Time (2007) BBC

Daytime

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.

We also meet a French caver who spent months in complete isolation to see what would happen to his sense of time - and discovered that we have an internal clock that drives our days. Michio self-experiments by being monitored over 24 hours to see how this clock shapes his whole body chemistry. And we test a family with a rare disease to uncover the very roots of the body clock itself.

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.

But time for us is even more than this. We have a unique knowledge of time. We 'know' past and future. It's an ability shared by no other animals... apart from a special few. King the Gorilla demonstrates his awareness of time to researchers in Miami. We meet a man with no memory and reveal how much we depend on being able to place ourselves in time. This special awareness of time raises some of the most important questions about time itself: Why does it only flow in one direction? Why can't we stop it, see it or hold it? And if it so elusive, then is it real or just a figment of our minds?

In this four-programme series, string theory pioneer Michio Kaku goes on an extraordinary exploration of the world in search of time. He discovers our sense of time passing and the clocks that drive our bodies. He reveals the forces of time that make and destroy us in a lifetime. He journeys to some of the Earth's most spectacular geological sites to look for clues to the extraordinary depths of time at a planetary level. Finally, he takes us on a cosmic journey in search of the beginning (and the end) of time itself.

1. DAYTIME

Time seems to drive every moment. It's the most inescapable force we feel. But do we experience time from within our minds and bodies or from the outside?

2. LIFETIME

The most powerful effect of time on our lives is the way it limits us. Our knowledge of death is so embedded in our lives and spirituality that, were immortality possible, would we lose the sense that makes us human?

3. EARTH TIME

We hold a unique knowledge of time, realising that it stretches deep into the past, and will continue into the future. How does this affect our sense of who we are?

4. COSMIC TIME

We've always structured our lives based on an unchanging past and a predictable and ordered future. But atomic and cosmic discoveries have changed all that. What is time itself? And will it ever end?