The Physics Book

RELATIVITY AND THE UNIVERSE 299 See also: The Doppler effect and redshift 188–191 ■ Seeing beyond light 202–203 ■ Antimatter 246 ■ Particle accelerators 252–255 ■ Matter–antimatter asymmetry 264 ■ The static or expanding universe 294–295 ■ Dark energy 306–307 begun a finite amount of time ago It appeared to me that who, on the radio in 1949, derided at a single point from what he there were two paths to the competing theory of Hubble called the “primeval atom” or and Lemaître as being a “big bang.” “cosmic egg.” Lemaître, a priest, truth, and I decided The catchy name stuck to describe did not think this idea was at odds to follow both of them. the ideas widely accepted today. with his faith; he declared an equal Georges Lemaître interest in seeking truth from the Residual heat point of view of religion and from theory. In this model, the universe A year earlier, Ukrainian physicist that of scientific certainty. He had had always existed. Matter formed George Gamow and American partly derived his theory of an continually in the space between cosmologist Ralph Alpher had expanding universe from Einstein’s other galaxies as they drifted apart, published “The origin of chemical theory of general relativity, but and the continuous creation of elements” to explain conditions Einstein dismissed the idea of matter and energy—at a rate of immediately after an exploding expansion or contraction for lack one particle of hydrogen per cubic primeval atom and the distribution of evidence of large-scale motion. meter every 300,000 years—kept of particles through the universe. He had earlier added a term called the universe in balance. The The paper accurately predicted the “cosmological constant” to his hydrogen would form into stars and cosmic microwave background field equations for general relativity thus give rise to heavier elements, radiation (CMBR)—the residual to ensure that they allowed for a and then planets, more stars, and heat left over from the Big Bang. static universe. galaxies. The idea was championed In 1964, the ideas received a huge by British astronomer Fred Hoyle boost when Arno Penzias and Robert In 1929, however, American Wilson detected CMBR by chance astronomer Edwin Hubble made a while attempting to use a large discovery that supported the idea antenna to conduct radio astronomy. of an expanding universe. By observing the change in light as The presence of CMBR in the objects moved away from Earth— universe all but ruled out the known as redshift—Hubble could steady-state theory. It pointed calculate how fast a galaxy moves to a much hotter period in the away and thus its distance. All universe’s history, where matter galaxies appeared to move away was clumping together to form ❯❯ from Earth, with those furthest away moving the fastest. Lemaître, it seemed, was on the right track. The steady-state model Despite such evidence, Hubble and Lemaître still faced stiff competition from the steady-state The best proof of the Big Bang is cosmic microwave background radiation (CMBR), seen here in an all-sky image of the minute fluctuations in the temperature of CMBR, taken by NASA’s WMAP satellite between 2003 and 2006. The variations from dark blue (cool) to red (hot) correspond to changes in density in the early universe.

300 THE BIG BANG galaxies, suggesting that the Big Bang theory holds that the universe evolved from universe had not always been an infinitely dense and hot primordial “singularity” the same. Its evident expansion (Lemaître’s “primeval atom”), which rapidly expanded, and the fact that galaxies were giving off vast amounts of heat and radiation. once much closer together posed a problem for steady-state theorists, Singularity Inflation ends and First atoms Present day who believed that the density of point the first particles and form matter in the universe is constant antiparticles form and unvarying over distance and time. There were later attempts to Inflation: First protons Earliest stars and reconcile steady-state theory with the universe and neutrons galaxies form CMBR and other discoveries, but to suddenly expands form little avail. The Big Bang theory is now the preeminent explanation for to expand faster than the speed Still fractions of a second after how our universe began. of light. Guth’s theory, though still the Big Bang, the electromagnetic unproven, helps explain why the force and the weak interaction The universe in infancy universe cooled and also why it separated and the universe cooled Finding CMBR proved crucial appears to be uniform, with matter enough for quarks and gluons to because it helped develop a picture and energy evenly distributed. bind together to form composite of how the universe probably particles—protons, neutrons, evolved, although Big Bang theory Immediately after the Big Bang, antiprotons, and antineutrons. cannot describe the exact moment physicists believe the universe Within three minutes, proton– of its creation 13.8 billion years ago was pure energy and the four neutron collisions produced the or what came before it (if anything). fundamental forces (gravity, the first atomic nuclei, some fusing into electromagnetic force, the strong helium and lithium. Neutrons were American physicist Alan Guth force, and the weak interaction) absorbed in these reactions, but was among the cosmologists who were unified. Gravity split away, many free protons remained. developed Big Bang theory in the and matter and energy were in an latter parts of the 20th century. In interchangeable “mass–energy” Opaque to transparent 1980, he proposed that cosmic state. At the start of inflation, the The early universe was opaque “inflation” occurred a tiny fraction strong nuclear force broke away, and remained so for a few hundred of a second (10–35 seconds, roughly and a huge amount of mass–energy thousand years. Hydrogen nuclei a trillionth of a trillionth of a formed. Photons—particles of light made up almost three quarters of trillionth of a second) into the life primed with electromagnetic its mass; the rest was helium nuclei of the universe. From its initial, energy—dominated the universe. with trace amounts of lithium and infinitely hot and dense point of Toward the end of inflation, still deuterium nuclei. Around 380,000 “singularity,” the universe began trillionths of a second after the Big years after the Big Bang, the Bang, a hot quark–gluon plasma universe had cooled and expanded The Big Bang was not an emerged—a sea of particles and enough for nuclei to capture free explosion in space; it was more antiparticles that continually electrons and form the first swapped mass for energy in hydrogen, helium, deuterium, and like an explosion of space. collisions of matter and antimatter. lithium atoms. Freed from their Tamara Davis For reasons still unknown, this interaction with free electrons and process created more matter than nuclei, photons could move freely Australian astrophysicist antimatter, and matter became the through space as radiation, and the main component of the universe.

RELATIVITY AND THE UNIVERSE 301 universe left its dark ages and Cosmic microwave became transparent. CMBR is background “noise” the residual light from this period. In 1964, American astronomers Stars and galaxies evolve It wasn’t until we exhausted Arno Penzias (pictured below, Astronomers now believe that every possible explanation for right) and Robert Wilson (left) the first stars formed hundreds of were working at the Holmdel millions of years after the Big the sound’s origin that we Horn Antenna at Bell Bang. As the universe became realized we had stumbled Telephone Laboratories in New transparent, dense clumps of Jersey. The large horn-shaped neutral hydrogen gas formed and upon something big. telescope was designed to grew under the force of gravity as Arno Penzias pick up incredibly sensitive more matter was pulled in from detections of radio waves. areas of lower density. When the the next generation of stars, which clumps of gas reached a high enough contained heavier elements and The two astronomers were temperature for nuclear fusion to were longer-lived, grouped together looking for neutral hydrogen occur, the earliest stars appeared. due to gravity, forming the first (HI)—atomic hydrogen with galaxies. These galaxies began to one proton and one electron, Physicists modeling these stars grow and evolve, some colliding which is abundant in the believe they were so huge, hot, and with each other to create more universe but rare on Earth— luminous—30 to 300 times as big and more stars within them of all but were hampered by a as the sun and millions of times shapes and sizes. The galaxies strange background noise. brighter—that they prompted then drifted further apart as the Wherever they pointed the fundamental changes in the universe expanded over the next antenna, the universe sent universe. Their ultraviolet light few billion years. There were back the equivalent of TV re-ionized hydrogen atoms back fewer collisions, and the universe static. Having first thought into electrons and protons, and became relatively more stable, that birds or faulty wiring when these relatively short-lived as it is today. Filled with trillions could be the cause, they then stars exploded into supernovae, of galaxies and spanning billions consulted other astronomers. after around a million years, they of light years, it is still expanding. They realized they were created new heavier elements, such Some scientists believe that it will picking up cosmic microwave as uranium and gold. About one expand forever, until everything background radiation (CMBR), billion years after the Big Bang, spreads out into nothingness. residual heat from the Big Bang, first predicted in 1948. The momentous discovery earned the pair the Nobel Prize in Physics in 1978. The furthest known galaxy, An observable timeline as seen by the Hubble space telescope, Big Bang theory has enabled was probably formed about 400 million scientists to get a firm grasp years after the Big Bang. It is shown on the origins of our universe, here as it appeared 13.4 billion providing a timeline that stretches years ago. back 13.8 billion years to its very first moments. Crucially, most of its predictions are testable. Physicists can recreate the conditions after the Big Bang took place, while CMBR offers direct observation of an era that started when the universe was a mere 380,000 years old. ■

302 IN CONTEXT EAVNILSOOIUNBGELEHISMNAOTTTER KEY FIGURES Fritz Zwicky (1898–1974), DARK MATTER Vera Rubin (1928–2016) BEFORE 17th century Isaac Newton’s theory of gravity leads some to wonder if there are dark objects in the universe. 1919 British astronomer Arthur Eddington proves that massive objects can warp spacetime and bend light. 1919 Fritz Zwicky, a maverick Swiss astronomer, puts forward the existence of dark matter for the first time. AFTER 1980s Astronomers identify more galaxies believed to be full of dark matter. 2019 The search for dark matter continues, with no definitive results so far. T he universe as it seems to be does not make sense. Looking at all the visible matter, galaxies should not exist— there simply is not enough gravity to hold them all together. But there are trillions of galaxies in the universe, so how can this be? This question has plagued astronomers for decades, and the solution is no less vexing—matter that cannot be seen or detected, better known as dark matter. The idea of invisible matter in the universe stretches back to the 17th century, when English scientist Isaac Newton first put forward his theory of gravity. Astronomers around this time

RELATIVITY AND THE UNIVERSE 303 See also: The scientific method 20–23 ■ Laws of gravity 46–51 ■ Models of matter 68–71 ■ Curving spacetime 280 ■ Mass and energy 284–285 ■ Discovering other galaxies 290–293 ■ Dark energy 306–307 ■ Gravitational waves 312–315 There has to be a lot of In 1919, Arthur Eddington set out Other astronomers began to apply mass to make the stars to prove Einstein’s theory. He had the same methods to other galaxies orbit so rapidly, but we can’t measured the positions of stars and clusters, and reached the same see it. We call this invisible earlier that year, before traveling to conclusion. There simply was not the island of Príncipe, off the west enough matter to hold everything mass dark matter. coast of Africa, to view the same together, so either the laws of Vera Rubin stars during an eclipse. He was gravity were wrong, or there was able to work out that the positions something going on that they just began to wonder if there could be of the stars had changed slightly could not see. It could not be dark objects in the universe that as their light bent around the large something like a dark nebula, reflected no light, but could be mass of the sun—an effect now which can be seen by the light detected by their gravitational known as gravitational lensing. it absorbs. Rather, it had to be effects. This gave rise to the idea of something else entirely. black holes, and the idea of a dark More than a decade later, in nebula that absorbed rather than 1933, Fritz Zwicky made a startling Galactic spin reflected light was proposed in discovery. While studying a cluster American astronomer Vera Rubin the 19th century. of galaxies called the Coma Cluster, was able to shed light on the he calculated that the mass of the problem. In the late 1970s, while It would take until the following galaxies in the cluster must be far working at the Carnegie Institution century, however, for a greater greater than the observable matter of Washington, she and her fellow shift in understanding how things in the form of stars in order to hold American colleague Kent Ford worked. As astronomers began to the cluster together. This led him were bemused to discover that study more and more galaxies, they to reason there was unseen matter, the Andromeda Galaxy was not started to have more and more or dunkle materie (“dark matter”), rotating as it should be. From ❯❯ questions about how the galaxies holding the cluster together. were able to exist in the first place. Ever since, the hunt has been on for Real location mysterious dark matter and dark of the galaxy energy (invisible energy driving the expansion of the universe)—and Light path astronomers today are getting close. without gravitational Invisible universe lensing Albert Einstein’s general theory of relativity was key to understanding Apparent A telescope on gravity and ultimately dark matter. location of Earth receives It suggested that light itself could the galaxy distorted images be bent by the gravitational mass of the distant of large objects, with such objects Light bends around galaxy actually warping spacetime. the large mass of the galaxy cluster In gravitational lensing, the observed position of a distant galaxy is changed by the effect of the gravity of a nearer galaxy cluster, which causes light from the distant galaxy to travel past the galaxy cluster along a curved path.

304 DARK MATTER In a spiral galaxy, the ratio of was not concentrated at its center, 26.8% Ordinary dark-to-light matter is about a but was spread across the galaxy. 4.9% matter factor of ten. That’s probably This would explain why the orbital Dark a good number for the ratio of speed was similar throughout the 68.3% matter our ignorance-to-knowledge. galaxy—and the best way to Dark explain this observation was if energy Vera Rubin there were a halo of dark matter surrounding the galaxy and holding Visible matter—the atoms that make their observations, they found it together. Rubin and Ford had, up stars and planets—represents a tiny that the edges of the galaxy were indirectly, found the first evidence proportion of the universe. Most of the moving at the same speed as the for an invisible universe. universe’s energy density is composed center of the galaxy. Imagine an of invisible dark matter and dark energy. ice skater spinning with her arms Hide and seek outstretched—her hands are Following Rubin and Ford’s energy,” which makes up about moving faster than her body. If discovery, astronomers started to 68 percent of the mass-energy the ice skater then pulls in her appreciate the scale of what they content of the universe. arms, she spins faster as her mass were witnessing. In the 1980s, moves toward her center. But building on Eddington’s work Together, dark matter and dark this was not the case with the showing that large masses could energy make up 95 percent of the Andromeda Galaxy. bend spacetime, many instances known universe, with visible of gravitational lensing caused by matter—the things that can be At first the two astronomers dark matter were spotted. From seen—accounting for just 5 did not realize the implications of these, astronomers calculated that percent. With so much dark matter what they were seeing. Gradually, a vast 85 percent of the mass in and dark energy present, it ought however, Rubin began to work the Universe was dark matter. to be easy to find. They are called out that the mass of the galaxy “dark” for a reason, however—no In the 1990s, astronomers direct evidence has yet been found The stars at the center of noted something unusual about to confirm that either dark matter a spinning galaxy ought to the expansion of the universe: it or dark energy exists. was accelerating. Gravity, as they orbit faster than those understood it, should have meant Astronomers are fairly certain at the edge. that the expansion would at some that dark matter is some sort of point slow down. In order to explain particle. They know it interacts Most galaxies seem to be this observation, astronomers came with gravity because they can see surrounded by a halo of up with something called “dark its effect on galaxies on a huge invisible dark matter scale. But strangely, it appears to whose gravitational force But stars at the edge of a have no interactions with regular acts on the outer stars. galaxy move just as fast as matter; if it had, it would be possible to see these interactions those at the center. taking place everywhere. Instead, astronomers think that dark matter The mass of the galaxy passes straight through ordinary is not concentrated at the matter, making it incredibly difficult to detect. center of the galaxy. That hasn’t stopped scientists from trying to detect dark matter, however, and they believe they are getting closer. One of the candidate particles for dark matter is called a weakly interacting massive particle

RELATIVITY AND THE UNIVERSE 305 (WIMP), and while such particles It is not clear if dark matter is a Vera Rubin are incredibly difficult to find, single particle or many, nor if it it is theoretically not impossible experiences forces like regular Vera Rubin was born in that they exist. matter does. It may also be Philadelphia, Pennsylvania, composed of a different particle in 1928. She developed an The great unknown called an axion, which is much interest in astronomy at an In their search for dark matter, lighter than a WIMP. early age and pursued science scientists have tried building vast at college, despite being told detectors, filling them with liquid, Ultimately, there is still much by her high school teacher to and burying them underground. to learn about dark matter, but it choose a different career. She The idea is that if a dark matter has clearly had a major impact on was rejected by the Princeton particle passed through one of astronomy. Its indirect discovery University astrophysics these detectors, as seems likely to has led astronomers to reason that graduate program as it did be happening all the time, it would there is a vast, unseen universe not admit women, and instead leave a noticeable trace. Examples that simply cannot be measured enrolled at Cornell University. of such efforts include the Gran at the moment, and while that Sasso National Laboratory in Italy, might seem daunting, it is In 1965, Rubin joined the and the LZ Dark Matter Experiment fascinating, too. The hope in the Carnegie Institution of in the US. coming years is that dark matter Washington, where she opted particles will finally be detected. for the uncontroversial field of Physicists at CERN’s Large Then, in a similar way to how mapping the mass of galaxies. Hadron Collider (LHC) near Geneva, the detection of gravitational She won numerous prizes for Switzerland, have also tried to find waves has changed astronomy, the discovery that mass was dark matter, looking for any dark astronomers will be able to probe not concentrated at a galaxy’s matter particles that might be dark matter and find out what it center, hinting at the produced when other particles are really is, and understand with existence of dark matter. The smashed together at very high certainty exactly what effect first woman to be allowed to speeds. So far, however, no such it has on the universe. Until observe at the Palomar evidence has been found, although then, everyone is in the dark. ■ Observatory, Rubin was an it is hoped that future upgrades to ardent champion of women the LHC may result in success. While mapping the Andromeda in science. She died in 2016. Galaxy’s mass, Vera Rubin and Kent Today the hunt for dark matter Ford realized that the mass was spread continues in earnest, and while across the galaxy, and so must be held astronomers are fairly certain it together by a halo of invisible matter. is there, much remains unknown. Key works 1997 Bright Galaxies, Dark Matters 2006 “Seeing Dark Matter in the Andromeda Galaxy”

306 IDTANHONGEMURIUNENNDKAIINTVEOENESWRTSNE DARK ENERGY IN CONTEXT U ntil the early 1990s, no one Riess—set out to measure the rate was really sure what the of expansion of the universe. Using KEY FIGURE fate of the universe would powerful telescopes, they observed Saul Perlmutter (1959–) be. Some thought it would expand very distant Type 1a supernovae (see forever, others that it would become flowchart, below). To their surprise, BEFORE static, and others still that it would they saw that the supernovae were 1917 Albert Einstein proposes collapse into itself. But in 1998, two fainter than they had expected, a cosmological constant to teams of American astrophysicists— with a more reddish hue, and so counteract gravity and keep one led by Saul Perlmutter, and the must be further away. The two the universe static. other by Brian Schmidt and Adam teams reached the same conclusion: 1929 Edwin Hubble finds If a white dwarf (the remnant core of a star) orbits a giant star, proof that the universe accreting stellar material, it can cause a Type 1a supernova. is expanding. A Type 1a supernova has a By measuring the brightness 1931 Einstein calls the known brightness, so and redshift of each supernova, cosmological constant his its apparent magnitude “greatest blunder.” its distance and speed (brightness as seen from Earth) relative to Earth can AFTER shows how far away it is. 2001 Results show that dark be calculated. energy probably makes up a large portion of the energy– There is an invisible force The light from distant mass content of the universe. at work, pushing the supernovae has taken longer universe apart. than expected to reach Earth, 2011 Astronomers find indirect evidence for dark energy in so cosmic expansion the cosmic microwave must be accelerating. background (CMB). 2013 Models of dark energy are refined, showing it to be very similar to Einstein’s predicted cosmological constant.

RELATIVITY AND THE UNIVERSE 307 See also: The Doppler effect and redshift 188–191 ■ From classical to special relativity 274 ■ Mass and energy 284–285 ■ The static or expanding universe 294–295 ■ The Big Bang 296–301 ■ Dark matter 302–305 ■ String theory 308–311 Saul Perlmutter Saul Perlmutter was born on of the universe. He had to September 22, 1959, in Illinois, work hard to earn time on large and grew up near Philadelphia, telescopes, but his efforts paid Pennsylvania. He earned a off, and Perlmutter was awarded bachelor’s degree in physics from the Nobel Prize in Physics in Harvard University in 1981, and 2011, alongside Brian Schmidt a doctorate in physics from the and Adam Riess. University of California, Berkeley, in 1986. He was made a professor Key works of physics there in 2004. 1997 “Discovery of a Supernova In the early 1990s, Perlmutter Explosion at Half the Age of the became intrigued by the idea Universe and its Cosmological that supernovae could be used Implications” as standard candles (objects of 2002 “The Distant Type Ia known brightness that can be Supernova Rate” used to measure distances across space) to measure the expansion the supernovae were moving at a gravity and pushes matter away. Astronomers now believe that dark faster rate than would be expected This mysterious force was named energy makes up a huge portion if gravity were the only force acting “dark energy.” If there were such of the mass–energy content of the on them, so cosmic expansion must an energy field pervading the universe—about 68 percent— be accelerating over time. universe, Perlmutter, Schmidt, and which could have big implications. Riess thought that it could explain It is possible that the universe will Mysterious force the expansion. continue expanding at an ever- This discovery went against the increasing rate, until galaxies are idea that gravity should eventually Albert Einstein had come up moving apart faster than the speed pull everything together again. It with a similar concept in 1917. His of light, and eventually disappearing became apparent that the overall cosmological constant was a value from view. Stars in each galaxy energy content of the universe must that counteracted gravity and might then do the same, followed by be dominated by something else allowed the universe to remain planets, and then matter, leaving entirely—a constant, invisible force static. But when the universe was the universe as a dark and endless that works in the opposite way to shown to be expanding, Einstein void trillions of years from now. ■ declared that the constant was a If you’re puzzled about mistake and dropped it from his The gravity of this white dwarf is what dark energy is, you’re theory of relativity. pulling material away from a nearby giant star. When its mass has reached in good company. Today, dark energy is still about 1.4 times the current mass of the Saul Perlmutter thought to be the most likely cause sun, a Type 1a supernova will occur. of cosmic expansion, although it has never been observed directly. In 2011, however, while studying the remnants of the Big Bang (known as the cosmic microwave background, or CMB), scientists suggested that a lack of large-scale structure to the universe hinted at the existence of dark energy, which would act against gravity to prevent large structures of matter forming.

308 IN CONTEXT TAHTRAEPAEDSSTRINY KEY FIGURE Leonard Susskind (1940–) STRING THEORY BEFORE 1914 The idea of a fifth dimension is touted to explain how gravity works alongside electromagnetism. 1926 Swedish physicist Oscar Klein develops ideas of extra unobservable dimensions. 1961 Scientists devise a theory to unify electromagnetism and the weak nuclear force. AFTER 1975 Abraham Pais and Sam Treiman coin the term “Standard Model.” 1995 American physicist Edward Witten develops M-theory, which includes 11 dimensions. 2012 The Large Hadron Collider detects the Higgs boson. P article physicists use a theory called the “Standard Model” to explain the universe. Developed in the 1960s and 1970s, this model describes the fundamental particles and forces of nature that make up everything and hold the universe together. One problem with the Standard Model, however, is that it does not fit with Albert Einstein’s theory of general relativity, which relates gravity (one of the four forces) to the structure of space and time, treating them as a four-dimensional entity called “spacetime.” The Standard Model cannot be reconciled with the curvature of spacetime according to general relativity.

RELATIVITY AND THE UNIVERSE 309 See also: Laws of gravity 46–51 ■ Heisenberg’s uncertainty principle 220–221 ■ Quantum entanglement 222–223 ■ The particle zoo and quarks 256–257 ■ Force carriers 258–259 ■ The Higgs boson 262–263 ■ The equivalence principle 281 The Standard String theory Each of these Model of particle presents elementary particles, according to physics can explain particles as tiny strands of supersymmetry, has energy, each with its own everything distinctive vibration. a corresponding except gravity. superpartner. But string theory This could be the The properties of cannot be tested missing link between one vibrating string as the energy required correspond to those of the to do so is higher than Einstein’s theory of graviton, the predicted relativity and the we can create. Standard Model. force carrier of gravity. Quantum mechanics, on the weak force. Different bosons are known bosons is the force carrier for other hand, explains how particles responsible for carrying the different gravity, leading scientists to come interact at the smallest of levels— forces between fermions. The up with a hypothetical, yet-to-be- on an atomic scale—but cannot Standard Model allows physicists detected particle called the graviton. account for gravity. Physicists have to describe what is known as the tried to unite the two theories, but Higgs field—a field of energy thought In 1969, in an attempt to explain in vain—the issue remains that to pervade the entire universe. The the nuclear force, which binds the Standard Model is only able interaction of particles within the protons and neutrons within the to explain three of the four Higgs field gives them their mass, nuclei of atoms, American physicist fundamental forces. and a measurable boson called the Leonard Susskind developed the Higgs boson is the force carrier for idea of string theory. Coincidentally, Particles and forces the Higgs field. But none of the American–Japanese physicist In particle physics, atoms consist Yoichiro Nambu and Danish ❯❯ of a nucleus made up of protons Quark and neutrons, surrounded by Each string has its own electrons. The electron—and the Proton distinctive vibration quarks that make up the protons Nucleus and neutrons—are among the According to string theory, 12 fermions (matter particles): Neutron Atom elementary particles—such elementary, or fundamental, particles as electrons and the quarks that are the smallest known Electron that make up protons and building blocks of the universe. Vibrating string neutrons—are strings or Fermions are subdivided into filaments of energy. Each quarks and leptons. Alongside string vibrates at a different these fermions, there are bosons frequency, and the vibrations (force carrier particles) and four correspond to the speed, spin, forces of nature: electromagnetism, and charge of the particles. gravity, the strong force, and the

310 STRING THEORY physicist Holger Nielsen To build matter itself from find that three of the four forces of independently conceived the same geometry—that in a sense nature, namely electromagnetism, idea at the same time. According is what string theory does. the strong force, and the weak to string theory, particles—the force, may have existed at the same building blocks of the universe— David Gross energies at the Big Bang—a key are not pointlike, but rather tiny, step toward unifying these forces one-dimensional, vibrating strands American theoretical physicist in a Grand Unified Theory. of energy, or strings, which give rise to all forces and matter. When When the Higgs boson, predicted Together, string theory and strings collide, they combine and by British physicist Peter Higgs supersymmetry gave rise to vibrate together briefly before in 1964, was eventually detected superstring theory, in which all separating again. in 2012 by CERN’s Large Hadron fermions and bosons and their Collider, it was lighter than superpartners are the result of Early models of string theory expected. Particle physicists had vibrating strings of energy. In were problematic, however. thought that its interactions with the 1980s, American physicist They explained bosons but not Standard Model particles in the John Schwarz and British physicist fermions, and required certain Higgs field, giving them their Michael Green developed the idea hypothetical particles, known as mass, would make it heavy. But that elementary particles such as tachyons, to travel faster than light. that was not the case. The idea of electrons and quarks are outward They also required many more superpartners, particles that could manifestations of “strings” vibrating dimensions than the familiar four potentially cancel out some of the on the quantum gravity scale. of space and time. effects of the Higgs field and produce a lighter Higgs boson, In the same way that different Supersymmetry enabled scientists to address this vibrations of a violin string produce To get around some of these early problem. It also allowed them to different notes, properties such as problems, scientists came up with mass result from different vibrations the principle of supersymmetry. of the same kind of string. An In essence, this suggests that the electron is a piece of string that universe is symmetric, giving each vibrates in a certain way, while a of the known particles from the quark is an identical piece of string Standard Model an undetected that vibrates in a different way. partner, or “superpartner”—so each fermion, for example, is paired with In the course of their work, a boson, and vice versa. Schwarz and Green realized that string theory predicted a massless particle akin to the hypothetical Leonard Susskind Born in New York City in 1940, theory landscape.” This radical Leonard Susskind is currently idea was intended to highlight the Felix Bloch Professor of the large number of universes Physics at Stanford University in that could possibly exist, forming California. He earned his PhD a mind-boggling “megaverse”— from Cornell University, New York, including, perhaps, other in 1965, before joining Stanford universes with the necessary University in 1979. conditions for life to exist. Susskind remains highly In 1969, Susskind came up regarded in the field today. with the theory for which he is best known—string theory. His Key works mathematical work showed that particle physics could be 2005 The Cosmic Landscape explained by vibrating strings at 2008 The Black Hole War the smallest level. He developed 2013 The Theoretical Minimum his idea further in the 1970s, and in 2003, coined the phrase “string

RELATIVITY AND THE UNIVERSE 311 Particles unable to devise an experiment that can test string theory leads Reflection Supersymmetric scientists like Glashow to question turns particles particles whether it belongs in science at all. into superparticles (superpartners) Others disagree, and note that experiments are currently underway According to supersymmetry, every boson, or force carrier particle, has a to try to look for some of these massive “superpartner” fermion, or matter particle, and every fermion has a massive effects and provide an answer. The “superpartner” boson. Superstring theory describes superpartners as strings that Super-Kamiokande experiment in vibrate in higher octaves, like the harmonics of a violin. Some string theorists predict Japan, for example, could test that superpartners may have masses up to 1,000 times greater than that of their aspects of string theory by looking corresponding particles, but no supersymmetric particles have yet been found. for proton decay—the hypothesized decay of a proton over extremely graviton. The existence of such a Key quantum theories such as long timescales—which is particle could explain why gravity superposition and entanglement predicted by supersymmetry. is so weak compared with the other also dictate that particles can be three forces, as gravitons would in two states at once. They must Superstring theory can explain leak in and out of the 10 or so produce a gravitational field, which much of the unknown universe, dimensions required by string would be consistent with general such as why the Higgs boson is so theory. Here, at last, appeared to relativity, but under quantum theory light and why gravity is so weak, be something Einstein had long that does not seem to be the case. and it may help shed light on the sought, a theory that could describe nature of dark energy and dark everything in the universe—a If superstring theory can resolve matter. Some scientists even think “Theory of Everything.” some of these problems, it might be that string theory could provide the unifying theory physicists have information about the fate of the A unifying theory been looking for. It might even be universe, and whether or not it will Physicists hunting for an all- possible to test superstring theory continue to expand indefinitely. ■ encompassing theory encounter by colliding particles together. At problems when considering black higher energies, scientists think The walls of the Super-Kamiokande holes, where general relativity they could potentially see gravitons neutrino observatory in Japan are lined theory meets quantum mechanics dissipating into other dimensions, with photomultipliers that detect light in trying to explain what happens providing a key piece of evidence emitted by neutrinos interacting with when a vast amount of matter is for the theory. But not everyone the water inside the tank. packed into a very small area. Under is convinced. general relativity, the core of a black hole, known as its singularity, could Unraveling the idea be said to have essentially zero size. Some scientists, such as American But under quantum mechanics, that physicist Sheldon Glashow, believe does not hold true because nothing the pursuit of string theory is futile can be infinitely small. According to because no one will ever be able to the uncertainty principle, devised prove whether or not the strings it by German physicist Werner describes truly exist. They involve Heisenberg in 1927, it is simply not energies so high (beyond the possible to reach infinitely small measurement called Planck energy) levels because a particle can that they are impossible for humans always exist in multiple states. to detect, and may remain so for the foreseeable future. Being

312 IN CONTEXT SRPIPAPCLEETSIMINE KEY FIGURES Barry Barish (1936–), GRAVITATIONAL WAVES Kip Thorne (1940–) BEFORE 1915 Einstein’s theory of general relativity provides some evidence for the existence of gravitational waves. 1974 Scientists indirectly observe gravitational waves while studying pulsar stars. 1984 In the US, the Laser Interferometer Gravitational- Wave Observatory Project (LIGO) is set up to detect gravitational waves. AFTER 2017 Scientists detect gravitational waves from two merging neutron stars. 2034 The LISA gravitational wave mission is expected to launch into space in 2034 to study gravitational waves. I n 2016, scientists made an announcement that promised to revolutionize astronomy: in September 2015, a team of physicists had found the first direct evidence for gravitational waves, ripples in spacetime caused by the merging or collision of two objects. Up to this point, knowledge of the universe and how it works was derived mainly through what could be seen, in the form of light waves. Now, scientists had a new way to probe black holes, stars, and other wonders of the cosmos. The idea of gravitational waves had already existed for more than a century. In 1905, French physicist Henri Poincaré initially postulated

RELATIVITY AND THE UNIVERSE 313 See also: Electromagnetic waves 192–195 ■ Seeing beyond light 202–203 ■ From classical to special relativity 274 ■ Special relativity 276–279 ■ Curving spacetime 280 ■ Mass and energy 284–285 ■ Black holes and wormholes 286–289 Two massive objects in space, such as two black holes, gravitational waves would move enter orbit around each other. particles as they passed by, which, in theory, could be detectable. Over time, the two objects Eventually they collide and Scientists then set about devising start to spiral in closer and merge into a single object, experiments that might be able to measure these disturbances. closer, orbiting faster producing a massive and faster. amount of energy. The earliest efforts at detection were unsuccessful, but in 1974, The waves arrive at Earth, Most of this energy takes the American physicists Russell Hulse creating a noticeable form of gravitational waves, and Joseph Taylor found the first indirect evidence for gravitational signature in instruments, which travel across the waves. They observed a pair of allowing scientists to work out universe at the speed of light. orbiting neutron stars (small stars where the waves came from. created by the collapse of giant stars), one of which was a pulsar the theory that gravity was He returned to the idea in a new (a rapidly spinning neutron star). transmitted on a wave, which paper on gravitational waves in As they spun around each other he called l’onde gravifique—the 1918, suggesting they might exist and drew closer, the stars were gravitational wave. A decade later, but that there was no way to ever losing energy consistent with the Albert Einstein took this idea to measure them. By 1936 he had radiation of gravitational waves. another level in his theory of general swung back again and stated the The discovery took scientists one relativity, where he proposed that waves did not exist at all. step closer to proving the existence gravity was not a force but rather a of gravitational waves. curvature of spacetime, caused by Searching for the unseeable mass, energy, and momentum. It was not until the 1950s that The wave machines physicists started to realize that Although such large and fast-moving Einstein showed that any gravitational waves might well be masses as neutron stars orbiting massive object causes spacetime to real. A series of papers underlined each other produced potentially the bend, which can in turn bend light that general relativity had indeed largest gravitational waves, those itself. Whenever a mass moves and predicted the existence of the waves would produce an incredibly changes this distortion, it produces waves, as a method of transferring small effect. But from the late 1970s, waves that travel out from the mass energy via gravitational radiation. a number of physicists, including at the speed of light. Any moving American–German Rainer Weiss ❯❯ mass produces these waves, even The detection of gravitational everyday things such as two people waves, however, posed huge The wave is assumed spinning in a circle, although such challenges for scientists. They were to propagate with the waves are too small to be detected. fairly certain that the waves were present throughout the universe, speed of light. Despite his theories, Einstein but they needed to devise an Henri Poincaré wrestled with his own belief in experiment sensitive enough to gravitational waves, noting in 1916 detect them. In 1956, British that “there are no gravitational physicist Felix Pirani showed that waves analogous to light waves.”

314 GRAVITATIONAL WAVES and RonaldDrever, from Scotland, Mirror began to suggest that it might be possible to detect the waves Beam splits by using laser beams and an into two instrument called an interferometer. In 1984, American physicist Kip Storage tube Reflected beam Thorne joined with Weiss and Drever Laser beam Partially to establish the Laser Interferometer reflective mirror Gravitational-Wave Observatory Beam (LIGO), with the aim of creating splitter Photo an experiment that would be able detector to detect gravitational waves. LIGO uses laser beams to detect gravitational waves. One beam is fired In 1994, work began in the at a partially reflective mirror, which splits the beam down two storage tubes set US on two interferometers, one at a right angle. Each beam passes through another partially reflective mirror and at Hanford, Washington, and the bounces between this and a mirror at the end of the tube, with some light from other at Livingstone, Louisiana. each tube meeting at the beam splitter. If there are no gravitational waves, the Two machines were necessary to beams cancel each other out. If waves are present, they cause interference verify that any detected wave was between the beams, creating flickering light that registers on a photo detector. gravitational rather than a random, local vibration. The research was direction, the tubes were built at and in September 2015 they were led by American physicist Barry right angles to each other, in an turned back on, now able to scan Barish, who became director of L shape. In theory, a wave that a much greater area of space. LIGO in 1997 and created the LIGO distorts spacetime would change Within days, the new, more Scientific Collaboration, a team of the length of each tube, stretching sensitive instruments had picked 1,000 scientists around the world. one and compressing the other up tiny split-second ripples in This global collaboration gave the repeatedly until the wave had spacetime, reaching Earth from a project renewed impetus, and by passed. To measure any minute cataclysmic event somewhere deep 2002 scientists had completed the change, a laser beam was split in in the universe. two LIGO machines. Each consisted two, then shone down each tube. of two steel tubes, 4 ft (1.2 m) wide Any incoming gravitational wave Scientists were able to work out and 2.5 miles (4 km) long, protected would cause the beams of light to that these gravitational waves had inside a concrete shelter. reflect back at different times, as been produced by two black holes spacetime itself is stretched and colliding about 1.3 billion light Because gravitational waves shortened. By measuring this years from Earth and creating 50 interact with space by compressing change, the scientists hoped to times more power than all the and stretching it in a perpendicular work out where the gravitational stars in the universe at that waves were coming from and moment. Known as stellar black Ladies and gentlemen, we what had caused them. holes, they each had an estimated have detected gravitational mass of 36 and 29 times the mass Cataclysmic ripples of the sun, forming a new black hole waves. We did it! Over the next eight years, no that was 62 times the sun’s mass. Professor David Reitze waves were recorded, a situation The remaining mass—three times complicated by the machines that of the sun—was catapulted American laser physicist and picking up interference, such as into space almost entirely as LIGO director wind noise and even the sound of gravitational waves. By measuring trains and logging machinery. In the signals received from the two 2010, it was decided to completely LIGO sites—backed up by the overhaul both LIGO machines, Virgo interferometer in Italy— scientists were now able to look

RELATIVITY AND THE UNIVERSE 315 back in time to the origin of the universe, revealing ever more Kip Thorne gravitational waves and study new about its origins and expansion, portions of the universe that were and even, potentially, its age. Born in Utah in 1940, Kip simply inaccessible before. They Thorne graduated in physics could do this by matching the Pushing space boundaries from the California Institute of signals they detected with the Astronomers are also working on Technology (Caltech) in 1962 patterns they expected to see new experiments that could probe before completing a doctorate from different spacetime events. gravitational waves in even greater at Princeton University in detail. One of these is a mission, 1965. He returned to Caltech Since the initial detection of organized by the European Space in 1967, where he is now gravitational waves in 2015 and the Agency (ESA), called LISA (Laser the Feynman Professor of breakthrough announcement of Interferometer Space Antenna). Theoretical Physics, Emeritus. their discovery in 2016, many more LISA, due to launch in 2034, will potential gravitational wave signals consist of three spacecraft flown Thorne’s interest in have been found. Most have been in a triangle, each separated by gravitational waves led to the black hole mergers, but in 2017, 1.5 million miles (2.5 million km). founding of the LIGO project, LIGO scientists made their first Lasers will be fired between the which he has supported by confirmed detection of gravitational craft and the signals produced identifying distant sources waves produced from the collision studied for any evidence of of the waves and devising of two neutron stars, around 130 minuscule movement that could be techniques for extracting million years ago. the ripples of gravitational waves. information from them. For his work on gravitational Signals from afar LISA’s observations over such waves and LIGO, Thorne LIGO and Virgo continue to a vast area will allow scientists to was awarded the Nobel Prize detect gravitational waves on detect gravitational waves from a in Physics in 2017, alongside an almost weekly basis. The variety of other objects, such as collaborators Rainer Weiss equipment is regularly upgraded supermassive black holes, or even and Barry Barish. as lasers become more powerful from the dawn of the universe. and mirrors more stable. Objects The secrets of deepest space Thorne also lends his barely the size of a city can be may eventually be unlocked. ■ physics knowledge to the arts: detected across the universe, being the 2014 film Interstellar was squashed together in dramatic When two neutron stars collide, based on his original concept. events that push the boundaries they release visible gamma rays and of physics. The discovery of invisible gravitational waves, which gravitational waves is helping reach Earth at virtually the same scientists probe the very nature of moment millions of years later. Key works 1973 Gravitation 1994 Black Holes and Time Warps 2014 The Science of Interstellar

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318 DIRECTORY A s Isaac Newton himself memorably put it, in a letter to Robert Hooke in 1675, “If I have seen further, it is by standing on the shoulders of Giants.” Ever since its beginnings in Mesopotamia, in the fourth millennium bce, the story of science has been one of collaboration and continuity. From natural philosophers to inventors, experimenters, and, more recently, professional scientists, far more people have made important contributions to this story than could possibly be explored in detail across the preceding chapters of this book. The following directory therefore attempts to offer at least an outline of some other key figures in our still-unfolding quest to understand the way our universe works—from the tiniest nucleus to the furthest galaxy. ARCHIMEDES much of his career in Cairo, Egypt. a range of fields, including physics. Little is known of his life but he initially He developed a theory of motion that c. 287 bce–c. 212 bce worked as a civil engineer, and made recognized the concept later known as contributions to medicine, philosophy, inertia and the influence of air resistance, Born in the Greek colony of Syracuse and theology, as well as physics and and also set out an early argument that on the Mediterranean island of Sicily, astronomy. Al-Haytham was one of the the speed of light must be finite. Archimedes was one of the most important first proponents of the scientific method, See also: Laws of motion 40–45 engineers, physicists, and mathematicians devising experiments to prove or ■ The speed of light 275 of the ancient world. Little is known of disprove hypotheses. He is best known his early life, but he may have studied at for his Book of Optics (1021), which JOHANNES KEPLER Alexandria, Egypt, in his youth. Although successfully combined various classical later acclaimed for his groundbreaking theories of light with observations of 1571–1630 mathematical proofs, particularly in the anatomy, to explain vision in terms of field of geometry, in his lifetime he was light rays reflected from objects, gathered German mathematician and astronomer famous mainly for inventions such as the by the eye, and interpreted by the brain. Johannes Kepler found fame in the “Archimedes screw” water pump and the See also: The scientific method 20–23 1590s for a theory that attempted to compound pulley, as well as his famous ■ Reflection and refraction 168–169 link the orbits of the planets to the discovery—upon which he is said to have ■ Focusing light 170–175 geometry of mathematical “Platonic shouted “Eureka!”—of Archimedes’ solids.” He became assistant to the principle, which describes the AVICENNA great Danish astronomer Tycho Brahe, displacement of water. When the Romans who was compiling the most accurate invaded Sicily, Archimedes devised a c. 980–1037 catalog of planetary motions so far number of ingenious weapons to defend attempted. After Tycho’s death in his city. He was killed by a Roman soldier Ibn Sina (known in the West as 1601, Kepler continued and developed despite orders that he be captured alive. Avicenna) was a Persian polymath his work. The success of his 1609 See also: The scientific method born near Bukhara, in present-day laws of planetary motion, which placed 20–23 ■ Fluids 76–79 Uzbekistan, into the family of a the planets on elliptical (rather than well-placed civil servant of the Persian circular) orbits around the sun, HASAN IBN AL-HAYTHAM Samanid dynasty. He displayed a completed the “Copernican revolution” talent for learning from his youth, and paved the way for Newton’s c. 965–1040 absorbing the works of many more general laws of motion and classical as well as earlier Islamic universal gravitation. Arabic scholar al-Haytham (sometimes scholars. Although best known today See also: Laws of gravity 46–51 known in the West as Alhazen) was for his hugely influential works on ■ The heavens 270–271 born in Basra, now in Iraq, but spent medicine, he wrote widely across ■ Models of the universe 272–273

DIRECTORY 319 EVANGELISTA TORRICELLI in 1701, he trained as a merchant before telescopes of the time, and began pursuing his scientific interests and to systematically study the stars, 1608–1647 mixing with many leading thinkers assisted from 1772 by his sister of the day, including Ole Rømer and Caroline. His discovery of the Born in the province of Ravenna, Gottfried Leibniz. He lectured on planet Uranus in 1781 won him an Italy, Torricelli showed his talent chemistry and learned how to make appointment to the role of “King’s for mathematics at an early age, and delicate glass parts for scientific Astronomer” for Britain’s George III. was sent to be educated by monks instruments such as thermometers. In 1800, while measuring the properties at a local abbey. He later traveled to This led in 1724 to his concept of of different colors of visible light, Rome, where he became secretary a standardized temperature scale he discovered the existence of and unofficial student to Benedetto (though Fahrenheit’s own choice of infrared radiation. Castelli, a professor of mathematics “fixed” temperature points was later See also: Electromagnetic waves and friend of Galileo Galilei. Torricelli revised to make the scale that still 192–195 ■ The heavens 270–271 became a disciple of Galilean science bears his name more accurate). ■ Models of the universe 272–273 and shared many discussions with See also: The scientific method 20–23 Galileo in the months before his death ■ Heat and transfers 80–81 PIERRE-SIMON LAPLACE in 1642. The following year, Torricelli published a description of the first LAURA BASSI 1749–1827 mercury barometer—the invention for which he is best known for today. 1711–1778 Growing up in Normandy, France, See also: The scientific method 20–23 Laplace showed an early talent for ■ Pressure 36 ■ Fluids 76–79 The daughter of a successful lawyer mathematics. He entered the university in Bologna, Italy, Bassi benefited at Caen at the age of 16, and went on GUILLAUME AMONTONS from a privately tutored education, in to become a professor at the Paris which she showed an early interest Military School. Throughout a long 1663–1705 in physics. In her teens, she became career he not only produced important fascinated by the still-controversial work in pure mathematics, but also Paris-born Guillaume Amontons theories of Isaac Newton. After applied it to areas ranging from the was the son of a lawyer. He devoted receiving a doctorate in philosophy prediction of tides and the shape of himself to science after losing his at the age of 20, she became the first Earth to the stability of planetary hearing in childhood. Largely self- woman to hold a university chair in orbits and the history of the solar taught, he was a skilled engineer and the study of science. Working at the system. He was the first to suggest inventor, devising improvements to University of Bologna, she met and that our solar system formed from various scientific instruments. While married a fellow lecturer, Giuseppe a collapsing cloud of gas and dust, investigating the properties of gases, Veratti, and the pair worked closely and was also the first to put the he discovered the relationships throughout the rest of their careers. objects we now call black holes between temperature, pressure, Bassi devised many advanced on a mathematical footing. and volume, though he was unable experiments to demonstrate the See also: Laws of gravity 46–51 to quantify the precise equations accuracy of Newtonian physics and ■ Models of the universe 272–273 of the later “gas laws.” He is best wrote widely on mechanics and ■ Black holes and wormholes 286–289 remembered for his laws of friction, hydraulics. In 1776, she was appointed which describe the forces of static as the university’s professor of SOPHIE GERMAIN and sliding friction affecting bodies experimental physics. whose surfaces are in contact with See also: Laws of motion 40–45 1776–1831 each other. ■ Laws of gravity 46–51 See also: Energy and motion 56–57 Born to a wealthy Parisian silk ■ The gas laws 82–85 ■ Entropy and the WILLIAM HERSCHEL merchant, Germain had to fight the second law of thermodynamics 94–99 prejudices of her parents in order to 1738–1822 follow her interest in mathematics. DANIEL GABRIEL FAHRENHEIT Initially self-taught, from 1794 she William Herschel was a German-born obtained lecture notes from the 1686–1736 astronomer who moved to England École Polytechnique, and had private at the age of 19. He read widely on tuition from Joseph-Louis Lagrange. Born in Danzig (now Gdansk in acoustics and optics, and a permanent Later, she also corresponded with Poland) to a German merchant family, musical appointment in Bath, from 1766, Europe’s leading mathematicians. Fahrenheit spent most of his working allowed him to pursue these interests Although best known for her work life in the Netherlands. Orphaned in earnest. He built the finest reflecting in mathematics, she also made

320 DIRECTORY important contributions to the physics and made key contributions to the that uranium compounds emitted rays of elasticity when she won the Paris design of the first transatlantic telegraph even if they were not phosphorescent. Academy’s competition (inspired by cable, which was being planned in Becquerel was the first person to the acoustic experiments of Ernst the 1850s. The project’s eventual discover the existence of “radioactive” Chladni) to mathematically describe success in 1866 led to public acclaim, materials, for which he shared the the vibration of elastic surfaces. a knighthood, and eventually elevation 1903 Nobel Prize with Marie and See also: Stretching and squeezing to the peerage. Pierre Curie. 72–75 ■ Music 164–167 See also: Heat and transfers 80–81 See also: Polarization 184–187 ■ Internal energy and the first law ■ Nuclear rays 238–239 JOSEPH VON FRAUNHOFER of thermodynamics 86–89 ■ The nucleus 240–241 ■ Heat engines 90–93 1787–1826 NIKOLA TESLA ERNST MACH Apprenticed to a glassmaker in 1856–1943 Germany after being orphaned at 1838–1916 the age of 11, the young Fraunhofer A Serbian–American physicist saw his life transformed in 1801 after Born and raised in Moravia (now and inventor, Nikola Tesla was his master’s workshop collapsed and he part of the Czech Republic), Austrian a hugely important figure in the was pulled from the rubble by a rescue philosopher and physicist Mach studied early establishment of widespread party of local dignitaries. The Prince physics and medicine at the University electrical power. After proving his Elector of Bavaria and other benefactors of Vienna. Initially interested in engineering talent in Hungary, he encouraged his academic leanings the Doppler effect in both optics was employed by Thomas Edison’s and ultimately enrolled him in a and acoustics, he was encouraged companies in Paris and later in glassmaking institute, where he by the invention of Schlieren New York, before quitting to market was able to pursue his studies. photography (a method of imaging his own inventions independently. Fraunhofer’s discoveries allowed otherwise-invisible shock waves) to One of these, an induction motor that Bavaria to become the leading investigate the dynamics of fluids could be powered by an alternating center of glass manufacturing for and the shock waves formed around current (AC) system, proved hugely scientific instruments. His inventions supersonic objects. Although best important to the widespread adoption include diffraction grating, for known for this work (and the “Mach of AC. Tesla’s many other inventions dispersing light of different colors, number” measurement of speeds (some of them ahead of their time) and the spectroscope, for measuring relative to the speed of sound), he included wireless lighting and power, the precise positions of different also made important contributions radio-controlled vehicles, bladeless features in a spectrum. to physiology and psychology. turbines, and improvements to the See also: Diffraction and interference See also: Energy and motion 56–57 AC system itself. 180–183 ■ The Doppler effect and ■ Fluids 76–79 ■ The development of See also: Electric current and redshift 188–191 ■ Light from the statistical mechanics 104–111 resistance 130–133 ■ The motor effect atom 196–199 136–137 ■ Induction and the generator HENRI BECQUEREL effect 138–141 WILLIAM THOMSON, LORD KELVIN 1852–1908 J.J. THOMSON 1824–1907 The third in a family of wealthy 1856–1940 Parisian physicists, which would Belfast-born William Thomson was go on to include his son Jean, After demonstrating an unusual talent one of the most important figures in Becquerel pursued joint careers in for science at an early age, Joseph 19th-century physics. After studying engineering and physics. His work John Thomson, who was born in at the universities of Glasgow and involved studies of subjects such Manchester, UK, was admitted to Cambridge, UK, the talented Thomson as the plane polarization of light, study at Owens College (now the returned to Glasgow as a professor geomagnetism, and phosphorescence. University of Manchester) at the age at the age of just 22. His interests were In 1896, news of Wilhelm Röntgen’s of just 14. From there he moved on to wide-ranging—he helped establish discovery of X-rays inspired Becquerel the University of Cambridge, where he the science of thermodynamics, to investigate whether phosphorescent distinguished himself in mathematics calculated the great age of Earth, materials, such as certain uranium before being appointed as Cavendish and investigated the possible fate salts, produced similar rays. He soon Professor of Physics in 1884. He is of the universe itself. He found wider detected some kind of emission from chiefly known today for his discovery fame, however, as an electrical engineer the salts, but further tests showed of the electron in 1897, which he

DIRECTORY 321 identified by careful analysis of the EMMY NOETHER LAWRENCE BRAGG properties of recently discovered “cathode rays.” A few months after the 1882–1935 1890–1971 discovery, he was able to show that the particles within the rays could German mathematician Noether As the son of William Henry Bragg be deflected in electric fields, and showed a gift for mathematics and logic (1862–1942), professor of physics to calculate the ratio between their at an early age and went on to earn a at the University of Adelaide in mass and electric charge. doctorate at the University of Erlangen, Australia, Lawrence Bragg took an See also: Atomic theory 236–237 Bavaria, Germany, despite policies early interest in the subject. After the ■ Subatomic particles 242–243 discriminating against female students. family moved to the UK for William In 1915, the mathematicians David to take a chair at the University of ANNIE JUMP CANNON Hilbert and Felix Klein invited her Leeds, Lawrence enrolled at the to their prestigious department at the University of Cambridge. It was 1863–1941 University of Göttingen to work on here, as a postgraduate student in interpreting Einstein’s theory of 1912, that he came up with an idea The eldest daughter of a US senator relativity. Here, Noether went on to for settling the long-running debate for Delaware, Jump Cannon learned make huge contributions to the about the nature of X-rays. He reasoned about the stars at an early age from foundations of modern mathematics. that if X-rays were electromagnetic her mother, who subsequently However, in physics she is best known waves rather than particles, they encouraged her interest in science. for a proof, published in 1918, that the should produce interference patterns She flourished in her studies, despite conservation of certain properties (such due to diffraction as they passed a bout of scarlet fever that left her as momentum and energy) is linked through crystals. Father and son almost entirely deaf. She joined the to the underlying symmetry of systems developed an experiment to test staff of Harvard College Observatory and the physical laws that govern them. the hypothesis, not only proving that in 1896, to work on an ambitious Noether’s theorem and its ideas about X-rays are indeed waves, but also photographic catalog of stellar symmetry underpin much of modern pioneering a new technique for spectra. Here, she manually classified theoretical physics. studying the structure of matter. some 350,000 stars, developing the See also: The conservation of energy 55 See also: Diffraction and interference classification system that is still ■ Force carriers 258–259 ■ String theory 180–183 ■ Electromagnetic waves 192–195 widely used today and publishing 308–311 the catalogs that would eventually ARTHUR HOLLY COMPTON reveal stellar composition. HANS GEIGER See also: Diffraction and interference 1892–1962 180–183 ■ Light from the atom 196–199 1882–1945 ■ Energy quanta 208–211 Born into an academic family in Geiger was a German physicist who Wooster, Ohio, Compton was the ROBERT MILLIKAN studied physics and mathematics at youngest of three brothers, all of the University of Erlangen in Bavaria, whom obtained PhDs from 1868–1953 Germany, earning his doctorate and Princeton University. After becoming receiving a fellowship at the University interested in how X-rays could reveal Robert Millikan was born in Illinois of Manchester, UK, in 1906. From 1907, the internal structure of atoms, he and studied classics at Oberlin he worked under Ernest Rutherford at became head of the physics department College in Ohio, before being diverted the university. Geiger had previously of Washington University in St. Louis, into physics by a suggestion from his studied electrical discharge through in 1920. It was here in 1923 that his professor of Greek. He went on to earn gases, and the two men formulated a experiments led to the discovery of a doctorate from Columbia University method of harnessing this process to “Compton scattering”—the transfer and began work at the University of detect otherwise-invisible radioactive of energy from X-rays to electrons that Chicago. It was here in 1909 that he particles. In 1908, under Rutherford’s could only be explained if the X-rays and graduate student Harvey Fletcher direction, Geiger and his colleague had particle-like, as well as wavelike, devised an ingenious experiment to Ernest Marsden carried out the famous properties. The idea of a particle-like measure the charge on the electron “Geiger–Marsden experiment”—showing aspect to electromagnetic radiation for the first time. This fundamental how a few radioactive alpha particles fired had been proposed by both Planck constant of nature paved the way at thin gold foil bounce back toward the and Einstein, but Compton’s discovery for the accurate calculation of many source, and thereby demonstrating the was the first incontrovertible proof. other important physical constants. existence of the atomic nucleus. See also: Electromagnetic waves See also: Atomic theory 236–237 See also: Atomic theory 236–237 192–195 ■ Energy quanta 208–211 ■ Subatomic particles 242–243 ■ The nucleus 240–241 ■ Particles and waves 212–215

322 DIRECTORY IRÈNE JOLIOT-CURIE where he became fascinated by absorbing pairs of photons (later quantum physics. In the 1920s, demonstrated in 1961). In 1930, she 1897–1956 collaboration with Western colleagues married and moved to the US with led to successes such as his description her American chemist husband, but The daughter of Marie and Pierre Curie, of the mechanism behind alpha found it difficult to obtain an academic Irène showed a talent for mathematics decay and radioactive “half-life.” position. From 1939, she worked at from an early age. After working as a In 1933 he defected from the Columbia University, where she became radiographer during World War I, she increasingly oppressive Soviet Union, involved in the separation of uranium completed her degree and continued her eventually settling in Washington, isotopes needed for the atomic bomb studies at the Radium Institute founded by D.C. From the late 1930s, Gamow during World War II. In the late 1940s, her parents, where she met her husband- renewed an early interest in cosmology, at the University of Chicago, she to-be, chemist Frédéric Joliot. Working and in 1948, he and Ralph Alpher developed the “nuclear shell model,” together, they were the first to measure outlined what is now called “Big Bang explaining why atomic nuclei with the mass of the neutron in 1933. They nucleosynthesis”—the mechanism by certain numbers of nucleons (protons also studied what happened when which a vast burst of energy gave rise and neutrons) are particularly stable. lightweight elements were bombarded with to the raw elements of the early universe See also: Nuclear rays 238–239 radioactive alpha particles (helium nuclei), in the correct proportions. ■ The nucleus 240–241 ■ Nuclear and discovered that the process created See also: Nuclear rays 238–239 bombs and power 248–251 materials that were themselves radioactive. ■ The particle zoo and quarks 256–257 The Joliot-Curies had successfully ■ The static or expanding universe DOROTHY CROWFOOT HODGKIN created artificial radioactive isotopes, an 294–295 ■ The Big Bang 296–301 achievement for which they were awarded 1910–1994 the 1935 Nobel Prize in Chemistry. J. ROBERT OPPENHEIMER See also: Nuclear rays 238–239 After learning Latin specifically to pass ■ The nucleus 240–241 ■ Particle 1904–1967 the entrance exam, Hodgkin studied accelerators 252–255 at Somerville College, Oxford, before New York–born Oppenheimer’s genius moving to Cambridge to carry out work LEO SZILARD began to flourish during a postgraduate on X-ray crystallography. During her period at the University of Göttingen, doctorate, she pioneered methods of 1898–1964 Germany, in 1926, where he worked with using X-rays to analyze the structure Max Born and met many other leading of biological protein molecules. Born into a Jewish family in Budapest, figures in quantum physics. In 1942, Returning to Somerville, she continued Hungary, Szilard showed early talent by Oppenheimer was recruited to work on her research and refined her techniques winning a national prize in mathematics calculations for the Manhattan Project, to work on increasingly complex at the age of 16. He finished his education to develop an atomic bomb in the US. molecules, including steroids and and settled in Germany, before fleeing to A few months later, he was chosen to penicillin (both in 1945), vitamin B12 the UK with the rise of the Nazi party. head the laboratory where the bomb (in 1956, for which she was awarded Here, he cofounded an organization to would be built. After leading the project the Nobel Prize in Chemistry in 1964), help refugee scholars, and formulated to its conclusion at the end of World War and insulin (finally completed in 1969). the idea of the nuclear chain reaction— II, when atomic bombs were dropped See also: Diffraction and interference a process that harnesses a cascade of on Hiroshima and Nagasaki in Japan 180–183 ■ Electromagnetic waves neutron particles to release energy from with devastating results, Oppenheimer 192–195 atoms. After emigrating to the United became an outspoken critic of States in 1938, he worked with others to nuclear proliferation. SUBRAHMANYAN make the chain reaction a reality as part See also: The nucleus 240–241 CHANDRASEKHAR of the Manhattan Project. ■ Nuclear bombs and power 248–251 See also: Nuclear rays 238–239 1910–1995 ■ The nucleus 240–241 ■ Nuclear MARIA GOEPPERT MAYER bombs and power 248–251 Born in Lahore (which was then 1906–1972 part of India but is now in Pakistan), GEORGE GAMOW Chandrasekhar obtained his first Born into an academic family in degree in Madras (now Chennai) and 1904–1968 Katowice (now in Poland), Goeppert continued his studies at the University of studied mathematics and then physics Cambridge from 1930. His most famous Gamow studied physics in his home at the University of Göttingen in work was on the physics of superdense city Odessa (then part of the USSR, but Germany. Her 1930 doctoral thesis stars such as white dwarfs. He showed now in Ukraine), and later in Leningrad, predicted the phenomenon of atoms that in stars with more than 1.44 times

DIRECTORY 323 the mass of the sun, internal pressure some more controversial views, gravity. Hawking also became renowned would be unable to resist the inward including his nonacceptance of as a science communicator after the pull of gravity—leading to a catastrophic the Big Bang theory. 1988 publication of his book A Brief collapse (the origin of neutron stars and See also: Nuclear fusion in stars 265 History of Time. black holes). In 1936, he moved to the ■ The static or expanding universe See also: Black holes and wormholes University of Chicago, becoming a 294–295 ■ The Big Bang 296–301 286–289 ■ The Big Bang 296–301 naturalized US citizen in 1953. ■ String theory 308–311 See also: Quantum numbers 216–217 SUMIO IIJIMA ■ Subatomic particles 242–243 ALAN GUTH ■ Black holes and wormholes 286–289 1939– 1947– RUBY PAYNE-SCOTT Born in Saitama Prefecture, Japan, Iijima studied electrical engineering Initially studying particle physics, 1912–1981 and solid-state physics. In the 1970s, Guth changed the focus of his work he used electron microscopy to study after attending lectures on cosmology Australian radio astronomer Ruby crystalline materials at Arizona State at Cornell University in 1978–1979. Payne-Scott was born in Grafton, New University, and continued to research He proposed a solution to some South Wales, and studied sciences at the structures of very fine solid particles, of the big unanswered questions the University of Sydney, graduating in such as the newly discovered “fullerenes” about the universe, by introducing 1933. After early research into the effect (balls of 60 carbon atoms), on his return the idea of a brief moment of violent of magnetic fields on living organisms, to Japan in the 1980s. From 1987, he “cosmic inflation,” which blew up a she became interested in radio waves, worked in the research division of small part of the infant universe to leading to her work at the Australian electronics giant NEC, and it was dominate over all the rest, just a fraction government’s Radiophysics Laboratory here, in 1991, that he discovered and of a second after the Big Bang itself. on radar technology during World identified another form of carbon, Inflation offers explanations for questions War II. In 1945, she coauthored the cylindrical structures of immense such as why the universe around us first scientific report linking sunspot strength, now known as nanotubes. seems so uniform. Others have taken numbers to solar radio emissions. She The potential applications of this new the idea as a springboard for suggesting and her coauthors later established material have helped to spur a wave our particular “bubble” is one of many an observatory that pioneered ways of of research in nanotechnology. in an “inflationary multiverse.” pinpointing radio sources on the sun, See also: Models of matter 68–71 See also: Matter–antimatter asymmetry conclusively linking the radio bursts ■ Nanoelectronics 158 ■ Atomic theory 264 ■ The static or expanding universe to sunspot activity. 236–237 294–295 ■ The Big Bang 296–301 See also: Electromagnetic waves 192–195 ■ Seeing beyond light 202–203 STEPHEN HAWKING FABIOLA GIANOTTI FRED HOYLE 1942–2018 1960– 1915–2001 Perhaps the most famous scientist of After earning a PhD in experimental modern times, Hawking was diagnosed particle physics at the University of Hoyle was born in Yorkshire, UK, and with motor neuron disease in 1963, Milan, Gianotti joined CERN (the read mathematics at the University while studying for his doctorate in European Organization for Nuclear of Cambridge before working on the cosmology at the University of Research) where she was involved development of radar during World War II. Cambridge. His doctoral thesis in 1966 in the research and design of several Discussions with other scientists on the demonstrated that the Big Bang theory, experiments using the organization’s project fired an interest in cosmology, in which the universe developed from various particle accelerators. Most while trips to the US offered insight an infinitely hot, dense point called a significantly, she was project leader into the latest research in astronomy singularity, was consistent with general on the huge ATLAS experiment and nuclear physics. Years of work relativity (undermining one of the last at the Large Hadron Collider, leading led in 1954 to his theory of supernova major objections to the theory). Hawking the data analysis that was able to nucleosynthesis, explaining how spent his early career investigating confirm the existence of the Higgs heavy elements are produced inside black holes (another type of singularity), boson, the final missing element heavyweight stars and scattered and in 1974 showed that they should in the Standard Model of particle across the universe when they emit a form of radiation. His later work physics, in 2012. explode. Hoyle became famous addressed questions about the evolution See also: Particle accelerators 252–255 as both an author and a popular of the universe, the nature of time, and ■ The particle zoo and quarks 256–257 scientist, although he espoused the unification of quantum theory with ■ The Higgs boson 262–263

324 GLOSSARY In this glossary, terms defined atom was thought to be the smallest Constant A quantity in a within another entry are identified part of matter, but many subatomic mathematical expression that with italic type. particles are now known. does not vary—often symbolized Absolute zero The lowest possible Beta decay A form of radioactive by a letter such as a, b, or c. temperature: 0K or –459.67°F decay in which an atomic nucleus (–273.15°C). gives off beta particles (electrons Cosmic microwave or positrons). background (CMB) Faint Acceleration The rate of change of microwave radiation that is velocity. Acceleration is caused by a Big Bang The event with detectable from all directions. force that results in a change in an which the universe is thought to The CMB is the oldest radiation object’s direction and/or speed. have begun, around 13.8 billion in the universe, emitted when years ago, exploding outward the universe was 380,000 years Air resistance The force that from a singularity. old. Its existence was predicted resists the movement of an object by the Big Bang theory, and it through the air. Blackbody A theoretical object was first detected in 1964. that absorbs all radiation that falls Alpha particle A particle made on it, radiates energy according to Cosmic rays Highly energetic of two neutrons and two protons, its temperature, and is the most particles, such as electrons and which is emitted during a form efficient emitter of radiation. protons, that travel through space of radioactive decay called at close to the speed of light. alpha decay. Black hole An object in space that Cosmological constant A term Alternating current (AC) An is so dense that light cannot escape that Albert Einstein added to his electric current whose direction its gravitational field. general relativity equations, which reverses at regular intervals. See is used to model the dark energy also Direct current (DC). Bosons Subatomic particles that that is accelerating the expansion exchange forces between other of the universe. Angular momentum A measure particles and provide particles of the rotation of an object, which with mass. Dark energy A poorly understood takes into account its mass, shape, force that acts in the opposite and spin speed. Circuit The path around which an direction to gravity, causing the electric current can flow. universe to expand. About three- Antimatter Particles and atoms quarters of the mass–energy of that are made of antiparticles. Classical mechanics A set the universe is dark energy. of laws describing the motion of Antiparticle A particle that is the bodies under the action of forces. Dark matter Invisible matter same as a normal particle except that can only be detected by its that it has an opposite electric Coefficient A number or expression, gravitational effect on visible charge. Every particle has an usually a constant, that is placed matter. Dark matter holds equivalent antiparticle. before another number and galaxies together. multiplies it. Atom The smallest part of an Diffraction The bending of element that has the chemical Conductor A substance through waves around obstacles and properties of that element. An which heat or electric current spreading out of waves past flows easily. small openings.

GLOSSARY 325 Direct current (DC) An Element A substance that is inversely proportional to the electric current that flows in cannot be broken down into other square of the distance from one direction only. See also substances by chemical reactions. the source of gravity. Alternating current (AC). Energy The capacity of an object Force A push or a pull, which moves Doppler effect The change in or system to do work. Energy or changes the shape of an object. frequency of a wave (such as a light can exist in many forms, such as or sound wave) experienced by an potential energy (for example, the Fraunhofer lines Dark absorption observer in relative motion to the energy stored in a spring) and lines found in the spectrum of the wave’s source. kinetic energy (movement). It sun, first identified by German can change from one form to physicist Joseph von Fraunhofer. Elastic collision A collision in another, but can never be created which no kinetic energy is lost. or destroyed. Frequency The number of waves that pass a point every second. Electric charge A property Entanglement In quantum of subatomic particles that physics, the linking between Friction A force that resists or causes them to attract or repel particles such that a change in one stops the movement of objects that one another. affects the other no matter how are in contact with one another. far apart in space they may be. Electric current A flow of Fundamental forces The four objects with electric charge. Entropy A measure of the disorder forces that determine how matter of a system, based on the number of behaves. The fundamental forces Electromagnetic force One of the specific ways a particular system are the electromagnetic force, four fundamental forces of nature. may be arranged. gravity, the strong nuclear force, It involves the transfer of photons and the weak nuclear force. between particles. Event horizon A boundary surrounding a black hole within Galaxy A large collection of stars Electromagnetic radiation which the gravitational pull of the and clouds of gas and dust that is A form of energy that moves black hole is so strong that light held together by gravity. through space. It has both an cannot escape. No information electrical and a magnetic field, about the black hole can cross Gamma decay A form of which oscillate at right-angles its event horizon. radioactive decay in which to each other. Light is a form an atomic nucleus gives off of electromagnetic radiation. Exoplanet A planet that orbits high-energy, short-wavelength a star that is not our sun. gamma radiation. Electromagnetic spectrum The complete range of electromagnetic Expression Any meaningful General relativity A theoretical radiation. See also Spectrum. combination of mathematical description of spacetime in which symbols. Einstein considered accelerating Electroweak theory A theory frames of reference. General that explains the electromagnetic Fermion A subatomic particle, relativity provides a description of and weak nuclear force as one such as an electron or a quark, gravity as the warping of spacetime “electroweak” force. that is associated with mass. by energy. Electron A subatomic particle Field The distribution of a force Geocentrism A historic model with a negative electric charge. across spacetime, in which each of the universe with Earth at its point can be given a value for center. See also Heliocentrism. Electrolysis A chemical change that force. A gravitational field in a substance caused by passing is an example of a field in which Gluons Particles within protons and an electric current through it. the force felt at a particular point neutrons that hold quarks together.

326 GLOSSARY Gravitational wave A distortion protons, but a different number Nuclear fusion A process whereby of spacetime that travels at the of neutrons. atomic nuclei join together to form speed of light, generated by the heavier nuclei, releasing energy. acceleration of mass. Light year A unit of distance that Inside stars such as the sun, this is the distance traveled by light in process involves the fusion of Gravity A force of attraction one year, equal to 5,878 trillion miles hydrogen nuclei to make helium. between objects with mass. (9,460 trillion km). Massless photons are also Nucleus The central part of an affected by gravity, which Leptons Fermions that are only atom. The nucleus consists of general relativity describes affected by two of the fundamental protons and neutrons and contains as a warping of spacetime. forces—the electromagnetic force almost all of an atom’s mass. and the weak nuclear force. Heat death A possible end state Optics The study of vision and for the universe in which there are Magnetism A force of attraction the behavior of light. no temperature differences across or repulsion exerted by magnets. space, and no work can be done. Magnetism arises from the motion Orbit The path of a body around of electric charges or from the another, more massive, body. Heliocentrism A model of the magnetic moment of particles. universe with the sun at its center. Particle A tiny speck of matter Mass A property of an object that is that can have velocity, position, Higgs boson A subatomic particle a measure of the force required to mass, and electric charge. associated with the Higgs field, accelerate it. whose interaction with other Photoelectric effect The emission particles gives them their mass. Matter Any physical substance. of electrons from the surfaces of Our entire visible world is made certain substances when light Ideal gas A gas in which there are of matter. hits them. zero inter-particle forces. The only interactions between particles in Molecule A substance made of two Photon The particle of light that an ideal gas are elastic collisions. or more atoms that are chemically transfers the electromagnetic force bonded to one another. from one place to another. Inertia The tendency of an object to keep moving or remain at rest Momentum An object’s mass Piezoelectricity Electricity that until a force acts on it. multiplied by its velocity. is produced by applying stress to certain crystals. Insulator A material that reduces or Neutrino An electrically stops the flow of heat, electricity, neutral fermion that has a Plane A flat surface on which any or sound. very small, as yet unmeasured, two given points can be joined by mass. Neutrinos can pass right a straight line. Interference The process whereby through matter undetected. two or more waves combine, either Plasma A hot, electrically charged reinforcing each other or canceling Neutron An electrically neutral fluid in which the electrons are free each other out. subatomic particle that forms part from their atoms. of an atom’s nucleus. A neutron is Ion An atom, or group of atoms, made of one up-quark and two Polarized light Light in which the that has lost or gained one or down-quarks. waves all oscillate in just one plane. more of its electrons to become electrically charged. Nuclear fission A process Positron The antiparticle whereby the nucleus of an atom counterpart of an electron, with Isotopes Atoms of the same element splits into two smaller nuclei, the same mass but a positive which have the same number of releasing energy. electric charge.

GLOSSARY 327 Potential difference The Resistance A measure of how Supernova The result of the difference in energy per unit of much a material opposes the flow collapse of a massive star, causing charge between two places in of electric current. an explosion that may be billions an electric field or circuit. of times brighter than the sun. Semiconductor A substance that Pressure A continual force per unit has a resistance somewhere between Superposition In quantum area pushing against an object. The that of a conductor and an insulator. physics, the principle that, until it pressure of gases is caused by the is measured, a particle such as an movement of their molecules. Singularity A point in spacetime electron exists in all its possible with zero length. states at the same time. Proton A particle in the nucleus of an atom that has positive charge. A Spacetime The three dimensions Thermodynamics The branch proton contains two up-quarks and of space combined with a fourth of physics that deals with heat and one down-quark. dimension—time—to form a its relation to energy and work. single continuum. Quanta Packets of energy that exist Time dilation The phenomenon in discrete units. In some systems, a Special relativity Einstein’s whereby two objects moving relative quantum is the smallest possible theory that an absolute time or to each other, or in different amount of energy. absolute space are impossible. gravitational fields, experience Special relativity is the result of a different rate of flow of time. Quantum electrodynamics considering that both the speed (QED) A theory that explains the of light and the laws of physics Uncertainty principle A property interaction of subatomic particles in are the same for all observers. of quantum mechanics whereby the terms of an exchange of photons. more accurately certain qualities, Spectrum The range of the such as momentum, are measured, Quantum mechanics The branch wavelengths of electromagnetic the less is known of other qualities of physics that deals with subatomic radiation. The full spectrum ranges such as position, and vice-versa. particles behaving as quanta. from gamma rays, with wavelengths shorter than an atom, to radio Velocity A measure of an object’s Quark A subatomic particle that waves, whose wavelength may speed and direction. protons and neutrons are made from. be many kilometers long. Voltage A common term for Radiation An electromagnetic Spin A quality of subatomic electrical potential difference. wave or a stream of particles particles that is similar to emitted by a radioactive source. angular momentum. Wave An oscillation that travels through space, transferring energy Radioactive decay The process Standard Model The framework from one place to another. in which unstable atomic nuclei of particle physics in which there emit particles or electromagnetic are 12 fundamental fermions—six Wavelength The distance between radiation. quarks and six leptons. two successive peaks or two successive troughs in a wave. Redshift The stretching of light String theory A theoretical emitted by galaxies moving away framework of physics in which Weak nuclear force One of the from Earth, due to the Doppler effect. point-like particles are replaced four fundamental forces, which acts This causes visible light to move by one-dimensional strings. inside an atomic nucleus and is toward the red end of the spectrum. responsible for beta decay. Strong nuclear force One of the Refraction The bending of four fundamental forces, which Work The energy transferred electromagnetic waves as they binds quarks together to form when a force moves an object move from one medium to another. neutrons and protons. in a particular direction.

328 INDEX Page numbers in bold refer to main entries. atoms 66, 68–71, 110 Brattain, Walter 154, 155 light from 196–199, 217 Brewster, David 187 A models 206, 216–217, 218, 220, 241, 242–243 Brout, Robert 262 splitting 71, 248–251, 252, 253, 285 Brown, Robert 107, 237 Abd al-Rahman al Sufi 268, 290 Brownian motion 71, 106, 107, 110, 237 aberration, chromatic and spherical 174 attraction Brus, Louis 230 acceleration forces of 102–103 bubble chambers 244, 259 and repulsion 120–121, 122, 126 Bullialdus, Ismael 49 energy and motion 56 Bunsen, Robert 115, 180, 190, 197, 216 gravitational 35, 44, 49, 77 Avicenna 318 Buridan, Jean 37 laws of motion 16, 32–34, 43, 44–45, 53 Avogadro, Amedeo 67, 79, 85, 236 butterfly effect 111 accretion disks 289 Buys Ballot, C.H.D. 189–190 actions, and equal reactions 45 B aeronautics 78 C air pressure 83–84, 91, 106–107 B-mesons 264 air resistance 35, 42, 44, 45, 50 Bacon, Francis 20, 23 Cabrera, Blas 159 airflow 78 Baker, Donald 200 Cajori, Florian 166 al-Ghazali 70 Balmer, Johann Jakob 197–198 calculus 27, 29–30 al-Khwarizmi, Muhammad Musa 26, 28 Bardeen, John 152, 155, 228 caloric theory 86, 87, 88, 107, 108 Albert, Wilhelm 72 Barish, Barry 312, 314, 315 Cannon, Annie Jump 321 algebra 28, 30–31 barn-pole paradox 283 capacitors 253 Allen, John F. 79, 228 barometers 83, 84, 106 Capra, Fritjof 223 alpha particles/radiation 234, 238, 239, 240–241, Bartholin, Rasmus 163, 185 Cardano, Gerolamo 29 243, 247, 252, 253 baryons 245, 256 Carnot, Sadi 13, 67, 86, 90, 91–93, 92, 96 Alpher, Ralph 299 Bassi, Laura 319 carrier particles 224, 257, 259, 262, 309, 311 alternating current (AC) electricity 150–151, 153 batteries 120, 128, 129, 131, 134, 141, 148–149 cathode rays 195, 234, 242 amber 120, 124, 125, 130 Becquerel, Edmond 208 cathodes 153, 195, 242 Amontons, Guillaume 319 Becquerel, Henri 234, 238, 239, 320 Caton, Richard 156 Ampère, André-Marie 121, 134, 136, 137, 144, Beeckman, Isaac 82, 83, 275 Cauchy, Augustin-Louis 72 146, 179, 187 Bell, Alexander Graham 135 Cavendish, Henry 130 Ampère–Maxwell law 146–147 Bell, John Stewart 207, 222, 223 Celsius, Anders 80 amplitude 203 Bell Burnell, Jocelyn 163, 202, 203 Cepheid variables 291–292, 293 amplitude modulation (AM) radio 153 Berkeley, George 45 CERN 223, 235, 246, 264 ampullae of Lorenzini 156 Bernoulli, Daniel 36, 52, 53, 66, 76–79, 77, 106–107 anatomy 22 Bernoulli, Jacob 74 Gargamelle bubble chamber 259 Anderson, Carl D. 235, 245, 246, 247, 264 beta particles/radiation 234, 235, 239, 258–259 Large Hadron Collider (LHC) 252, 263, 278, Andrews, Thomas 100, 101 Bethe, Hans 265, 284 Andromeda Galaxy 268, 269, 290, 292–293, Big Bang 255, 264, 269, 293, 296–301, 307, 310 284, 285, 305, 308, 310 303–304, 305 Big Crunch 295 Super Proton Synchrotron 255, 258, 259, 262 animals, bioelectricity 128, 129, 156 binary stars 190–191 Chadwick, James 216, 234, 235, 243, 248, 253 anodes 153, 242 bioelectricity 128, 129, 156 chain reactions 249, 250, 251, 284–285 anti-electrons 245, 246 Biot, Jean-Baptiste 85, 187 Chandrasekhar, Subrahmanyan 216, 286, 287, antimatter 127, 231, 246, 300 birefringence 163, 185, 186 322–323 matter–antimatter asymmetry 264 Black, Joseph 66, 80–81, 86, 91 chaos theory 111 antineutrinos 259 black holes 216, 269, 286–289, 303, 311, 312, Charles, Jacques 66, 82–84 antineutrons 300 charm quarks 235, 256, 257, 264 antiprotons 127, 246, 300 313, 314, 315 Chernobyl 248, 251 antiquarks 257 blackbody radiation 67, 114, 115, 116, 117, 208–209 Clapeyron, Benoît Paul Émile 67, 93 aperture synthesis 202, 203 Bohr, Niels 196, 198–199, 199, 206, 207, 212, 216–217, Clarke, Edward 197 Arago, François 182, 183, 187 Clausius, Rudolf 67, 82, 86, 88–89, 96, 97–99, Archimedes 27, 77, 318 218, 220, 221, 222, 234, 240, 241, 243 108, 110 Archytas 167 Boltzmann, Ludwig 79, 96, 106, 107, 108–111, Clegg, Brian 231 Aristarchus of Samos 22 clocks 38–39 Aristotle 12, 20, 21, 22, 32–3, 34, 42, 43, 48, 70, 109 cloud chambers 244–245 164, 167, 212, 268, 270, 271, 272, 275 Bolyai, János 30 clusters, galaxy 303 Aruni 69 Bombelli, Rafael 29 Cockcroft, John 252–254, 255 Aspect, Alain 207, 223, 228 bonds 100, 102–103 collisions Atkins, Peter William 96 Borelli, Giovanni 49 momentum 37, 54 atomic bombs see nuclear weapons Born, Max 207, 217, 218, 251 particles 127, 133 atomic clocks 38, 39, 229, 282 boron 85, 154, 253 color spectrum 114, 115, 117, 177, 182, 183, atomic decay 238, 239, 258–259 Bose–Einstein condensates 79 192, 193 atomic mass 236 bosons 225, 235, 247, 257, 258, 259, 262–263, 308, compasses 122, 123, 135, 144 atomic structure 13, 67, 123, 196, 198–199, 216, complex numbers 29 217, 218, 220, 240–243 309, 310, 311 compound microscopes 174–175 atomic theory 69–71, 85, 236–237, 240–243 Boyle, Robert 66, 68, 73, 74, 78, 82–84, 90, 106 compounds 67, 71, 237 atomism 66, 69, 70–71 Boyle, William 176 Compton, Arthur 206, 208, 211, 214, 245, 321 Bradley, James 188 computational fluid dynamics (CFD) 79 Bragg, Lawrence 321 Brahmagupta 26, 29 Bramah, Joseph 36, 71 Brand, Hennig 196

INDEX 329 computers decoherence 231 electricity 120–121 data storage 157 Democritus 66, 68–70, 69, 71, 236 electric current 121, 130–133, 140, 141, 149, 153 electronics 153–154, 155 Descartes, René 28, 37, 42, 43, 56, 176, 280 electric fields 127, 128, 132, 145–147, 149, 155, quantum computing 207, 222, 223, 228, deuterium 265, 284, 300 156, 159, 163, 193, 210, 213, 244, 254 230–231 Deutsch, David 207, 228, 231 electric motors 136–137, 139 Dewar, James 100 electric potential 128–129, 131, 137, 156 condensates 79, 228 Dhamakirti 70 electric vehicles 141 condensation 67, 102 dichroic minerals 187 electrical resistance 131, 132–133 conduction 81 diffraction 163, 180–183 generating 87, 121, 148–151 conduction bands 154 digital revolution 153 conductors 131, 132, 133, 138, 141, 146 diodes 152, 153, 253 electrodynamics 137 Conselice, Christopher 290 Diophantus of Alexandria 28 electrolysis 126 conservation of charge 127, 264 dipole-dipole bonds 102 electrolytes 131 conservation of energy 55, 66, 86, 87, 88, 89, Dirac, Paul 31, 159, 219, 224, 234, 246, 260, 264 electromagnetism 13, 121 direct current (DC) electricity 150, 153 96, 109, 258 distance discovery of 134–135, 137 conservation of momentum 37, 54 electromagnetic fields 147, 224–225, 254, 260 convection 81 measuring 18–19 electromagnetic induction 138–141, 144–145, Cooper, Leon 155, 228 in space 291–293 Copenhagen interpretation 207, 218, 219, 220, DNA (deoxyribonucleic acid) 23 149, 193–194 Dollond, John 174 electromagnetic radiation 114, 115, 116, 141, 221, 222 doping 153, 154–155 Copernicus, Nicolaus 12, 16, 20, 22–23, 33, 42, Doppler, Christian 163, 188–191, 189 194, 195, 198, 202, 208 Doppler effect 163, 188–191, 200 electromagnetic spectrum 163, 192, 194–195, 209 48, 268, 270, 271, 272, 273, 290 double-slit experiment 178, 187, 206, 212, electromagnetic waves 132, 138, 144, 147, corpuscular model of light 177, 178, 181, 183, 213, 215 Drebbel, Cornelis 174 179, 187, 210, 213–214, 276, 277 186, 187 Drever, Ronald 313–314 fundamental force 127, 159, 235, 247, 256, 257, cosmic dust 292 du Bois-Reymond, Emil 156 cosmic egg 299 du Châtelet, Émilie 17, 54, 86, 87, 89, 96 258, 259, 261, 262, 300, 308, 309, 310 cosmic microwave background radiation du Fay, Charles François 125 quantum theory 224, 260 Dudgeon, Richard 36 electron microscopes 229–230 (CMBR) 298, 299–301, 306, 307 Dussik, Karl 200 electron neutrinos 257, 261 cosmic rays 234, 244, 245, 246, 247, 256 dynamos 140–141, 149–150 electronics 152–155 cosmological constant 294, 295, 299, 306, 307 electrons Coulomb, Charles-Augustin de 120–121, 124–126, E bonds 102 cathode rays 195 127 electricity, electrical charge 120–121, 124–127, 131 Cooper pairs 228 Cowan, Clyde 235, 258, 259, 261 Earth discovery of 126–127, 152–153, 198, 234, 240, CP symmetry 264 CPT symmetry 264 age of 97–98 242, 256 Crab Nebula 98, 271 circumference 19, 272 electrical energy 121, 133, 134, 140, 141 Crick, Francis 23 energy 97 electronics 152–155 critical points 101, 102, 103 geocentrism 22, 23, 48, 176, 270–273, 298 free 151, 154, 300 Cronin, James 264 gravity 50 nuclear decay 258, 259 Crookes, William 240 magnetism 122–123, 134 nuclear fusion 251 crystals 154–155, 184, 185, 186, 187, 195 orbit of sun 189 orbits 198–199, 216–217, 218, 231, 234, 241 rotation on axis 53 particle theory 209–211, 212–215, 218, 221, piezoelectric 201 spherical 268, 272, 273, 280 Ctesibius 90 echolocation 200, 201 224, 242–243, 257, 309 cubits 16, 18–19 eclipses 269, 270, 271, 272, 280, 303 spin 157 Curie, Jacques 200, 201 Eddington, Arthur 265, 269, 280, 284, 285, 302, superposition state 230–231 Curie, Marie 201, 234, 238–239, 239, 248 303, 304 superstring theory 310 Curie, Pierre 159, 200, 201, 238, 239, 248, 283 Edison, Thomas 121, 148–151, 151 electroscopes 123, 125 Curtis, Heber 292, 293 Egypt, ancient 16, 18–19, 21, 26, 273 electrostatic discharge 125 cyclotron accelerators 254 Einstein, Albert 13, 31, 98, 141, 211, 224, 279, electroweak force 224, 225, 258 Cygnus X-1 286, 288, 289 282, 311 elements atomic theory 236 basic 68–69, 70 D Brownian motion 71, 106, 107, 110, 111, 237 combination of 67, 237 cosmological constant 294, 295, 299, 306, 307 formation of 71, 236, 237 D-mesons 264 equivalence principle 281 emission lines 180, 197–198, 199 da Vinci, Leonardo 75 general theory of relativity 42, 44, 45, 48, 51, Empedocles 176 d’Alembert, Jean Le Rond 56 empiricism 21–22 Dalton, John 67, 68, 84, 234, 236–237, 237, 241 269, 274, 280, 281, 287, 294, 298, 299, 303, energy 66–67 Daniell, John 128, 129, 149 308, 309, 311, 312, 313 concept of 88, 96 dark energy 235, 269, 294, 295, 304, 306–307, light 198, 220, 275 conservation of 55, 66, 86, 87, 88, 89, 109, 258 mass–energy equivalence 55, 249, 279, 284, 285 conversion of 87–88, 96 311 photoelectric effect 114, 206, 209–210, 214 heat engines 90–93 dark matter 23, 235, 269, 302–305, 311 quantum entanglement 222–223, 231 heat and transfers 80–81 dark nebulae 303 special theory of relativity 48, 51, 144, 146, internal 88–89 dark stars 286–287 147, 179, 219, 222, 223, 260, 268–269, 274, kinetic 54, 57, 87, 137, 254, 279 data storage 157 276–279, 281, 284, 287 laws of thermodynamics 67, 86, 88–89, 96–99, 110 Davenport, Thomas 137 Ekimov, Alexey 230 mass-energy equivalence 279, 284 Davidson, Robert 136 elastic modulus 72, 75 and motion 56–57 Davisson, Clinton 214 elasticity 66, 73, 74, 75 potential 54, 57, 86, 87, 89 Davy, Humphry 139 thermal radiation 114–117 de Broglie, Louis 206, 212, 214, 215, 218, 220 energy quanta 208–211 de Forest, Lee 153 energy transfer 96 de Groot, Jan Cornets 34 Englert, François 262 de la Tour, Charles Cagniard 101 entanglement, quantum 207, 222–223, 228, 231, de Vaucouleurs, Gérard 290 311 entropy 67, 89, 96, 98–99, 111 Epicurus 68, 70, 71 epicycles 271

330 INDEX equivalence principle 281 Fresnel, Augustin-Jean 163, 168, 179, 180, and universe 294, 295, 300, 301, 302–304, 307 Eratosthenes 19, 272 181–183, 182, 187 and velocity 42 ergodic hypothesis 109 Gray, Stephen 130–131 Erlanger, Joseph 156 friction 42, 43, 44, 45, 87 Green, George 128 escape velocity 289 Friedel, Georges 184 Green, Michael 310 Essen, Louis 38, 229 Friedmann, Alexander 191, 294–295, 295 Gregory, James 183 Euclid 16, 26, 27–28, 30, 162, 168, 280 Gribbin, John 210 Euler, Leonhard 17, 29, 52, 53, 57, 74, 75, 76, G Grimaldi, Francesco Maria 32, 35, 49, 180–181, 182 Gross, David 310 77, 79 galaxies 269, 270, 289, 290–293, 294, 295, 298, 299, Grünberg, Peter 157, 158 evaporation 101, 102 300, 301, 302, 303–304, 307 Guericke, Otto von 66, 91 event horizons 287, 288, 289 Galfard, Christophe 218 Guralnik, Gerald 262 Everett, Hugh 220 Galilei, Galileo 12, 22, 23, 33, 43, 72, 83, 164 Guth, Alan 300, 323 exclusion principle 206, 217 experiments 12, 20, 21, 23, 66 falling bodies 16, 32–35, 42, 49, 50, 281 H pendulums 17, 38–39, 52 F relativity 268, 274, 276–277, 281 Hafele, Joseph 282 speed of light 175 Hagen, C. Richard 262 Fahrenheit, Daniel 80, 319 telescopes and space 48–49, 162, 172, 173, Hahn, Otto 249 falling bodies 17, 32–35, 49, 50 half-life 239 Faraday effect 147, 187 268, 271, 272, 273, 290 Hall, Chester Moore 174 Faraday, Michael 101, 131, 139, 141, 197, 277 thermoscopes 80, 81 Halley’s Comet 271 Galilei, Vincenzo 167 Hamilton, William Rowan 42, 54, 56, 57 dynamos 140–141, 149 Galois, Évariste 30–31 hard-disk drives (HDD) 157 electric motor 136, 138, 139 Galvani, Luigi 128, 129, 156 harmonic motion 52–53 electricity 124, 126, 127, 128 galvanometers 139, 140 harmonics 166 electromagnetic induction 121, 136, 144–145, 146 gamma radiation 163, 195, 202, 234, 239, 243, Harrison, John 38, 39 electromagnetism 121, 134, 138–141, 148, 187 253, 284 Hau, Lene 79 magnetic fields 121, 147, 148 Gamow, George 252–253, 299, 322 Hawking, Stephen 287, 289, 323 Faraday’s law 146, 149 gases 70, 71, 76, 78 Hawking particles 289 Ferdinando II de’ Medici 80 changes of state and bonds 100–103 heat Fermat, Pierre de 29, 57, 162, 168, 169 combination of 85 Fermi, Enrico 235, 242, 248–250, 251, 258 forces of attraction 102–103 and color 117 fermions 257, 309, 310, 311 gas laws 66–67, 82–85, 100 conservation of energy 55 ferromagnetism 123 kinetic theory 79, 85 dissipation 98, 99 Fert, Albert 157, 158 liquefaction 100 entropy 98–99 Fessenden, Reginald 192 Gassendi, Pierre 68, 70–71 Joule heating 133 Feynman diagrams 225 Gasser, Herbert Spencer 156 laws of thermodynamics 86, 88–89, 96–99 Feynman, Richard 147, 158, 207, 215, 222, 224, Gauss, Carl Friedrich 61–62, 144, 146, 280 and light 114–115 225, 228, 230–231, 260 Gay-Lussac, Joseph 66, 67, 82, 83, 84, 85 and motion 90–93, 107, 114 Fitch, Val 264 Geiger, Hans 198, 234, 240, 243, 321 and temperature 80, 86 Fizeau, Armand 190 Geissler, Heinrich 197 see also kinetic energy Fizeau, Hippolyte 275 Gell-Mann, Murray 235, 247, 256–257, 257 heat death theory 98 Fleming, John Ambrose 140, 152, 153 generators, electrical 138, 141, 149 heat energy 67, 87, 93, 99, 114, 133, 249, 250 fluids 36, 66, 76–79 geocentrism 22, 23, 48–49, 176, 270–273 heat engines 67, 90–93, 96, 97, 99 applied fluid dynamics 79 geometry 27–28, 29 heat flow 96–97, 110 changes of state and bonds 100–103 Georgi, Howard 159 heat transfer 80–81, 89, 114 fluorescence 196–197 geothermal energy 151 heavenly bodies 270–271 force carriers 224, 235, 258–259, 262, 309, 311 Gerlach, Walter 206 Heaviside, Oliver 144 force fields 145–146 Germain, Sophie 319–320 Heisenberg, Werner 37, 207, 218–219, 220–221, forces germanium 154, 155 221, 246, 278, 311 equal action-reaction 45 Gianotti, Fabiola 323 heliocentrism 22, 23, 33, 42, 48–49, 268, 271, fluids 76–79 giant magnetoresistance (GMR) 157, 158 273, 290 fundamental 127, 159, 225, 235, 245, 247, 259, Gibbs, Josiah 96 Helmholtz, Hermann von 55, 86, 87, 88, 89, 96, 193 Gibbs, Willard 106, 111 Henlein, Peter 38 261, 262, 300, 309, 310 Gilbert, William 120, 122, 123, 134, 136 Henry, Joseph 135, 136, 140 and motion 43, 44, 45 Glashow, Sheldon 159, 224, 235, 262, 311 Heraclitus 68 stretching and squeezing 72–75 gluons 225, 247, 255, 257, 300 Herapath, John 82, 106, 107 see also electromagnetism; friction; gravity; Goeppert-Meyer, Maria 217, 322 Hero of Alexandria 90, 91, 162, 168, 169 Gordon, James 141 Herschel, William 114, 163, 192–193, 202, 319 magnetism; strong nuclear force; weak Goudsmit, Samuel 157 Hertz, Heinrich 144, 147, 192–194, 193, 202, 210 nuclear force GPS navigation 191, 228, 229, 282 Hertzsprung, Ejnar 292 Ford, Kent 303–304, 305 Gramme, Zenobe 149 Hess, Victor 234, 244, 245 fossil fuels 67, 87, 151 Grand Unified Theory (GUT) 159, 310 Hewish, Antony 203 Foucault, Léon 174, 275 gravitational fields 269, 287, 311 Higgs, Peter 262–263, 263 Fourier, Joseph 52, 133 gravitational lensing 303, 304 Higgs boson 225, 235, 257, 262–263, 308, 309, Frahm, Hermann 52 gravitational mass 287, 303 310, 311 frames of reference 26, 51, 274, 277, 278, 282–283 gravitational waves 274, 305, 312–315 Higgs field 262, 263, 309, 310 Franklin, Benjamin 120, 124, 125 gravitons 309, 311 Hipparchus 270, 271 Franklin, Rosalind 23 gravity 32–35 Hippasus 27 Fraunhofer, Joseph von 183, 216, 320 equivalence principles 281 Hiroshima 251 Fraunhofer lines 183, 190, 216 fundamental force 159, 225, 301 Hodgkin, Alan 156 free energy 96 general relativity 30 Hodgkin, Dorothy Crowfoot 322 free falling 32–35, 50 laws of 46–51 frequency 116, 117, 153, 164, 165, 188, 189, 190, string theory 308–311 199, 208, 210, 228, 230

INDEX 331 Hooft, Gerard ’t 159 Kepler, Johannes 31, 42, 48–49, 173, 209, 272, Lobachevsky, Nikolai 30 Hooke, Robert 51, 73 273, 281, 318 lodestones 120, 122–123 Lomonosov, Mikhail 107 gravity 49 Kibble, Brian 60, 62, 63 London dispersion bonds 102, 103 light 162–163, 177, 178, 180, 181 Kibble, Tom 262 longitude 39, 72 microscopes 162, 174 Kilby, Jack 152, 158 Lorentz, Hendrik 144, 274 springs 66, 72–75 kinetic energy 17, 54, 57, 67, 87, 107, 137, 254, 279 Lorenz, Edward 111 time 38, 39, 72, 73 kinetic theory of gases 67, 74, 77, 78, 79, 85, Lovelace, Ada 29 Hoyle, Fred 299, 323 Lovell, Bernard 202 Hubble, Edwin 191, 269, 270, 290, 292, 293, 294, 106–110, 110, 145 Lucretius 100, 176, 212 295, 298, 299, 306 Kirchhoff, Gustav 72, 114, 115–117, 115, 130, 180, Huggins, William and Margaret 190 190, 193, 197, 216 M Hulse, Russell 269, 313 Klein, Oscar 308 Hund, Friedrich 229 Kleist, Georg von 120, 128 M-theory 308 Huxley, Andrew 156 Knoll, Max 172 Mach, Ernst 109, 110, 111, 320 Huygens, Christiaan Köhler, August 172 macrostates 109 light 147, 163, 169, 177–178, 179, 181, 182, 183, 185 Koshiba, Masatoshi 261 Magellanic Clouds 261, 291, 292 momentum 37 magnetic fields 53, 121, 127, 132, 157, 246 time 16, 19, 38–39, 52, 73 L hydraulics 36 dynamos 141, 149 hydroelectricity 151 Ladenburg, Rudolph W. 199 electromagnets 134–135 hydrogen bonds 102–103 Lagrange, Joseph-Louis 17, 56, 57, 146 force fields 144–147 hydrogen fuel cells 151 Lamb shift 260 induction 138–140 hydrostatic pressure 78 lambda baryons 245 light 163, 185, 187, 192, 193, 213 hypotheses 20, 21, 22 Land, Edwin H. 184 motor effect 136–137 Landau, Lev 264 MRI scanners 230 I Langevin, Paul 200, 201, 282–283, 283 nuclear fusion 251, 265 Langsdorf, Alexander 244 sun 203 Ibn al-Haytham, Hasan (Alhazen) 12, 22, 30, 176, 318 Laplace, Pierre-Simon 63, 286, 319 superconductors 228 Ibn Sahl 12, 162, 168, 169 lasers 199, 230, 314, 315 magnetic induction 254 Iijima, Sumio 323 latent heat 81 magnetic monopoles 159 induction, electromagnetic 138–141, 144–145, 149, latitude 39 magnetism 120–121, 122–123 Laue, Max von 195 magnets 193–194 Lauterbur, Paul 230 making 134–135 induction rings 139–140 Le Verrier, Urbain 48 particle accelerators 254 inductive charging 141 Leavitt, Henrietta Swan 290, 291–292, 293 magnification 172–175 Industrial Revolution 13, 66, 74, 81, 86, 90, 148 Lee, Tsung-Dao 259 Malus, Étienne-Louis 184–187, 186 inertia 43, 44, 53, 56 Leibniz, Gottfried 26, 28, 29, 42–45, 42, 54, 88, 169 Manhattan Project 225, 250–251, 259 inertial frames of reference 274, 277 Lemaître, Georges 288, 298–299, 298 Mansfield, Peter 230 infrared radiation 81, 114, 117, 163, 193, 194, 202 length contraction 283 Marconi, Guglielmo 192 Ingenhousz, Jan 80, 81, 96 Lenoir, Étienne 90 marine chronometers 38, 39 insulators 131, 154 lenses 172–175, 177 Marsden, Ernest 198, 234, 240 integrated circuits (ICs) 152, 155, 158 Lenz, Emil 140 mass interference, diffraction and 181–183 leptons 257, 309 laws of gravity 51, 281 interferometry 275, 312, 314, 315 Leucippus 66, 69, 70, 236 laws of motion 43, 44–45, 49 internal combustion engines 90 Lewis, Gilbert 208 mass-energy equivalence 55, 279, 284 internal energy 88–89 lift 76, 78 and velocity 37, 44, 54, 88, 214 interplanetary scintillation (IPS) 203 light 162–163 mass ratios 71, 236, 237 ionization 125, 234, 245 massive stars 287, 288 ions 129, 131, 149, 156, 244, 245 bending 176, 177, 269, 280, 281, 287, 303 materials, strength of 66, 74, 75 IPK (International Prototype Kilogram) 60, 61, 62, 63 diffraction and interference 180–183 mathematics 16, 17, 24–31 ITER agreement 265 Doppler effect and redshift 188–191 matrix mechanics 207, 218–219 echolocation 200–201 matter 66, 235 JK electromagnetic theory of 115, 144, 147, 260 Big Bang 300 electromagnetic waves 192–195 changes of state and bonds 71, 100–103 Jacobi, Moritz von 136 focusing 170–175 fluids 76–79 Jansky, Karl 202 from atoms 196–199, 217 gas laws 82–85 Jeans, James 117, 209 and heat 114–115 matter-antimatter asymmetry 264 Joliot-Curie, Frédéric 243, 253 nature of 212 models of 68–71, 196 Joliot-Curie, Irène 243, 253, 322 polarization 184–187 stretching and squeezing 74–75 Jordan, Pascual 218 reflection and refraction 22, 162–163, 168–169, 172, visible 304 Josephson, Brian 228 176–177 matter waves 214 Joule, James Prescott 17, 55, 67, 86, 87–88, 89, seeing beyond 202–203 matter-antimatter annihilation 71 speed of 147, 268, 274, 275, 277–278, 279, 282, 283 Maupertuis, Pierre-Louis 56 108, 114, 130 wave and particle theories 212–215, 218 Maxwell, James Clerk 30, 60, 103, 137, 145 Jupiter 22, 23, 48–49, 268, 272, 273 light bulbs 133 electromagnetism 13, 56, 114, 121, 138, 141, K-mesons 264 light quanta 210, 211 Kant, Immanuel 35 light waves 163, 176–179, 180–199, 212–215, 287, 312 144–147, 159, 192–194, 213, 224, 260, 276, 277 kaons 256, 264 lightning 125, 127 kinetic theory of gases 76, 79, 85, 106, 108, 110 Kapitsa, Pyotr 79, 228 Lilienfeld, Julius 152 light model 163, 179, 187, 192–194, 213, 260 Keating, Richard 282 linear accelerators (linacs) 254 Maxwell-Boltzmann distribution 110 Kelvin–Planck statement 99 Lippershey, Hans 173 Mayer, Julius von 55, 86, 87, 89, 96 Lippmann, Gabriel 201 measurement 16–17 liquefaction 100, 103 distance 18–19 liquids 36, 70, 71, 76, 100–103

332 INDEX SI Units and physical constants 60–63 nanoelectronics 121, 158 137, 138, 144 in space 291–293 nanoparticles 230 oscillations speed of light 147, 275 Navier, Claude-Louis 72, 79 temperature 80 nebulae 115, 191, 270, 271, 292 electromagnetism 193, 194, 213, 254 time 17, 38–39 negative numbers 26, 29 harmonic motion 52–53 mechanics, classical 48, 51, 57 nerve cells 156 light 163, 184, 185, 187, 213 megaverse 310 neutrino oscillation 261 neutrino 261 Meissner effect 228 neutrinos 235, 257, 258–259, 261 pendulums 17, 39 Meitner, Lise 242, 248, 249–250 neutron stars 203, 268, 287, 312, 313, 315 sound 165, 166, 167, 201 Mercury 48 neutrons 216, 225, 234, 235, 243, 247, 248, 250, P (parity) symmetry 264 Mersenne, Marin 164 Pais, Abraham 308 mesons 235, 247, 256, 264 255, 256, 257, 258, 259, 285, 300, 309 Papin, Denis 91 Messier 87 289 Newcomen, Thomas 81, 90, 91 paradoxes 27, 214, 220, 282–283 Messier, Charles 270 Newton, Isaac 51, 106, 107, 109 parallax 291, 292 metallic bonds 74 Parkin, Stuart 157 metric system 17, 18, 19, 60–61 atoms 66, 71, 100 Parry, Jack 38 metrology 17, 62 calculus 26, 29 Parsons, Charles 148 Michell, John 286–287, 289 fluids 76, 78, 79 particle accelerators 127, 235, 247, 252–255, 263, 285 Michelson, Albert 147, 268, 275 laws of gravity 32, 48–51, 73, 126, 281, 302 particle physics 127, 234–235 microprocessors 152, 155 laws of motion 12, 17, 37, 42–45, 52, 53, 54, 56, antimatter 246 microscopes 162, 172, 174–175 atomic theory 236–237 microstates 109 57, 108, 110, 274, 276, 277, 278, 298 Grand Unified Theory 159 microwaves 147, 194, 254 light 163, 169, 177, 180, 181, 183, 185, 186, Higgs boson 262–263 miles 19 magnetic monopoles 159 Milky Way 202, 203, 269, 270, 286, 289, 290, 192, 206, 212, 213, 216 matter-antimatter asymmetry 264 291, 292, 293 telescope 174 neutrinos 261 Miller, William Allen 190 vision of the universe 22, 31, 99, 107 nucleus 240–241 Millikan, Robert 124, 127, 211, 321 Newtonian liquids 78 particle accelerators 252–255 Minkowski, Hermann 269, 276, 280 Nielsen, Holger 310 particle zoo and quarks 256–257 Mirkin, Chad 121, 158 Nierste, Ulrich 264 Standard Model 31, 225, 235, 257, 261, 262, mirror universe 264 Nishijima, Kazuhiko 256 mirrors 162, 172, 174 Noddack, Ida 249 263, 264, 308, 309, 310 Misener, Don 79, 228 Noether, Emmy 31, 321 string theory 308–311 molecular bonds 102–103 novae 292 strong force 247 molecular movement 79, 108 Noyce, Robert 152 subatomic particles 13, 242–245 Moletti, Giuseppe 32, 33 nuclear decay 238, 239, 258–259 particle zoo 256–257 momentum 17, 37, 54, 87 nuclear fission 242, 249–251, 252, 265, 285 Pascal, Blaise 17, 36, 75, 76, 78, 82 Monardes, Nicolás 196 nuclear fusion 251, 285 Pauli, Wolfgang 206, 216, 217, 235, 258 monopoles, magnetic 159 in stars 261, 265, 301 Pauling, Linus 23 Moon 270, 271, 272 nuclear physics 234–235 Payne, Cecilia 50 gravity 50 force carriers 258–259 Payne-Scott, Ruby 323 landings 35, 49 nuclear bombs and power 248–251 pendulums 17, 38–39, 52 orbit round Earth 48, 281 nuclear fusion in stars 265 Penrose, Roger 288 Moore, Gordon 158 nuclear rays 238–239 Penzias, Arno 299, 301 Morley, Edward 268, 275 nuclear power 148, 151, 195, 235, 247, 248–251, Pepys, Samuel 73 motion 265, 284 Peregrinus, Petrus 122–123 dichotomy paradox 27 nuclear reactions 285 Perkins, Jacob 90 energy and 54, 55, 56–57, 87 nuclear waste 265 Perlmutter, Saul 306–307, 307 falling bodies 32–35 nuclear weapons 235, 248, 250–251, 265, 284, 285 Perrin, Jean Baptiste 71, 107 harmonic 52–53 nucleons 247 phlogiston 107 heat and 90–93, 107, 114 nucleus, atomic 234–235, 240–241 phosphorus 154 hydraulics 36 creation of first 300 photoelectric effect 114, 179, 193, 206, 208, laws of gravity 46–51 discovery of 148, 198, 241 209–210, 211, 214, 216 laws of 12, 17, 40–45, 52, 53, 54, 56, 57, 108, electrons orbit 216–217, 240, 241 photolithography 155, 158 force carriers 258–259 photons 179, 206, 208, 209, 211, 214, 215, 216, 110, 276, 277, 278, 298 model of 257 220–221, 224, 230, 257, 260, 263, 300 measuring 17 nuclear fission and fusion 249, 250, 251, 252, photovoltaic cells 151 momentum 37, 87 physical constants 60–63 relativity 274, 276–279 265 Pickering, Edwin Charles 291, 293 speed of light 275 particle accelerators 253 piezoelectricity 200–201 motors, electric 136–137, 139 subatomic particles 242–243, 309 pions 247 Mouton, Gabriel 17 number 26–31 Pirani, Felix 313 MRI scanners 228, 230 pitch 162, 164–177, 188, 190 muon neutrinos 257, 261 OP Pixii, Hippolyte 137, 141, 148, 149 muons 235, 245, 247, 257 Planck energy 311 music 52, 162, 164–167 observations 21, 22, 23 Planck, Max 13, 206, 211, 220–221 Ohl, Russel 154 blackbody radiation 67, 114, 117, 214 N Ohm, Georg Simon 121, 130, 132–133, 132 energy quanta 67, 179, 198, 208–211 Oliphant, Mark 265 heat engines 99 Nagaoka, Hantaro 241 Onnes, Heike Kamerlingh 100, 121, 130, 228 Planck’s constant 62, 63, 199, 209, 214, 221 Nagasaki 251 Oppenheimer, Robert J. 250, 251, 288, 322 planetary motion 42, 48–49, 167, 270–273 Nakano, Tadao 256 orbits plasma 71, 251 Nambu, Yoichiro 262, 309–310 Plato 12, 21, 70, 167 circular 271 Platz, Reinhold 76 electrons 198–199, 216–217, 218, 231, 234, 241 Podolsky, Boris 220 elliptical 48, 50 Poincaré, Henri 312–313 Oresme, Nicole 16, 34 Poisson, Siméon-Denis 128, 183 Ørsted, Hans Christian 121, 122, 134, 135, 136, polarization 147, 163, 179, 180, 182, 183, 184–187

INDEX 333 poles, magnetic 123, 159 radio frequency (RF) waves 254 shock waves 110 Polyakov, Alexander 159 radio telescopes 202–203 Shockley, William 155 positrons 127, 234, 245 radio waves 114, 141, 147, 163, 191, 192, 193, SI (Système International) units 17, 18, 19, 60–63, 127 potential difference 129, 130, 131, 133, 138, 140 Siemens, Werner von 149 potential energy 54, 57, 86, 87, 89 194, 202, 230 silicon 121, 153, 154, 155, 158 Power, Henry 84 radioactive beta decay 71 Simmons, Michelle Yvonne 228 power stations 121, 138, 141, 148, 150, 235, 248, 251 radioactivity 98, 201, 238–239, 248, 249, 251, 265, 285 singularities 287, 288, 300, 311 Preskill, John 159 rainbows 187 Slipher, Walter 191 pressure 36 Rankine, William 55, 86, 88, 89, 96, 97, 98, 110 Smith, George E. 176 redshift 191, 295, 299 Smoluchowski, Marian von 106, 107, 110, 111 air 83–84 Reed, Mark 228 Snellius, Willebrord 162, 169 fluids 66, 77, 78, 100–101 reflected/refracted light 22, 162–163, 168–169, 172, Snyder, Hartland 288 primeval atom 299 Socrates 12, 21 prisms 114, 177, 183, 187, 192, 213 174, 186–187 Soddy, Frederick 239 probability, entropy and 96, 111 Reines, Frederick 235, 258, 259, 261 solar cells 208 probability waves 219, 229 Reitze, David 314 solar neutrinos 261 Proclus 26, 30 relativity 141, 268–269, 274, 276–279 solar power 87, 151 protons 127, 225, 230, 234, 235, 243, 245, 247, solar radiation 98 249, 251, 255, 256, 257, 258, 259, 265, 300, 309 Galilean 274, 276 solar system, models of 22, 23, 42, 48–49, 176, 268, particle accelerators 252, 253, 254 general theory of 42, 44, 45, 48, 51, 269, 274, 281, Proust, Joseph 236 270–273, 298 Ptolemy 22, 168, 268, 270, 271, 272, 273 287, 294, 298, 299, 303, 308, 309, 311, 312, 313 solid-state physics 154 pulsars 163, 203, 312, 313 paradoxes of special 282–283 solids 70, 71, 100 Pythagoras 26, 27, 162, 164–167, 167, 272 special theory of 48, 51, 144, 146, 147, 179, sonar 201 sound 162–163 QR 219, 222, 223, 260, 268–269, 274, 277–279, 281, 284, 287 music 162, 164–167 quanta 67, 117, 179, 198, 206–207, 208–211, 214, 216, 224 resistance 121, 131, 132–133 piezoelectricity and ultrasound 200–201 quantum applications 226–231 Riccati, Giordano 75 sound waves 162, 163, 164–167, 178, 188, 189, 200–201 quantum chromodynamics 260 Riccioli, Giovanni Battista 32, 35, 49 space quantum computing 207, 222, 223, 228, 230–231 Richardson, Lewis Fry 200–201 measuring distance in 291–293 quantum cryptography 223 Riemann, Bernhard 30 photoelectric effect in 210 quantum dots 228, 230 Riess, Adam 306, 307 relativity 268–269, 274 quantum electrodynamics (QED) 225, 260 right-hand rule 140 and time 43, 45, 268, 274, 277, 278–279, 280, 281 quantum entanglement 207, 222–223, 228, 231, 311 Rittenhouse, David 183 spacetime 269, 276, 280 quantum field theory 224–225 Ritter, Johann 193 black holes and wormholes 286–289 quantum gravity scale 310 Robinson, Ian 62 curvature 269, 274, 280, 281, 287, 294, 302, 303, quantum imaging 229–230 Röntgen, Wilhelm 192, 195 quantum leaps 216–217 Rosen, Nathan 220 304, 308, 313 quantum mechanics 70, 117, 127, 157, 218–219, rotation 53 dimensions of 269, 280, 308, 310, 311 Rubin, Vera 302, 303–304, 305 gravitational waves 312–315 222, 224, 241, 243, 260, 309, 311 Ruska, Ernst 172 mirror universe 264 quantum numbers 216–217 Rutherford, Ernest 107, 234–235, 241 Spallanzani, Lazzaro 200 quantum particles 220–221, 224, 229 atomic model 198, 242–243 spectography 190, 191 quantum physics 206–207, 208, 212, 221, 228 nucleus 240–241, 248, 252, 253 spectral lines 183, 190, 199, 217 radiation 234, 238, 239, 248 spiral galaxies 304 energy quanta 208–211 Rydberg, Johannes 198 spiral nebulae 191, 292 Heisenberg’s uncertainty principle 220–221 Ryle, Martin 203 springs 72–74 matrices and waves 218–219 squeezing 72–75 quantum applications 226–231 S SQUIDS (superconducting quantum interference quantum entanglement 222–223 devices) 228 quantum field theory 224–225 Saint-Victor, Abel Niepce de 238 St-Venant, Jean Claude 72 quantum numbers 216–217 Sakharov, Andrei 264 Standard Model 31, 225, 235, 257, 261, 262, 263, wave-particle duality 212–215 Salam, Abdus 224, 235, 262 264, 308, 309, 310 quantum spin 206, 230 satellites 50–51, 53, 202, 210, 229 Stanley, William 150–151 quantum theory 207, 211, 214, 220, 223, 231, Savery, Thomas 91 stars 270–271, 312 260, 295, 311 Scheele, Carl 80, 81, 96 black holes and wormholes 286–289 quantum tunneling 229, 253 Schmidt, Brian 306, 307 color 163, 188–190 quark-gluon plasma 255, 300 Schrieffer, John 155, 228 distance from Earth 291–293 quarks 224, 225, 235, 247, 255, 256–257, 259, 262, Schrödinger, Edwin 56, 196, 207, 212, 218, evolution of 284–285, 301 300, 309, 310 nuclear fusion 265 qubits 228, 230–231 219, 220, 222 temperatures 117 radar 147, 191 Schrödinger’s cat 218, 221 see also galaxies; planetary motion; universe radiant heat 81 Schuckert, Sigmund 148 state, changes of 100–103 radiation 234–235 Schuster, Arthur 246 static electricity 123, 127, 146, 254 blackbody 67, 114, 115, 116, 117, 208–209 Schwartz, John 310 statistical mechanics 104–111 cosmic 244, 245 Schwarzschild, Karl 269, 286, 287–288, 289 statistical thermodynamics 109–110 cosmic microwave background 298, 299–301, Schwarzschild radius 287 steam engines 66, 80, 81, 86, 90–93, 96, 106, 149 Schwinger, Julian 225, 260, 264 stellar black holes 314 306, 307 scientific method 16, 20–23 Stenger, Victor J. 211 electromagnetic 114, 115, 116, 141, 194, 195, Scientific Revolution 16, 20, 22, 33, 42, 72, 268 Stern, Otto 206 Scott, David 32, 35, 49, 281 Stevin, Simon 18, 19, 34 198, 202, 208 Sebastian, Suchitra 213 Stewart, Balfour 115–116 energy quanta 208–211 Seebeck, Thomas 152 Stokes, George Gabriel 79, 197 nuclear 238–239 semiconductors 152, 153, 154, 155, 229, 230 Stonehenge 270 thermal 112–117 Shapley, Harlow 292, 293 Stoney, George J. 124, 126, 242 ultraviolet 193 shells, electron 216, 217, 241, 243 strain 74, 75 Shen Kuo (Meng Xi Weng) 122 strangeness 235, 256 Strassmann, Fritz 249

334 INDEX stress 74, 75, 78 dilation 278, 282 laws of motion 42, 44, 45 stretching 72–75 measuring 17, 38–39, 52 and mass 37, 44, 54, 88, 214 string theory 308–311 relativity 268–269, 274, 276–279 momentum 17, 37 strong nuclear force 159, 225, 235, 247, 256, 257, and space 43, 45, 277, 278–279, 280, 281 orbital 50, 51 thermodynamic arrow of 67, 99 Venus 49 259, 260, 300, 309, 310 tokamak reactors 251, 265 Vesalius, Andreas 20, 22, 23 Strutt, John (Lord Rayleigh) 117, 209 Tomonaga, Shin’ichiro¯ 225, 260 Viète, François 28 Sturgeon, William 135, 137, 138 Tompion, Thomas 73 Vikings 184 subatomic particles 13, 71, 126, 198, 206, 224, 234, top quarks 235, 255, 256, 257, 262 Villard, Paul 234, 238, 239 torques 137 viscosity 76, 78, 79 242–247, 253, 256–257 Torricelli, Evangelista 36, 77, 82, 83, 84, 106, 319 visible light 114, 193, 194, 195, 197, 238 sun torsion 126 Vogel, Hermann Carl 190 Townes, Charles 196 volcanic activity 97 energy 261, 285 Townley, Richard 84 Volta, Alessandro 120, 121, 128, 129, 130, 131, gravity 49 transducers 201 134, 149 heliocentrism 22, 48–49, 268, 270–273, 290 transformers 139, 150–151 W bosons 235, 257, 258, 259, 262, 263 magnetic field 203 transistors 152, 153, 154, 155, 158, 229 Wallis, John 17, 37, 54 position of 292, 293 Treiman, Sam 308 Walton, Ernest 253–254, 255 super-hot stars 199 triodes 153 watches 72–73 Super-Kamiokande 261, 311 turbines water 100, 101, 103 superconductivity 103, 121, 132, 155, 228 steam 141, 151 Waterston, John 106, 107–108 superfluids 79, 228–229 wind, wave and tide 151 Watson, James 23 supermassive black holes 202, 203, 289, 315 Turing, Alan 231 Watt, James 66, 80, 81, 86, 91 supernovae 261, 288, 301, 306–307 twin paradox 282–283 wave power 151 superposition 220, 221, 311 wave–particle duality 179, 206, 210, 212–215, 220, superstring theory 311 UVW 221, 229–230 supersymmetry 309, 310–311 wave function 219, 220 surface tension 102 Uhlenbeck, George 157 weak nuclear force 159, 224, 225, 235, 245, 256, suspension bridges 75 ultrasound 200–201 257, 258, 259, 262, 300, 308, 309, 310 Susskind, Leonard 279, 308, 309, 310 ultraviolet catastrophe 117, 209 weather forecasts 111 symmetry breaking 262 ultraviolet light 117, 163, 179, 193, 195, 197, 208, Weinberg, Steven 224 synchrotron accelerators 254 Weiss, Pierre-Ernest 122 Szilard, Leo 322 209, 210, 238, 301 Weiss, Rainer 313–314, 315 uncertainty principle 207, 218–219, 220–221, 222 Westinghouse, George 151 T universe 268–269 Wheeler, John 288 white dwarfs 287, 306, 307 tachyons 310 accelerated expansion 188, 294, 298 Wien, Wilhelm 116 tau neutrinos 257, 261 Big Bang 296–301 Wild, John 200 taus 257 black holes and wormholes 286–289 Wilkins, John 19 Taylor, Joseph 269, 313 curved 280 Wilson, Alan Herries 152 telescopes 13, 115, 162, 172–174, 191, 202–203, 268, curving spacetime 280 Wilson, Charles T.R. 244, 245 dark energy 306–307 Wilson, Robert 299, 301 289, 292, 301, 306 dark matter 302–305 WIMPs (weakly interacting massive particles) 23, temperature discovering galaxies 269, 290–293 304–305 energy of 97–98 wind power 151 changes of state 101, 102 expanding 191, 269, 293, 294–295, 298, 299, 301, wireless telegraphy 194 and heat 80, 86 Witten, Edward 308 and resistance 132 303, 306–307, 311 Wollaston, William Hyde 216 stars 117 future of 98, 99, 289, 294–295, 301, 306 work and energy 67, 88, 89, 96 and thermal radiation 114–115 gravitational waves 312–315 wormholes 286, 288 temperature fields 145 heavenly bodies 270–271 Wren, Christopher 37 tensile strength 75 Higgs field 262–263 Wu, Chien-Shiung 258, 259 Tesla, Nikola 150, 320 models of 271, 272–273, 299–300 Wu Xing 69 Tevatron 255 origins of 255, 269, 298–301 Thales of Miletus 12, 20, 21, 27, 120, 122, 124 shape of 295 XYZ Theory of Everything 311 Standard Model 308–309, 310 thermal radiation 112–117 static 268, 294–295 X-ray diffraction 23, 214 thermodynamics 67, 91–92, 93, 111 string theory 308–311 X-rays 114, 163, 195, 206, 208, 211, 234, 238, 239 laws of 67, 86, 88–89, 96–99, 110 uranium 238–239, 249, 250 Yang, Chen Ning 259 statistical 109–110 Urey, Harold C. 265 Young, Thomas 54, 72, 88, 102, 179 thermoelectric effect 152 vacuum tubes 152, 153, 154, 155, 195, 242 thermometers 80 vacuums light 163, 168, 176–179, 181–182, 186, 187, 192, Thompson, Benjamin (Count Rumford) 54, 55, 66, gas laws 66, 83 206, 212, 213, 215, 287 86, 87, 114 heat engines 91 modulus 75 Thomson, George 214 light in 274, 275, 277 Yukawa, Hideki 235, 247 Thomson, J.J. 124, 145, 153, 320–321 valence bands 154 Z bosons 235, 257, 258, 259, 262, 263 atomic model 242–243 valves 153 Zeilinger, Anton 222 discovers electron 126–127, 198, 208, 212, 218, van der Waals, Johannes Diderik 67, 100, 102–103, 103 Zeno of Elea 27 van Leeuwenhoek, Antonie 172, 175 zero, concept of 26, 28 234, 236, 238, 240, 242 van Musschenbroek, Pieter 120, 128 Zwicky, Fritz 302, 303 Thomson, William (Lord Kelvin) 320 vaporisation 101, 102 vector fields 146 absolute zero 84, 107, 114 velocity magnetoresistance 157 constant 274, 277, 282 thermodynamics 67, 88, 89, 96–99, 108, 110 escape 289 Thorne, Kip 312, 314, 315 fluids 66, 77 timbre 165 time atomic clocks 229

335 UOTATIONS The following primary quotations are attributed 130 A tax on electrical energy 246 Opposites can explode to people who are not the key figure for the Helen Czerski, British physicist Peter David, American writer relevant topic. and oceanographer 252 A window on creation MEASUREMENT AND MOTION 134 Each metal has a certain power Michio Kaku, American physicist Alessandro Volta, Italian physicist 18 Man is the measure of all things and chemist 260 Nature is absurd Protagoras, Greek philosopher Richard Feynman 156 Animal electricity 20 A prudent question is one Luigi Galvani, Italian physicist 261 The mystery of the missing neutrinos half of wisdom John N. Bahcall, American astrophysicist Francis Bacon, English philosopher 157 A totally unexpected scientific discovery 262 I think we have it 24 All is number 2007 Nobel Prize Committee Rolf-Dieter Heuer, German particle physicist Motto of the Pythagoreans 158 An encyclopedia on the head of a pin RELATIVITY AND THE UNIVERSE 32 Bodies suffer no resistance but Richard Feynman, American theoretical from the air physicist 275 The sun as it was about eight Isaac Newton, English mathematician minutes ago and physicist SOUND AND LIGHT Richard Kurin, American anthropologist 38 The most wonderful productions 170 A new visible world 281 Gravity is equivalent to acceleration of the mechanical arts Robert Hooke, English physicist David Morin, American academic Mary L. Booth, American journalist and physicist 180 Light is never known to bend into 55 Energy can be neither created the shadow 282 Why is the traveling twin younger? nor destroyed Isaac Newton Ronald C. Lasky, American academic Julius von Mayer, German chemist and physicist 196 The language of spectra is a true 286 Where spacetime simply ends music of the spheres Abhay Ashtekar, Indian theoretical 58 We must look to the heavens for Arnold Sommerfeld, German physicist the measure of the Earth theoretical physicist Jean Picard, French astronomer 294 The future of the universe 202 A large fluctuating echo Stephen Hawking, British cosmologist ENERGY AND MATTER Bernard Lovell, British physicist and radio astronomer 302 Visible matter alone is not enough 76 The minute parts of matter are Lisa Randall, American theoretical physicist in rapid motion THE QUANTUM WORLD James Clerk Maxwell, Scottish physicist 308 Threads in a tapestry 208 The energy of light is distributed Sheldon Glashow, American theoretical 80 Searching out the fire-secret discontinuously in space physicist Thomas Carlyle, Scottish philosopher Albert Einstein, German-born theoretical physicist 312 Ripples in spacetime 86 The energy of the universe Govert Schilling, Dutch science writer is constant 212 They do not behave like anything Rudolf Clausius, German physicist that you have ever seen and mathematician Richard Feynman 100 The fluid and its vapor become one 222 Spooky action at a distance Michael Faraday, British physicist Albert Einstein ELECTRICITY AND MAGNETISM NUCLEAR AND PARTICLE PHYSICS 124 The attraction of electricity 238 A veritable transformation of matter Joseph Priestley, British philosopher Ernest Rutherford, New Zealand–born and chemist British physicist 128 Potential energy becomes 242 The bricks of which atoms are palpable motion built up William Thomson (Lord Kelvin), J.J. Thomson, British physicist Irish–Scottish physicist

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