Index
anthropic principle, 199, 243–248. See also selection effects
approximation, appeal for interpreting quantum theory
Bacon, Francis, 17
Bell, John
survey of proposals about measurement problem, 141–146, 292
against Everett, 149
biography, 183
biased sampling. See selection effects
Born-rule probabilities, in quantum theory, 143, 175–179
branch, in Everettian quantum theory. See Everettian multiverse
between possible worlds, 17–18, 280–283
coherent state, 152
combinatorial conception of possible worlds, 101–104
concrete/abstract distinction, 106–107, 119–121, 281
confirmation of a cosmological multiverse, difficulties about, 238–240
constant of nature, as varying in string theory, 196–197
contingency,
of laws of nature, e.g. in Hume, 35–37, 41–42, 44–45
of laws of nature, in modern metaphysics, 84–85, 93–96
of laws of nature, in cosmological multiverse, 200–203, 218–222, 243–248
of laws of nature, in Wilson’s proposal, 284–290
of the state of the universe, 159–160, 200–205
Cosmic microwave background (CMB), 204–205
and standard model, 207–210, 211, 217, 277
cosmological constant, the problem of, 235, 247, 265–266
cosmological multiverse compared with Everettian multiverse, 200–205, 256–260
seeing other bubbles, 277
cosmology
counterfactual conditionals, 85–90
decision theory, 68–70, 178–179
determination. See supervenience
determinism, 73–74, 96–98, 136–137
in Everettian quantum theory, 171–175
double-slit experiment, 278–280, 292
Eddington Arthur, 242, 263–264, 295–296
eigen-quantity, 135
eigenstate, 135
eigenvalue, 135
equation of motion, 71
Everett, Hugh, 188. See also Everettian multiverse
Everettian multiverse, 146–179, 187–193
splitting or diverging of worlds, 148–150, 286–287
explaining definite appearances, 148–150
appealing to decoherence, 148, 150–160
my assessment, 167–171, 272–274
seeing other worlds/branches, 278–280
Everettian multiverse as philosophical multiverse, proposed by Wilson, 284–287
Everettian multiverse compared with cosmological multiverse, 200–205, 256–260, 274–277
explanation, philosophical accounts of, 222–225
extension. See reference, in semantics
field conception of matter
in quantum mechanics of a quantum particle, 127–129
in quantum field theory, 132–134
fine tuning, as a problem, 196–198
illustrated by cosmological constant problem, 235
illustrated by mass of Higgs boson, 235–237
fine tuning, explained as being generic or typical, 199
illustrated by flatness and horizon problems, 226–227
by appeal to topology, 230–231
by appeal to effective field theories, 231–233
by appeal to probability, 233–234
fine tuning, explained as being likely to be observed. See selection effects
fine tuning of several parameters, 245–247, 258, 265
flatness problem, 212–213, 226–227
Fock space, 132–134. See also quantum state, as assignment of amplitudes to classical configurations
Frege, Gottlob
general relativity, 31–32, 274
generic, the strategy (Gen). See fine tuning, explained as being generic or typical
Hartle and Srednicki’s Scheme, 249–252
history, in Everettian quantum theory. See Everettian multiverse
horizon problem, 212–213, 226–227
Hume, David, 35–37, 41, 48, 50–52, 291
imagination, as proposed explanation of modality, 98–101
induction, problem of, 35–37. See also Hume, David
inflation
as solving flatness and horizon problems, 195–196, 215–216
mechanism from string theory, 198
mechanism from inflaton field, 216–217
intension. See sense, in semantics
interference terms, 151, 278–280
interpretations of quantum theory
as responses to measurement problem, surveyed, 141–146
Kent’s interpretation, 186
Landsman’s interpretation, 186
modal interpretations, 185
pragmatist interpretations, 184
Kent, Adrian, 186
Landsman, Nicolaas, 186
Laws of nature, 14–15, 84, 97, 286–287
Leggett, Anthony, 187
Leibniz, Gottfried, 40
Lewis, David
proposals about semantics, 76–83, 85–90
proposals about metaphysics, 83–85, 90–98
proposal about the nature of possible worlds, 110–112
his proposal applied to Everettian multiverse, 285–287
his critique of other proposals, 105–110, 110–112,
against seeing other possible worlds, 17–18, 280–283, 293
logic, from 1600 to 1900, 39–47
mathematics, pure, 42–46, 54–55, 118–121
measurement problem of quantum theory, 134–141
proposed solutions, apart from Everett, 141–146
amplitudes interpreted in terms of probabilities of measurement results, 129–131
as a problem on the cosmic scale, 203–204, 260
method. See philosophical method
mixtures, probabilistic, 151–155
proper (ignorance-interpretable) vs. improper, 154–155
modal metaphysics, 64–68, 98–113
multiverse proposals, three proposals and three associated questions, 1–8
relations between proposals, 200–206, 218–222, 283–290
lack of causation between universes, 277–283
Newton, Isaac
his theory of gravity, 29–32, 47, 52–53
his influence on philosophy, 37–39
objects as patterns, in Everettian quantum theory. See Everettian multiverse
Observation, explanation of a value as likely to be observed, the strategy (Obs). See selection effects
Omega (Ω), the ratio of universe’s actual density to its critical density, 213, 226–227, 245–246
quantum particle, 127–129, 130–131
as an excitation of quantum field, 134
caution vs confidence about a concept, 12–15, 57–58
the beguiling power of words, 15–18
philosophical multiverse, 57–122
contrasted with physical multiverses, 271–272
seeing other possible worlds, 280–283, 293
pilot-wave theory, 145–146, 182
Plutarch, 292
possible worlds
use in semantics, 74–83, 85–90
use in metaphysics, 83–85, 90–98
debate about their nature, 98–113
probability
the qualitative problem in classical physics, 172–173
the qualitative problem in Everettian quantum physics, 174–175
the quantitative problem, 175–179
as an approach to explaining fine tuning, 233–234
See also Born-rule probabilities, mixtures
projection postulate, 143, 157. See also wave function
Pythagoreanism, xv, 119–121. See also concrete/abstract distinction
quantum gravity, 274
quantum state, as assignment of amplitudes to classical configurations
for one or more particles, 127–129, 130–131
amplitudes interpreted in terms of probabilities of measurement results, 129–131
See also wave function
reduction
of pure mathematics to logic, 45–47, 48–49, 54–55, 59–62
reference, in semantics, 76–83
relations between philosophy and physics, 2–3
in historical context, 24–26, 35–39
in assessing multiverse proposals, 8–9, 10–12, 271–272, 287–290
relative state, in Everettian quantum theory, 157
Schrödinger’s cat, 139–141, 154–155. See also Everettian multiverse, objects as patterns
Schrödinger’s objection to Bohr, 169–171
selection effects
in general, 199, 222, 225, 240–243
set theory, 45–47, 59–62, 64–65, 105–110
state space, of a physical system, 70–73
string theory
basic idea, 196–198, 201, 218–219
prompting a multiverse proposal, xv, 196–198
superposition, 135–136, 137–139, 278–280
Tegmark, Max, 119–121, 254. See also concrete/abstract distinction
truth table, 79
as mistaken proposed explanation of modality, 101–104
typical, the strategy (Gen). See fine tuning, explained as being generic or typical
universe, sketch of thermal history, 210–212
not a state of nothing, 256
Wallace, David, 160–165, 190–193
wave function, 129
collapse of the wave function, 143, 182
collapse as a physical process in cosmology, 260
universal wave function, in Everettian quantum theory, 146–147
universal wave function, in quantum cosmology, 200–205, 261
See also quantum state, as assignment of amplitudes to classical configurations
Weinberg, Steven, 187, 247–248
Wilson, Alastair
proposal that the Everettian multiverse is the philosophical multiverse, 283–287, 293–295
world, in Everettian quantum theory. See Everettian multiverse