The Mirror World is no longer an imaginary device, a mirage in a distant future, it is a reality under construction. In Europe, Asia and on the American continent, large companies and the best universities are working to build the infrastructures, to define their functionalities, to specify their logistics. The Mirror World, in its asymptotic form, presents a quasi-continuous representation of the world in motion, integrating, virtually, all photographic perspectives. It is a new giant computational object, opening the way to new research methods or even probably to a new type of science. The economic and cultural stakes of this third platform are immense. If the Mirror World transforms access to knowledge for new generations, as the Web and Social Networks did in their time, it is our responsibility to understand and, if need be, bend its technological trajectory to make this new platform an environment for the critical knowledge of the past and the creative imagination of the future.