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Molecule: Electrically neutral particle made of one or more atoms held together by covalent (electronsharing) bonds. Muon: The second-generation charged lepton (see pp. 84–5). Neutrino: Uncharged lepton that interacts only via the weak force (though recent results show they do have a very small mass). There are three flavours of neutrinos, corresponding to the charged leptons: the electron neutrino νe, the muon neutrino νμ and the tau neutrino ντ. Neutron: Neutral, spin-half hadron consisting of one up quark and two down quarks. Nucleons: Protons and neutrons (i.e. those that make up the nucleus). Nucleus: The centre of the atom, containing its protons and neutrons. Omega (baryon): Composed of three strange quarks, the Ω- baryon was predicted by the Eightfold Way, which in turn helped with the development of the quark model. Parity: A symmetry of nature relating to the inversion of an odd number of spatial coordinates (see p. 101). Parton: Feynman’s name for sub-nucleonic particles, i.e. quarks and gluons. Photon: Spin-one exchange boson of the electromagnetic force. Pion (a.k.a. pi meson): Hadron consisting of two up or down quarks; depending on the exact quark content, pions can be positively-charged, negatively-charged or neutral. Positron: The antimatter equivalent of the electron (electric charge +1). Proton: Positively-charged, spin-half hadron consisting of two up quarks and one down quark. Quantization: The division of a quantity into discrete (i.e. non-continuous) values. Quantum chromodynamics (QCD): Quantum field theory describing the interactions of quarks and gluons (see pp. 118–21). Quantum electrodynamics (QED): Quantum field theory describing the interactions of charged matter and photons (see pp. 76–81). Quantum Field Theory (QFT): A mathematical model in which every point in space is associated with an infinite number of tiny springs, each representing a potential chunk of energy. All matter and forces may be thought of as ripples passing through this network of springs. Quark: Spin-half elementary particle that experiences all four fundamental forces (see pp. 107–17). Radioactivity: The processes by which atomic nuclei undergo some sort of decay, losing energy via the release of ionizing radiation. Renormalization (cf. QFT): Mathematical technique used to remove infinities from quantum field theories by absorbing them into measurable quantities (see p. 78). Special Relativity: Theory that works from two postulates: that the laws of physics are the same wherever you test them, and that the speed of light is a fixed constant of the universe. See Introducing Relativity for more information. Spin: Quantum-mechanical property of a particle relating to a sort of internal angular momentum that is almost entirely unlike spinning about its own axis. See Introducing Quantum Theory for a more thorough explanation! Standard Model: The quantum field theory that combines our knowledge of the strong, weak and electromagnetic forces that describe the interactions of the known fundamental particles (see p. 104 onwards). Strangeness: Before the quark model was formulated, this was the property assigned to particles containing strange quarks. Strong force: One of the four fundamental forces of nature. It is described by quantum chromodynamics. Only particles with colour charge experience the strong force. Supersymmetry: A hypothetical symmetry of nature that relates fermions and bosons. Tau (lepton): The third-generation charged lepton (see p. 122). Not to be confused with the Tau of the Tau-Theta puzzle (see below). Tau-Theta puzzle: The two decay modes of the positive kaon (also known as the K+) have differing final state parities. When both were observed in cosmic rays, it was thought that they must be due to the decay of two different particles, even though the mass and charge were the same. The puzzle was resolved when it was realized that parity could be violated, i.e. the parity of the final state did not have to be the same as the parity of the initial state (see pp. 100–03). Wave mechanics: Formulation of quantum mechanics where a particle’s properties (position, momentum, etc.) are described in terms of statistical distributions that resemble the mathematical description of waves. Weak force: One of the four fundamental forces of nature. It is mediated by the massive W and Z bosons. Both quarks and leptons experience the weak force. X-ray: High-energy electromagnetic radiation. 190
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Index accelerators 88–94, 108 aether 6, 23–6, 28–9 al-Haythem, Ibn 20 alpha (particles) 42, 44–7, 54, 56, 66 Anderson, Carl 69, 75, 80, 85 Anderson, P.W. 144 antimatter 75–6 anti-neutron 97 anti-proton 97 Aristotle 5 asymptotic freedom 121 atom 14, 57 atomic mass 53 atomic number 53 Avogadro, Amedeo 17 Bahcall, John 184 ba r yon 110, 117 Becquerel, Henri 40, 42, 59, 98 Berners-Lee, Tim 168 beta (particles) 42 Bethe, Hans 78 Bevatron 94, 97 Bjorken, James 111 Blackett, Patrick 76–7, 93, 165 Bohr, Niels 48–9, 57 Boltzmann, Ludwig 19 Born, Max 70 boson 105, 177 bottom quark 114 Brout, Robert 144–5 Brown, Robert 19 Butler, Clifford 92 Cabbibo, Nicola 114 cathode rays 26–31, 38 Chadwick, James 56 charge-parity (CP) 112 Charpak, Georges 165 cloud chamber 36, 64–9 Cockcroft, John 88 collimation 91 confinement 120 corpuscles 21, 23, 37, 52 cosmic rays 58–63, 66–8 Cosmotron 94 Coulomb, Charles- Augustin de 59 Cowan, Clyde, Jr. 123–4 Cronin, James 113 Crookes, William 28–9, 59 Curie, Marie 40 Curie, Pierre 40 Cyclotron 89 Dalitz, Richard 100 Dalton, John 16–19 dark matter 178 Davis, Raymond, Jr. 184 Davisson, Joseph 72 Davy, Sir Humphry 18 de Broglie, Louis 72 deep inelastic scattering 116 Democritus 15 Descartes, René 7–8, 21 Dirac, Paul 69–76 drift chambers 166 Dualism 7–8 Dyson, Freeman 79 Eightfold Way 108–9 Einstein, Albert 19, 52, 81 electromagnetic force 127–9 electron 30, 37, 121 electron volt 88 elements 6, 8, 14 Ellis, Jonathan 148 empiricism 9 Englert, François 144–5 Evans, Lyn 170 experimental philosophy 11–12 Faraday, Michael 27, 50, 59 Fermi, Enrico 99 fermion 105, 177 Feynman, Richard 12, 79, 116 fields 50 Fitch, Val Logsden 113 frequency 52 G-Stack 94 gamma rays 42 Gassendi, Pierre 21 Gay-Lussac, J.L. 17 Geiger, Hans 44–5 Geiger–Müller tube 163, 165 Geissler, J.H.W. 26–8 Gell-Mann, Murray 95, 97, 107–9 General Relativity 138 Gianotti, Fabiola 174 Glaser, Donald 96 Glashow, Sheldon 111, 130–2 gluon 119 Goldstein, Eugen 28 Goldstone, Jeffrey 143 graviton 179–81 gravity 106, 179–81 Gross, David 121 Guralnik, Gerald 144–5 hadron 117 hadronization 120 Hagen, Carl 144–5 Hawking, Stephen 182 Heisenberg, Werner 70 Heisenberg’s Uncertainty Principle 55 Hertz, Heinrich 32–4, 38 Hess, Victor 63, 75 hierarchy problem 176 Higgs, Peter 144–7 Higgs boson 146–55, 160–2, 169, 172–8 Hittorf, Johann 28 Hooke, Robert 21 Huygens, Christaan 21, 23 Iliopoulos, John 111 internet 168 ion 37, 53 ionization 37, 61–3, 163 ISABELLE collider 150 isotope 53 J/ Ps i 111 Joliot-Curie, Frédéric 56 Joliot-Curie, Irène 56 Jordan, Pascual 70 kaon 113 Kelvin, Lord (Thomson) 10 Kemmer, Nicholas 86 Kibble, Tom 144–5 kinetic theory 19 191

Index accelerators 88–94, 108 aether 6, 23–6, 28–9 al-Haythem, Ibn 20 alpha (particles) 42, 44–7,

54, 56, 66 Anderson, Carl 69, 75, 80,

85 Anderson, P.W. 144 antimatter 75–6 anti-neutron 97 anti-proton 97 Aristotle 5 asymptotic freedom 121 atom 14, 57 atomic mass 53 atomic number 53 Avogadro, Amedeo 17

Bahcall, John 184 ba r yon 110, 117 Becquerel, Henri 40, 42,

59, 98 Berners-Lee, Tim 168 beta (particles) 42 Bethe, Hans 78 Bevatron 94, 97 Bjorken, James 111 Blackett, Patrick 76–7, 93,

165 Bohr, Niels 48–9, 57 Boltzmann, Ludwig 19 Born, Max 70 boson 105, 177 bottom quark 114 Brout, Robert 144–5 Brown, Robert 19 Butler, Clifford 92

Cabbibo, Nicola 114 cathode rays 26–31, 38 Chadwick, James 56 charge-parity (CP) 112 Charpak, Georges 165 cloud chamber 36, 64–9 Cockcroft, John 88 collimation 91 confinement 120 corpuscles 21, 23, 37, 52 cosmic rays 58–63, 66–8

Cosmotron 94 Coulomb, Charles-

Augustin de 59 Cowan, Clyde, Jr. 123–4 Cronin, James 113 Crookes, William 28–9, 59 Curie, Marie 40 Curie, Pierre 40 Cyclotron 89

Dalitz, Richard 100 Dalton, John 16–19 dark matter 178 Davis, Raymond, Jr. 184 Davisson, Joseph 72 Davy, Sir Humphry 18 de Broglie, Louis 72 deep inelastic scattering

116 Democritus 15 Descartes, René 7–8, 21 Dirac, Paul 69–76 drift chambers 166 Dualism 7–8 Dyson, Freeman 79

Eightfold Way 108–9 Einstein, Albert 19, 52, 81 electromagnetic force

127–9 electron 30, 37, 121 electron volt 88 elements 6, 8, 14 Ellis, Jonathan 148 empiricism 9 Englert, François 144–5 Evans, Lyn 170 experimental philosophy

11–12

Faraday, Michael 27, 50, 59 Fermi, Enrico 99 fermion 105, 177 Feynman, Richard 12, 79,

116 fields 50 Fitch, Val Logsden 113 frequency 52

G-Stack 94 gamma rays 42 Gassendi, Pierre 21 Gay-Lussac, J.L. 17

Geiger, Hans 44–5 Geiger–Müller tube 163,

165 Geissler, J.H.W. 26–8 Gell-Mann, Murray 95, 97,

107–9 General Relativity 138 Gianotti, Fabiola 174 Glaser, Donald 96 Glashow, Sheldon 111,

130–2 gluon 119 Goldstein, Eugen 28 Goldstone, Jeffrey 143 graviton 179–81 gravity 106, 179–81 Gross, David 121 Guralnik, Gerald 144–5

hadron 117 hadronization 120 Hagen, Carl 144–5 Hawking, Stephen 182 Heisenberg, Werner 70 Heisenberg’s Uncertainty

Principle 55 Hertz, Heinrich 32–4, 38 Hess, Victor 63, 75 hierarchy problem 176 Higgs, Peter 144–7 Higgs boson 146–55,

160–2, 169, 172–8 Hittorf, Johann 28 Hooke, Robert 21 Huygens, Christaan 21, 23

Iliopoulos, John 111 internet 168 ion 37, 53 ionization 37, 61–3, 163 ISABELLE collider 150 isotope 53

J/ Ps i 111 Joliot-Curie, Frédéric 56 Joliot-Curie, Irène 56 Jordan, Pascual 70

kaon 113 Kelvin, Lord (Thomson) 10 Kemmer, Nicholas 86 Kibble, Tom 144–5 kinetic theory 19

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