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We live in a beautiful, fascinating, quantum world. We ourselves are quantum beings. All life and matter are quantum, and our technologies advance more and more based on our understanding of quantum principles. Yet most of us have only the vaguest sense of any of this.

In 1900, the German physicist Max Planck found that light is radiated from hot objects in chunks of energy, which he called “quanta.” This proved to be only the tip of the iceberg in a journey of discovery that has led to terms such as quantum revolution, quantum theory, quantum mechanics, and quantum world.

I have written this book to provide for the thoughtful general reader a readily understandable view into this quantum world. I present this view in the context of the rich history of discovery and conflict in science and human events experienced during the last one hundred and twenty years. To accomplish this task I have unabashedly borrowed and simplified from the best of what has been written or otherwise presented on this subject, in each case studiously avoiding any but the simplest of math that may have been involved.

Realize that, were this not a quantum world, atoms would be able to overlap each other, so the volume of any substance composed of atoms would be reduced perhaps a million billion times, but its weight would be the same as it is now. We would be tiny, only as tall as the thickness of a human hair, but still have our same weight. And we would have a different chemistry: elements would have entirely different appearances and properties. Molecules, if they existed, would be much different: no water, no air, perhaps only solids—atoms perhaps bound together only by gravitational attraction. Maybe no fire. Living things? In what form? Thought? Consciousness?

The clumping together of substances to form stars and galaxies would have transpired differently and would have taken much longer were it not for the unevenness in the early universe, possibly explained by quantum fluctuations. We probably wouldn't have our sun. No sunlight. No hospitable Earth.

Yet, we are as we are, galaxies do exist, and we have what surrounds us because of the quantum nature of the universe and the atom. Although we don't see it in our everyday lives, the inner workings of this world are very strange, strange to the point that the mind boggles.

“Quantum theory,” in its more mathematical formalism as “quantum mechanics,” explains not only this strangeness, but, together with Einstein's relativity, every observed aspect of the world around us, including the failings of classical Newtonian physics. “Not a single one of the theory's predictions has ever been shown wrong,”1 and it has opened new avenues for invention. Even five years ago it could be said that fully “one third of our economy depends on products based on it.”2

In regard to strangeness, first realize that events in our quantum universe are no longer absolutely determined and predictable from past events but instead are based on probabilities. There is “entanglement,” non-locality, what Einstein called “spooky action at a distance.”3 A measurement here on one object can instantaneously, faster than the speed of light, determine the outcome of a measurement made on another object far away, with nothing carrying the information in between. Our notion of cause and effect has to be changed. (Interestingly, the solution to all of this strangeness may be stranger still: that we live in just one of many parallel worlds.)

So how is it that engineers, with all of this probability and strangeness, have been able to project the motion of the planets, send rockets to the moon and beyond, and build machines that run with seeming precision? Well, the familiar classical ideas that they have used (and will continue to use) to describe the macro world can be viewed as a kind of physical shorthand. These ideas provide a practical, easier, and quicker way of very closely approximating for large objects (where even a tiny grain of sand is a very large object) the more detailed and precisely correct (but more cumbersome and often unnecessary) probabilistic workings of quantum physics.

Realize, however, that the modern tools that these engineers use for design and some of the components in their machines are actually products of the quantum view. These include the laser, superconductors, and all of the solid-state semiconductor electronic devices of the modern day.

In the chapters that follow, I explain how we have come to understand and use the quantum properties of our world to our advantage. In a chronological narrative starting in Part One, I first describe the “quantum revolution” that led to this understanding, and the controversy involved. I relate key experimental and theoretical results, including the discovery of the quantum, the probabilistic nature of physics, and the now accepted scientific view of the simplest of atoms, showing for example how these concepts led to the invention of the laser with all of its applications.

In Part Two, I briefly summarize the further development of the theory and describe its broader implications: entanglement, that events can't be both “objectively real” and “local,” and what we mean by these terms. Here, I also describe just a few potential new applications: super-powerful quantum computers that will operate for some applications at lightning speeds compared to conventional computers, quantum cryptography, and, in a flight of fancy, the prospect of entangled teleportation. (It's not what you think it is.)

In Part Three I provide a glimpse of the quantum's broad influence, from the tiniest of particles after the big bang to the formation of the stars and the galaxies. We consider black holes, supernovae, the Higgs boson, and the fundamental particles of our universe. Here I indicate the seeming incompatibility of quantum mechanics and general relativity at the intense energies following the big bang, with reference to sources on string theory and loop quantum gravity as possible solutions.

In Part Four, I make the connection from quantum theory to the practical world and what we see around us. I relate how the form and physics of many-electron atoms follows from the quantum configuration of the hydrogen atom, to explain chemistry and the nature of all substances. (For me this is the most important product of quantum mechanics: the provision of an understanding that is the practical engine of invention.)

I paint a picture of what happens inside the atom in a way that may even be enlightening to students and graduates in physics and chemistry. I conclude with short chapters introducing a bit about bonding and materials science, as background to the quantum wonders to be described in Part Five.

In this final part of the book I describe many of the inventions in materials and devices that have resulted from, or are explained by, our knowledge of quantum mechanics. I include superconductors and superconducting devices, fusion power, and the solid-state electronic quantum devices of the modern day. I also indicate developments under way to produce new superconductors, semiconductors, and other materials, including graphenes and nanotubes, with applications in medicine, electronics, and energy storage.

Throughout the book I provide glimpses into the lives and personalities of the often brilliant men and women who have moved this narrative forward. To distinguish these and other interesting bits of information from the main text, I have boxed the regions in which these digressions occur. Here and there I also provide extra explanation or background, sometimes out of chronological sequence. These passages are indented. Finally, for those who would like to dig deeper, I provide (1) a series of appendices related to specific chapters and (2) a list of books (and one lecture series on CDs) that I would recommend. I often cite these same books, each labeled for easy reference with a letter from A through Z. For those books beyond the first twenty-six, I use two identical letters: AA, BB, CC, and so on.

I welcome you now to Quantum Fuzz.

Michael S. Walker, PhD