The first detection of the CMB that opened a new field in cosmology

The Cosmic Microwave Background, the oldest signal that can be seen in the sky, is the direct proof that our Universe was extremely dense and hot several billion years ago. The first experimental detection of this fossil radiation has been performed in 1964 and has since then become a powerful tool to probe the formation and evolution of the Universe. Observations of this extremely faint signal pushes the boundaries of many technological developments notably in the fields of optics, detection and cryogenics for space applications