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What Is Real?: The Unfinished Quest for the Meaning of Quantum Physics

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The untold story of the heretical thinkers who dared to question the nature of our quantum universe
Every physicist agrees quantum mechanics is among humanity's finest scientific achievements. But ask what it means, and the result will be a brawl. For a century, most physicists have followed Niels Bohr's Copenhagen interpretation and dismissed questions about the reality underlying quantum physics as meaningless. A mishmash of solipsism and poor reasoning, Copenhagen endured, as Bohr's students vigorously protected his legacy, and the physics community favored practical experiments over philosophical arguments. As a result, questioning the status quo long meant professional ruin. And yet, from the 1920s to today, physicists like John Bell, David Bohm, and Hugh Everett persisted in seeking the true meaning of quantum mechanics. What Is Real? is the gripping story of this battle of ideas and of the courageous scientists who dared to stand up for truth.

384 pages, Hardcover

First published March 30, 2018

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About the author

Adam Becker

1 book172 followers
Adam Becker is a science writer with a PhD in astrophysics from the University of Michigan and a BA in philosophy and physics from Cornell. He has written for the New York Times, the BBC, NPR, Scientific American, New Scientist, and others. He has also recorded a video series with the BBC and several podcasts with the Story Collider. Adam is a visiting scholar at UC Berkeley's Office for History of Science and Technology and lives in California.

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Displaying 1 - 30 of 465 reviews
Profile Image for Manny.
Author 36 books15.2k followers
July 9, 2018
What is real?

This ought to be a question of burning interest to almost everyone, and yet, for some reason, hardly anybody over the age of seventeen seems to take it seriously. If you ask the adults, no one's sure whose responsibility it is. They send you over to talk to the sociologists, who shrug their shoulders; sorry guv, nuffin to do wiv us. Try philosophy, they're just down the street. The philosophers look embarrassed, and explain that yes, absolutely, they used to be in charge of it, but now it's been handed over to physics. The physicists tell you that of course they know the answer: there is no such thing as reality. If you aren't happy with that, go and talk with the sociologists. And round you go again. This book, I am pleased to say, does take the question seriously. Rather than limiting himself to one single viewpoint, which as we've seen lets it get away, Adam Becker pursues all three lines of investigation simultaneously, and manages to present something which looks surprisingly like an answer. It's a complicated answer, and you need a three hundred page book to explain it properly, but I would summarise it like this.

About a hundred years ago, a group of physicists made some astonishing discoveries. This work, which soon started going by the name of "quantum mechanics", had enormous philosophical implications: in comparison, the Copernican revolution was no more than a minor footnote. It showed that the nature of reality was completely different from what had previously been believed. It was also, unfortunately, rather difficult to understand, and could only be explained well in mathematical language. Even worse, it turned out to be a source of incredible military and economic power: it made possible the development of weapons and technologies that had previously not even been dreamed of.

Power, as is well known, corrupts, and this new power corrupted at every level. In particular, it corrupted intellectually. Physicists, who in the 1920s had been familiar with philosophy and well-disposed towards philosophical ways of thinking, became arrogant and impatient with the philosophers. What were they doing, sitting around dreaming about eternal verities, when physicists had important work to do? The physicists decided they could take care of the philosophy themselves. They cobbled together some theories from the currently fashionable positivist school and breathed a sigh of relief. We don't need to worry about what "reality" is; there is no such thing as "reality", and the mere fact that you ask the question shows you are an ignorant layman. We have a picture of what happens in quantum mechanics which we call the "Copenhagen interpretation", and it's the only possible answer. We have mathematically proved it.

A few people whispered that the proof seemed to have a hole in it and the Copenhagen interpretation didn't actually make sense, but they were ignored. Who cared what these crazy dissidents thought, when physics departments were being showered with money by people who wanted more magical devices? The math worked: it didn't matter what it "meant". In a phrase which came to encapsulate this whole world-view, shut up and calculate. The philosophers, who should have been keeping an eye on things under the academic world's informal separation-of-powers system, had lost all confidence. They no longer had any power. When they tried to object, they were slapped down by the physicists: no one cares what you say, when you don't understand the complex math on which quantum mechanics is based. Physicists who did understand the math and still had a philosophical outlook were contained in other ways. If they tried to publish work, it was usually rejected as "not real physics". If they persisted, they were labelled as unemployable, and refused promotion or worse.

It's an absolutely fascinating chapter in the development of human thought, and Adam Becker, who's done a huge amount of background research, explains it very well. He starts off with a quote from Ursula Le Guin, and if you're a fan of The Dispossessed you'll soon recognise the story: this is Shevek, but not as a fictional character. Read it and find out what's really been going on.
Profile Image for Prerna.
222 reviews1,784 followers
August 26, 2021
An embarassing thing for the physics community to admit is that we don't have a working description of reality. And it isn't just because of insufficient data, technological limits and incomplete theories - of course these problems exist, but in addition we don't seem to know what to make of the data we do have - to be precise we don't seem to know how to interpret the theories that exist and work really well for known systems. We have a recipe, we know how to plug in input and get really good results, but what does that reveal to us about reality? Strictly speaking, the Copenhagen interpretation of quantum mechanics goes so far as to deny an observer independent reality. And this is a blow to scientific realism - the idea that nature, or the universe itself, exists independent of us, or independent of our observations.

Scientific realism seems more obvious, but what dominates quantum mechanics today, as it did many decades ago when quantum mechanics was just gaining popularity, is the Vienna circle's logical positivism. Logical positivism only accepts statements that are verifiable as true - so, in line with Copenhagen's metaphysical interpretation of reality, the Vienna circle rejected any questions pertaining to the 'unobservable' and labelled them 'meaningless.' You have to appreciate the irony here. The Vienna circle was almost vehemently against metaphysics, yet their influence was crucial to ensuring that the Copenhagen interpretation's dominance.

Adam Becker writes extensively about the nature of many scientific debates over quantum foundations, he artfully presents the story of the invention and rise of the Copenhagen interpretation. Yet what sets this book apart from the other numerous ones on quantum physics is its search for alternatives, its in-depth examination of the work and the lives of the physicists who dared to question the validity of the Copenhagen interpretation and the subsequent ostracism they faced within the scientific community. He presents the three main alternatives: Bohm's pilot wave theory, Everett's many worlds interpretation and the GRW spontaneous collapse theory. This book is as much about physicists and their lives as it is about the physcis they developed. A central figure across all these stories is John Stewart Bell. Bell is now a cult figure, and in my opinion he is also one of the few amongst the disturbingly many who actually deserves that cult status. He was as humble as he was ingenious, and his careful examination of conditions of non-locality and contextuality changed the way we look at quantum mechanics, and therefore reality at large.

Becker also importantly points out that these disputes aren't unscientific in the same way that pseudoscientific claims are. Of course we have a case of scientism here, but it's a matter of perspectives and interpretations and not outright negation/denial of facts. We have a measurement problem and we have different ways of approaching that problem.

So what is real? We don't know, but as all scientists before us did, we must hope that we will have the answers some day.
Profile Image for David Katzman.
Author 3 books509 followers
June 6, 2019
A truly fantastic, lucid overview of the competing theories that purport to explain quantum mechanics. Becker takes an interesting approach that I’ve never read before, which is to put all the different theories into historical context. We learn a great deal about both the philosophical context and personalities that surrounded, supported and challenged the competing theories. What is at stake here is our understanding of the very nature of reality.

Although I’ve read a great deal about quantum theory, this book was an eye-opener. There are currently three leading theories to explain the Schrodinger Equation and what it says about the nature of the universe. The Copenhagen Interpretation, which was the first explanation and the most widely known, the de Broglie–Bohm Pilot Wave Theory, and the Many-Worlds Interpretation. There are several others out there as well, but these are the leading three at present and the ones that Becker spends the majority of his book explaining. There is a fourth, for example, that proposes the random collapse of the wave function, but it is not very popular at the moment. It seems a bit gimmicky to me, but it can’t be dismissed on that basis.

Becker demonstrates that although Copenhagen is still the most widely accepted by physicists, it has tremendous gaping holes of logic in it that fail to justify its popularity. Becker educates us thoroughly on how it came to be so popular despite the weakness of it. Much of it has to do with the cult of personality around key physicists who promoted it when it first came out—along with various political events, cultural and philosophical currents that complemented this theory. Since then, the challenges of understanding quantum mechanics have kept a kind of inertia among physicists, which creates reluctance for them to consider new theories. Einstein didn’t trust the Copenhagen interpretation and invented thought experiments that challenged it. The story goes that Niels Bohr overcame and dismissed Einstein’s objections and “won” the debate. But as Becker presents it, in fact, Bohr was a confusing, muddled communicator and a slow thinker who never actually understood Einstein’s thought experiments and only rejected them rhetorically not through actual logical debate. In the end, much of the defense of Copenhagen was simply assertion.

Einstein had two primary objections to the Copenhagen interpretation. The first was non-locality or what he called “spooky action at a distance.” He said there was no reason to trust that particles can instantaneously move from one location to another or instantaneously communicate over vast distances as is required by the Copenhagen Interpretation. He also objected to the mushy undefined nature of how an observation causes the collapse of the Schrodinger Wave function. Do events not occur in deep space if they aren’t being observed? And if not, then how do the processes continue on in time until they are observed? (For example, imagine an unobserved sun exploding far from any life forms. I million years later it collapses into a white dwarf star. Imagine no observer has “seen” the sun for the first million years but then a space-ship whizzes nearby and sees the white dwarf star. Did the sun not exist for the first million years of its explosion but then instantaneously leaps into white dwarf star state as if it had been observed in the past million years? You can see the absurdity of this. It would have to instantaneously assume a state and also instantaneously assume one million years of past history.) Does observation require consciousness to read a piece of data? Or does a mouse collapse the wave function? The theory can’t answer that question. There is also another big hole in the Copenhagen Interpretation, which is that it must posit a distinction between the quantum world and the “classic” world. Right now the theory proposes that “classical” objects—those that obey Newtonian physics—are just…bigger. And “small” objects obey quantum effects. An observation must be enacted by a “big” object that is classical in order to collapse the wave function. But Copenhagen can’t explain why bigger objects aren’t subject to quantum effects and where the boundary is between big and small. Nothing in the Schrodinger Equation itself ever signals that a collapse should occur. As far as the Schrodinger Equation knows, particles will continue in their undefinable states forever. Measurement is invented as an outside justification for finding particles somewhere rather than everywhere at once.

Copenhagen seems bankrupt to me. Too many holes are unexplained by it…it is clearly incomplete. The Pilot-Wave Theory plugs a few of the holes although it still suffers from non-locality, but in fewer cases than Copenhagen does. In general, Pilot-Wave theory solves the issue of the particle/wave duality. Particles ride on waves essentially so their behavior is not nearly as mysterious as it is in Copenhagen. Pilot Wave Theory does a great job of explaining the mysterious double-slit experiment, for example. Particles have definite locations within an atom, but we just can’t see them. They aren’t mysteriously smeared everywhere at the same time; they are moving along, following their pilot wave, and are simply found where they are found when measured. An observer isn’t required per se, so it solves the measurement problem. But it still requires non-locality in some situations. Some physicists still believe Einstein was wrong and the world may not be local. Particles may make faster-than-light instantaneous changes. Since Pilot-Wave theory is equivalent to the Schrodinger Equation mathematically, it is worth considering.

The Many-Worlds Interpretation has become much more recognized in recent years in popular culture as well as physics circles, but there still remains a lot of resistance to it as a theory because it requires you to adopt a very, very, very strange view of reality. Really, the Copenhagen explanation is also very, very strange, but because it maintains a certain mystery “we can never know,” it perhaps leaves some of that strangeness disguised.

On the plus side, the Many-Worlds Interpretation does in fact eliminate non-locality as an issue. Particles do not in fact ever instantly assume positions or change positions instantly nor do they communicate with their pasts to assume some certain state. Many Worlds also solves the observer issue. No observation is required. It also explains the related measurement issue. Similarly, no measurement is required to collapse the Schrodinger Equation. Nor is there any need to distinguish between classical or “big” objects and “small” or quantum objects. Everything is subject to quantum effects all the time. When a quantum particle interacts with another larger object, such as a “measurement device” they become entangled and unite into a larger and more complex Schrodinger Equation. There is no collapse, only constant entanglement.

It’s weirder than that though. In fact, it proposes that every single quantum state that has ever existed breaks off into a separate universe. The entire universe is an infinite multiplicity of universes that are all united as one giant quantum Schrodinger Equation. Every single state spins off as a new universe. Now that is supremely weird. But mathematically, it is also equivalent to the Copenhagen Interpretation and produces the same results. There are some challenges with the meaning of probability however, so it’s not a fully solved model for the universe. But it certainly answers many questions that Copenhagen doesn’t. And it also cures non-locality, which Einstein believed was impossible.

All that said, Becker points out that it is quite possible that a new interpretation could arise that would supersede all these as well, but he encourages the scientific pursuit of the meaning of the Schrodinger Equation and demonstrates why there is so much value in pursuing these mysteries.

What a great book. Recommended for anyone who enjoys cutting edge physics and written in a fashion that seems comprehensible to the layperson.
Profile Image for Max.
351 reviews428 followers
April 25, 2019
Becker explores the interpretation of quantum mechanics. He and the scientists he cites all accept the functionality, accuracy and mathematics of quantum mechanics, but disagree on what it tells us about the world. Does it merely provide information useful in making predictions for experiments and designing new technology or does it reveal an underlying reality. Becker digs into Niels Bohr’s Copenhagen Interpretation. He discusses alternatives such as David Bohm’s pilot-wave interpretation, Hugh Everett’s many-worlds interpretation, the spontaneous-collapse theory and decoherence. Becker gives us a brief history of the development of quantum mechanics and its interpretations beginning with Bohr and Einstein and their life long debate over the meaning of quantum mechanics. Particularly interesting was material about the development of alternative interpretations and how difficult it was for young physicists to challenge accepted beliefs. Becker, who has studied both physics and philosophy, makes the case for the important role of philosophy in interpreting what all the experiments and weird results tell us about the real world.

Becker reviews the double-slit experiment and well known thought experiments such as Schrodinger’s cat-in-box experiment. He uses these to illustrate his issues with the Copenhagen interpretation. Foremost is the Measurement Problem. In quantum mechanics fundamental particles are represented by a wave function which gives the probability of their being found in a particular location. However the Copenhagen interpretation holds that when we measure the particle the wave function collapses and only then do we find the particle in one specific place. This collapse is not supported by Schrodinger’s equation which is the math establishing the wave function of quantum mechanics. But it is a widely accepted postulate of many scientists who believe in the Copenhagen Interpretation. What constitutes a measurement is not clear. Is it when the particle is observed? Observed by who or what? Is it when the particle encounters a larger object?

Another important issue is that of a boundary between the quantum world and the everyday world. Bohr, the acknowledged father of the Copenhagen Interpretation, held that there was a separation between the quantum world where particles could be found almost anywhere until measured and the normal macro world we see every day. Where is that dividing line? How can the particles that are the building blocks for macro objects like us behave so differently and still create the world we observe? Recent experiments reveal quantum behavior in larger objects. One experiment coaxed a sixty carbon atom “buckyball” into a quantum state where it demonstrated interference with itself just like a photon in the double-slit experiment. More physicists today accept that quantum waves apply to macro objects further complicating the issues of measurement induced wave collapse and boundaries.

In 1952 David Bohm building on the work of Louis of de Broglie proposed a theory of pilot waves guiding particles. Both the waves and particles are always there even when no one is looking. The particle “surfs” the wave which determines its position. No need of an observer for the particle to materialize. A couple of years later Hugh Everett III determined that the “Copenhagen Interpretation is hopelessly incomplete…excluding in principle any deduction of classical physics from quantum theory, or any adequate investigation of the measuring process…as well as a philosophic monstrosity with a ‘reality’ concept for the macroscopic world and denial of the same for the microcosm.” He proposed that the wave function never collapsed. It simply split with each outcome continuing on and splitting again ad infinitum. Everett didn’t discuss many worlds in his “relative-state” theory. Bryce DeWitt in a 1957 Physics Today article dubbed it the many-worlds theory stoking the imagination leading to its popularization. Modern concepts in cosmology such as inflation and string theory invoked the multiverse making Everett’s many-worlds seem less strange and by the 21st century it was second in popularity among physicists to the Copenhagen interpretation.

Bohm, Everett and others who proposed solutions that encompassed a quantum reality were derided by the physics establishment. Their work was not deemed worthy of consideration by serious scientists even though Bohm and Everett were brilliant physicists. As the century wore on more physicists became receptive to alternative interpretations. Becker recounts the frustrations of many young physicists interested in the foundations of quantum mechanics who were actively discouraged or ostracized for questioning an accepted successful theory. One inspiration was the work of John Bell. Bell started his investigation of quantum mechanics after reading Bohm. In a 1964 paper Bell put forth a convincing argument that nature was nonlocal, a feature of Bohm’s pilot wave interpretation that had been heavily criticized by the Copenhagen adherents. Nonlocality means that entangled photons share a single wave function thus they synchronize their quantum states instantaneously at any distance violating special relativity. Subsequent experiments have supported Bell’s theorem which has been referred to as “the most profound discovery of science.” However, if the wave function splits into multiple branching worlds as Hugh Everett III proposed, locality would be maintained.

The Copenhagen Interpretation holds that quantum mechanics provides useful information, but does not reveal any underlying reality. Until the wave function collapses there is only a mathematical probability of the location of a particle. The particle is nowhere. It only appears when a measurement is made. While this became the widely accepted view, some respected physicists did not buy in. These included Einstein and Schrodinger in the 1920s and 50 years later Nobel Prize winner Murray Gell-Mann. Gell-Mann wrote “The fact that an adequate philosophical presentation [of quantum physics] has been so long delayed is no doubt caused by the fact that Niels Bohr brainwashed a whole generation of theorists.” Bohr was a charismatic figure with great influence over other top physicists. His complete disdain of alternative interpretations became conventional wisdom stifling any young physicist interested in being taken seriously from pursuing alternatives. The rise of cosmology in the last half of the twentieth century helped create support for those who didn’t accept Bohr’s views. Gell-Mann and James Hartle noted “Measurements and observers cannot be fundamental notions in a theory that seeks to discuss the early universe when neither existed.”

Bohr’s views were likely influenced by the trending philosophy in Weimar Germany. Logical Positivism developed by the “Vienna Circle” built on the work of physicist and philosopher Ernst Mach. The positivists believed that anything not observable was meaningless. Applied to the quantum this means imputing the existence of particles prior to observation is meaningless. Mach was Wolfgang Pauli’s godfather. Pauli, a preeminent physicist born and raised in Vienna, was an influential supporter of positivism and Bohr. Bohr stated flatly “There is no quantum world.” “Isolated material particles are abstractions…” This begs the question where do particles come from when an observation is made. Reacting to such views Einstein noted “What I dislike in this kind of argumentation is the basic positivistic attitude which seems to me to come to the same thing as [Irish philosopher George] Berkeley’s principle, esse est percipi [to be is to be perceived].” Einstein believed there was a real quantum world that existed when not observed. He believed quantum mechanics was an incomplete theory.

One may ask why different interpretations of the same mathematics matter. Regardless of interpretation the math delivers the same results. Schrodinger’s equation still applies whether interpreted as Copenhagen or many-worlds. Becker offers a good example. In the sixteenth century Tycho Brahe proposed that the sun and moon rotated around the earth and the other planets around the sun. Copernicus had earth rotating around the sun too. At the time both models gave the same predictions of the planets motions. So why care which was right? Obviously only the Copernicus model led to a better understanding and more fruitful research.

The disparity in interpretation reflects that between physicists and philosophers. One hundred years ago scientific curricula included course work in philosophy. Einstein studied Mach and Bohr studied Kant. Few physicists today get training in philosophy changing their approach to interpretation. Many scientists associate philosophy with Continental philosophers who are suspicious of scientific claims. However, Becker points out that philosophers of physics use an analytic approach that accepts science and applies logical rigor to the interpretation of its results. Becker with training in both concludes “Stating that the conclusions of the Copenhagen interpretation are ‘inevitable’ or ‘forced upon us by the mathematics of the theory’ is simply wrong. It is not true that it’s meaningless to talk about reality existing independently of perceptions, that we must think of the world solely as the subject of our observations. Solipsism and idealism are not the message of quantum physics.” “There is something real out in the world, that somehow resembles the quantum. We just don’t know what that means yet. And it’s the job of physics to find out.”
Profile Image for Clif Hostetler.
1,178 reviews882 followers
September 1, 2023
“Quantum physics is the most successful theory in all of science. It predicts a stunning variety of phenomena, and use of its characteristics makes possible the design of much modern technology. But deep in the unobservable foundation of quantum physics is the world of atomic and subatomic particles with behavior that doesn’t follow the rules of what is generally perceived as “real.” In the world of very tiny things, it’s possible to be in two places at the same time, to communicate instantaneously (a.k.a spooky action at a distance), and to edit past history and/or anticipate future measurements.

This book provides a history of how the world of physicists has dealt with the question of what’s real. Since the establishment of the Copenhagen Interpretation in the 1920s, the generally accepted orthodox answer is that there’s no problem. Physicists who take this position consider it pointless to ask what is real because such things are by definition unobservable (i.e. only observable measurable things have meaning).

Since the equations of quantum physics give predictable results, most physicists have stopped asking why and have concentrated instead on making advances in technological designs. This has led to the often repeated phrase, “shut up and calculate”. Physicists who proposed to ponder questions of reality received no research funding.

Nevertheless, a variety of theories have been proposed over the past hundred years to explain the behavior of subatomic particles. This book introduces the reader to the work and lives of physicists who dared to question the limitations of the Copenhagen Interpretation. The development of three main alternative theories are described: (1) pilot wave theory, (2) many worlds interpretation, and (3) GRW spontaneous collapse theory. A central figure across all these stories is John Stewart Bell and his Bell's theorem.

This book provides an Appendix that I think provides a succinct summary. It describes an experiment with baffling results, and then it gives four explanatory views of how and why the results are what they are. I have placed a copy of this Appendix in the following

I don't claim to understand this subject. I try to occasionally read books like this in the hopes that some wisdom and insight will stay with me.

The following is link to article from New York Times:
Even Physicists Don’t Understand Quantum Mechanics
Profile Image for Radiantflux.
458 reviews473 followers
June 6, 2018
59th book for 2018.

A very interesting and accessible book on quantum ontology.

With no math (!) Becker takes the reader effortlessly through nearly a hundred years of back-and-forth debate as what quantum mechanics implies about the universe we live in.

The history itself is fascinating. I had no idea (blush) that Heisenberg (of uncertainty fame) was actually a Nazi who headed the Nazi's atomic bomb project, which according to Heisenberg (postwar) was unsuccessful as he was really a nice guy who didn't want to blow up things, and according to Becker was incompetent. According to Becker, Heisenberg was actually the one who coined the "Copenhagen Agreement" in the postwar period as a way of cementing his role in the foundation of QMs and upgrading his status post-Hitler, and by doing so made it seem there was a standard interpretation when there wasn't.

Einstein (who I had been raised to think of as just never getting QM) comes across as particularly sharp in his critique, and was concerned about the implications of non-locality that he saw lurking at the heart of the standard interpretation of QM; which is of course at the heart of Bell's inequality theorem. QM's grandfather Bohr comes as a bit of an arsehole, stopping any dissent into his standard positivist interpretation of QM. His waving away of the measurement problem, of there being two worlds (a QM world of the small, and a classical world of the big), can be seen in retrospect as incoherent and vastly damaging to the field.

(If I understood things correctly) Einstein's major concern with the Copenhagen Interpretation of QM was that not only were a particle's properties (momentum, energy etc) unknown until the collapse of QM wave function, they in didn't exist according to the Copenhagen Interpretation until that point. Einstein saw that this led to two possibilities: either QM was incomplete and these properties existed but were unmeasurable (i.e., there were "hidden variables - God doesn't play dice!) or the nature of the properties was fixed at the time of measurement (i.e., the Copenhagen Interpretation). If the latter, this would in turn imply that in certain situations (i.e., where particles were quantumly entangled) information about these properties would be transmitted instantaneously (i.e., faster than the speed of light and locality would fail). Naturally Einstein preferred the situation where QM was incomplete and locality was upheld.

David Bohm, later derived a model of QM that was completely consistent with the maths of the Copenhagen Interpretation, but did involve hidden non-local variables (i.e., at any particular moment a particle has a definite momentum, energy, spin etc). As a bonus this Bohmian interpretation gave simple explanations of classic problems like the double-slit experiment, as well as QM entanglement, but perhaps because it involved non-locality (or because it contradicted the Copenhagen Interpretation) was largely dismissed and forgotten.

Hugh Everett, looking for a quick doctoral topic, decided to avoid the measurement problem altogether by supposing the wave function never collapsed, and thereby developed what has become known as the Many Worlds interpretation of QM. Naturally his work was also ignored by the physics establishment at the time, and he had to radically reedit his thesis in order to pass.

Later John Bell (a particle physicist at CERN, who by his own account worked on QM foundations on Sundays) developed a theoretical test to see if local hidden variables could exist within QM. His paper, published in an obscure journal, was eventually tested years later at Berkeley for the first time in the early 1970s, and showed that non-locality was upheld (i.e., there were no local hidden variables - God does play with dice!). What this means for the World is hard to get your head around, and I join my better Einstein in thinking this is a very weird result indeed. It is shocking to learn that the postdoc who did these brilliant experiments, was unable to get tenure afterwards, because this work was regarded as quasi-worthless by the general physics community in the 1970s.

In an irony of fate, this very non-locality is the very basis for modern quantum computing.

Strongly recommended.

5-stars.
Profile Image for Mario the lone bookwolf.
805 reviews4,979 followers
December 20, 2018
Interdisciplinarity between scientists, philosophers and neuroscientists will eventually crack the well-deciphered code of reality.

Please note that I have put the original German text to the end of this review. Just if you might be interested.

The game of knowledge acquisition has always been played back and forth between three groups. The philosophers, scientists and, more recently, the neuroscientists. Philosophers can design the inspirational ideas for the other two groups in the field and make colorful mixtures together. Scientists work on experiments, detection methods and ever better instruments.

The case of neuroscientists and brain researchers is more complicated. They have the option to observe the thoughts of physicists and philosophers live in practice. What makes them even more interdisciplinary than the two other groups. Because all together, the theories for consciousness, its function and the forces acting on it can be observed. For instance which neuronal level defines which state of consciousness in reality. Which, in turn, raises new questions for the philosophers, who pass these on to the natural scientists, ...

The fact that quantum mechanics was also the key to unleashing atomic forces is often overlooked in the face of spooky, distant effects. But it were these theories that created the foundations for further insights in physics and astrophysics, which in turn inspired the earliest nuclear weapons. If such potential could be used more than 70 years ago, then what would happen in 700 years? What kind of weapon would that be that doesn´t use the clumsy and sluggish atoms but the even smaller bricks of reality? Which chain reactions could be unleashed?

How long the misery of the science war around the Copenhagen interpretation served as an impediment on one of the significant fields of research is one example of discord in science. To remain serious and publishable, researchers had to pay attention to their reputation and, above all, circumvent the vague hypotheses of philosophy and some humanities. And to prevent any ideological debates and vendettas between oppositely arguing scientists or to question their own belief too critically. They should only research in a given direction under a certain paradigm.

From soon 100 years ago, with the debate beginning in the early 20th century, until now, this was a reason for the disunity of many researchers. Besides, there was the danger of losing their own life's work legitimacy. If even Einstein doubted and sometimes despaired because that much dissonance existed between his theories and the hypotheses. Or if, like John Bell, one just got ingratitude and problems for working out the basics of quantum computing. What's more, it was more economical to begin with real applications than marketing just ideas, which finally discredited the philosophers.

As so often, one has tended to think in extremes. Instead of finding insight in the middle between and perhaps the solution too. In the case of quantum physics, one extreme is the opinion that in observation there is only one unpredictable, random reality. One of two conditions or possibilities and just one form of reality at the same time for an observing person. Indeed the misunderstood "choice" between two conditions or properties and also complementary theories. But definitely not more that, which is explainable or examinable. The long-prevailing Copenhagen interpretation (Bohr) that blocked other approaches for a long time. "This one random state may perhaps be complementary to another state and thus there is no real reality because we cant´ observe it." Point and end of the debate.
The other party fundamentally questions the validity of the accessible reality and suspects unknown factors. (Einstein). The beginning of a dispute that continues to this day.

Either everything is so clear and easy, or everything is just fake and signifies nothing. So everything, almost solipsistic, only related to the ego or the total dissolution of ego. Absolute behavioral patterns of particles without individual properties or hidden variables that "God uses to throw dice." A dead or alive cat or endless variations of necromantic zombie cats. Determinism or variations of free will in all orders of magnitude. Predetermination by a higher entity or it's own decision. Two pretty opposing points of view.

It is difficult to reconcile both understandable experiments and mathematics as well as pure thought experiments. Now, after a long period of stagnation, the time has come to test the theories in practice thanks to better technology. And subsequently, rehabilitate the advocates of the once ridiculed theses. But there is also the option that different approaches are right in different circumstances because there is not just one reality.

Today (2018) the allegedly specific hypotheses are under attack by two sides. On a large scale by gravitational waves, black holes, ... and on a small scale by neutrinos, quanta,…. Today, just as Bohr, many researchers make the mistake of defending their doctrine like a clucking hen on top of their eggs and aggressively picking each helpless doctorand or student who dares to choose a different point of view. Funny to look at, but more in the field of tragedy. Because the real greatness is to revise a life's work occasionally and to search with the obtained wisdom for the new, better theory of everything. Because incomplete hypotheses are not perfect formulas, but only auxiliary vehicles to finding a better theory.

Interdisziplinarität zwischen Naturwissenschaftlern, Philosophen und Neurowissenschaftlern wird irgendwann den gut dechiffrierten Code der Realität knacken.

Der Spielball der Erkenntnis wird seit jeher zwischen drei Gruppen hin und her gespielt. Den Philosophen, Naturwissenschaftler und, seit jüngerer Vergangenheit, den Hirnforschern. Philosophen können die inspirierenden Ideen für die zwei anderen Gruppen in der Praxis konzipieren und bunte Mischungen zusammen basteln. Naturwissenschaftler tüfteln an Experimenten, Nachweisverfahren und immer besseren Instrumenten.

Der Fall der Neurowissenschaftler und Gehirnforscher ist diffiziler. Ihnen eröffnet sich die Option, die Gedanken der Physiker und Philosophen in der Praxis live zu beobachten. Was sie noch interdisziplinärer als die 2 anderen Gruppen macht. Denn sowohl die Theorien für Bewusstsein, seine Funktion als auch die darauf wirkenden Kräfte lassen sich beobachten. Etwa für welches neuronale Level welcher Grad an Bewusstsein Realität definiert. Was wiederum neue Fragen für die Philosophen aufwirft, die diese an die Naturwissenschaflter weiter reichen,…

Dass an der Quantenmechanik auch der Schlüssel zur Entfesselung der atomaren Kräfte lag, wird angesichts von spukhafter Fernwirkung gern übersehen. Doch schufen erst diese Theorien die Grundlagen für weitere Erkenntnisse der Physik und Astrophysik, die wiederum die ersten Kernwaffen inspirierten. Wenn vor über 70 Jahren derartiges Potential freigesetzt werden konnte, was dann erst in 700 Jahren? Was wäre das für eine Waffe, die sich nicht den plumpen und trägen Atomen, sondern der noch kleineren Ebenen der Realität bedient?

Wie lange die Misere um den Wissenschaftskrieg der Kopenhagen Interpretation als Hemmschuh gedient hat, zeigt einen der großen Zwiespälte der Forschung auf. Um seriös und publizierbar zu bleiben, mussten Forscher auf ihre Renommee achten und vor allem die Hypothesen der Philosophie und mancher Geisteswissenschaften umgehen. Und um etwaigen ideologischen Debatten und Vendettas zwischen gegensätzlich argumentierenden Wissenschaftlern vorzubeugen oder ihren eigenen Glauben nicht zu kritisch zu hinterfragen. Sie dürften nur in eine vorgegeben Richtung unter einem Paradigma forschen.

Das war vor 100 Jahren mit Beginn der Debatte bis weit ins 20 Jahrhundert hinein ein Grund für die Zerrissenheit vieler Forscher. Noch dazu, wenn dabei die Gefahr bestand, eigenen Lebenswerken die Legitimation abzuerkennen. Wenn selbst Einstein zweifelte und mitunter verzweifelte, weil genau diese Dissonanz zwischen seinen Theorien und den Hypothesen bestand. Oder wenn man, wie John Bell, nur Undank für die Erarbeitung der Grundlagen der Quantencomputer bekam. Noch dazu kam, dass sich ökonomisch mit realen Anwendungen mehr anfangen ließ als mit der Vermarktung von Ideen, was die Philosophen endgültig diskreditierte.

Wie so oft tendierte der Mensch dazu, in Extremen zu denken. Anstatt im Mittelweg sein Glück und vielleicht die Lösung zu finden. Im Fall der Quantenphysik ist das die Meinung, dass es in der Beobachtung nur die eine unvorhersagbare, zufällige Realität gibt. Den einen von zwei Zuständen oder Möglichkeiten, beziehungsweise nur eine Form von Realität zur selben Zeit für eine beobachtende Person. Zwar schon die unverstandene "Wahl" zwischen zwei Zuständen oder Eigenschaften und auch komplementäre Theorien, aber definitiv nicht mehr als das. Die lange vorherrschende und andere Ansätze blockierende Kopenhagener Interpretation (Bohr). Dieser eine zufällige Zustand kann vielleicht komplementär mit einem anderen Zustand sein und damit gibt es keine echte Realität. Punkt und Ende der Debatte. Die andere Partei zweifelt die Aussagekraft der zugänglichen Realität grundsätzlich an und vermutet unbekannte Faktoren. (Einstein). Der Beginn eines bis heute andauernden Streits.

Entweder alles ist so was von eindeutig oder alles ist nur fake und Schall und Rauch. Also alles, fast solipsistisch, nur auf das Ego bezogen oder die totale Auflösung von Ego. Absolute, durch Naturkonstanten bestimmte Verhaltensmuster von Teilchen ohne individuelle Eigenschaften oder versteckte Variablen, nach denen Gott doch würfelt. Eine tote oder eine lebendige Katze oder unendliche Variationen von nekromantischen Zombiekatzen. Determinismus oder Variationen von freiem Willen in allen Größenordnungen. Vorbestimmung durch eine höhere Entität oder eigene Entscheidung. Zwei ziemlich extreme Standpunkte.

Es ist schwer, sowohl nochvollziehbare Experimente und Mathematik als auch reine Gedankenxperimente unter einen Hut zu bringen. Nun ist, nach langer Stagnation, die Zeit gekommen, um die Theorien dank besserer Technik in der Praxis zu testen. Und nachträglich die Verfechter der einst lächerlich gemachten Thesen zu rehabilitieren. Wobei auch die Option bestünde, dass verschiedene Theorien unter verschiedenen Umständen recht haben, weil es einfach nicht nur die eine Realität gibt.

Heute (2018) werden die sicher gemeinten Hypothesen von zwei Seiten angenagt. Im Großen mit den Gravitationswellen, schwarzen Löchern, … und im Kleinen mit Neutrinos und Quanten. Wie auch Bohr begehen heute viele Forscher den Fehler, wie die Glucke auf dem Ei auf ihrer Lehrmeinung sitzen zu bleiben und aggessiv jeden hilflosen Doktoranden zu picken, der eine andere Ansicht vertritt. Lustig anzusehen, aber eher im Bereich der Tragik. Weil wirkliche Größe darin besteht, auch mitunter ein Lebenswerk zu revidieren und mit der erlangten Weisheit an der neuen, besseren Theorie von allem zu forschen. Denn unvollständige Hypothesen sind keine absoluten Formeln, sondern nur Hilfsvehikel bis zum Finden einer besseren Theorie.
Profile Image for Matt.
752 reviews578 followers
May 6, 2019
Gee-whiz! What is real? How the Heisenberg should I know?

This book left me more in doubt about our (my?) reality than before I read it but I guess that’s a good thing.

When you hear the words Quantum Theory and you only have a vague notion about some cat in a box, that’s neither dead nor alive (or perhaps both at the same time?) but want to learn more, this is the book for you. Although QT usually involves some rather complicated and evolved maths, this text gets by completely without it. Instead you’ll get a coherent picture about the history, philosophy, and, naturally, the science around QT from the early stages to current time. Although the equations and formulas of QT obviously can predict events and qualities of the universe with astonishing precision, even after more than ninety years there is still no conclusive/unique interpretation of those formulas, which means we still don’t know “the inmost force which binds the world, and guides its course”. I find this rather weird, and, honestly, a bit unsettling. So much of our current technology depends on results of Quantum research, but we don’t even know exactly how and why it works!?

The acting characters in this story, mostly physicists, are introduced to the reader through biographical notes, anecdotes, quotations and so on: Bohr and Born (there’s also another called Bohm, and it’s hard to tell those three apart), Einstein, of course, and Schrödinger (the cat guy), Heisenberg (the uncertainty guy). Those I heard about before. But I only had a vague picture of Everett and his many-world-interpretation as well as Bell and his theorem. All of these and many others are introduced in detail and it’s a pleasure to read about them, about their struggles in search of reality (or refusal to do so). Given the fact that some of the people were German and Jewish and a great part of the story is set around the Nazi reign and WWII gives the book an additional historic flavor that I quite liked.

The concluding chapter wraps up with some intriguing discussion about what science in general could mean for us, how it should work, and why it matters. We are all born scientists, explorers of the world we perceive around us, until it’s educated out of us. Get some of it back and read this book, why don’t you?


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Profile Image for Charlene.
875 reviews619 followers
November 9, 2018
If this book were a meal, it would be bursting with such flavor that you could not help going back for seconds. Indeed I read it a second time and chose to listen to Sean Carroll's Mysteries of Modern Physics lectures, from The Great Courses series, as the accompanying glass of wine and dessert because it reenforced the ideas presented in Becker's book. Listening to Sean Carroll's lecture series along with reading this book allowed me to think about how all of the discoveries made in the quantum world apply to time. I warn you though, it's a rabbit hole. Since there are no final answers yet, your brain might get caught in an obsessive trap. I have now moved on to re-reading Lisa Ranall's Warped passages, not because I am convinced of other dimensions, but because thinking about pocket dimensions and/or bubble universes seemed extremely important to me after reading Becker and Carroll together. I also can't seem to stop thinking about how all of this relates to gravity, and keep rereading sections of Gravity's Engines by Caleb Scharf. Sometimes I feel so sad when I realize I will die before someone can answer the burning questions in my mind about the way the universe works, but nothing feels better than thinking about what we do know.

While mainly focusing on the measurement problem in quantum physics (does the wave function collapse) , Becker recounts the history of many of the major discoveries and provided an extremely intuitive account of the following aspects of quantum mechanics:

Heisenberg's uncertainty principle
Double slit
Schrödinger's cat
Everett's many worlds
Copenhagen Interpretation (probability / wave function collapse)
The Bohr - Einstein debates
EPR paradox

Becker included in depth and intensely refreshing biographies of John Bell and his inequality and David Bohm's unorthodox ideas. The biography of Bohm was particularly of interest to me because not too long ago I finished a series of books about the discovery of quantum theory and while many of those books covered the other people highlighted in this book, none of them covered Bohm in the manner Becker did.

I really cannot recommend this book highly enough. Rating a book like this always makes me realize how my previous 5 star ratings muddy the waters. I want there to be a 6 star rating you could use once or twice a year, so that you can really set a book apart from others. This book would be worthy of that 6 star rating.
Profile Image for Ramin.
95 reviews13 followers
March 27, 2018
Here's a brief excerpt of my review of "What is Real?" for Nature magazine, which was just published today. Please check out the full review here: https://www.nature.com/articles/d4158...


All hell broke loose in physics some 90 years ago. Quantum theory emerged — partly in heated clashes between Albert Einstein and Niels Bohr. It posed a challenge to the very nature of science, and arguably continues to do so, by severely straining the relationship between theory and the nature of reality. Adam Becker, a science writer and astrophysicist, explores this tangled tale in What Is Real?.

Becker questions the hegemony of the Copenhagen interpretation of quantum mechanics. Propounded by Bohr and Werner Heisenberg in the 1920s, this theory holds that physical systems have only probabilities, rather than specific properties, until they’re measured. Becker argues that trying to parse how this interpretation reflects the world we live in is an exercise in opacity. Showing that the evolution of science is affected by historical events — including sociological, cultural, political and economic factors — he explores alternative explanations. Had events played out differently in the 1920s, he asserts, our view of physics might be very different.

Becker lingers on the 1927 Solvay Conference in Brussels, where 29 brilliant scientists gathered to discuss the fledgling quantum theory. Here, the disagreements between Bohr, Einstein and others, including Erwin Schrödinger and Louis de Broglie, came to a head. Whereas Bohr proposed that entities (such as electrons) had only probabilities if they weren’t observed, Einstein argued that they had independent reality, prompting his famous claim that “God does not play dice”. Years later, he added a gloss: “What we call science has the sole purpose of determining what is.” Suddenly, scientific realism — the idea that confirmed scientific theories roughly reflect reality — was at stake...
Profile Image for Peter Tillman.
3,779 reviews428 followers
October 31, 2022
This is a pretty good science-history account of the birth and progress of quantum physics in the early to mid 2oth century. It's not riveting reading, but I learned a fair amount about some of the scientists working in the field, and the zeitgeist in Europe then. Especially memorable was the mid-1930s, when Hitler came to power and promptly fired all the Jewish scientists in German (and later, other) universities. What a foolish move on his part, and what a bonanza of scientific talent for America and the West! (And far worse was to come . . .) Max Planck tried to reason with the new Chancellor, telling him how much damage he would do to German science. Hitler practically foamed at the mouth, and snapped "Then we shall have to do without science for a few years!" How fortunate for the (soon to be) Allies that Hitler was no better as a Commander in Chief. Though he did ample damage before his defeat . . . But I digress.

Particularly interesting was the account of the career of Niels Bohr, who mumbled at seminars and wrote scientific papers so rambling and opaque that no one else seemed to really understand him. Yet he remained an icon of 20th century physics. And he was capable of great kindness, as when he told Enrico Fermi that he was certain to get the Nobel prize (and US$ 1 million) in the near future. Fermi and family were more than ready to move out of Fascist Italy, as Hitler's anti-Jew campaign was being pressed there too. Fermi asked for the Prize that year (1938), took his family to Stockholm for the ceremony, and never looked back. When Fermi arrived in the US, he immediately began work on nuclear fission, and helped build the world's first nuclear reactor. He became a key scientist for the Manhattan Project, and has been called the "architect of the nuclear age." Other scientists at Los Alamos were in awe of his quick thinking and scientific abilities. Good thing the Nazis and Fascists ran him off, eh?

I'd read more of the book, but it's already overdue, and I have so many others lined up on the shelf, competing for my attention. An enviable position, to be sure! It's a good time to be a reader! I'm about halfway in, and while I could return someday . . .
Profile Image for David.
24 reviews3 followers
October 24, 2018
This reads like an edge-of-the-seat detective story about quantum physics. I never thought this subject was particularly friendly to being portrayed with this kind of drama. Most reading on sub-atomic physics is a kind of slog; a perfunctory sweat-labor with the objective of obtaining a walking around knowledge of the subject.

This book sets out the characters and the stakes involved with great narrative momentum. The assumptions behind the phenomenally successful equations of quantum physics (known as the "quantum foundations") are exposed as unresolved philosophical issues. The questions surrounding the measurement problem ("who is doing the measuring", "what constitutes a 'measurer'?", "why does physics insist on a discontinuity between laws ruling the very small and large?") are still out there. And the fundamental ontological dilemma of exactly what is being measured goes begging.

This detective story never does find its culprit. That could be a problem for some but merely the effort to re-frame the basic assumptions and ask questions that have gone neglected through the power of the "Copenhagen interpretation" to squelch dissent turns this into a delicious peek into the politics of scientific discourse in general and physics in particular.

The book also considers the disaster that is logical positivism and the absolute necessity we face today of moving beyond excuses of solipsism, moral relativism and the primacy of a strictly measurable universe in this time of monumental crisis. The dilemma of living life as fully human and allowing for all humankind to continue to flourish hinges crucially on our ability to see where we have been misled by these pernicious philosophical assumptions.
Profile Image for Bart.
416 reviews102 followers
June 23, 2021
While 'What Is Real?' is marketed as a popular science book, it should be mandatory reading for professional physicists, as it is a critical history of their field first and foremost, trying to explain why a problematic theory like the Copenhagen interpretation of quantum mechanics has endured for so long.

It works both as a solid overview of the science and possible interpretations of quantum theory, and as a sociological history of the workings of the field – both from a European and American perspective. There is much to learn here: about quantum science, about science as a practice, and about philosophy of science as well.

(...)

Full review on Weighing A Pig Doesn't Fatten It
Profile Image for Jonathan.
960 reviews1,086 followers
March 31, 2020
Without doubt one of the best popular science books I have ever read. Well written, fascinating and a genuine page-turner. Highly recommended
Profile Image for Goatboy.
230 reviews88 followers
October 20, 2021
A clearly written, narrowly focused, historically centered deep dive into a seemingly essential (yet surprisingly undecided after all this time) question rooted in the origin of quantum physics and its practice over the last 100 some odd years...

If we assume that quantum physics and the measurements and predictions it allows us to make about the world are true - which at this point seems to have been proven to some extent (or at least not yet disproved) - then what does it actually tell us at its root about the world we live in?

At the basis of quantum physics lies Schrödinger's equation, superposition, and the wave function along with its apparent collapse. But what does that mean? If it collapses, then why does it collapse? If a measurement collapses it then what exactly constitutes a measurement? Does it have to collapse, and if not, what other explanations can we find to explain what lies at the seeming heart of the quantum universe (if that universe actually exists at all)?

Lives and careers were made and ruined by daring to ask and answer these questions.

Adam Becker relates the history of this fascinating still undecided kernel within quantum physics, and does so with a verve and excitement that made this book a true joy to read. There is perhaps a bit too much repetition in the last true chapter for those who have been paying attention, but that's a small complaint against one of the more interesting science history books I've read in a while.

If you have any interest in the stories behind the Story of quantum physics, this book is for you.
Profile Image for Pavle.
457 reviews172 followers
November 4, 2019
Sjajna popnauka koja za svoj predmet uzima povremeno gangsterske sukobe u naučnoj zajednici oko toga koja interpretacija kvantne mehanike je zapravo najbliža istini. Svoj fokus Beker više baca na nešto što na površini izgleda apsurdno – naime, da nauka povremeno može biti vrlo dogmatska. Ili da makar to mogu biti naučnici koji se njom bave.

Veliki akteri u burnoj istoriji ove nauke ovde su u prvom planu i može se tu puno toga naučiti, shvatiti, doznati, jer Beker koncizno prelazi preko naučnih osnova – a posebno Belove teoreme - dominantno se baveći filozofskim implikacijama kvantnog sveta na ovaj naš klasični (šmrc jednačine šmrc). Svakako ono što najviše vredi ovde je neverovatan uvid u iza kulisa naučnih krugova jedne fascinantne oblasti koja danas kroz misreprezentacije sačinjava 90% popularnog sajfaj sadržaja. Prapočeci i počeci, kulminacije i obrti, istorija kvantne mehanike lako se može uporediti sa istorijom čovečanstva na mikro, mezo i makro nivou, jer, kako to obično biva, i naukom se bavi neko ko mora na svakih dva sata u toalet.

5-
Profile Image for Alexander.
67 reviews64 followers
September 1, 2021
This is basically a book on the history and sociology of modern physics. This book beautifully illustrates how science is full of prejudice, dogma, and blind ideology. Becker successfully illustrates that science is a human process and that scientists' cultural backgrounds and personalities do, in fact, influence how they conduct science. This goes contrary to the idea that scientists always start with hypotheses and then seek to falsify them. The reality is that many scientists start with conclusions and then seek to cherry-pick the evidence to defend those conclusions, something Lawyers are particularly good at.

This is exemplified by how the dissident voices are marginalized in the academic community. In particular, the voices of those who recognized the Copenhagen Interpretation as a corrupt pseudoscientific dogma and insisted that we should keep asking "What is real?" rather than just accepting the dogmas of scientific institutions. Such people have been made unemployable, labelled as “not real physicists,” and had their publications rejected by journals despite later finding valuable insights.

In classical mechanics, you look at the system and see what is really there. There was no controversy or mystery surrounding observation. However, the measurement problem with quantum mechanics is that quantum systems seem to take on a superposition of multiple states before measurement and a definite state upon measurement. Bohr, Einstein, and Schrödinger talked about this briefly, but soon after, people stopped talking about it, and it even became disreputable to talk about it.

Think about it like this: when you observe a quantum system, such as an electron, you disturb the system because to observe the system, you are striking it with photons. Imagine looking for your wallet in a dark room using a mighty flashlight. Every time you find the wallet, you knock it away with your powerful beam of light. Similarly, when you observe an electron, you inadvertently disturb its delicate quantum system (you become entangled with its wave function or something). Now, this analogy is probably terrible, but it's just an analogy, and I'm not a physicist. On the other hand, we see superposition all the time, e.g., waiting on your blood test results. While you are waiting, the result is in a superposition of positive and negative with different probabilities for each. Once you receive the result, the superposition collapses to a definite state of either positive or negative, but not both.

The Schrödinger Equation works, but how does it actually work? This is a question that for many decades has been considered a heresy within the physics community. Physicists around the world stubbornly and ideologically believed that it is a meaningless question to ask. However, the situation is getting better today as technology advances and more physicists think philosophically because unemployment in physics is rising. A lot of physicists are forced to do postdocs in philosophy.

Hugh Everett's Many Worlds seems to me to be the most plausible and logically consistent explanation of quantum mechanics. It introduces no assumptions other than the Schrödinger Equation (which is empirically true), so it gets the green light from Occam's razor. Many Worlds states that the wave never goes away and that you, the observer, are part of the same wave function as the system you are observing. However, Many Worlds requires that you take on a very radical view of reality. My personal hot-take is that we should treat Many Worlds as provisionally true and keep searching for better explanations of the quantum. The rising interest in quantum computing seems like a promising opportunity for answering more questions about "What is real?"

Now you might ask, "Why can we assume the Schrödinger Equation?" The answer to this question is that the Schrödinger Equation is the kind of thing physicists like to call a Law of Nature because it is deterministic and it has predictive power. It states that there are things in the world called waves, and they move in a perfectly predictable way through the mathematics of the Schrödinger Equation. Maybe someday, when we reconcile the quantum with General Relativity, we will find that the Schrödinger Equation is incomplete, but for now, physicists like to call it a Law of Nature. This reminds me of this funny response by Scott Aaronson in his Scientific American interview about whether P = NP. He said, "If we were physicists, we would state that P does not equal NP as a Law of Nature and move on with our lives."

Adam Becker argues that scientists should undergo more training in analytical philosophy because we are increasingly faced with problems that fall on the boundary between science (testable predictions) and metaphysics. Totally agree with him. I think people in computing and biotech should be taking philosophy classes as part of their training too.

This book really illustrates the propensity of human beings to seek certitude and their disinclination towards saying, "We don't know."

Check out this interview with Adam Becker if you're interested in a high-level view and don't want to read a whole book on this [https://youtu.be/em7dkYZTetE](https:/... .
Profile Image for Ed Erwin.
1,045 reviews121 followers
April 13, 2018
QM is undeniably non-intuitive and weird, but the Copenhagen Interpretation(s) are far more weird than necessary, and have been used to sell a lot of quack-pot ideas. There are other interpretations, which are still weird, but much less so. The other interpretations don't require crazy claims about conscious observers affecting the behavior of electrons or cats that are alive and dead at the same time and so forth.

This book has ZERO equations and very few diagrams. You do not need to be a math whiz to understand it. It still might make your brain hurt, but it is mostly stories about people and history.

This book explains, briefly, what some of these other interpretations are, and why they aren't as well known.
* Firstly, the Copenhagen Interpretation works fine for practical purposes. As long as you can accept some hand-waving arguments about what situations cause "wave function collapse" you can just go about your business and solve practical equations and you will get the right answer.
* University physics courses today are all about solving practical problems. Physics students aren't expected to worry about philosophical underpinnings, and professors don't have time to try to teach it anyway.
* David Bohm had trouble spreading his ideas largely because the FBI or CIA got him run out of the country and stuck in Brazil due to the red scare. He was unable to attend conferences or visit other physicists.
* Hugh Everett left the world of Physics for personal reasons, so didn't publicize his ideas much.
* Niels Bohr had close personal relationships with many physicists, and they tended to accept his interpretations over those of Einstein or others, even when Bohr's writings are so confusing that nobody knows what they mean.
* Respectable physics journals refused to publish articles about interpretation issues.

Adam Becker is trained in both physics and philosophy and that gives him the tools he needs to tell this story. He even managed to convince me that philosophy is not totally useless (though I still think some of it is.)

I would give this book 6 stars if it could tell me which interpretation of QM is correct. Unfortunately nobody can do that yet. But at least people are actively studying the problem again.

My favorite part is probably the appendix where he works through an experiment and shows how it is interpreted in the Copenhagen interpretation as well as three other interpretations. In CI, it appears like magic is happening. In all others, it is still weird, but much less so.
Profile Image for Sato.
38 reviews12 followers
March 21, 2020
What a delightful adventure! I really appreciate what Adam Becker has done, probably not only because of his incredible book, but also because I belong to the minority who think the Copenhagen Interpretation is not satisfying and “Shut up and Calculate” doesn’t add up.

Quantum physics is tremendously successful and although it is considered the physics of ultra-small but there is really no boundary to its incredible contribution to the present progress in life.



Niels Bohr, Heisenberg, Pauli and others are truly founders of the first interpretation of quantum physics,the Copenhagen Interpretation. But the Copenhagen interpretation assumes a mysterious division between the microscopic world governed by quantum mechanics and a macroscopic world of [measurement] apparatus and observers that obeys classical physics.

For what matter, why should we care? Its mathematics makes accurate predictions; isn’t that enough?Quantum physics works, but ignoring what it tells us about reality means papering over a hole in our understanding of the world—and ignoring a larger story about science as a human process.

As Einstein said this “epistemology-soaked orgy” should come to an end. Albert Einstein was someone who was not on the same track with Copenhagen Interpretation, mainly because of its inability to have a realist approach about the real phenomena, and to some degree for its “spooky action at a distance” nature or its non-locality. Schrodinger, was also someone who never made compromise with Neils Bohr’s vague discussions and there were few physicists who dared to question the Copenhagen Interpretation.

A misunderstanding: Based on the 1926 Einstein’s famous “God doesn’t play dice”, almost all the Copenhagen physicists reffered Einstein’s problem to uncertainty principle, but in fact Einstein’s concern was with non-locality not uncertainty principle.

Schrodinger’s discovery of wave function and Max Born discovery of “a particle’s wave function in a location yields the probability of measuring the particle in that location “ were potential motives for further elaboration for Heisenberg to present “Uncertainty principle”. But Heisenberg and Schrodinger’s quest to show a more coherent nature of Quantum mechanics is probably the first interesting quests over the Copenhagen Interpretation.

Von Neuman’s interepretation: Von Neumann’s solution was to make the observer—whoever was looking—responsible for wave function collapse. “We must always divide the world into two parts, the one being the observed system, the other the observer,” Von Neumann said. “Quantum mechanics describes the events which occur in the observed portion of the world, so long as they do not interact with the observing portion, with the aid of the [Schrödinger equation], but as soon as such an interaction occurs, i.e. a measurement, it requires the [collapse of the wave function].”

Von Neuman’s character as the most brilliant mathematician of his age never let the voice of Grete Hermann, someone who proved him wrong be listened just because she was a woman. Von Neuman’s proof and credit helped the popularity of Copenhagen Interpretation for decades later after the World war and the Manhattan Project.

Bohm’s interpretation: In Bohm’s interpretation of quantum physics, much of the mystery of the quantum world simply falls away. Objects have definite positions at all times, whether or not anyone is looking at them. Particles have a wave nature, but there’s nothing “complementary” about it—particles are just particles, and their motions are guided by pilot waves. This simple idea allowed Bohm to cut through the thicket of quantum paradoxes. The Copenhagen interpretation doesn’t let you ask what’s happening to Schrödinger’s cat before you look in the box, insisting only that it’s meaningless to talk about the unobservable. But, in Bohm’s pilot-wave interpretation, not only can you ask but there’s an answer: before you look in the box, the cat is either dead or alive, and opening the box merely reveals which is true. The act of observation has nothing to do with the condition of the cat.

The theory of quantum gravity: John Wheeler, was obsessed with his own disreputable problem, general relativity. Despite the theory’s universal acceptance, it wasn’t seen as a reasonable field of research at the time. Wheeler was interested in the same problem Einstein was trying to solve: marrying general relativity to quantum physics in a single theory of quantum gravity, with the ultimate goal of describing the entire universe, including its origin, in the still more disreputable nascent field of quantum cosmology.

The many world interpretation: Rejecting both von Neumann and Bohr, Everett came up with his own solution to the measurement problem. Rather than explaining wave function collapse, Everett stated that wave functions never collapse at all. This in itself was not new; Bohm said the same thing. But Bohm had also added particles with definite positions into the theory, which accounted for the outcomes of measurements. Everett didn’t add particles—he didn’t think he needed them. Instead, he insisted that a single universal wave function was all there was: a massive mathematical object describing the quantum states of all objects in the entire universe. This universal wave function, according to Everett, obeyed the Schrödinger equation at all times, never collapsing, but splitting instead. Each experiment, each quantum event, spun off new branches of the universal wave function, creating a multitude of universes in which that one event had every possible outcome. Everett’s shocking idea came to be known as the “many-worlds” interpretation of quantum physics.

Bell’s theorem: Bell’s theorem really leaves only three unequivocal possibilities: either nature is nonlocal in some way, or we live in branching multiple worlds despite appearances to the contrary, or quantum physics gives incorrect predictions about certain experimental setups. No matter the outcome, Bell’s work presents a threat to the Copenhagen interpretation. Perhaps because it contradicts the widely received wisdom, physicists have long had particular difficulty understanding the true implications of Bell’s theorem—in fact, the misunderstandings began before it was even published. Bell’s work had inspired a full-blown quantum rebellion, the first truly widespread and serious challenge to the Copenhagen interpretation from within the physics community since the Bohr-Einstein debates.
Profile Image for Erik.
343 reviews297 followers
February 7, 2019
In his book Superintelligence, philosopher Nick Bostrom tells a story about an evolutionary algorithm tasked with designing an efficient oscillator. After running through many generations, it eventually presented a “solution” with a strange absence: it had no power source!

At first, the engineers declared the design a failure. Upon closer examination, however, they discovered the algorithm had reconfigured its circuit board into a makeshift radio receiver to pick up oscillating signals from nearby lab computers. The circuit then amplified this signal to produce the desired oscillation pattern. It was a solution that certainly worked… but only at that exact location in those exact circumstances.

This is an interesting story because it reveals an opaqueness that’s already becoming a major issue in the type of ‘black box’ machine learning that’s become popular recently. Because neural network deep learning or genetic algorithms aren’t ‘rule-based’ like the old expert systems were, their solutions are often beyond the understanding of those who created them. Which is a little worrying. Sure, it’s no big deal that AlphaGo is much better at Go than any of its designers - Go is just a game - but what about future black-box AIs that design governments or medicines - or new laws of physics?

In a way, that last one is already true. If you’re not familiar with it already, go read the wikipedia article on Schrodinger’s Equation. It’s very clear it’s a mathematical trick that is quantitatively accurate, but provides almost no qualitative explanation. Indeed, the article admits as much: The Schrödinger equation provides a way to calculate the wave function of a system and how it changes dynamically in time. However, the Schrödinger equation does not directly say what, exactly, the wave function is. What a remarkable state of affairs that is! We don’t even know what it is we’re calculating the values of! It’d be like if I handed you a phone and asked, “How many grozoiacs is this?” You did some math and found the phone was 19.3 grozoiacs. On the basis of that calculation, we knew the phone required 70 watts of power. But… wtf is a grozoiac?

And of course, there’s the strange relationship between the equation and waveform collapse caused by a ‘measurement’ or an ‘observation.’ No one actually seems to know what exactly those words mean either. As John Bell asked, “Was the wave function waiting to [collapse] for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer for some highly qualified measurer - with a PhD?”

That’s what I mean about physics already being opaque. In a way, quantum mechanics is like a black-box AI system that serves up accurate calculations but whose inner workings remain mysterious.

That’s the core idea explored in What is Real?: this weird tension between how incredibly accurate and useful Quantum Mechanics is and how it nevertheless doesn’t seem to help us understand anything.

Now, there’s two sides to this book. On one hand, it’s a tome of science history. I have nothing but good to say about this aspect. It’s exhaustively researched and gives a real sense of being ‘in the room’ with physics greats like Niels Bohr and Albert Einstein. While I found myself a little disillusioned to see these scientific luminaries engage in petty tribalism and stubborn close-mindedness (fool that I am, I expected better), I nevertheless thoroughly enjoyed getting to know these legends more as humans than as mere names attached to equations. And I really do think learning WHERE and HOW equations came about actually assists in understanding them.

For example, when I first learned Schrodinger’s Equation, it felt so different than previous math theories and equations. Honestly, for the longest time, I thought I just didn’t get it. I could do the math, but I didn’t know what it meant or how it worked. It felt like magic. Well, after reading this book, it’s clear the very people who created it, didn’t get it either. Knowing that, I see I was pondering the equation in the wrong way. I was trying to decipher a hidden meaning that I thought already existed, when my task should have been more about creating a hidden meaning that has not yet been found.

Now I do have some issues with this book. Because, in addition to being a science history, there is a second side: an argument against the Copenhagen Interpretation and its underlying philosophy of logical positivism. While I’m sympathetic to that aim, I was less impressed by how the author went about it.

As a quick summary, the Copenhagen Interpretation essentially draws a sharp line between the ‘quantum world’ (if it even admits that such a thing exists) and the ‘classical world’ (the macroscopic world that we inhabit). In this interpretation, quantum systems don’t really have definite, deterministic states UNTIL they are ‘observed’ or ‘measured.’

As I briefly mentioned above, there’s quite a few problems with this interpretation, which is why Einstein himself disliked it. What constitutes a measurement or observation? And is there really such a distinction between the quantum world and the classical world? All objects - a cup, you, me, a measuring device - are themselves made up of quantum particles. Shouldn’t that make them subject to the rules of quantum mechanics too?

What is Real? explores these problems in great depth and vivacity, and I’m completely on board in seeing the Copenhagen Interpretation as a flawed or incomplete interpretation that needs to be evolved. However, as I said, I was less impressed with how the author went about making this argument. In particular, he seems to fall into two very common philosophy traps:

Major Flaw #1: Absolutism

Extreme skepticism is a hallmark of philosophy. Rene Descartes’ famous Cogito Ergo Sum (I think, therefore I am) represents the only absolutely true statement he thought he could say, at least to begin with. Because he’s thinking, he knows he exists in some form. But everything else? Uncertain. Every sense experience he has might be the result of a deception by some demon. This type of radical skepticism is not only not rare in philosophy, I’d say it’s the norm. To a great many philosophers and thinkers (including, apparently, the writer of this book), unless you can be 100% absolutely certain about something, then you should treat it with absolute skepticism. This is what I call Absolutism, and I find it an entirely ludicrous stance to take, ill-suited to practicing useful philosophy or thought.

Consider this passage from the book, which purports to counter the falsification/verification ideas of Karl Popper and logical positivism (that is, that any good scientific theory should be able to be proven wrong):
Looking out your window and saying, “It’s raining outside” [would be foolish because it] assumes that your view through the window’s glass gives you an accurate picture of the outside world, and that your eyes are functioning properly, and that the dimmed light and falling droplets are in fact caused by a rain cloud and not an alien spaceship blotting out the Sun and dropping some exotic substance onto your front lawn.

Is this a reasonable stance to take?

Sure, it’s possible that my window has suddenly become a TV screen or that - despite there never being an alien spaceship before - there suddenly is one now, but if quantum mechanics has given us any one lesson to be applied to normal life, it’s that the question shouldn’t be “is it possible?” but rather “is it probable?”

Indeed, the great skeptic David Hume himself acknowledged the silliness of extreme skepticism when he invoked his ‘problem of induction’: just because something happened in the past doesn’t mean it will continue to happen in the future. Because of this, it is actually impossible to state anything with 100% certainty. Therefore, extreme skepticism is simply not a valid approach to philosophy or science.

In the final chapter, the author laments - a sadness I share - the disrespect modern scientists such as Stephen Hawking have for philosophy. But is it any wonder they do so, when philosophers seriously suggest that we ought to be skeptical that the raindrops we see and feel are even real?

Major Flaw #2: One-sided Pragmatism

This is a rhetorical fallacy I witness often. It’s a form of ‘moving the goalposts’, in which a person makes an argument rooted in pragmatism (i.e. that we’re interested in an idea’s practical effects upon ourselves and the world rather than any inherent truth or reality) without considering the pragmatic arguments of the other side. It’s kinda like if my opponent and I are playing a game of tennis, but right in the middle of it, I run off the court and onto a basketball court and slam dunk the ball and say, “Booya, I just won.” It’s like well… that wasn’t the game we were even playing…?

Let me give an example. Suppose I’m arguing about the truth claims of religion. Let’s say, Christianity. I say something like, Well we have all these dinosaur fossils. Why aren’t dinosaurs mentioned in Genesis? Did God just accidentally leave that whole epoch out, in His account of the creation of Earth? If He did, or if we must pretend He didn’t by taking a metaphorical approach, doesn’t that constitute a serious flaw in the Bible?

To which a Christian might respond, Well, you know what? Sure there’s some mysteries, but it doesn’t matter. I don’t want to live in a universe in which there isn’t a God, where it’s all just chaos. Believing in God gives me purpose in life. It makes me feel good.

This is what I mean about one-sided pragmatism. To avoid the issue, the Christian switched to a pragmatic argument that would be, of course, easily countered by an opposing pragmatic argument: Do you really want to live in a universe created and managed by a God who failed the (relatively) simple task of writing an accurate book?

Well the author of What Is Real? does this very thing. He makes various pragmatic arguments about opposing the Copenhagen interpretation & logical positivism not necessarily because they are more true but because diversity of perspective has pragmatically positive outcomes.

Which I don’t disagree with. But nowhere does the author then discuss the pragmatic positives of the Copenhagen Interpretation, logical positivism, and the ‘shut up and calculate’ approach to doing physics: they grant peace to the pursuit of science.

I sometimes say that one of the big differences between science and almost everything else is that science offers a means of resolving a dispute without resorting to violence.

If I say the universe was created by the flying spaghetti monster and you say the universe was created by Yahweh, how can we resolve this dispute? Or if I say that Republicans are ruining the US and you say that Democrats are ruining it, is there any mathematical process or conclusive evidence we can offer to prove our side correct? Well, no. Both of those situations are rooted in natural language, which is rife with ambiguity. As such, there really is no way to resolve our dispute, except by some form of violence.

But that isn’t the case with science - at least science when restricted by a logical positivist or instrumentalist perspective. If I claim the Many-worlds Interpretation is correct and you claim the Bohm pilot-wave theory is correct, we actually do have a non-violent means of resolving our dispute. We go to the math and say, Which one of these makes accurate predictions? If they are both equally accurate, then - functionally speaking - there is no difference. We’re both correct, we’re both accurate, until such time as the experimentally testable predictions of our theories diverge.

But again, that’s only within a logical positivist perspective. A scientific realist perspective - which the author advocates and which holds that science should NOT merely be limited to math and experimental verification - has a weakness in this regard. From a realist’s perspective, there IS a difference between the pilot-wave theory and many-worlds interpretation, and only one of us can be correct. But since I’ve not restricted my perspective to what can be mathematically, experimentally verifiable, then what means do we have to resolve our dispute?

Well, none.

Now of course I’m not suggesting that ‘realist’ scientists with competing theories are running around bashing each other with canes or maces, as politicians and zealots are wont to do. But there is something to be said about nurturing a perspective that says we should do our best to restrict our view of the world only to what we can verify and for everything else, let us admit our ignorance.

To conclude, I quite liked this book. I’m a firm believer that living in the universe without understanding physics or math is like living in France without being able to speak French. Sure you can get along just fine… but what beauty, what clarity, what meaning will you be missing? In that respect, I consider this book - flaws and all - nothing less than a primer for the Universe, at least as we currently understand it. If you’re at all sympathetic to that perspective, then you’ll probably enjoy What is Real? too.

[Note: Though I use the word 'math' a lot in my review, this book doesn't actually contain any and you don't need any to enjoy or understand it]
Profile Image for Márcio.
572 reviews1 follower
December 3, 2023
First of all, Adam Becker doesn't answer the question he proposed in the title of his book. He is not at fault when one considers the second part of the title. Indeed, the meaning of quantum physics is not over yet, regardless of the amount of scientific work we already achieved since someone proposed a physics of the microscopic world, one which resulted in what is now called Copenhagen interpretation of quantum physics, though it is not an interpretation or a theory or a total agreement at all. Weird? Ahahaha

Becker has what I like in a scientist who likes to write scientific books: he is clear in his writing, wit, humorous when it feels like and most of all, he digs in deep and brings the best out of what he decided to show to his public.

Different from what we are used to today, until around the beginning of WWII, a university degree required much more than studying the subjects concerning a certain branch of knowledge. It was no surprise then that a physicist, a chemist, a biologist, a mathematician, etc., was instructed in philosophy or other necessary subjects to achieve an ampler vision of his area. Thus, when quantum physics came to be, and because of its strangeness, scientists needed to create paradoxes or interpretations to be able to explain its complexity. Regardless of the Schrödinger equations and his paradoxes, in the end, Bohr and Heisenberg started prevailing among scientists (it still does): the Copenhagen interpretation. It was the crowing of a positivistic vision of the world as well, one which Einstein didn't enjoy, even though he was ok with the new field of knowledge. In any case, the years before WWII were friendly with theoretical discussions, studies and experiments. But, with the war, a new vision of the fields of knowledge took its place for practical reasons, that is, either industrial or military.

With all of that, many of those who tried to oppose the Copenhagen interpretation, or bring theoretical thinking back to universities, were treated with mockery, when not swept under the rug or had their careers ruined.

It is stupid to think that science shall only work into experimental works that lead to profits or so on. Until a certain point around the 1950s and 1960s, cosmology/astronomy was looked at with strangeness, it was not profitable at all, and who cared about the state of the universe? Who cared about Einstein's theories on relativity? What was their use for?

Oh, dear! Don't be so stupid. How do you think your GPS works? Go study a lot more! And say a "thank you" to Einstein.

Here is Becker:

So how does science work? (...) The long answer would take another book. But the short answer is that science involves a combination of experiment, mathematical and logical reasoning, unifying explanations, and biases that scientists bring to the table from their own lives and the cultures they live in. We work to reduce those biases; we don’t always succeed, but the explicit attempt to account for and reduce those biases is an important part of the process, properly conducted. The whole edifice of science is geared toward this goal. And, given the phenomenal explanatory power and predictive success of science, it would be foolish in the extreme to give scientific truths no more credence than idle speculation, religious articles of faith, or deeply held cultural values. Science, done right, works hard to respect absolutely no authority at all other than experience and empirical data. It never succeeds entirely, but it comes closer and has a better track record than any other method we apes have found for learning about the world around us, a world we never made.

Becker, all along with his fantastic book, explains all of this and much more, bringing names of so many scientists I had never heard of, but who contributed with so much to the state of knowledge we have today. As an example, I appreciated a lot when he introduced John Stewart Bell, the North Irish physicist who worked in order to bring the further need of theoretical studies in quantum mechanics, but also in science as a whole. Contrary to most scientists who demanded an observer in quantum mechanics (thus, something of an anthropocentric vision), Bell stood for am observer-free quantum mechanics, insofar physical theories ought not to be concerned with observables.

It’s certainly true that we’ll get the same answers when doing quantum-mechanical calculations whether we prefer the Copenhagen interpretation, the many-worlds interpretation, the pilot-wave interpretation, or anything else. Even alternatives to quantum physics, like spontaneous-collapse theories, will give the same answers in nearly every situation. Some people have argued, as Wolfgang Pauli did to Bohm, that, because the different interpretations don’t make new predictions, we should just stick with Copenhagen—a silly argument, since you could say “we should just stick with many-worlds” or any other interpretation with that same reasoning appeal in “alternative” circles. Rather than giving a humbling and strange vision of the universe, the Copenhagen interpretation makes physics familiar and comfortable. If we are to have any hope of understanding the universe, we must dare to imagine a world that is not bounded by our limited perspective.

I will be looking for more of Becker's books and I wish he continues to bring us so much sage in the future!
Profile Image for Ari.
744 reviews83 followers
October 3, 2019
Quantum mechanics is one of the most solid, well-tested parts of physics. Everybody (at least, everybody relevant to this book) agrees how to use quantum mechanics to do things like predict the behavior of semiconductors and molecular bonds. But not everybody agrees on what the theory "means" -- what sorts of things exist in the universe and so forth.

This is not a tightly focused book. Instead of stating a claim and then proving it, the reader is treated to a loosely chronological discussion of the history of interpretation of quantum mechanics, with long biographical, philosophical, and technical asides. A knowledgeable reader may find themselves skimming a lot. While the book lacks academic crispness, it does have a full machinery of notes and references, and an academic reader shouldn't have any trouble putting it in the context of the relevant professional literature.

The book has a few controversial claims at its core: Becker argues that the "Copenhagen interpretation" is a mishmash of slogans that lack coherence, and that cannot even be applied without some tacit notion of what qualifies as a measurement. Becker reconstructs the Bohr-Einstein debates and shows that Bohr largely missed the point Einstein was making: Bohr managed to vindicate the uncertainty principle, but Einstein was bothered by nonlocality, not uncertainty. It happens that the universe really is non-local, as Bell showed, but that is strange and alarming and should be acknowledged squarely and not hidden in talk of waveness or particle-ness.

I should summarize the problem that interpretations of quantum mechanics address.

In quantum mechanics, there's a rule that describes how a system evolves, called the wave equation. The {Schroedinger, Dirac} wave function is deterministic, continuous, and it assigns a certain amplitude to every point in space: it says "there is this much electron at this point," where the amount of electron is a complex number. There is also a rule (the Born Rule) that says that if you do a measurement, the chance of finding a particle at a given point is squared amplitude of the wave function at that point. The Born Rule is probabilistic and discontinuous. A big part of the problem of interpreting quantum mechanics is to explain how those pieces fit together.

Most physics books will tell you that "the standard interpretation is the Copenhagen Interpretation, worked out by Bohr et al, and it goes like this..." As Becker shows, however, there isn't any real agreement about what the Copenhagen interpretation actually says. There is a whole set of claims that get lumped together under that label -- and these claims are distinct and sometimes incompatible. There is a Copenhageny mood or style, not a clear interpretation. Bohr personally was both very charismatic, widely respected, and highly obscure. This made it easy for different people to offer distinct views while sincerely or otherwise ascribing them to Bohr.

All those confusing and quasi-mystical explanations -- "particles are sometimes waves and sometimes particles but you can't see both at once", "wave functions collapse after measurement", etc are all Copenhagen-ish tropes. Bohr talked that way and was avowedly mystical about it. And "consciousness causes collapse" was floated by ultra-respectable hard-headed physicist and Nobellist Eugene Wigner; even von Neumann might have inclined to that view.


Disclaimer: Adam is a classmate and friend of mine -- I'm in the acknowledgements -- I went into this book highly sympathetic to his view. I am not a physicist, but have done considerable reading and coursework related to the physics, philosophy, and history in this book; I'm not quite an expert but was already aware of most of the facts.
February 27, 2019
This isn't a bad book. It's just poorly titled. The title should have been "The History and Hidden Politics Behind Quantum Physics." That title won't sell books though. It seems to me that the publisher had a conversation with the author and said, "Let's call it 'What Is Real?' It will be intriguing and will broaden your audience so that more people will buy it. The author agreed and at the tail end of the book, figured he should probably go ahead and address this "What Is Real?" question so he tacked on the last two pages (literally, I'm pretty sure that's the only time he addressed that question).

Understand, I am not a physics genius in any way, shape or form. The book did give a good overview of the evolution of thought in quantum physics over the last 100 years so that I had a better understanding. I learned that there have been two schools of thought in quantum physics that have been highly influenced by politics among scientists and how the science got supported by the government or universities.

I'm not sure what I was expecting from this book but I definitely didn't expect it to really read like a history book. Only in the last chapter does the author address more of what quantum physics (or foundations?) means for everyday life and ponder some of the larger questions. Also, if you are thinking that this book will even mildly entertain theories by Deepak Chopra (whom I haven't studied enough to have an informed opinion) or his ilk with regard to how quantum physics could be influencing the mind, the body, the spirit, etc., don't bother. Chopra is essentially lumped in with the other, as the author puts it, "quantum health-care scams." I find it interesting that for most of the book, the author subtly defends scientists who were willing to entertain what used to be considered pseudo-science and then turns around to quickly criticize what is considered pseudo-science today. Seemed a little hypocritical.

Again, great book if you're interested in the history of quantum thought. Retitle it please!
Profile Image for R Nair.
122 reviews52 followers
September 24, 2018
Terrific work not only on the history of quantum mechanics but also the dogmatic influence of Bohr's Copenhagen interpretation of Quantum mechanics on Physics. This book really delves into how physicists correctly pointing out the problems within the Copenhagen interpretation were not taken seriously for decades based purely on blind faith that reality could not be explained within the Quantum mechanical framework. The 'shut-up and calculate' paradigm has been the workhorse of physics for such a long time that actual philosophy has been pushed out of mainstream physics as almost pseudoscience. Incidentally the last time such foundational questions about the meaning of reality in quantum mechanics were raised, it was by physicists like Albert Einstein who had had a solid education in philosophical thought.
This book is reminiscent of Manjit Kumar's well written Quantum: Einstein, Bohr and the Great Debate About the Nature of Reality but more updated and so far, having the best explanation of Bell's theorem and its significance to modern physics for the layman in recent times that I have come across. Having read this in conjunction with Anil Ananthaswamy's Through Two Doors at Once: The Elegant Experiment That Captures the Enigma of Our Quantum Reality only enhanced the practical aspects of the complex experiments referred to in this book. This book also deals with Bohmian mechanics (Pilot wave theory), Spontaneous collapse theories and the Many worlds interpretation of quantum mechanics very well.
Profile Image for Seth Benzell.
239 reviews15 followers
July 14, 2018
I am ambivalent about this book.

On the one hand, I nearly put the book down a few chapters in. The early material about the initial development of quantum theory was all old news to me, covered (better) in books like ``Thirty Years Which Shook Physics." The actual mechanics of quantum theory are not covered in depth. The only part of this book I felt was novel was the details of how central Bohr was to how QM is thought about.

The book's novelty for me starts about halfway in, after WWII. The discussion of how alternatives to the Copenhagen Interpretation arose and were suppressed is compelling and provocative. The discussion of why the 'Measurement Problem' is indeed a problem is very well articulated.

The social science in the background-- which posits that government funding (which favored 'shut up and calculate' pragmatism), path dependence, Bohr's network centrality -- are all interesting hypotheses that point to both the 'incommensurablity' of different paradigms as well as the role of the political and social in the development of science. I wish the author had speculated on how lessons we learn from this history might help us to do better science in the future.

The book also has very good, if perhaps too extreme, takedowns of logical positivism and verificationism. I agree that they are inadequate (logical positivism is on its face an oxymoron, and 'the decisive experiment'-- as pointed out by 'Two Dogmas'-- can always be dodged by the modification of ancillary hypotheses), but do think they have something to say. One difference between science and non-science is testable prediction (if not the only difference), if not the only one. The example used in the book -- of heliocentrism being observationally equivalent to ptolemyic astronomy -- was only true temporarily. Foundations of Physics, then, might be thought of as proto- or pre- science, until it is able to generate predictions different from Copenhagen.

As an alternative to LP and verificationism, the author proposes a very vague demarcation principle -- one so broad (i.e. science 'tries to integrate distinct knowledges into a unified theory') that I think astrology or theology fit snugly. His more practical demarcation, that e.g. religious groups 'aren't really interested in scientific truth' is inadequate philosophically, because as he points out normal science is often motivated by things outside real science. The author just seems to assume Scientific Realism as true (claiming that this is the consensus of philosophers of science, and painting all continental philosophers' opinions as being prima facie not relevant for some reason; dissing Kuhn for not being sufficiently realist). This is a position I lean towards as well, but needs to be actually argued against a idealist stance (although I think he does well arguing against the instrumentalist stance -- does that term appear? -- in his takedown of positivism).

Finally the book's actually descriptions of quantum riddles -- such as Bell's Thm -- were adequate but still left me with lots of questions. His first appendix -- explaining the 'delayed choice' experiment through 4 different QM interpretations -- also left me looking for clarification. I would also have appreciated more discussion of actual attempts to test different interpretations -- doesn't Deutch have one for many worlds he pushes?

Overall recommended to someone interested in philosophy of science. "Beginning of Infinity" I would recommend first though.
Profile Image for antimemoir.
54 reviews34 followers
June 11, 2020
"فلسفه، فیزیک کوانتوم، تاریخ" به مثابه "بروسکتا، پیتزا مارگاریتا، تیرامیسو"

چه ترکیب محشری! الان که این متن رو می‌نویسم یه نشئگی اگزیستانسیال رو تجربه می‌کنم و از خیالِ دنیاهای موازی‌ای که با باز کردن در اون جعبه که یه گربه داخلشه بوجود میارم مغزدرد گرفتم.
خب مثلا صد سال پیش فیزیک نیوتنی به ما می‌گفت یه الکترون مثل یه توپ فوتباله؛ وقتی الان بدونیم کجاست و سرعتش چیه می‌تونیم پیش‌بینی کنیم ده دقیقه دیگه کجاست و باعث چه اتفاق‌هایی می‌شه. فیزیک کوانتوم اومد گفت نهههه! الکترون یه تابع موجی داره! چشمات رو ببند، این تابع موج رو بردار بذار توی اون فرمولی که شرودینگر میگه ببین چقدر دقیق‌تر همه چیز رو پیش‌بینی می‌کنیم. دنیا عوض شد. از توستری که صبح نونم رو گرم کرد بگیر تا این کامپیوتری که الان دارم اینا رو باهاش می‌نویسم، بدون فیزیک کوانتوم هیچ کودوم وجود نداشتن. تا اینجا همه چی خوب! مشکل از اونجایی شروع می‌شه که ما چشمامون رو باز می‌کنیم. به محض اینکه شروع می‌کنیم به مشاهده و اندازه‌گیری، اون تابع موج به طرز عجیب و غیرقابل پیش‌بینی‌ای تغییر می‌کنه. پس وقتی چشمامون بسته‌ست یه جوری باید دنیا رو توصیف کنیم و وقتی چشمامون رو باز می‌کنیم کلا یه جور دیگه (هولی شت). یعنی هوشیار بودن ما داره دنیا رو عوض می‌کنه؟! به این اتفاق میگن "مشکل اندازه‌گیری".
این کتاب روند کشف و تحول فیزیک کوانتوم رو در قالب بررسی تاریخی فیزیکدان‌های مطرح قرن اخیر مثل انیشتین، نیلز بور، هایزنبرگ، شرودینگر، فون نویمان،‌ دیوید بوهم، هیو اورت و ...، و همچنین حلقه‌های فلسفیِ علاقه‌مند به فلسفه علم مثل "حلقه وین" توصیف می‌کنه. در واقع حلقه وین، "اثبات‌گراییِ منطقی" رو بوجود آورد و اعتقاد داشت که هر چیزی که نتونیم مشاهده‌ش کنیم بی‌معنیه. فیزیکدان‌هایی مثل نیلز بور و هایزنبرگ تحت تاثیر این فلسفه، "تفسیر کپنهاگی" از فیزیک کوانتوم رو بوجود آوردن. تفسیر کپنهاگی میگه ما قبل از اینکه ذره‌ای رو مشاهده نکردیم نباید بهش موجودیت و حقیقتی نسبت بدیم. نیلز بور خیلی صاف و پوست کنده اومد گفت اصلا دنیای کوانتومی وجود نداره (!!!)، ما فقط یه سری فرمول ریاضی درست کردیم که بهمون کمک میکنه بهتر پیش‌بینی کنیم ولی در واقع هیچ معنایی پشت هیچ کودوم از این فرمول‌ها وجود نداره، انقدر به این مشکل اندازه‌گیری پیله نکنید، "خفه شید و محاسبه کنید"! انیشتین ولی از این مدل فکر کردن خوشش نمیومد، تفسیر کپنهاگی رو ناقص می‌دونست و برای دنیای کوانتومی موجودیت قائل بود. کتاب در ادامه شرح میده که به خاطر کاریزما و حلقه اطرافیان نیلز بور، تفسیر کپنهاگی پذیرفته میشه و سالیان سال فیزیکدان‌ها خفه میشن و فقط محاسبه می‌کنن؛ یه جوری که هر کسی درباره معنای کوانتوم یا مشکل اندازه گیری حرف میزده سریع توسط جامعه علمی طرد و بی سواد قلمداد می‌شده. کتاب در نهایت توضیح میده که در چنین شرایط عجیبی، چطوری یه سری تفسیر آلترناتیو مثل تفسیر "دنیاهای چندگانه" راه خودشون رو بلاخره باز کردن. تفسیرهایی که بهتر می‌تونن دنیا رو توضیح بدن، بدون اینکه مشکل اندازه‌گیری رو بوجود بیارن.
حالا سوال اینجاست که وقتی فرمول‌های ریاضی فارغ از تفسیر یه چیز مشابه رو پیش‌بینی می‌کنن، چرا باید به تفسیری که می‌کنیم اهمیت بدیم؟ معادلات شرودینگر در هر صورت صادقه، فارغ از اینکه تفسیر کپنهاگی داشته باشیم یا تفسیر دنیاهای چندگانه. نویسنده یه مثال خوب میاره. تو قرن ۱۶ تیکو براهه اومد گفت که خورشید و ماه اطراف زمین می‌چرخن و باقی سیارات به دور خورشید. از اون طرف نیکلاس کوپرنیک اومد گفت نه بابا این زمینه که داره دور خورشید می‌چرخه. با این‌که هم مدل براهه و هم مدل کوپرنیک حرکت سیارات رو مثل هم پیش‌بینی می‌کردن، ولی این مدل کوپرنیک بود که دید ما رو نسبت به واقعیت دنیا روشن کرد و زمینه‌ساز تحقیقات و اکتشافات بیشتر شد.

خوندن این کتاب رو به افرادی که به فیزیک، فلسفه علم، درک حقیقت هستی و حتی داستان ساخت بمب اتم در جنگ جهانی دوم علاقه دارن توصیه می‌کنم. بخوانید و کام‌روا شوید ای جویندگان معنا :)
Profile Image for Daisyread.
131 reviews25 followers
February 3, 2024
“If you were to watch me by day, you would see me sitting at my desk solving Schrödinger’s equation… exactly like my colleagues. But occasionally at night, when the full moon is bright, I do what in the physics community is the intellectual equivalent of turning into a werewolf: I question whether quantum mechanics is the complete and ultimate truth about the physical universe.”
-Sir Anthony Leggett, winner of the 2003 Nobel Prize in Physics

I want more werewolf physicists!

“So many people today—and even professional scientists—seem to me like somebody who has seen thousands of trees but has never seen a forest. A knowledge of the historic and philosophical background gives that kind of independence from prejudices of his generation from which most scientists are suffering. This independence created by philosophical insight is—in my opinion—the mark of distinction between a mere artisan or specialist and a real seeker after truth.” —Albert Einstein

RTC
Profile Image for Adrian Buck.
287 reviews56 followers
July 8, 2019
Niels Bohr, famous for the lack of clarity in his use of words, once suggested that clarity was complementary to truth; this suggests the clearer a statement is the less true it is, and the truer a statement is the less clear it is. Becker is a very clear writer: I was surprised that I was able to read a book on quantum physics so fluently. The way that Becker has done this without peddling us a load of falsehoods, is by not writing about quantum physics as such, but by writing a book about the historical and philosophical conditions in which quantum mechanics was developed. He has also eliminated all the equations and much of the philosophical argument from his account. This probably made it much easier for me to read, I studied philosophy at college, and wish I studied history. But I'm feeling short changed on the physics front.

Becker wants to argue that although the majority of researchers working in quantum physics are happy to accept the Copenhagen Interpretation of the meaning of quantum mechanics, they shouldn't be: the Copenhagen Interpretation has stopped the development of physics and the discovery of quantum relativity - the theory of everything. He argues that this situation came about for three main reasons:
- The influence of Logical Positivism on the development of quantum theory
- Complacency about Neumann’s proof the of Copenhagen Interpretation
- Government funding of quantum research that isn’t interested in the foundations of quantum theory

I would like my review to offer a succinct definition of the Copenhagen Interpretation but find that on reading and understanding ‘What is real?’ I am unable to do so. In Becker’s defence he does suggest that the Copenhagen Interpretation is a bit of a cover up term, alluding to how the initial generation quantum physicists understood their own work with and around Niels Bohr at the University of Copenhagen’s Institute of Theoretical Physics. A term later coined and promoted by Werner Heisenberg to distract people from what he did during the war.

Becker suggests a key element of the Copenhagen Interpretation is that physics doesn’t actually have to explain the nature of quantum reality. He argues that under the influence of Logical Positivism, the early quantum physicists believed that science's job was to merely account for observable phenomena, not to explain how the ‘real’ nature of the ‘objects’ that cause that behaviour. Interestingly Bohr was not a logical positivist, but a Kantian and as such was open to the idea of a idealist metaphysics. I like Kant and would have liked to see a Kantian discussion of quantum physics. A Kantian for example could argue not that the reality of quantum objects is not outside the remit of science, but it outside the 'Bounds of Sense' a non-empirical world which we cannot subsume under the concepts of our understanding: a theory of everything will always lie outside the realm of empirical knowledge.

Despite the absence of reality from the Copenhagen Interpretation, another reason that the majority of scientists are happy to accept it is because they believe that John von Neumann mathematically proved that the Copenhagen Interpretation is not only true, but the only one possible. But Becker argues not only that Neumann's proof is wrong, but foolish, and to add further insult a mere girl had shown it as such way back in 1935, of course the girl was ignored because male chauvinism, and the quantum research world had to wait until 1966 when John Bell put them straight. Wow! Suddenly, reading this book was no mere exercise in curiosity - I had skin in the game.
I teach British and American Civilisation in a Hungarian secondary school, one of the topics I have to cover is Hungarians that have contributed to the civilisation of the UK or US, so I cover John von Neumann. I teach my kids about his contribution to quantum mechanics, this is what I tell them:

"Neumann’s work in Germany with David Hilbert culminated in his book 'The Mathematical Foundations of Quantum Mechanics' (1932), which reconciled the apparently contradictory theories of Erwin Schrödinger and Werner Heisenberg. It concluded that quantum phenomena really were indeterminate, not the result of as yet undiscovered deterministic physics. This convinced most physicists to accept the indeterminacy of the quantum world. Albert Einstein, however, refused to abandon his belief in determinism, insisting that “God does not play dice.""


Having read "What is real?" I have some problems with my own teaching materials. Most immediately, the meaning of 'indeterminate'. In the context of Einstein's 'dice' quotation, this seems to mean unpredictable. Another meaning of indeterminate is unmeasurable, and the measurement problem, unlike the random nature of quantum processes, is given much discussion in this book. Unfortunately understanding the measurement problem involves understanding the Schrödinger equation which gives rise to it, and that equation - like all others - although oft alluded to doesn't make it onto the page. This certainly makes it easier to read, but doesn't leave me in a position to correct my own teaching materials. My professional issues aside, the status of Neumann's proof is not adequately established in the book. Although described as failed, flawed and foolish, I can't say why: to do so would probably involve getting - again - some equations on the page, explaining what they mean and pointing out the errors in them. But then things would quickly get pretty murky pretty quickly. Becker moves on, concluding that Einstein's real problem was actually with the nonlocality - action at a 'spooky' distance - inherent in quantum mechanics, rather than the indeterminacy. The real thrust of the book is that the Copenhagen Interpretation needs to be replaced with a metaphysics that makes sense of the quantum world.

Becker’s observations about the effort of Government Research funding on the development of quantum physics are indisputable, he makes a nice comparison with quantum research in Nazi Germany and the Soviet Union. Thank God for America.

Becker concludes that to make progress in their science again, Physicists need to return to Philosophy, I'm not so sure. Kant's Critique of Pure Reason was expressly developed to epistemologically underwrite the classical world of Newtonian physics: i.e. the science came first, the philosophy later. Quantum physics is yet to find its Kant. But philosophical underpinnings, Kantian or Positivist seem to hold physics up as much spur it on. What physicists really need to do is come up with experimental ideas that test their theories, Bell showed this. In that the experimental demonstration on nonlocality in quantum physics is the big thing I learned from this book. Interestingly the result is a physically distribution of photons that are not reflect what we would expect to find statistically if locality was true.

The use of statistics to produce the result is interesting to me. When I was introduced to quantum physics in Advanced Physics and Chemistry at secondary school, I remember not being phased by the unpredictable nature of particles at the quantum level, because of the very large numbers of particles involved at the classical level. At the time I was also studying statistics, and we used the idea of approximate distributions, when very large numbers are involved, the (discrete) binomial distribution begins to look like the (continuous) normal distribution. When very large numbers of random quantum behaviours are aggregated the result is indistinguishable from classical behaviour. I've never seen the need for a boundary between quantum and classical worlds. We live in a quantum world that is usually classical, the difference is merely one of scale.
Profile Image for Jim Coughenour.
Author 4 books204 followers
June 11, 2018
One of the grand narratives of the 20th century is the history of physics – the elucidation of relativity by Einstein and the subsequent development of quantum physics by Bohr, Heisenberg, Schroedinger et al. Richard Rhodes provides a superlative account in The Making of the Atomic Bomb, but there is a wealth to choose from, and I seem to pick up one or another of these histories every year because I enjoy the story so much. Becker’s book is something different, more serious despite its sometimes jocular tone. He argues that many physicists have surrendered the search for the nature of reality, accepting an interpretation of quantum physics that works astonishingly well in practice but is fundamentally obscure, if not mistaken.

I won’t summarize the argument: if you’ve read this far you’ve probably already decided if this is your kind of book or not. For those who might be interested I’ll just say that Becker tells the standard story differently. Neils Bohr, treated as a secular saint by virtually everyone, is less winning here, and Heisenberg doesn’t get the usual pass for his activities during World War II. Einstein is treated as more perceptive than his challengers (he’s usually characterized as an old genius who can’t accept the fabled uncertainty of quantum reality). Even more interesting is the cast of characters Becker introduces from what was once the fringe of physics: David Bohm, Hugh Everett, and John Stewart Bell. Bohm and Bell have long fascinated me – Bohm for his theory of pilot waves and the “implicate order,” Bell for his theory of entanglement. I’d never heard of Everett, who is quite a character. In Becker’s account Bohr’s “Copenhagen interpretation” is a “tranquilizing philosophy,” an orthodoxy of dubious merit, and its doubters and heretics are punished by the faithful. Bright young physicists suffer from asking the wrong questions – Becker brings a few of their stories to life.

It’s a fascinating story, presented in terms a non-scientist can understand. Given Becker’s perspective, I’d expect some harsh reviews from other side of the debate. It demonstrates that long-standing philosophical questions endure, that clarity and honesty require responsibility and courage, and that the world is stranger than we think even when we make a fetish of its strangeness.
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