Alex Rudaj

[MUSIC PLAYING]

NARRATOR: How does the cosmos create life - form it? First, it creates stars and planets as gases in space. Eventually, life forms such as ourselves, life on Earth and elsewhere in the cosmos. Whether life forms are new species, or whether they are descendants of life on Earth or Earth-like life form, the question is posed.

JONATHAN: As astronomers, we see that some of these planetary systems are, in the long-term, very different life forms compared to Earth's ecosystem.

JANE: And like them, Earth's ecosystem is also changed by all sorts of random events, changes and perturbations. But we don't know how it all came together, why it all collapsed into a violent, explosive fit of chaos.

NARRATOR: Most of our planet Earth remains unchanged over the millions of years since it formed. Compared to our epoch, earth's atmosphere, oceans and continent are held together by interlaced magma on their floors that we call rock. With this rock, life forms survive and evolve. This rock also allows us to have a planet!

JONATHAN: So that's one hell of a planet. And at the scale of that, rocks could create lots of life forms. But now we turn to the second of the three questions in this book: what's happened to the rock on which the planet is ultimately made?

NARRATOR: So, the story begins soon after the planet formed - with great floods and eruptions of molten rock.

JANE: Of course, plate tectonics controls the flow of the rocks that build up the continents, so that you end up with the mega-structure we have today, with a landscape so diverse, geologically that we have all sorts of little peaks, and so on. It is these mountain chains that are responsible for most of the life forms that exist on the planet.

JONATHAN: However, by pouring in a tremendous amount of molten rock, it could turn that molten rock into even bigger rock, and turn that into even more, and on and on and on. At each stage, more rocks fall down, and the formation of new mountain ranges that have mountains millions of feet tall is common. So life forms are more numerous on a big rock than on a little rock.