Archives in general – and contemporary big data archives in particular – are about mapping the world. On a map the notion of the unknown establishes an uncertain and speculative territory, an archival terra incognita. Ancient Roman and Medieval cartographers used to denote these uncertain territories with the phrase HIC SVNT LEONES (here are lions) or HIC SUNT DRAGONES (here are dragons), inhabiting them with fantastical creatures that would instil both a fear of the unknown and the desire to colonize it. Later, scientists would replace these imaginative animals with a more scientific mapping of the world. Today, with big data, the science of patterning has reached new levels. There are thus few parts of the world – humans included – that are not constantly in the process of being mapped, archived and calculated with a view to detecting patterns and eliminate or colonize unknowns. Only, the tools have changed from cartographic instruments to algorithmic models. And the motivations have expanded from colonial conquests and naval navigation to also encompass societal securitization, civic management and capitalist exploitation. In addition, algorithmic mappings chart not only spaces but also temporalities, creating new archival folds in time in which the future is folded back into the past. Paradoxically, however, these new archival mapping mechanisms have not only created new forms of knowing; they have also given rise to whole new modes of unknowing in the form of technical, political, social and financial black boxes. In addition they make apparent a significant archival challenge in the age of big data: that the empirical past – no matter how comprehensively collected – can never preclude the arrival – or attack – of the unknown and the unexpected. Questions that arise from these developments are: what kind of uncertainties arise from the unknown? Under which circumstances can we speak of an unknown? To what extent is the unknown (or the unconscious) included in notions of knowledge? What new forms of interpretation emerge from gaps in archival knowledge? And how do we conjure meaning from them? What are the levels of detectability in digital archives? What kind of ignorance do big data archives produce? What kinds of politics emerge from the unknown (politics of possibility, probability and pre-emption etc.)? What are the chances of making oneself unknown to the archival apparatus? Speakers: Wendy Chun (Brown), Keller Easterling (Yale), Laura Kurgan (Columbia), Natasha Dow-Schüll (Princeton / MIT)