Termin:
27.11.2002
18:15
Hazard and Chaos in the Solar System
Jacques Laskar, L'Observatoire de Paris
Laplace could not explain the observed perturbations of the motion of Jupiter and Saturn. He assumed that these variations could be due to comets perturbations. This to a large extent motivated his interest in developing the probability theory, as he needed to know wheter the comets orbits were random or not.
Later on he demonstrated that these irregularities could actually be explained by the sole Newtonian interactions among the planets. From there, the determinism paradigm of Laplace probably originated, saying that the whole future and the whole past could be predicted by the simple knowledge of the present state and of the equations governing the universe.
In fact, the results obtained in recent years show the contrary: that the motion of the planetary orbits is chaotic and that it will not be possible to predict their precise evolution over more than a few millions of years. As well as for the orbits, the orientation of the rotation axis of the terrestrial planets have experienced a highly chaotic state during their history and in absence of the Moon the Earth orientation would still be chaotic with very large variations.
Moderation: Peter Michor, Universität Wien
Information:
Dr. Marianne Baumgart, Öffentlichkeitsarbeit, ÖAW
T (+43 1) 51581/1219, F (+43 1) 51581/1275
Marianne.Baumgart@oeaw.ac.at