Experimental time-domain astrophysics is on the verge of a new era as technological, computational, and operational progress combine to revolutionise the manner in which we study the time-variable sky. This proposal consolidates previous breakthrough work on wide-field surveys into a coherent program to advance our study of the variable sky on ever decreasing time-scales: from days, through hours, to minutes. We will watch how stars explode in real time in order to study the complex physics of stellar death, build new tools to handle and analyse the uniquely new data sets we are collecting, and shed light on some of the most fundamental questions in modern astrophysics: from the origin of the elements, via the explosions mechanism of supernova explosions, to the feedback processes that drive star formation and galaxy evolution.