The three discrete symmetries of nature C (invariance of the hamiltonian under charge conjugation - symmetrical equivalence between matter and antimatter), P (Parity conservation, invariance of the hamiltonian under space inversion) and T (time
reversal symmetry) are well known to be fundamentally violated. We discuss the possible relation of this symmetry violation to the observation of prevalence of matter over antimatter in the universe, the prevalence of L-aminoacids and D-sugars over D-aminoacids and L-sugars in the biochemistry of evolution (``homochirality'') and the observation of a unique time direction in natural processes. Particular stress will be laid on molecular spectroscopy as a possible experimental approach towards the symmetry violations connected with T and P [1,2]. Current calculations [3-9] on parity violation in molecules lead to orders of magnitude larger values than previously anticipated [10]. The consequences for the selection of biomolecular homochirality are discussed.

If time permits, we will discuss CPT symmetry violation and the hypothetical construction of an absolute molecular clock (defining an absolute time direction).

References:
1. M. Quack, Angew. Chem. Int. Ed. Engl. 28, 571 (1989)
2. M. Quack, Nova Acta Leopoldina NF 81, 137 (1999)
3. A. Bakasov, T.K. Ha, M. Quack, Proc. of the 4^th Trieste Conference (1995), Chemical Evolution: Physics of the Origin and Evolution of Life, Chela-Flores, J. and Rolin, F. (eds), p. 287 (1996), Kluwer publisher, Dordrecht
4. A. Bakasov, T.K. Ha, M. Quack, J. Chem. Phys. 109, 7263 (1998); and earlier references therein.
5. A. Bakasov, M. Quack, Chem. Phys. Lett. 303, 547 (1999)
6. R. Berger, M. Quack, J. Chem. Phys. 112, 3148 (2000)
7. R. Berger, M. Quack, Angew. Chemie -- ChemPhysChem (2000), in press
8. R. Berger, M. Quack, G. Tschumper, Helv. Chim. Acta (2000), in press
9. M. Quack, J. Stohner, Phys. Rev. Lett. 84, 3807 (2000)
10. R.A. Hegstrom, D.W. Rein, P.G.H. Sandars, J. Chem. Phys. 73, 2329 (1980)