If we, the physicist and philosopher decided to collaborate in order to write about physics' "black ideas," it was because the things that physics qualifies as "black" are fascinating: black sky, blackbody, black hole, dark matter, dark energy, etc. What lies behind these obscure terms? These are not just curious names, but ideas which have played – and sometimes still play – a critical role in physics, as astrophysicist Roland Lehoucq shows us. Moreover, not only is it necessary to examine how science is changing the meaning of the adjective "black," it is also vital to describe how this adjective "colours," in turn, the scientific term. That is why philosopher of science Vincent Bontems analyses what the adjective surreptitiously carries from the darkness of the imaginary into the scientific field. The black idea then becomes a black image, which inspires delectable daydreams. We therefore explain, on each occasion, the denotation of the adjective “black” – not only what it actually means to a physicist, but also its connotation; i.e., what it metaphorically, and at times unconsciously, brings to mind. In coupling the epistemological analysis of black ideas with a psychoanalysis of black images, we are following the example of philosopher Gaston Bachelard, who was already studying in tandem the historic evolution of thermal spread theories and the associations of images in ramblings on the topics of fire, science and the imaginary.Vincent Bontems, an ENS Ulm graduate, works in a CEA research laboratory. Among his important contributions are his interviews with Bernard Stiegler, published in 2008 (Economiede l’hypermatériel et psychopouvoir). Roland Lehoucq, who holds an agrégation in physics, is an astrophysicist at the AEC whose specialty is cosmic topology. Since the start of the 2015 school year, he has also been teaching Scientific Humanities at Sciences Po, Paris.
