Desc: Quels temps font-ils?: Directed by Hervé Lièvre. With Philippe Bouclet, Anne Coutureau, Oscar Lièvre. Despite its familiarity, the concept of time raises many difficulties whose number grows as we attempt to analyze it. For example, it is very difficult to define the time. However, physicists have managed to make time an operative concept. - What time is? Time is first an indefinable word. - Does time exist? What kind of existence we attribute to him? - How to compare, oppose, objective time and subjective time? - The time he runs evenly? Compared to What does it flows? Has it an original? Will it end? Is it reversible? Is it cyclical or linear? - The arrow of time, second law of thermodynamics, entropy - The relativistic revolution duration are not absolute, the concept of simultaneity between two events loses its meaning. - General relativity, gravitation theory: space-time couples to matter and energy. Problem of the origin of time. - The fact of operating a measurement on a quantum system he introduced irreversibility? - Can the particles back in time?