This fascinating National Geographic documentary, out on a Blu-ray/DVD set, explores the idea that we are surrounded by things unseen. Much of it is microscopic, from pollen in the air to mites on our skin—and as narrator Forest Whitaker says, there may still be millions of undiscovered microscopic species. But there are also things moving too fast for our eyes to catch—and too slow, along with light waves and colors we cannot discern.
