Everything is a computer RichardKenway Kenway Richard Theory of Everything conjecture 1: our Universe is completely described by a mathematical model TOE is unique: no free parameters one Universe (God is a mathematician) TOE is not unique: various parameter values are allowed a Multiverse (anthropic), or one Universe is chosen (intelligent design) includes quantum mechanics and so does not obviously exclude consciousness, free will, time travel, May 2006

Richard Kenway 2 May 2006 Richard Kenway 3 objective of physics the TOE guided by mathematical beauty/symmetry falsification by experiment/observation reverse engineering TOE today: General Relativity + Standard Model 25 free parameters unlikely to be fundamental constants our existence is very sensitive to their values not fully quantum gravity reality = TOE today

weird enough discrepancies with experiment new physics = progress May 2006 Richard Kenway 4 Standard Model matter, as we know it, is made of quarks and leptons interacting through four forces QCD May 2006 Richard Kenway 5

unified theory consequences all particles are manifestations of one fundamental entity quarks can change into leptons protons decay us u d May 2006 Richard Kenway 6 do protons decay? watch 50 kton of water 1km underground

(1 kton = 1033 protons) none observed lifetime p K 2.3 1033 years May 2006 Richard Kenway 7 calculating the proton lifetime u ? u lifetime p K 2.3 1033 years QCD factor new physics at 1016 GeV

if we compute the QCD factor, the experimental lifetime bound constrains theories of new physics this requires simulating how quarks and gluons make a proton May 2006 Richard Kenway 8 simulation

conjecture 2: the TOE may be simulated to arbitrary precision on a computer O D O e D e i S i S for imaginary time t i , e

i S e S ~ a probability Monte Carlo generation of quantum fields works for QCD other theories have a sign problem the motivation for quantum computers may need a quantum computer many worlds and their consequences enter here

May 2006 Richard Kenway 9 simulation of QCD integral over anti-commuting quarks and SU(3) gluons 1 D U m 1 S G U O DU det D U m e O U , , e Z

, 0 finite Euclidean spacetime lattice sparse linear equation solver (hybrid) Monte Carlo we cannot measure experimentally quark masses or mixings, only hadron masses and decays reverse engineer

quark masses (& mixings) + gauge coupling properties of hadrons Lattice QCD May 2006 Richard Kenway 10 computational cost and parallel computing 1 # operations L4.5 5.0 a 7.0 8.5 1

M PS 2.5 3.5 lattice spacing must be extrapolated to zero L keeping box large enough halving lattice spacing 500 computing speed a Moores law: microprocessor speeds double every 18-24 months performance number of processors May 2006 Richard Kenway

11 May 2006 Richard Kenway 12 determination of Standard Model parameters depressingly self-consistent only the Higgs boson is missing May 2006 Richard Kenway 13 dark energy

but most of our Universe is also missing! atoms 4% dark matter 23% inflaton, neutralino, axion, atoms + dark matter dark energy 73% May 2006 Richard Kenway 14 effective theories conjecture 3: reality is described by a finite set of effective theories each of which can be simulated S S e D T , e , x L L

x L D T , 1 simulation bridges between short (L) and long scale (L') computational cost of virtual reality is bounded but very large beginning with the TOE May 2006 Richard Kenway

15 reverse engineer our Universe today visible matter dark matter ? Millennium simulation May 2006 10,077,696,000 particles Richard Kenway 16 the challenge for computing Higgs boson or new physics

QCDOC the last pre-LHC machine must be found at LHC the next layer in the onion QCD is an effective theory will classical digital computers be sufficient? conjecture 4: everything can be simulated May 2006 everything is a simulation? Richard Kenway 17 life, the Universe, everything

nuclei neutron stars fusion solar weather chemistry designer materials complex molecules living organisms brain mind May 2006 Richard Kenway 18