We humans seem to run to the beat of time, often without being aware of how this is the case or how our perception of it may differ from another person’s, from nature’s rhythms or from our own internal clock. In the first episode of the series, string theory pioneer Michio Kaku witnesses one of the most extraordinary feats of timing in nature on a remote Californian beach.

Where does our sense of time passing come from? We all know it’s critical – as comedians demonstrate at a Soho comedy club. Michio discovers this critical timer (the stopwatch) in a brain-scan experiment at Duke University. It seems that this ‘sense’ of time is plastic: crash victims report that time seems to slow under extreme stress. We conduct a unique experiment to test this – by dropping someone 150 feet. Meanwhile, back at Duke an experiment with cocaine and marijuana on rats reveals the chemical process by which our sense of time is altered.