The so-called 'hard' or 'exact' sciences, with their necessary emphasis on technology and on the technical, are hardly reputed for being very human, and, conversely, the so-called 'human' sciences are often pronounced as 'soft' because they cannot be based on the certainties associated with the former. The search for truth - which is the essential dimension of the construction of a peaceful world - therefore has to navigate between considerations of a philosophical nature and the concrete data of the hard sciences. If, ever since the humanism of the Renaissance period, we have been happy to lay claim to the wisdom of one of its great writers, Rabelais, who taught a moral lesson to the young Pantagruel with the neat formula "science without conscience is the ruin of the soul", we nonetheless stand in awe before modern scientific advances and the extraordinary achievements that they have opened up. If everything is not permissible, at least everything seems possible!