Q
see Robinson arithmetic
q-hypergeometric functions
in hard hexagon problem, 1133
q-numbers
as generalizing numbers, 1168
QCD (quantum chromodynamics), 1057, 1061
and computational irreducibility, 1133
and experience of models in, 991
as simple physical model, 1025
QED
see Quantum electrodynamics
QSPR (quantitative structure-property relations), 1195
Quadratic congruential generators, 975
Quadratic Diophantine equations, 944
NP completeness of, 1146
Quadratic equations
as exactly soluble, 1133
Quadratic forms
and Diophantine equations, 1164
Quadratic functions
in Turing machines, 1144
Quadratic irrationals
and constructible reals, 1129
and continued fraction map, 955
and Penrose tilings, 932
and spectra, 1081
see also Sqrt (square root)
Quadratic maps, 921
and history of chaos, 971
Quadratic primes conjecture
as unsolved problem, 1166
Quadratic programming
and circle packings, 986
Quadratic residue sequences, 1090
in acoustic diffusers, 1183
and flat spectra, 1081
NP completeness in, 1145
Quadratures
as exact solutions, 1133
Quadrics
fit to curved surfaces, 1049
Quadtrees, 568, 1101
Quality factor
in image compression, 573
Quantifier elimination
and commutative groups, 1160
and real algebra, 1154
Quantifiers
higher-order, 1167
in predicate logic, 1151
in well-formed formulas, 1150
Quantitative traits, 1003
Quantization
and discreteness of networks, 528
of volume in spin networks, 1055
Quantized vortices
in neutron stars, 1188
Quantum chaos, 1056
and decoherence, 1064
Quantum chromodynamics
see QCD
Quantum computers, 1147
and NP completeness of factoring, 1090
and quantum history, 1058
vs. Turing machines, 771
Quantum cosmology, 1026, 1063
Quantum cryptography, 1058
Quantum-dot cellular automata, 1193
Quantum electrodynamics (QED)
as analogy for quantum gravity, 1054
effective coupling in, 1062
Feynman diagrams in, 1060
history of, 1056
Monte Carlo methods in, 1192
and point electrons, 1044
Quantum field theory, 1061
and computational irreducibility, 1133
difficulty of computations in, 1146
and discrete space, 1027
and energy conditions, 1053
and gravity, 1054
and knot theory, 1046
measurement in, 1065
and origins of mass, 1046
particles in, 540
planar diagrams in, 1040
and quantum computers, 1148
and quantum measurement, 1064
and random networks, 1038
simple effective theories in, 1026
and space as background, 1028
and ultimate theory of physics, 1025
and uniform spectra, 988
vacuum fluctuations in, 1062
|  | Quantum fluctuations
and noise, 969
Quantum gravity, 1054
and discrete space, 1027
and Hawking radiation, 1062
history of, 1025
path integrals in, 1057
as source of decoherence, 1063
and space vs. contents, 1028
and spin networks, 1055
undecidability in models of, 1138
Quantum groups
and spin networks, 1055
Quantum information theory, 1058
Quantum measurement, 542, 1062
vs. computational irreducibility, 1135
and multiway systems, 1036
Quantum mechanics, 537-545
and atomism, 876
Brillouin zones in, 988
and character of programs, 538
and Church's Thesis, 1126
discretization of, 1059
and existence of formulas, 1132
and free will, 752, 1135
and gauge invariance, 1045
history of, 1056
and history of randomness, 967
and history of statistics, 1082
and mechanistic explanations, 860
and new types of perception, 1106
and NP completeness, 771
and origins of Second Law, 1020
and PDEs, 923
on Pioneer 10 plaque, 1190
and randomness, 303, 539, 970
search for defining features of, 1059
in ultimate theory of physics, 469
and use of abstract models, 1026
and wave-particle duality, 1044
Quantum numbers
and network tangles, 527
Quantum potential, 1065
Quarantine of astronauts, 1180
Quark confinement
and computational irreducibility, 1133
Quarks
confinement of, 1061
as example of model, 992
masses of, 1046
and particle history, 1025
and QCD, 1057
as types of particle, 1043
Quartic equations
and computational reducibility, 1132
as exactly soluble, 1133
size of solutions to, 945
Quartz
hopper crystals in, 993
Quasars
and SETI, 1189
Quasi-Monte Carlo methods
and digit reversal, 905
as randomness application, 1192
and statistical tests, 1085
Quasicrystals, 994
diffraction patterns in, 1082
spectra in, 1080
Quasigroups, 945, 1171
Quasiperfect numbers, 911
Quasiperiodicity
in combinations of sines, 146
and turbulence, 998
Quaternions
and abstraction in math, 792
cellular automata based on, 886
as generalizing numbers, 1168
as non-commutative rings, 1153
Qubits (in quantum systems), 1147
Queen Anne's Lace, 1006
Quicksort algorithm, 1142, 1142'
Quincunx board
randomness in, 312
Quine-McCluskey procedure, 1095
Quintic equations, 945
as exactly soluble, 1133
numbers defined by, 916
solving as impossibility, 1137
unsolvability of, 1132
Quotient
basic example of, 854
and computational reducibility, 747
encoded as integer equation, 1160
Qur'an
calligraphy from, 874
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