The anthropic principle and the structure of the physical world

The basic features of galaxies, stars, planets and the everyday world are essentially determined by a few microphysical constants and by the effects of gravitation. Many interrelations between different scales that at first sight seem surprising are straightforward consequences of simple physical arguments. But several aspects of our Universe-some of which seem to be prerequisites for the evolution of any form of life-depend rather delicately on apparent `coincidences' among the physical constants.