Simply quantum physics DK

S I M P L Y QUANTUM PHYSICS CONTENTS DK LONDON Project Editor Miezan van Zyl US Editor Karyn Gerhard Art Editor Mik Gates Designer Clare Joyce Managing Editor Angeles Gavira Managing Art Editor Michael Duffy Production Editor Gillian Reid Senior Production Controller Meskerem Berhane Jacket Design Development Manager Sophia M.T.T Jacket Designer Akiko Kato Associate Publishing Director Liz Wheeler Art Director Karen Self Publishing Director Jonathan Metcalf First American Edition, 2021 Published in the United States by DK Publishing 1450 Broadway, Suite 801, New York, NY 10018 Copyright © 2021 Dorling Kindersley Limited DK, a Division of Penguin Random House LLC 21 22 23 24 25 10 001–322079–Feb/2021 All rights reserved Without limiting the rights under the copyright reserved above, no part of this publication may be reproduced, stored in or introduced into a retrieval system, or transmitted, in any form, or by any means (electronic, mechanical, photocopying, recording, or otherwise), without the prior written permission of the copyright owner Published in Great Britain by Dorling Kindersley Limited A catalog record for this book is available from the Library of Congress ISBN 978-0-7440-2848-5 Printed and bound in China For the curious www.dk.com This book was made with Forest Stewardship Council ™ certified paper—one small step in DK’s commitment to a sustainable future For more information go to www.dk.com/our-green-pledge THE QUANTUM WORLD VANISHINGLY SMALL The subatomic scale 10 THREE TINY PIECES The structure of the atom 12 PARTICLE ZOO Subatomic particles 14 WHAT IS LIGHT? Electromagnetic radiation  15 QUANTUM CONSTANT Planck’s constant 16 RIPPLES IN SPACE Waves 18 WAVE OR PARTICLE Particle-wave duality 20 HOLDING IT TOGETHER The strong nuclear force 21 THE FORCE OF DECAY The weak nuclear force 22 OPPOSITES ATTRACT The electromagnetic force 23 DRAWN TOGETHER Gravity PRE-QUANTUM PUZZLES 26 IDEAL BODIES Black-body radiation 27 UV CATASTROPHE The Rayleigh-Jeans law 28 PACKETS OF ENERGY Energy quantization 30 ENERGETIC STATES Atomic energy states 55 INFINITE REPETITION The cosmological interpretations 31 CLOUDS OF PROBABILITIES Electron orbitals 56 UNSEEN INFLUENCE Hidden-variable interpretations 32 PHOTON ENERGY The photoelectric effect 58 A QUANTUM HANDSHAKE The transactional interpretation 59 SPONTANEOUS COLLAPSE Objective-collapse hypothesis 60 SURVIVAL OF THE FITTEST Quantum Darwinism 61 THE OBSERVER’S BELIEF Quantum Bayesianism THE WAVE FUNCTION 36 DESCRIBING A QUANTUM STATE The wave function  62 38 IN TWO PLACES AT ONCE Superposition THROUGH THE MAZE Consistent histories  63 40 SQUARED WAVE The Born rule DIFFERENT VIEWS The relational interpretation 41 WAVE TRANSFORMATIONS Fourier transforms 42 NOT ALL IS KNOWABLE Heisenberg’s uncertainty principle QUANTUM PHENOMENA 44 PREDICTING CHANGE Schrödinger’s equation 66 46 EVADING MEASUREMENT The measurement problem  “SPIN” Intrinsic angular momentum  67 48 INSTANT COLLAPSE Collapsing the wave function FIELDS OF ATTRACTION Magnetic moments 68 PARADOX IN A BOX Schrödinger’s cat THE GREAT DIVIDE Fermions and bosons 69 NO ROOM FOR TWO Pauli exclusion principle 70 WHAT BARRIER? Quantum tunnelling 72 DISTANCE NO OBJECT Quantum entanglement  74 QUANTUM TELEPORTATION Transferring quantum states 75 UNSTABLE ENVIRONMENT Decoherence 76 INSIDE SOLID OBJECTS Solid-state physics 78 ALTERED STATES Bose-Einstein condensates 49 INTERPRETATIONS OF QUANTUM PHYSICS 52 54 UNDERSTANDING QUANTUM PHYSICS The Copenhagen interpretation EVERYTHING CAN AND DOES HAPPEN The many worlds interpretation  80 FLOWING WITHOUT FRICTION Superfluidity 81 ENDLESS CHARGE Superconductivity 82 STRANGE QUANTUM ATOMS Cold atom physics 83 UNUSUAL ORBITS Rydberg atoms QUANTUM TECHNOLOGY QUANTUM INFORMATION 106 NOT JUST ZEROS AND ONES Qubits 107 SUPERFAST Quantum computing 108 QUANTUM CODES Quantum cryptography 109 SIMULATORS Quantum simulation NUCLEAR PHYSICS 86 FIRING PHOTONS AT ATOMS Stimulated emission 87 HIGHLY CONCENTRATED Lasers 88 KEEPING TIME Atomic clocks 90 SOLID STATES Band theory of solids 91 SILICON CHIPS Transistors 92 LIGHT RELEASE Light-emitting diodes 93 CAPTURING PHOTONS Charge-coupled devices 94 LEVITATION Superconducting electromagnets 120 ON THE TRAIL OF ELUSIVE PARTICLES Particle detectors 95 TUNNELING PAIRS Josephson junctions 121 SIMPLY SMASHING Particle accelerators 96 SQUIDS Superconducting quantum interference devices 122 SMALLER THAN AN ATOM Quarks 98 LOOKING INSIDE Magnetic resonance imaging 112 SEEKING STABILITY Radioactivity 114 SPLITTING ATOMS Nuclear fission 116 COMBINING NUCLEI Nuclear fusion PARTICLE PHYSICS 123 NO STRONG INTERACTIONS Leptons 100 SEEING WITHOUT LIGHT Electron microscopes 124 THE QUANTUM WORLD EXPLAINED The Standard Model 102 ATOMIC PROBE Atomic force microscopy 126 FORCE CARRIERS Gauge bosons 127 WHY PARTICLES HAVE MASS The Higgs boson 128 THE OPPOSITE OF MATTER Antimatter 130 NOT SO STANDARD Beyond the Standard Model  132 UNIVERSAL FIELDS Quantum field theory 134 THE JEWEL OF PHYSICS Quantum electrodynamics 135 THREE-COLOR QUARK Quantum chromodyamics 150 IT’S IN OUR DNA A quantum theory of cell mutation 151 TUNNELING FOR A REACTION Enzymes and quantum physics 152 MAGNETIC PERCEPTION Quantum navigation 154 OUR SENSE OF SMELL The quantum nose 155 QUANTUM CONSCIOUSNESS? The quantum mind 156 INDEX QUANTUM GRAVITY 138 COMBINED FORCES A theory of everything 140 QUANTUM FOAM Planck length and time 142 TINY VIBRATING STRINGS String theories 143 TYING IT TOGETHER M-theory 144 THE FABRIC OF SPACE Loop quantum gravity QUANTUM BIOLOGY 148 PHOTONS AND FOLIAGE Photosynthesis CONSULTANT EDITOR Dr Ben Still is a prizewinning science communicator, particle physicist, and author He teaches high school physics and is also a visiting research fellow at Queen Mary University of London He is the author of a growing collection of popular science books and travels the world teaching particle physics using LEGO® CONTRIBUTORS Hilary Lamb is an award-winning journalist and author, covering science and technology She has written for previous DK titles, including The Visual Encyclopedia, How Technology Works, and The Physics Book Giles Sparrow is a popular-science author specializing in physics and astronomy He has written and contributed to bestselling DK titles, including The Physics Book, Spaceflight, Universe, and Science T H E Q U A N W O R L T U M D Quantum physics describes the way the universe behaves on the very smallest scales Far below the limits of even the most powerful microscopes, it governs the behaviors and interactions of atoms and the particles from which they are made—the fundamental building blocks of matter Scientists only confirmed the existence of subatomic particles with J.J Thomson’s discovery of the electron in 1897, but the possibility that these tiny particles can sometimes behave like waves, which is key to the strange behavior of the quantum world, was only suggested by Louis Victor de Broglie in 1924 QUARK 10 -18M NUCLEONS 10 -15M Quarks are one type of elementary particle and are building blocks for matter The electron particles that orbit in the outer shells of atoms are elementary particles on a similar scale to quarks THE SUBATOMIC SCALE ELECTRON ~10 -18M At the center of the atom is the nucleus—a dense region that contains nearly all of its mass The nucleus of hydrogen is a single subatomic proton particle with a diameter of 1.8 million billionths of a meter NUCLEUS 10 -14M–10 -15M ATOM 10 -10M Atoms are about 100,000 times smaller than any object that can be resolved with the naked eye Most of the atom is “empty” space Q U A N B I O L T U M O G Y At the most basic level, all the processes that make up what we call life come down to biochemistry—chemical interactions between a variety of complex molecules Perhaps it should not be surprising, then, to learn that quantum effects have a part to play Many pioneers in the field, including Erwin Schrödinger and Niels Bohr, predicted that quantum phenomena would play important roles in processes ranging from the harvesting of energy to genetic mutation, but it is only in the past few decades that our understanding of biochemistry has been able to reveal some of the details PHOTONS AND FOLIAGE SUNLIGHT Photosynthesis is the process by which plants manufacture sugars and other chemicals using energy from sunlight Its first step involves photons triggering chemical changes to molecules called chromophores Energy produced by these changes is transferred to other molecules, where it can be put to use with remarkable efficiency, involving synchronized vibration between different energy states Many biologists believe that photosynthesis has evolved to take advantage of the quantized nature of light energy, and some go further, suggesting that other quantum phenomena, such as superposition (see pp.38–39), may play a role Inside the energy factory A leaf is an electrochemical power plant that harnesses sunlight of specific wavelengths to trigger excitation in chromophores, and ultimately chemical changes in its pigment molecules 148 PHOTOSYNTHESIS PHOTONS LIGHT-COLLECTING MOLECULES Changes to pigments produce separated positive and negative ions, creating an “electrochemical potential” that can trigger other reactions REACTION CENTER LO NG ES TR OU TE SH OR TE ST RO UT E Incoming light carries energy corresponding to its color Chromophores can be excited by high-energy violet and blue photons and low-energy red ones, but midrange green light is reflected back Energy is transferred via neighboring chromophores to the reaction center with high efficiency Each molecule in the chain is always ready to receive the energy in turn, so it is suggested that quantum phenomena aid the cells in finding the most efficient paths PHOTOSYNTHESIS 149 IT’S IN OUR DNA The process of mutation plays a vital role in evolution by introducing random changes to DNA, the self-replicating biochemical molecule that carries instructions for making living things Mutations involve individual chemical units called “bases” (the individual letters of the DNA code) abruptly changing from one form to another Because bases seem inherently stable, some scientists think that quantum tunneling (see pp.70–71) is needed to leap energy barriers within their structure and allow them to change Bases bond in specific pairs—adenine to thymine, and guanine to cytosine Quantum change One form of mutation may start with a quantum event in which a proton from one base tunnels to its neighbor This alters the length of the bond between them and triggers an error when the DNA is replicated 150 A T T A G C C G REPLICATION BASE PAIRS BASE PAIRS DOUBLE HELIX Base pairing ensures that DNA can be replicated by “unzipping” and rebuilding the opposite strand A QUANTUM THEORY OF CELL MUTATION DNA STRAND DNA consists of a chain of base pairs linked by sugar-phosphate “backbones” that twist into a spiral, or helix, shape Catalytic process SUBSTRATES Catalysis involves changing the structure of two or more chemicals to allow a reaction between them In some cases, the barrier to reaction appears to be overcome only through quantum tunneling The chemicals involved in the reaction may initially be drawn to separate areas of the enzyme surface by weak attractive forces ENZYME ACTIVE SITE TUNNELING FOR A REACTION Chemicals called enzymes are found throughout our bodies, aiding processes such as digestion (the breaking down of food into useful nutrients) They are thought to work by lowering the energy barrier between molecules called substrates so that they undergo reactions, but the precise way in which they this remains poorly understood One theory is that they this by creating conditions in which electrons are able to bridge the gap between molecules using quantum tunneling (see pp.70–71) ENZYME-SUBSTRATE COMPLEX As the substrates bond to the enzyme, chemical changes allow them to overcome the energy barrier that prevents a reaction, forming a product that is then released PR OD ENZYMES AND QUANTUM PHYSICS UC T 151 Radical pairs can only be in one of two states (called singlet or triplet), and the Earth’s magnetic field may affect these states Each of the states may trigger a different chemical signal being sent to the bird’s brain MESSAGES TO THE BRAIN CHEMICAL REACTION MAGNETIC FIELD See the force Migrating bird species navigate with great precision, even when flying over terrain or in weather conditions where there are no visual landmarks to guide them 152 QUANTUM NAVIGATION CRYPTOCHROME LIGHT CHEMICAL REACTION RADICAL PAIRS Photons cause some molecules to split into radical pairs—each with one electron from the previously shared chemical bond Molecules of the cryptochrome protein are found on the retina of the birds’s eye The bonds that form these cryptochrome molecules may be disturbed by incoming photons MAGNETIC FIELDS N EARTH S MAGNETIC PERCEPTION Seasonal migrations see many different bird species fly vast distances between their winter and summer habitats Experiments have demonstrated that birds rely on some sort of internal “compass” to navigate, and some scientists have proposed explanations that quantum effects are responsible Proteins called cryptochromes found in the retina of the eye form pairs of molecules with correlated spins (see p.66) in blue light, and these spins can be oriented by magnetic fields, perhaps allowing birds to see Earth’s magnetism QUANTUM NAVIGATION 153 OUR SENSE OF SMELL OLFACTORY BULB The traditional understanding of our sense of smell, known as the “lock and key” model, involves a scent molecule (odorant) fitting into a receptor cell in the nose and triggering a sensory response But is that the whole story? The unproven “vibrational” theory of olfaction uses quantum effects to offer a solution to some outstanding questions It suggests that our odor reception involves a quantum tunneling effect, driven by the vibrations of scent molecules The molecular structure of odorants is not static, but instead vibrates rapidly, emitting infrared energy in different “modes” akin to musical harmonics ODORANT MOLECULES Quantum-tuned for smell? According to one model, signals to our brain are triggered when electrons from an odorant molecule tunnel into our receptor proteins, boosting these complex molecules from one energy level to another 154 THE QUANTUM NOSE QUANTUM CONSCIOUSNESS? Conscious thought appears to be a uniquely human ability—but could our ability to reason, imagine, and assess problems be rooted in quantum physics? Several renowned physicists have argued that the unique aspects of our brains might arise from the harnessing of quantum phenomena such as entanglement (see pp.72–73) and superposition (see pp.38–39), but others doubt that quantum uncertainty could be sustained for long enough in our warm, wet bodies for any brain function to take advantage of it, due to decoherence (see p.75) Quantum thinking? The brain’s ability to solve problems that are not solvable by traditional computing methods could mean that it is harnessing superpositions and acting as a quantum computer (see p.107) THE QUANTUM MIND 155 INDEX Page numbers in bold refer to main entries A absolute zero 82, 94 alpha decay 70, 113 alpha particles 113 amplitude wave function 36–37, 40 waves 14, 17 antimatter 128–29 antiparticles 128, 132 atomic clocks 88–89 atomic energy states 30, 40 atomic force microscopy (AFM) 102–103 atoms cold atom physics 82 quantum model 11 Rydberg 83 solid-state physics 76–77 splitting 114–15 stimulated emission 86 structure of 10–11, 25, 30, 31, 65 see also nuclei, atomic B band theory of solids 90, 92 baryons 12, 135 Bell, John Stewart 47, 57 Bell-state analyzer 74 Bell’s theorem 57 beta decay 21, 113 beta particles 21 Big Bang 55, 121, 138, 140 biochemistry 147 birds, migrations 152–53 bits 106, 107 black-body radiation 26, 27, 28 156 INDEX Bloch spheres 106 Bohr, Niels 10, 30, 147 Bohr model 10, 30, 31 Born, Max 40 Born rule 40, 53 Bose-Einstein condensates 78–79, 82 Bose-Einstein statistics 68, 80 bosons 13, 21, 68, 79, 81, 119, 130, 134 Bose-Einstein condensates 78–79 brain function 155 branes 142, 143 bubble chambers 120 C Calabi-Yau manifold 143 capacitors 93 cell mutation 150 chain reactions 114–15 change, predicting 44–45 charge-coupled devices (CCDs) 93 classical physics 28, 38, 51, 53 closed vibrating strings 142 cloud chambers 120 coherence 75 cold atom physics 82 color charge 122, 135 composite particles 119, 122 computer chips 91 computers, classical 107 conduction 76, 81 conjugate variables 43 consciousness 155 consistent histories 62 constructive waves 17 Cooper pairs 81, 94, 95 Copenhagen interpretation 52–53, 56, 59 cosmological interpretation 55 coulomb forces 71, 117 cryptochromes 152, 153 cryptography 108 crystalline structure 76–77 D dark energy 131 dark matter 130 data storage, solid state 90 de Broglie, Louis Victor 7, 56 decoherence 75 degrees of belief 61 destructive waves 17 diffraction 16, 18 digestion 151 digital imaging 93 dimensions, hidden 143 diodes, light-emitting 90, 92 DNA 150 doping 91 double slit experiment 18–19 E Einstein, Albert 23, 32, 52, 63, 115 electric charge atoms 10–11 particles 67 electrical current 81 electromagnetic attraction 11, 22 electromagnetic energy 97 electromagnetic fields 14, 121 electromagnetic force 20, 22, 119, 123, 126, 134, 139 electromagnetic radiation 14, 16, 26–27 electromagnetic repulsion 20, 22, 69 electromagnetic spectrum 14 electromagnetic waves 25 electron detectors 100, 101 electron microscopes 100–101 electron orbitals 31 electronics 85, 90–91 electrons 12, 22, 46–47, 112 accelerated 100 antimatter 128–29 atomic clocks 88 atomic structure 10–11 band theory of solids 90 clouds 11 Cooper pairs 81, 94, 95 energy states 30, 31, 69, 83, 94 Higgs field 127 jumping between energy levels 30, 88 LEDs 92 magnetic moments 67 photoelectric effect 32–33 quantum electrodynamics 134 quantum field theory 132 Rydberg 83 size solid-state physics 76–77 spin state 38, 106 stimulated emission 88 superconductivity 81 superposition 38–39 transistors 91 wavelike properties 18–19 wavelength 100 electroweak force/theory 139 elementary particles 12, 68, 119, 122, 123, 124–25 elements atoms 10 creating 116–17 energy antimatter 128–29 nuclear fission 114–15 nuclear fusion 116–17 photosynthesis 148–49 energy quantization 28–29 energy shells 10, 30, 31, 69 energy states 30, 78, 86, 88, 90, 94, 148 entanglement see quantum entanglement environmental factors 60, 75 enzymes 151 equilibrium point 36 Everett, Hugh III 54 excited states 30, 86, 87 F feedback electronics 102 fermions 12, 68, 69, 76, 81, 119, 124–25, 130, 134 Feynman diagrams 134 fission, nuclear 114–15 force carrying particles 119, 124–25, 126 Fourier transforms 41 frequency microwave radiation 88, 89 wave function 41 fundamental forces 20–23, 125, 126, 137, 138–9, 142, 144 fusion, nuclear 116–17 General Relativity 23, 133, 137, 138, 140 genetic mutations 147, 150 gluons 13, 20, 122, 125, 126, 135 grand unified theories 138–39 gravitational fields 144, 145 gravitons 23, 142 gravity 23, 130, 131, 140–41 theories of everything 138–39, 142–45 green light 33 ground states 30, 86 H hadrons 12, 13, 122 half-life 113 Hamiltonian operator 44 Heisenberg, Werner 42–43 helium 116 hidden variables 56–57, 60 Higgs bosons 13, 66, 124–25, 127, 133 Higgs field 127, 133 hydrogen 83, 99, 116, 128–29 IJK infrared radiation 14, 27 insulation 76 interference 16, 18–19, 58 intrinsic angular momentum 66, 67 ions 76, 81, 83, 87, 109 Josephson junctions 95, 96, 97 kinetic energy 82 G L gamma decay 113 gamma rays 113 gauge bosons 68, 124, 125, 126 Large Hadron Collider 121 lasers 82, 87, 102, 103, 109 lattice, geometric 76–77, 81, 94, 109 INDEX 157 leptons 12, 21, 123, 124–25 levitation, magnetic 94 light absorption 86 charge-coupled devices 93 coherent 86, 87 electromagnetic radiation 14, 22 lasers 87 light-emitting diodes (LEDs) 90, 92 photoelectric effect 32–33 photosynthesis 148–49 speed of 15, 74, 80 stimulated emission 86 light energy 148 light quanta 28, 30, 32 loop quantum gravity 144–45 M M-theory 143 Maglev transport systems 94 magnetic fields electromagnetic radiation 14 electron microscopes 100, 101 MRI 98–99 quantum navigation 152–53 SQUIDs 96–97 subatomic particles 67 superconductors 94 magnetic flux 96 magnetic moments 67, 99 magnetic resonance imaging 94, 98–99 magneto-optical traps 82 magnets, superconductors 94 many worlds interpretation 54 mass, particles 127 158 INDEX matter and antimatter 128–29 atoms 10 electromagnetic radiation 14, 15 and light 25 unusual states of 65 matter particles 14, 20, 21, 68, 122, 124–25, 128 matter waves 56, 100 measurement problem 46–47 mesons 12, 13, 135 metals, photoelectric effect 32–33 microwaves 14, 88 migrations, seasonal 152–53 momentum 41, 42–43 MRI scanners see magnetic resonance imaging multidimensional space 143 multiple states 38 multiple universes 54, 55 muon neutrinos 12, 123, 125 muons 12, 124 N nanoscale 102–103 neutrinos 123, 124–25 neutron stars 117 neutrons 8, 10, 12, 13, 20, 21, 70, 112–13, 122 nuclear fission 114–15 nuclear fusion 116 Newton, Isaac 35, 45 nuclear fission 111, 114–15 nuclear fusion 71, 111, 116–17 nuclear physics 111–19 nuclei, atomic 20, 111 nuclear fission 114–15 nuclear fusion 116–17 size 8, unstable 21, 65, 112–13 nucleons O objective collapse hypothesis 59 observable universes 55 observed/unobserved events 52–53, 59, 61, 63 olfaction 154 open vibrating strings 142 optical amplification 87 oscillations 14, 88–9 P p-orbitals 31 parallel universes 54, 55 particle accelerators 121, 130 particle detectors 18, 120, 121 particle physics 119–35 particle-wave duality 18–19 Pauli exclusion principle 69, 79 photodiodes 102 photoelectric effect 32–33 photons 13, 18, 22, 25, 46–47, 108, 113, 124, 126, 127, 152 charge-coupled devices 93 color and energy 30 LEDs 92 photoelectric effect 32–33 photosynthesis 148–49 Planck’s constant 15 polarization 106 quantum electrodynamics 134 stimulated emission 86 photosynthesis 148–49 pilot wave theory 56–57 pions 13 pixels 93 Planck, Max 28 Planck length 9, 140–41 Planck scale 9, 140–41, 144 Planck time 140–41 Planck’s constant 15, 44 plum pudding model 10 pointer state 60 position measuring 46–7 uncertainty principle 42–43 positrons 128–9 possibility waves 58 prime factors 107 principal quantum number 83 probability 35, 36–37, 40, 48, 53, 61, 62 protons 8, 10, 11, 12, 13, 20, 21, 22, 70, 112–13, 122, 128 MRI 98–9 Q QBism 63 quantum Bayesianism 61 quantum biology 147–55 quantum chromodynamics (QCD) 135 quantum computers 75, 105, 107, 109 quantum cryptography 108 quantum Darwinism 60 quantum electrodynamics (QED) 134 quantum entanglement 56, 57, 72–73, 74, 85, 107, 155 quantum field theory 119, 132–33, 134 quantum foam 140–41 quantum gravity 137–45 quantum information 105–109 quantum leaps 29 quantum magnetism 109 quantum mechanics 29, 41, 42, 46, 49, 133, 137, 138, 140 interpretations of 51–63 quantum mind 155 quantum navigation 152–53 quantum numbers 83, 130 quantum phenomena 65–83 quantum physics, interpretations of 51–63 quantum revolution 65 quantum simulation 109 quantum states 36–37 quantum superposition see superposition quantum technology 85–103 quantum teleportation 74 quantum tunneling 70–71, 95, 150, 151 quantum uncertainty see uncertainty principle quarks 8, 12, 20, 21, 67, 122, 124–25, 126, 127, 128, 131, 135 qubits 74, 106, 107 R radiation 14, 26–27 radical pairs 152 radio waves 14, 99 radioactive decay 21, 49, 65, 112–13 radioactivity 111, 112–13 Rayleigh-Jeans law 27 red light 32 reflection 16, 26 refraction 16 relational interpretation 63 resistance, electrical 81, 94 Rutherford model 10 Rydberg atoms 83 S s-orbitals 31 satellite navigation 88 satellite timekeepers 85 scalar bosons 125 Schrödinger’s cat 49 Schrödinger, Erwin 44–45, 49, 147 Schrödinger’s equation 44–45, 46, 48, 52 semiconductors 85, 92, 93, 96 sifted key 108 silicon chips 91 simulators 109 single state 39 smell, sense of 154 solid state physics 76–77, 90 solids, band theory 90 space-time 23, 137, 138, 141, 144 sparticles 131 Special Relativity 63 spectroscopy 87 spin 57, 66, 67, 72–73 electrons 38, 130 fermions and bosons 68 protons 98, 99 radical pairs 153 spin down 66, 68, 73 spin foam 144 spin networks 144, 145 spin up 66, 68, 72 squarks 131 SQUIDs 95, 96–97 Standard Model 119, 124–25, 127, 132 beyond the 130–31 stellar fusion 71, 117 stimulated emission 86, 87 string theories 137, 142, 143 strong nuclear force 20, 119, 122, 126, 139 subatomic particles 12–13 atomic structure 10 discovery of 7, 111 fermions and bosons 68 leptons 123 Pauli exclusion principle 69 quantum tunnelling 70–71 quarks 122 INDEX 159 subatomic scale 8–9 sun 23 sunlight 148–49 superconducting loops 96, 97 superconducting quantum interference devices see SQUIDs superconductivity 81, 94–97 superfluidity 80, 81 superforce 138–29 superposition 35, 38–39, 46–47, 48, 49, 106, 107, 108, 148, 155 supersymmetry 130–31 T teleportation see quantum teleportation temperature Bose-Einstein condensates 78–79 cold atom physics 82 and electromagnetic radiation 26–27 superconductivity 81 superfluidity 80 theories of everything 138–39, 142–45 thermal radiation 26 time 23, 44–45, 58, 88–89 transactional interpretation 58 transistors 90, 91 trapped ions 109 U ultraviolet catastrophe 27, 28 ultraviolet radiation 15, 27, 33 uncertainty principle, Heisenberg’s 42–43, 51, 132, 141, 155 universe cosmological interpretation 55 many worlds interpretation 54 theory of everything 138–39 unobserved events 52 V vibrating strings 142 vibrational theory of olfaction 154 viruses 100, 102 visible light 14 W W bosons 13, 21, 124, 126 wave function 35, 36–37, 52, 54, 55, 56, 60, 61, 62, 63, 70, 72, 75 Born rule 40 Fourier transforms 41 measurement problem 46–47 Schrödinger’s equation 44–45 spontaneous collapse 59 squared 40, 53 superposition 38–39, 46–47 transactional interpretation 58 uncertainty principle 42–3 wave-function collapse 35, 48, 49, 51, 53, 54, 56, 58, 59, 62, 63 waves 16–17 particle-wave duality 18–19 weak force 21, 119, 126, 139 XYZ X-rays 14, 112 Z bosons 13, 21, 125, 126 ACKNOWLEDGMENTS DK would like to thank the following for their help with this book: Dominic Walliman for work on the contents list; Mik Gates, Dan Crisp, and Dominic Clifford for illustrations; Katie John for proofreading; Helen Peters for the index; Senior Jacket Designer Suhita Dharamjit; Senior DTP Designer Harish Aggarwal; Jackets Editorial 160 INDEX Coordinator Priyanka Sharma; Managing Jackets Editor Saloni Singh All images © Dorling Kindersley For further information see: www.dkimages.com ... STRANGE QUANTUM ATOMS Cold atom physics 83 UNUSUAL ORBITS Rydberg atoms QUANTUM TECHNOLOGY QUANTUM INFORMATION 106 NOT JUST ZEROS AND ONES Qubits 107 SUPERFAST Quantum computing 108 QUANTUM CODES Quantum. .. REACTION Enzymes and quantum physics 152 MAGNETIC PERCEPTION Quantum navigation 154 OUR SENSE OF SMELL The quantum nose 155 QUANTUM CONSCIOUSNESS? The quantum mind 156 INDEX QUANTUM GRAVITY 138... Model  132 UNIVERSAL FIELDS Quantum field theory 134 THE JEWEL OF PHYSICS Quantum electrodynamics 135 THREE-COLOR QUARK Quantum chromodyamics 150 IT’S IN OUR DNA A quantum theory of cell mutation