“The Arc of Oblivion” explores a quirk of humankind: in a universe that erases its tracks, we humans are hellbent on leaving a trace. Set against the backdrop of the filmmaker’s quixotic quest to build an ark in a field in Maine, the film heads far afield – to salt mines in the Alps, fjords in the Arctic, and ancient libraries in the Sahara – to illuminate the strange world of archives, record-keeping, and memory.