Astro-physicist and star-gazer Hubert REEVES takes us in his lecture, delivered on 27 February 2006, on a journey
through space and time, starting with the question « why is the sky dark at night » when there are so many shining
stars in the universe and they should be lighting up the heavens. REEVES suggests that the answer to this
conundrum was first given by Edgar Allen POE, who hinted that it was because many of those stars are so distant
that their light has not yet had time to reach us. REEVES goes on to discuss the age of the universe since the « Big
Bang » roughly 14 billion years ago and its continuous expansion with galaxies receding ever further and faster.
Will dark energy slow down this expansion, or is this expansion accelerating as new findings, following Hubble’s
observations since 1995, seem to suggest? Or will the universe end, and when, with a Big Bang, a Big Freeze or
a Big Crunch ?
The article includes an overview of the major theories and findings about the nature, the origins and the extent
of the universe during the past 25 years as well as an analysis of the instruments used to explore it (optical and
radio telescopes, satellites, the analysis of light rays…). Following the lecture, the author replied to questions on
the curvature of space, the different colours of galaxies, fossil radiations, the limitless nature of the universe, with
no origin, no centre and no periphery, black holes, general relativity theory and quantum physics.