The Sun as reference

The motions of the Sun and Moon form the basis of our calendars. The measurement of mechanical time is largely based on the periodic reoccurrence of certain phenomena: the rhythm of day and night, the seasons, or the cyclic reappearance of the planets and stars in the sky. The flow of change is attested by the apparently irreversible global evolution of the Cosmos. Cosmic time, eternity's yardstick, is the measure of universal change, of the evolution of matter, and this evolution is essentially one of nuclear complexification, driven by stellar forces.

The material evolution we are speaking of here is at work in all galaxies. Every part of the Universe is evolving, and the driving force is the stars. Everywhere on Earth, there are men, women and children; everywhere in the sky, there are stars. The star seems to be the best-adapted form of the visible Universe.

The path that leads from the multitude of anonymous and abstract elementary particles generated in the original explosion to the grass in the meadows, to the rain and the wind, to the infinite variety of shapes and states, to the profusion of feelings, must necessarily pass through the stars. Stars are an essential link between the primordial raw material that came out of the Big Bang and complex material with the ability to think. Nuclear astrophysics is the bridge between elementary particle physics and life.