Hugging a long, curving wall in the National Academy of Sciences’s second-floor gallery, the video installation “Blue Dreams” is as immersive and expansive as an ocean view. Yet the imagery that flits across the seven contiguous screens depicts the seas’ microbial networks, which a gallery note calls “our planet’s smallest yet most vital living systems.” Devised by Rebecca Rutstein and the Ocean Memory Project, the video uses photographic, abstract and computer-generated material to render visible the infinitesimal.