taught westerners how to achieve the supreme spiritual state called enlightenment. Was Krishnamurti enlightened? “In some ways, yes,” Bohm replies. “His basic thing was to go into thought, to get to the end of it, completely, and thought would become a different kind of consciousness.”

Of course, Bohm says, you can never truly plumb your own mind; any attempt to examine your thought changes it--just as the measurement of an electron alters its course. We cannot achieve final self-knowledge, Bohm seems to imply, any more we can achieve a final theory of physics.

Was Krishnamurti a happy person? Bohm seems puzzled by my question. “That's hard to say,” he replies. “He was unhappy at times, but I think he was pretty happy overall. The thing is not about happiness, really.” Bohm frowns, as if realizing the import of what he has just said.

I say goodbye to Bohm and his wife and depart. Outside, a light rain is falling. I walk up the path to the street and glance back at Bohm's house, a modest white-painted cottage on a street of modest white-painted cottages.

In Wholeness and the Implicate Order, Bohm insists on the importance of “playfulness” in science, and in life, but Bohm, in his writings and in person, was anything but playful. For him, truth-seeking was not a game, it was a dreadful, impossible, necessary task. Bohm was desperate to know, to discover the secret of everything, but he knew it wasn’t attainable, not for any mortal being. No one leaves the fish tank alive.

Two months after our meeting, Bohm died of a heart attack.

Further Reading:

See my free online book My Quantum Experiment as well as my profile of another quantum visionary, John Wheeler.