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

3. 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...

4. The electro-magnetic force

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

6. Special Relativity

7. Quantum Mechanics

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

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

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

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

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

15. Multiplets According to the Yang-Mills-theory PN Nucleons pions Yang-Mills bosons

16. Peter Higgs

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

18. St. Weinberg S.L. Glashow A. Salam

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

20. ProtonLambda Antiproton Pi-plusPi-zero The hadronic particles …

21. The Yang-Mills Color Field Quantum Chromo Dynamics

22. Quark species quarks s u d uu dd ss Antiquarks up down ccc charm strange t b tt bb top bottom weak strong

23. Graviton Generation IGeneration II The Standard Model Gauge Bosons g Higgs Generation III Leptons Quarks

24. Total cross sections CESR DORIS PEP PETRA TRISTAN

25. Gravitation The fourth force:

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

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

28. The SuperString Theory

29. A Black Hole