The story of quantum mechanics is a fable of wonder and bewilderment. It has elements of science, philosophy, religion, and dare I say magic. It’ll turn your mind upside down, and sometimes it’ll make you question the existence of an all-powerful creator out there. Even though I find its concepts difficult to grasp, I’ve always been fascinated by it. Some of the concepts presented in this chapter are hard to understand; however don’t be troubled. Nobody has been able to fully describe what this all means, not even the titans of physics fully understand quantum mechanics. However that doesn’t mean we can’t be fascinated by it. The great physicist Richard Feynman once said: If somebody tells you he understands quantum mechanics, it means he doesn’t understand quantum mechanics. This chapter is my take on this fascinating fable and how the struggle of two titans of science shaped its past, present, and future.
The story of quantum mechanics is a fable of wonder and bewilderment. It has elements of science, philosophy, religion, and dare I say magic. It’ll turn your mind upside down, and sometimes it’ll make you question the existence of an all-powerful creator out there. Even though I find its concepts difficult to grasp, I’ve always been fascinated by it. Some of the concepts presented in this chapter are hard to understand; however don’t be troubled. Nobody has been able to fully describe what this all means, not even the titans of physics fully understand quantum mechanics. However that doesn’t mean we can’t be fascinated by it. The great physicist Richard Feynman once said: If somebody tells you he understands quantum mechanics, it means he doesn’t understand quantum mechanics. This chapter is my take on this fascinating fable and how the struggle of two titans of science shaped its past, present, and future.
Unlike special relativity, quantum mechanics was not the inspired product of one mind. It developed, in fits and starts, over a period of 25 years (1900–1925), and many cooks stirred the broth. Even now, a century later, quantum mechanics raises profound conceptual questions. Every competent physicist can “do” quantum mechanics, and the predictions it makes are in spectacularly good agreement with experimental results; there can be little doubt that quantum mechanics is “right.” On the other hand, as Richard Feynman once remarked, “nobody understands quantum mechanics.” I'll tell the story in two parts. First the history (how the essential pieces of the puzzle were assembled), and then the implications (what the finished picture has to say about our world). Photons Like relativity, quantum mechanics began with the study of light. In both cases, this historical association is misleading. Relativity, really, has nothing to do with light – to be sure, it involves that magic speed limit, c , and of course the most familiar thing that travels at speed c is light. So light is a convenient vehicle for introducing the subject. But it is perfectly possible to imagine a universe in which there is no such thing as light, and yet relativity might still be valid. Quantum mechanics, too, starts with light – in this case the “quantum” of light (the photon). But, as it turns out, this is just one rather specialized example of much more general principles – in fact, a rather bad example, because photons are by their nature relativistic (they travel at the speed of light), and it would be more natural to begin with the quantum mechanics of slow-moving objects, in analogy with Newtonian mechanics.
[I] think I can safely say that nobody understands quantum mechanics. Richard Feynman, The Character of Physical Law Quantum mechanics [is] that mysterious, confusing discipline, which none of us really understands but which we know how to use. It works perfectly, as far as we can tell, in describing physical reality, but it is a ‘counter-intuitive discipline’… Murray Gell-Mann, Questions for the Future [The quantum] postulate implies a renunciation as regards the causal space-time co-ordination of atomic processes. Niels Bohr, Atomic Theory and the Description of Nature It should be emphasized, however, that the probability function does not in itself represent a course of events in the course of time. It represents a tendency for events and our knowledge of events. The probability function can be connected with reality only if one essential condition is fulfilled: if a new measurement is made to determine a certain property of the system. [T]he idea of an objective real world whose smallest parts exist objectively in the same sense as stones or trees exist, independently of whether or not we observe them…is impossible … Werner Heisenberg, Physics and Philosophy [In] quantum theory it is the principle of causality , or more accurately that of determinism , which must be dropped and replaced by something else.… We now have a new form of the law of causality.… It is as follows: if in a certain process the initial conditions are determined as accurately as the uncertainty relations permit, then the probabilities of all possible subsequent states are governed by exact laws. Max Born, The Restless Universe
This chapter first takes up the claims the quantum mechanics make about themselves. It is devoted to some of the more popular aspects of quantum mechanics. The chapter looks at what quantum mechanics has to say about matter and energy and some of its major philosophical and scientific perplexities. There is sometimes confusion between the terms quantum mechanics and quantum mechanics. Before quantum mechanics, the discoveries of Sir Isaac Newton permeated every aspect of western thought for over 200 years—not just in science, but arts, literature, philosophy, and religion. Abandoning logic and scientific methodology, scientists began to concoct and follow new and mysterious theories that no one could understand, were unproveable, and yet were somehow intriguing enough to stick one’s attention. The early 1920s witnessed fundamental difficulties in quantum physics. Many physicists are unaware that the interpretation of modern quantum mechanics implies that energy and matter do not exist independently of the observer.
Richard Feynman famously declared, "I think that I can safely say that nobody really understands quantum mechanics." Sean Carroll lamented the persistence of this sentiment in a recent opinion piece entitled, "Even Physicists Don't Understand Quantum Mechanics. Worse, they don't seem to want to understand it." Quantum mechanics is arguably the greatest achievement of modern science and by and large we absolutely understand quantum theory. Rather, the "understanding" to which these two statements evidently refer concerns the ontological status of theoretical constructs. For example, "Do quantum wave functions accurately depict physical reality?" The quantum measurement problems represents a collection of such queries and the conundrums to which they lead. Most physicists are content with foregoing such metaphysical issues, falling back on Bohr's Copenhagen interpretation, and then get on with the business of doing physics. I suspect that Carroll would criticize these physicists as being too dismissive of the wonderful mysteries of quantum mechanics by relegating its role to that of an algorithm for making predictions. Quite to the contrary, I maintain that those who still pursue a resolution to the measurement problem are burdened with a classical view of reality and fail to truly embrace the fundamental quantum aspects of nature.
Mr Administrator,Dear colleagues,Ladies and gentlemen,“I think I can safely say that nobody understands quantum mechanics”. This statement, made by physicist Richard Feynman, expresses a paradoxical truth about the scientific theory that revolutionised our understanding of Nature and made an extraordinary contribution to our means of acting on and gaining information about the world. In this lecture, I will discuss quantum physics with you by attempting to resolve this paradox. And if I don’...
In this monograph I present the basic structure of an interpretation of quantum mechanics. Chapter 1 outlines the central ideas behind the interpretation and illustrates them by means of examples: Subsequent chapters fill in the details of the interpretation. But it is important to begin by explaining what I take an interpretation of quantum mechanics to be, and why any further interpretation needs to be offered. After all, quantum mechanics (in some form) is by now both a foundation for much of contemporary physics and a veteran of more than sixty years of intermittent but sometimes intense reflection on its content and meaning. What more can be, or should be, said about the interpretation of this theory? Many physicists believe that no more needs to be said: that there is basically only one way of understanding quantum mechanics, due to Bohr, Heisenberg, Pauli, and others, and that the only remaining interpretative task is that of the physics teacher, who seeks to perfect ways of conveying this understanding to new generations of students. Sir Rudolf Peierls, one of the more lucid and distinguished of these physicists, even objects to the use of the familiar term ‘Copenhagen interpretation’ to refer to the way of understanding quantum mechanics due to Bohr, Heisenberg, Pauli, and others. Because this sounds as if there were several interpretations of quantum mechanics. There is only one. There is only one way in which you can understand quantum mechanics.[…]