Time (2007) BBC

Cosmic Time

Throughout history, one thing has never changed - time. It is something we rely on to plan our lives, and it is consistent, regular and ceaseless. But is it? High in the Alps, Michio encounters a mystery - tiny particles called muons which shouldn't exist. They don't last long enough to be detected on Earth - and yet here they are. The answer to this mystery lies in one of the greatest discoveries of all time - Einstein's theory of relativity. The faster you travel, the slower time ticks. So time is not fixed at all.

Michio goes on a journey to places where time becomes very strange. Inside atoms, time blurs to such an extent that something can be in two places at once. Within extreme places in space, like black holes, time is squeezed to such an extent that, to an observer, it seems to stand still. Time is more variable that it could ever have been thought possible. It can even, theoretically, move backwards. This leads to one of the most extraordinary possibilities - a time machine. This episode shows a graphical representation of what it might look like: the size of a planet and consuming unimaginable amounts of energy but still a possibility.

Finally, Michio tackles the greatest questions of all - did time itself have a beginning, and will it have an end? He explains how the time capsule of the stars revealed the evolution of the Universe - and pointed the way to the ultimate beginning, the Big Bang, 13.6 billion years ago. And the future? Michio discovers that the cosmos of the stars is only a moment in the Universe's history, that we live in the stelliferous age - the age of the stars - the second of the Universe's five ages of time. But Michio explains that it is hardly an age at all: within the entire lifetime of the Universe the stars shine for less than a finger-click of history.

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?