When Albert Einstein called quantum entanglement “spooky action at a distance” he wasn’t very far off the mark with his choice of words. Quantum physics has a long list of phenomena too strange to be believed – particles that sometimes behave like waves, cats that are simultaneously dead and alive, and acts of observation that instantly create what is being observed. It is not just us poor laymen who are left bereft of this profound knowledge of the building blocks of reality. The great Richard Feynman himself said before he died: “I still get nervous with it...I cannot define the real problem, therefore I suspect there’s no real problem, but I’m not sure there’s no real problem.”

Has the question of what is real been ignored for far too long in the quantum sphere? Adam Becker’s new book What is Real attempts to trace the history of modern quantum physics over the last hundred years and unearth the ontological and epistemological problems at the heart of the science.

Does it exist?

In modern physics there are perhaps no two bigger names than that of Albert Einstein and Niels Bohr. The Einstein-Bohr debate is a particularly famous one in the history of the physical sciences and has shaped the entire discourse of the field. In the popular imagination the basic problem between the two was not as much ontological as it was epistemological (one can refer to Bohr’s paper titled “Discussions with Einstein on Epistemological Problems in Atomic Physics”). While Einstein believed that (for example) an electron was real, that it existed no matter if it was observed or not, Bohr on the other hand in his Copenhagen interpretation of quantum physics said that the very act of observation caused existence. The electron in question had no “independent reality in the ordinary physical sense”.

It was upon this fundamental difference that the two greatest physicists of their age fought, and history granted victory to Bohr. Becker’s book, however, re-opens the accounts of this monumental struggle and discovers that handing a win to Bohr foreclosed a confrontation with certain ontological problems in modern physics, most important of which is the book’s titular question, what is real?

Einstein’s frustration with Bohr’s epistemological theories was best expressed in an essay where he compared the latter to Bishop Berkeley, who had said “esse est percipi” (to be is to be perceived). Einstein was referring to one of the most vital philosophical debates of the 18th century, which had been resolved in a fashion by Immanuel Kant. Berkeley’s theory that the world did not exist outside our minds was a real philosophical problem. Kant’s solution to the conundrum was to posit two separate spheres, the phenomenal sphere of appearance, and noumena, which were things in themselves, without having to be perceived through our senses.

Speaking from a finite human perspective, Kant argued that we can never see beyond appearances to be able to speak of things as they are in themselves. With this one idea, he both conserved Berkeley’s profound insight – that we can only know appearances and nothing besides – and destroyed it by arguing that things necessarily exist in themselves too, though we cannot speak of them in any definitive way. Even attempting to do so would result in insoluble antinomies or contradictions, he argued.

Becker notes that Bohr was deeply influenced by Kant, and one can see many similarities between their ideas. Like Kant, Bohr also thought that it was pointless to talk about sub-atomic particles before they became phenomena for observation, in an act called measurement. Before this measurement took place, he said, the particles, like Kant’s thing in itself, didn’t have any properties to speak of. Bohr’s interpretation, known as the Copenhagen interpretation, was a deadly blow to the consistency of the classical physical world and Einstein, himself a destroyer of Newton’s three dimensional mechanistic universe, would have none of it. Till his dying day he continued to believe that quantum physics was somehow incomplete and that Bohr was wrong.

Backing Albert

Becker’s book starts off from this philosophical confrontation between these two giants and weaves a narrative around almost one hundred years of modern quantum physics. Characters like Werner Heisenberg, Erwin Schrodinger, John Stewart Bell, John Wheeler, and Hugh Everett play important roles in the growing challenge to Bohr’s orthodox interpretation.

Becker’s book is meant for the lay reader, and it admirably explains the intricacies of quantum physics in a way that even I, who last opened a science textbook in school, could understand. His lucidity and clarity are not a ploy to cover up for lack of rigour and knowledge – he has a PhD in astrophysics as well as a bachelor’s degree in philosophy. His approach to the topic combines an awareness of the latest developments in quantum physics with a central philosophical problematic that makes this book very different from other works that attempt to popularise modern science.

While the history of science has proved Bohr and the Copenhagen interpretation right many times over, Becker sides with Einstein in his book precisely because the latter had some pertinent questions which still remain unanswered. In a paper published in 1935 with Boris Podolsky and Nathan Rosen titled “Can Quantum Mechanical Description of Physical Reality Be Considered Complete?” (known as the EPR Paradox) Einstein argued that either quantum mechanics is incomplete or reality is non-local, that it can act at a distance, beating the speed of light.

Following the work of physicists like David Bohm, who challenged the Copenhagen orthodoxy, Becker traces the subterranean history of quantum physics since then as efforts to prove Einstein’s second proposition correct. The solutions to the problem however turn out to be even more spooky and mindboggling than Einstein could have imagined – from Bohm’s pilot waves, to Hugh Everett’s many worlds interpretation, where reality branches out into multiple dimensions at every throw of the quantum dice.

No dissent, we are physicists

What makes Becker’s attempt unique is that he brings to the foreground the hegemonic nature of a dominant scientific theory in crushing dissent. “Ideological superstructures” (Werner Heisenberg’s phrase) play a much less important role in the sciences than in any other field, but they still exist, and the treatment meted out to David Bohm, as recounted by Becker, is remarkable in this respect. Bohm was removed from his post as assistant professor at Princeton for his Communist leanings, and after his questioning of the Copenhagen orthodoxy became known, he never regained a tenured post again in an American or European university (which, as most scientists will agree, is a death blow to one’s research aspirations).

Bohm’s persistence in the face of such obvious hardship (he had to leave the United States and live in Brazil for many years) did bear fruit when his ideas came to the attention of people like John Stewart Bell. His famous formulation of Bell’s Inequality proved that quantum reality was definitively non-local, and that Einstein was right in a way. Becker ends his book with a survey of the current theories dominating the field, and it is evident that the Copenhagen hegemony has been dented, if not broken. But can Becker really provide an answer to what is truly real?

In the end Becker’s What is Real cannot really give a definitive answer to the titular question. The story of reality remains incomplete, but not for a lack of trying. Recent experiments like the Big Bell Test (results of which were published in May 2018) are opening up philosophical problems which quantum physicists had been trying to avoid for years with their motto of “Shut up and calculate”.

The scene in philosophy is no less different, with Continental philosophers being forced to confront new critiques of the Kantian revolution. Contemporary philosophical movements like Speculative Materialism are trying to break the back of post-Kantian orthodoxy with their critique of correlationism and their insistence on speaking of what things are really like in themselves – although in doing so, they have come up with some seriously bizarre ideas like Quentin Meillassoux’s denial of any permanent physical law other than the Absolute Necessity of Contingency and Graham Harman’s idea that no two objects can ever directly interact with each other, known as Vicarious Causation. In these times, being a realist is not as easy as it sounds. What Becker’s book leaves us with a profoundly unsettling question: what do we do when reality is the weirdest choice?

What is Real: The Unfinished Quest for the Meaning of Quantum Physics, Adam Becker, Basic Books.