IS THE UNIVERSE DUE ANOTHER BIG BANG?

New theories and observations are shedding fresh light on the very beginnings of the cosmos, and the formation of the first stars and galaxies. But they're also revealing new and unexpected mysteries

- Giles Sparrow

Ask any astronomer about the very beginnings of the universe, and they're likely to describe the Big Bang theory. Some 13.8 billion years ago, they'll say, the universe was born out of nothing, in an explosion that unleashed the expanding dimensions of space and time, alongside vast amounts of energy. In the moments that followed, most of this energy transformed into the building blocks of matter - subatomic particles of varying mass and complexity which eventually came together to form simple atoms, and then coalesced to create giant, short-lived stars and the nuclei of the first galaxies.

There's a wealth of evidence to show that the Big Bang theory is broadly correct. For instance, even today the universe is still growing at tremendous speed, with widely separated galaxies and galaxy clusters being pulled apart as the space between them expands.

What's more, when powerful telescopes cus on the galaxies farthest from Earth (whose light set out on its journey towards us many billions of years ago), they see violent star systems still in the process of formation. Most tellingly of all, the entire universe is filled with the weak afterglow' of the Big Bang itself - the Cosmic Microwave Background Radiation (CMBR) that comes from all over the sky and is otherwise inexplicable.