The 1927 Solvay Congress In Chapter 4, we left Einstein in early 1926, cautiously optimistic that Schrödinger's scheme might provide what Heisenberg's could not, and did not attempt to – a mathematical description of atomic processes that could also give a physical picture of what was actually occurring. But the demonstration that the two formalisms were equivalent severely dented such optimism. It was still possible for Einstein to prefer Schrödinger's version as offering more hope for future physical interpretation. Thus it is interesting to review the recommendations Einstein made for Nobel Prizes [1]. In 1928, Einstein suggested that Heisenberg and Schrödinger might share a prize, adding ‘With respect to achievement, each one … deserves a full Nobel prize although their theories in the main coincide in regard to reality content.’ However, Einstein was cautious enough to add that ‘it still seems problematic how much will ultimately survive of [their] grandiosely conceived theories’, and gave precedence to de Broglie, also mentioning Davisson, Germer, Born and Jordan. By 1931, more convinced that quantum theory would last (and with de Broglie the 1929 prizewinner), Einstein plumped for Heisenberg and Schrödinger, commenting that ‘In my opinion, this theory contains without doubt a piece of the ultimate truth. The achievements of both men are independent of each other, and so significant that it would not be appropriate to divide a Nobel prize between them.’
The 1927 Solvay Congress In Chapter 4, we left Einstein in early 1926, cautiously optimistic that Schrödinger's scheme might provide what Heisenberg's could not, and did not attempt to – a mathematical description of atomic processes that could also give a physical picture of what was actually occurring. But the demonstration that the two formalisms were equivalent severely dented such optimism. It was still possible for Einstein to prefer Schrödinger's version as offering more hope for future physical interpretation. Thus it is interesting to review the recommendations Einstein made for Nobel Prizes [1]. In 1928, Einstein suggested that Heisenberg and Schrödinger might share a prize, adding ‘With respect to achievement, each one … deserves a full Nobel prize although their theories in the main coincide in regard to reality content.’ However, Einstein was cautious enough to add that ‘it still seems problematic how much will ultimately survive of [their] grandiosely conceived theories’, and gave precedence to de Broglie, also mentioning Davisson, Germer, Born and Jordan. By 1931, more convinced that quantum theory would last (and with de Broglie the 1929 prizewinner), Einstein plumped for Heisenberg and Schrödinger, commenting that ‘In my opinion, this theory contains without doubt a piece of the ultimate truth. The achievements of both men are independent of each other, and so significant that it would not be appropriate to divide a Nobel prize between them.’
Quantum theory is a phenomenally successful cornerstone of physics. But a recent poll among quantum physicists shows that there is still little agreement on what the theory tells us about physical reality. Yet precious bits of consensus are emerging. As always, Albert Einstein was ahead of his time. Quantum theory was still in its infancy, its formalism a mere sketch, and its implications only beginning to be realized. Yet Einstein, in 1917, already spotted what would trouble him throughout his lifetime. He concluded that the nascent theory, which he had helped initiate, seemed to leave “time and direction of elementary processes,” such as the spontaneous emission of radiation from a molecule, “to chance” 1. Einstein's conclusion was visionary. It was also incredibly bold, for it suggested a radical departure from the powerful, centuries-old deterministic and causal worldview of classical physics. But Einstein also immediately expressed his discomfort with the idea of fundamental chance. In fact, his worries were just the seed of what would turn into one of the longest and most heated debates in the history of physics. What does quantum theory mean, and what does it tell us about the nature of reality? Some of the brightest minds in physics locked horns over these issues. Besides Einstein, there were Niels Bohr, Erwin Schrödinger, Werner Heisenberg, Pascual Jordan, Carl Friedrich von Weizsäcker, Wolfgang Pauli, and Richard Feynman, just to name a few. Ask anyone today working on foundational questions in quantum theory and you are likely to hear that there is still no consensus on many of these questions—all the while, of course, everybody seems to be in perfect agreement on how to apply the quantum formalism when it comes to making experimental predictions. Remarkably, there has never been any serious attempt to find out what the current opinions of the community really are and how they may be correlated. We jumped on the opportunity and polled 33 participants at a 2011 conference on “Quantum Physics and the Nature of Reality” (Fig. 1) 2. (We hasten to add that our poll is to be understood as merely a snapshot and certainly cannot claim to be representative.) As soon as we had collected the questionnaires, the respondents eagerly asked to hear the results. Evidently, we had not been the only curious party. What did we find? The fundamental questions, it seems, still elicit radically different responses. Take the quantum state—represented by the wavefunction—as an illustration. The wavefunction is the central mathematical symbol of quantum mechanics. It allows us to make incredibly accurate predictions, be it in atomic, molecular, or solid-state physics. But how are we to interpret it? Is it itself a physical property, or does it merely represent our knowledge? Our poll revealed a tie between these two positions. And not only that: a third of respondents preferred a mix of both viewpoints—perhaps a sign that a more nuanced view, or even a synthesis of views, may be on the horizon. Only 3% of those polled thought that quantum states never refer to a single system but only to ensembles of systems. Perhaps this departure from the ensemble view—a view that, we suspect, remains more popular in the physics community at large—has to do with the fact that experiments with single quantum systems have become routine in today's quantum-information laboratories. Sharp disagreement was in evidence on another deep question. Abraham Pais, Einstein's biographer, recalled that “during one walk Einstein suddenly stopped, turned to me and asked whether I really believed that the moon exists only when I look at it” 3. Putting the issue differently, are the physical properties of objects well defined before we actually measure them? Half of the respondents in our poll believed that they sometimes were, while the other half said that they never were. These two positions correspond to radically different ways of understanding the function of measurement: either as simply ascertaining—at least sometimes—of what is already there, or as an act of genuine creation. The role of measurement is also at the heart of another perennial favorite of foundational discussions, the measurement problem. The measurement problem highlights a curious fact about quantum theory: while the act of measurement assumes a fundamental role, it is not described—not without interpretive contortions, anyway—by the dynamical law of quantum theory, the Schrödinger equation. For decades, the measurement problem was seen by many as the main stumbling block for quantum theory, sparking a storm of rivaling attempts to deal with this perceived issue. Today, the waters seem to have calmed and attention shifted elsewhere, as only less than a fourth of respondents consider the measurement problem “a severe difficulty threatening quantum mechanics.” Changing attitudes are also evident when it comes to the issue of chance Einstein had brought to light in 1917. Today, the question of the randomness of quantum events no longer seems to be all that contentious. Most of our respondents accepted randomness as irreducible or a fundamental concept in nature (or both). Less than one-tenth of respondents thought that quantum randomness was merely apparent rather than fundamental, and no one believed in a hidden determinism governing quantum events. We wish we could hear Einstein's opinion today. Why have attitudes and priorities changed? It's hard to say, but we think there may be several driving forces. The rapid ascent of quantum information science has not only led to applications such as secure cryptography and the promise of lightning-fast quantum computers, but has also shed new light on foundational problems and handed us new tools for addressing them. Our poll shows that these tools are considered a welcome addition, with three-fourths seeing quantum information as a breath of fresh air for foundational investigations. There is also optimism about the future technological development of quantum information, with more than 75% of respondents expecting a working and useful quantum computer to be realized within the next fifty years. Such optimism might be rooted in the astonishing experimental progress we have witnessed over the past decades, another driving force behind changing attitudes. We are now at stage where almost perfect experimental control of single quantum systems has been achieved. The 2012 Nobel Prize in physics was awarded for just such experiments. This has put at our fingertips the ability to actually carry out the thought experiments—or approximations thereof, at any rate—that the founders of quantum theory had dreamed up. Take Schrödinger's cat. In 1935, Schrödinger wanted to illustrate what seemed to him an absurd prediction of the new theory: that the strange quantum superpositions of the atomic world can be amplified to everyday objects. Schrödinger's object of choice was a cat in a specifically prepared box. Quantum theory then suggested that the state of the cat should become transformed into a bizarre quantum superposition of being simultaneously alive and dead. But what Schrödinger had intended as a “burlesque” 4 thought experiment is now approaching experimental reality. Over the last decades, researchers have become increasingly skilled in breeding small versions of Schrödinger's cat. While they don't involve actual cats, they do already involve large biological molecules. Our respondents, it seems, were inspired by such developments. A solid two-thirds majority declared that they don't expect any fundamental limit in this enterprise of observing larger and larger objects in superpositions of macroscopically distinct states. No limit, then, for quantum theory—something that Bohr had already suggested when he, in some of his early thought experiments, considered apparatuses that included macroscopic parts behaving in quantum-mechanical ways. There are other new trends. Why do people seem to be much more at ease with relativity theory than with quantum theory? For one, both special and general relativity theory are grounded in a few simple physical principles. By contrast, quantum theory is lacking such a foundation and is instead based on a rather abstract mathematical body. Today, several researchers are out to change this situation, trying to derive quantum theory from a small set of physical or information-theoretic principles. They hope that in this way, we will understand why we have this peculiar theory to begin with. A majority in our poll regarded such “reconstructions” of quantum theory as giving useful insights, indicating once more that any new tool that promises fresh insights is embraced with an open mind. To be sure, many (albeit not all) of the questions we asked in the poll are interpretive questions. This means that unless we should find out some day that quantum theory is in fact not always valid—in which case we would have to rethink the whole game—experiments arguably can't play the role of the arbiter. Some physicists will conclude from this that we need not bother with such questions, and relegate them to philosophy. We think this is too quick. Many ideas in physics didn't come out of thin air, but came about when someone started looking at a problem with a certain philosophical disposition. In this sense, we may think of the plurality of views in quantum mechanics as productive. Every interpretation highlights some aspect of quantum theory, is particularly suited for explaining particular phenomena, and may inspire new technologies—such as the quantum computer—or even new physics. What, then, does the future hold? Half of the respondents in our poll believe that in fifty years from now, we will probably still be coming together for conferences on the fundamental questions of quantum theory. But what kinds of questions will be on the agenda? Will we still be worrying about the same problems as today? Or will these problems have been solved—or found to be less relevant—and our focus shifted to new questions once again? Who knows. But the location of the conference where we conducted the poll may tell a story. It was the place of a monastery, and a central position in the battle between Catholics and Protestants during the seventeenth century. Many of the questions that were hotly debated back then are no longer of interest to many people today, and other, new questions have since taken center stage in our society. Maybe some of the battles over the interpretation of quantum theory will meet a similar fate.
The 1927 Solvay conference was perhaps the most important in the history of quantum theory. Contrary to popular belief, questions of interpretation were not settled at this conference. Instead, a range of sharply conflicting views were extensively discussed, including de Broglie's pilot-wave theory (which de Broglie presented for a many-body system), Born and Heisenberg's 'quantum mechanics' (which apparently lacked wave function collapse or fundamental time evolution), and Schrödinger's wave mechanics. Today, there is no longer a dominant interpretation of quantum theory, so it is important to re-evaluate the historical sources and keep the debate open. This book contains a complete translation of the original proceedings, with essays on the three main interpretations presented, and a detailed analysis of the lectures and discussions in the light of current research. This book will be of interest to graduate students and researchers in physics and in the history and philosophy of quantum theory.
One critic of Quantum Physics was, reportedly, Albert Einstein, to whom this quote is ascribed: “Quantum mechanics is certainly imposing. But an inner voice tells me that it is not yet the real thing. The theory says a lot, but does not really bring us any closer to the secret of the 'old one'. I, at any rate, am convinced that He does not throw dice”. In this booklet, criticisms towards some claims of some Nobel Prize Laureates in Physics, such as Max Planck, Louis de Broglie, Erwin Schrodinger, Max Born, Werner Heisenberg, Paul Dirac, Richard Feynman, Gerardus 't Hooft, are explained with detailed math.'s physical descriptions as to where these famous physicists were wrong. In Chapter 1 of this booklet it is shown that Maxwell's equations and Classic Physics, can explain some of the phenomena such as the Photoelectric Effect satisfyingly. In Chapter 2 it is explained that, though well encouraging, still taking the Nobel Prizes' money would be unethical and immoral, since that money was initially earned by the sale of dynamite which was also used, unfortunately, for killings. Justice would have been if that money would have been given to its victims or to their surviving families.
The Bohr-Einstein debate, the most interesting intellectual contest in science of this century, began in the late afternoon of October 24,1927, at the Fifth Solvay Conference in Brussels, Belgium. 50 (Einstein had not attended the meeting in Como a month before, at which Bohr first introduced complementarity.) The theorists Bohr, Born, de Broglie, Brillouin, Dirac, Einstein, Ehrenfest, Heisenberg, Pauli, Planck, and Schrödinger were in attendance, as well as the experimentalists Bragg, Compton, Madame Curie, and Debye. The eminent Dutch theorist H.A. Lorentz, the grandfather of relativity (after whom the theory’s space-time transformations were named), chaired the sessions. The organizers had chosen “Electrons and Photons” as the official title of the conference, but a better one might have been: “Quantum Mechanics: What Does it Mean?” As Einstein’s opinion had become widely known, fireworks were expected. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
I. The year 1927 is a landmark in the evolution of physics — the year which saw the obsequies of the notion of causality. To avoid misconceptions, it should not be thought that the concept fell a victim to the unbridled antipathy of certain physicists or their indulgence in fancies. The truth is that men of science came, very reluctantly and almost against their will, to recognize the impossibility of giving a coherent causal description of the happenings on the atomic scale, though some of them — curiously enough, amongst them Planck, Einstein, de Broglie, Schrodinger — could never bring themselves to accept wholeheartedly so drastic a renunciation of classical ideals. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
The founding fathers of quantum mechanics had already perceived the essence of the difficulties of quantum mechanics; today, after almost a century, the discussions are still lively and, if some very interesting new aspects have emerged, at a deeper level the questions have not changed so much. What is more recent, nevertheless, is a general change of attitude among physicists: until about 1970 or 1980, most physicists thought that the essential questions had been settled, and that “Bohr was right and proved his opponents to be wrong”. This was probably a consequence of the famous discussions between Bohr, Einstein, Schrödinger, Heisenberg, Pauli, de Broglie, and others (in particular at the Solvay meetings [1–3], where Bohr's point of view had successfully resisted Einstein's extremely clever attacks). The majority of physicists did not know the details of the arguments. They nevertheless thought that the standard “Copenhagen interpretation” had clearly emerged from the infancy of quantum mechanics as the only sensible attitude for good scientists. This interpretation includes the idea that modern physics must contain indeterminacy as an essential ingredient: it is fundamentally impossible to predict the outcome of single microscopical events; it is impossible to go beyond the formalism of the wave function (or its generalization, the state vector ∣ψ) and complete it.