Approaches to Quantum Gravity

IndexAdS/CFT duality, 17, 28, 169, 172–179, 182–184,188–190, 195, 207, 210, 229–231algebraic quantum field theory, 136, 138, 235, 236analog gravity, 100–102, 104, 109, 157, 158, 329,395, 513, 539anomalies, 239, 241, 242, 246, 248, 275, 489, 490anthropic principle, 23, 197approximation(semi-)classical, 91, 92, 104, 141, 248, 253, 290,293, 333, 357, 363, 396, 436, 437, 444, 496,510, 511, 517, 518, 523, 525, 559–561, 563,564, 576continuum, 141, 142, 147, 325–329, 337, 344, 356,357, 363, 370, 373, 374, 379, 381–384, 390,391, 393, 397–404, 414–416, 420, 422, 423,540, 559, 577asymptotic freedom, 115, 120, 123, 125, 126asymptotic safety, 111, 112, 114–117, 122–124, 126,159–162, 357background(in)dependence, 4, 44, 45, 47, 63, 64, 69, 80, 107,108, 110, 129, 130, 134, 136, 137, 139–142,144, 145, 147, 148, 157, 161, 178, 211, 213,217, 219, 222–226, 230, 235, 236, 243, 244,246–249, 272, 274, 287, 288, 290, 327–329,334, 348, 356, 357, 374, 549, 550, 559–561partial, 47, 63geometry, 4, 62, 84, 124, 137, 145, 161, 235, 236,272, 313, 336, 348, 349, 549, 552, 563spacetime, 157, 172, 313, 393, 401black hole, 17, 24, 28, 40, 126, 137, 152, 174–177,181, 183, 191, 196–200, 202, 203, 206, 231,248, 332, 388, 391, 395, 462, 475, 509, 555entropy, 9, 17, 175, 176, 188, 189, 191, 248, 253,255, 394, 395, 402–404, 411, 549, 556, 566evaporation, 126, 177, 178, 183, 388branes, 28, 169, 174, 180, 182, 188, 189, 213, 217,219, 220, 224, 225canonical constraints, 56, 58, 78, 81, 141, 155, 237,239, 240, 243, 245–247, 254, 255, 258, 265,267, 273–276, 283–285, 323, 328, 374, 378,379, 382, 386, 389, 391, 415, 512, 513, 516canonical quantum gravity, 9, 46, 144, 196, 235, 318,319, 323, 325, 328, 333, 373, 386, 393categorical state sum, 90, 91category theory, 85–87and Feynman diagrams, 86and quantum gravity, 90and topology, 88n-categories, 87, 89, 90, 95, 97nerve of a category, 88tensor categories, 85, 86, 90, 142causal diamonds, 30, 33, 191–198, 201, 202, 204,206, 207, 231causal set theory, 326, 327, 329, 393–411, 422, 423,542, 550causal sets, 10, 26–30, 32, 36, 38, 39, 42, 65, 70, 96,104, 129, 136–139, 152–154, 327, 393,397–399, 404–407, 410, 422causal sites, 49, 94–96, 155–157causality, 3, 8, 13, 14, 17, 29, 40, 52, 69, 94–96, 105,138, 155, 163, 164, 193–195, 206, 207, 236,284, 323, 326, 328, 345, 348, 357, 395, 397,398, 404, 406, 417, 541, 549, 550, 559, 561,562, 566, 567cellular automata, 18Chern–Simons theory, 214, 220, 290, 298, 555, 556,558classical gravity variables, 47–54, 56, 60–62, 81,159–161, 243, 244, 253–257, 259, 276, 286,287, 291, 311, 325coarse graining, 91–93, 142, 164, 326, 327, 329, 399,400conformal field theory, 171, 179, 180, 183, 188, 189,207, 211, 219, 221, 224, 230, 372, 419conformal structures, 50, 52, 57–59consistent histories, 70, 71, 74, 91–93cosmological constant, 3, 17, 22–24, 28, 41, 42, 106,108–110, 116, 117, 122, 124, 126, 153, 184,190, 197, 210, 229–231, 298, 307, 318, 335,347, 348, 355–357, 364, 408, 459, 491, 496,497, 500, 509, 538, 542, 549, 557, 561, 562580