Utrecht University The Nature of and Gerard t

Utrecht University The Nature of and Gerard ’t Hooft Stockholm, August 27, 2004

Sir James Clark Maxwell 1831 -1879 - Statistical Mechanics - Thermodynamics - Improved the mathematical formulation of Michael Faraday’s theories of electricity and magnetic lines of force. . .

The electro-magnetic force

Albert Einstein 1879 – 1955 1905: - Photo-electric effect - Special Relativity - Brownian motion; statistical mechanics 1915: General relativity (gravitation)

Special Relativity

Quantum Mechanics

Special Relativity + Quantum Mechanics = Elementary Particle Physics ( = High Energy Physics = Quantum Field Theory )

photon 1969 Leptons antileptons mesons Hadrons This is only 4 % of the matter in the Universe ! (See Licia Verde’s talk) baryons anti

Known from experiment Forces: the ELECTRO MAGNETIC force the forces the STRONG force the WEAK force

The Yang-Mills Field C. N. Yang and R. L. Mills, 1954

Yang - Mills quanta - o + proton - + o neutron

Multiplets According to the Yang-Mills-theory P N Nucleons pions Yang-Mills bosons

Peter Higgs

Breaking Rotational Symmetry THIS becomes an essential degree of freedom. . . … turning the gauge force carriers massive ! And THIS is the Higgs degree of Freedom

S. L. Glashow St. Weinberg A. Salam

Weinberg’s lepton model Leptons Gauge bosons Weinberg Model Higgs Anti – Leptons

The hadronic particles … Proton Antiproton Lambda Pi-plus Pi-zero

The Yang-Mills Color Field Quantum Chromo Dynamics

Quark species weak quarks Antiquarks u u u d d d c strong c c s s t t b b s t b up down charm strange top bottom

The Standard Model Generation III Leptons Quarks Gauge Bosons g Higgs Graviton

Total cross sections CESR DORIS PEP PETRA TRISTAN

The fourth force: Gravitation

The highway across the desert Today’s Limit … Planck length : GUTs

SU(4) x SU(2) Further unification SO(10) 3 generations

The Super. String Theory

A Black Hole