The heart of scientific enquiry lies in the understanding we amass from observation and experiment. In physics, this enquiry changes as we vary the scale, wherein, at the smallest scale we arrive at quantum mechanics. The point at which a paradigmatic shift occurs, the “quantum to classical transition” is hotly debated and poorly understood. This project will address not “where” but rather “how” this transition occurs, and look at how effective descriptions of nature emerge from the microscopic physics of underlying many-body quantum systems. The activities will blend theoretical work from complexity theory and quantum information to direct experiments with many-body ultra-cold atomic quantum gases. Such work is needed because not only will it answer open scientific problems, but also because it will bridge the gap between foundational physics and algorithmic complexity, establishing new pathways for the discovery of physical laws. The deliverables will primarily be peer-reviewed articles; presentations at international conferences and a local seminar series among the participating institutions in Vienna. The project has the potential for enormous impact by uncovering a robust and systematic prescription of how large scale behaviours emerge from microscopic principles.