The Quantum World: Quantum Physics for Everyone Book

Similar concepts and stories to his other book 101 Quantum Questions with some different info, photos, and stories included. I enjoyed his easy style of explanations and the illustrations and tables included, as well as his anecdotes. Our existence is such a miracle. This crazy gift and experience of life fills me with gratitude to be able to be here and a part of it all.

"The year 1926 was right in the middle of a golden age of physics. In a brief few years, 1924 to 1928, physicists came up with some of the most important--and startling--ideas that science has ever known. . . the insight that a single electron or photon can be moving in two or more different ways at the same time (as if you could be driving due north and due west simultaneously, or window shopping in New York and Boston simultaneously). . ." pg. 3

"The longest known time is the 'lifetime of the universe'--that is, the apparent duration of the expansion of the universe, currently estimated to be 13.7 billion years, or early 10 to the 18th s." pg. 16

"So, roughly speaking, we have three layers of complexity [in the physical world]. There is, in the top layer--the visible layer--great complexity (rippling water, trembling leaves, the weather). Underlying this complexity is a layer of startling simplicity uncovered by scientists over the past few centuries (Newton's gravity, Maxwell's electromagnetism, Dirac's quantum electron). In the deepest layer, complexity rears its head again. Tiny deviations from simplicity appear. But these are not like the complexities of our immediate environment. They reflect what may be a still deeper, subtler simplicity." pg. 59

"Fortunately for the structure of the universe and for us humans, the lightest baryon has nowhere to go. It is stable, because there is no lighter baryon into which it can decay. That lightest baryon is the proton. It seems to live forever. Nearest neighbor to the proton is the neutron, just a bit heavier. This means that the neutron is unstable: it can decay into the lower-mass proton (and an electron and antineutrino) without violating the law of baryon conservation or the law of energy conservation. Left alone, the neuron lives, on average, a whole fifteen minutes before it vanishes in a puff of three other particles. Fortunately again for us humans, the neutron is stabilized within atomic nuclei, so certain combinations of up to 209 protons and neutrons can bundle together and live forever. This means that our world is made of scores of different elements, not just the single element hydrogen. And it's all because mass is energy and energy is mass." pg. 69-70

"Among the massless particles is the still hypothetical graviton, the force carrier of gravity." pg. 73

"Indeed, you literally 'see' photons nearly every waking moment, day and night. They carry part of the Sun's energy to Earth, and bring the light emitted by every star, planet, candle, light bulb, and lightning flash to your eyes. Billions of photons each second carry information from the page you are reading. And there are lots of photons that you don't see--those that carry radio and television and wireless-phone signals, heat from warm walls, and X rays through your body. The universe is filled with low-energy photons, the so-called cosmic background radiation, left over from the Big Bang. All in all, there are about a billion photons in the universe for every material particle." pg. 76

"Here is the stunning generality that physicists now believe to be true. Every interaction in the world results ultimately from the emission and absorption of bosons (the force carriers) by leptons and quarks at spacetime points. Three-prong vertices lie at the heart of every interaction." pg. 86

"The 'big four' conserved quantities of the large-scale world--energy, momentum, angular momentum, and charge--are also conserved in the subatomic world. This is no surprise, for everything in the large-scale world is built ultimately of subatomic units. So you can think of the causal link going from small to large: energy, momentum, angular momentum, and charge are conserved in the large-scale world because they are conserved in the subatomic world. The conservation laws that govern these quantities are regarded as absolute. An absolute conservation law is one for which no confirmed violation has ever been seen and which is believed to be valid under all circumstances. Moreover, we have theoretical reason to believe that these four laws are absolute. Relativity and quantum theory join to predict that these laws should be valid. But experiment is the final arbiter. No amount of beautiful theory trumps experiment. Calling these conservation laws absolute must be as tentative as every other firm pronouncement about nature." pg. 159-160

"There is a rule here: the stronger the interaction, the more numerous the constraints. The strong interaction is hemmed in by the most conservation laws and the most invariance principles; the electromagnetic interaction, by slightly fewer; and the weak interaction, by still fewer. Is gravity, the weakest of all interactions, an even more flagrant violator of conservation laws and invariance principles? That's a wonderfully interesting question to which we do not yet know the answer, because, so far, gravitational effects have not been detected at the level of particle reactions." pg. 168

"In 1956, physicists collectively turned pink with embarrassment when two young Chinese-American theorists, Tsung-Dao Lee (then twenty-nine and at Columbia University) and Chen Ning Yang (then thirty-three and at the Institute for Advanced Study in Princeton), pointed out that there was no experimental evidence whatsoever for the validity of parity conservation in weak interactions. They suggested that P violation would help clear up an oddity that had appeared in particle data, and called on experimenters to test the validity of the principle. That same year Lee's Columbia colleague Chien-Shiung Wu undertook an experiment whose results the next year provided dramatic evidence that P conservation, although 'self-evident,' is not true. Almost one once, other groups using other methods confirmed her finding." pg. 171

"One may reasonably claim that conservation laws, being based on the properties of empty space and on other symmetries, are the most profound expressions of physical law. On the other hand, they may be, as once claimed by the eminent mathematician and philosopher Bertrand Russell, mere 'truisms,' because, he asserted, the conserved quantities are defined in just such a way that they must be conserved. I like to think that both points of view can be correct. If the aim of science is the self-consistent description of nature using the simplest set of basic assumptions, what could be more satisfying than to have basic assumptions so elementary, even 'obvious' (such as the uniformity of space and time), that the laws derived from them can be called truisms? The scientist, inclined to call most profound that which is simplest and most general, is not above calling a truism profound. And is it not true that the discovery of anything that remains constant throughout all processes of change is a remarkable achievement, regardless of the arbitrariness of definition involved?" pg. 183

"Whenever you look at a photon (that is, look at a detector, or actually register the photon on the retina of your eye), you see it at a point. When you aren't looking, it is a ghostly wave propagating through space just as electromagnetic waves do in classical theory." pg. 198

"A wave, to be called a wave at all, must have at least one crest and one trough. It must rise and fall--perhaps repeatedly, but at least once. It can't be defined at a point. Its physical extension must be at least as great as its wavelength. So it is the wave nature of the electron, and specifically the wavelength of the electron, that determines the size of an atom. How does the electron decide whether to snuggle up close to the nucleus with a small wavelength, or range far from the nucleus with a large wavelength? Oddly enough, the answer is related to the reason that a marble, set rolling within a curved bowl, finally settles to the lowest point of the bowl. The marble seeks the state of lowest energy. So does the electron." pg. 200

"The lesson: waves are an excellent tool of analysis if the wavelength is much smaller than the thing being analyzed. If the wavelength is much larger than the thing being analyzed, no details can be revealed. The wave has a certain 'fuzziness' dictated by its wavelength." pg. 211

"Nothing--not antimatter or anything else--is truly a source of energy, for energy can only be transformed, not created or destroyed. When you 'consume' energy, you are really transforming it from a more useful to a less useful form (and usually paying for the privilege). Yet it is commonplace (and handy) to talk about energy sources. In everyday usage, an energy source is either stored energy (as in gasoline or a battery--or, hypothetically, in antimatter) or energy in transit (as in solar energy or wind). Among the concepts of physics, energy is the most multifaceted, so there is a rich variety of energy transformations that find practical use.
Energy that is put to use may have been stored for only a little while or no time at all, as in the wind that drives a sailboat. Or it may have been stored for dozens of years, as in the wood that burns in a fireplace. Or for millions of years, as in the coal that fuels a power plant. Or for billions of years, as in the uranium driving a nuclear reactor (its origin being supernova explosions long ago). At the outer limit of store time is the hydrogen that powers the Sun, dating from soon after the Big Bang some fourteen billion years ago." pg.

"If you ask, 'What is the momentum of an electron at a particular moment as it moves in its lowest-energy state of motion in a hydrogen atom?' the quantum physicist answers, 'It is a mixture of a vast number of different momenta.' Suppose you persist and ask, 'But can't you measure the electron's momentum and find out what it is?' Then the quantum physicist must answer, 'Yes, I can--and if I do, I find a particular momentum. The very act of measurement selects one among the many mixed momenta.' That is where superposition and probability join hands. If the measurement is repeated many times with many identical atoms, many different results will be achieved. The probability of any particular result is determined by the way in which the different momenta are mixed. They are stirred together with different 'amplitudes,' one for each momentum; and the square of each amplitude gives the probability that that particular momentum will be measured. Now comes a very important point. Superposition does not mean that an electron may have one momentum or another momentum and we just don't know which it has. It means that the electron literally has all the momenta at once. If you can't visualize this, don't worry. Neither can the quantum physicist. He or she has learned to live with it." pg. 228

"When the superposition involves two or more systems that become separated in space, it is usually called entanglement. It's a good word. You can see that the states of the two photos flying apart are indeed entangled--a bit like family members whose lives are entangled no matter how far apart they dwell. But from a fundamental point of view, superposition and entanglement are really the same thing. The reason is that two superposed systems constitute a single system. There is no difference in principle between two superposed states of a single atom and two superposed atoms. The two photons flying apart in the example discussed in the previous paragraph are really parts of a single system. A single wave function describes their joint motion." pg. 231

"In our own solar system, there is some dark matter--namely, the planets and asteroids. But the total mass of all this dark matter is much less than the mass of the Sun. To a good approximation, the mass of the luminous Sun is the same as the mass of the entire solar system. An alien astronomer would not be far wrong if he or she (or it) took account of the mass of the Sun and ignored the mass of unknown and unseen objects in the Sun's vicinity. It was logical to assume that other solar systems would be like our own--a massive central star surrounded by some puny chunks of dark matter. Luminosity, I should add, refers not just to visible light. Astronomers also 'see' objects in the sky with infrared and ultraviolet waves, radio waves, and X rays. Dark matter is truly dark, emitting no detectable radiation of any kind. (Cold matter and massive black holes do radiate a bit, but not enough to be seen over cosmic distances.)" pg. 242-243

"A rhyming word game that my wife and I used to play with our children goes by various names. We call it Stinky Pinky. One person gives a definition, such as 'superior pullover,' and the others try to guess the answer: 'better sweater.' Or they try to figure out that a 'disillusioned mountaintop' is a 'cynical pinnacle.' And so on. what is 'quantum mechanics'? It is an 'eerie theory.' In this book I have used fundamental particles as well as atoms and nuclei to illustrate this point. Physicists themselves often say that their heads swim when they think too hard about quantum mechanics. As I have stated earlier in this book, quantum mechanics is eerie not just because it violates common sense. It is strenge for deeper reason: it deals with unobservable quantities; it shows that nature's fundamental laws are probabilistic; it permits particles to be in two or more states of motion at the same time; it allows a particle to interfere with itself; it says that two widely separated particles can be entangled. All of this leads many physicists to believe that quantum mechanics, despite its long and unblemished record of success in accounting for subatomic phenomena, is incomplete. More and more physicists are agreeing with John Wheeler: 'How come the quantum?' is a good question." pg. 247

Book: borrowed from SSF Main Library.