Neurologist Oliver Sacks tells us about his fascination with time. As his soon-to-be-published essay in the New Yorker will tell you, he's been fascinated by time and has used photography to get inside it since he was a little boy. We'll hear a recording of a baby becoming a young woman, in "Nancy Grows Up." "Nancy Grows Up" by Tony Schwartz from "Tony Schwartz Records the Sounds of Children" FW05583, provided courtesy of Smithsonian Folkways Recordings. © 1970. Used by permission.

How did we get from a sundial - using the sun to tell us about the passing of time - to standarized time?

Radiolab takes a spin through the history of time, making a stop at the way the railroads changed our experience of time and Rebecca Solnit, author of River of Shadows: Eadweard Muybridge and the Technological Wild West joins us to describe how a photographs stopped time to create a horse floating in the air.

Plus Jay Griffiths, author of A Sideways Look at Time, introduces us to the variety of clocks - spice clocks, flower clocks, potato clocks - that predated the wristwatch.