Throughout the centuries, people from different cultures have had lots of theories and ideas of how the world was created. From Zeus and the Titans, to giant cosmic eggs or the Garden of Eden, stories were used to explain creation.

However science gradually overtook storytelling to explain the beginning of everything. The Big Bang is one of the terms used to explain the origin of the universe. But what does it mean?

“The idea is that the universe hasn’t been here forever,” says author and broadcaster Simon Singh. “It was created about 14 billion years ago, in a hot, dense, compact state and it expanded and exploded outwards. After a few hundred thousand years what you get is this debris beginning to form galaxies. If we think about that as the age of the universe, then the Earth was formed about 5 billion years ago and humans come into existence right at the very end.”

Simon Singh wrote a book about the Big Bang because he thinks it’s the most important discovery ever made, and a great story as well. So what came before the Big Bang - what went bang? “That’s the question that nobody really knows the answer to,” says Simon.

Racing galaxies

The Big Bang theory started in 1927, when Belgian priest George Lemaitre proposed the idea of a universe born at a single instant in the past and expanding outwards from that moment.
Edward Hubble proved Lemaitre’s theory by proving that the galaxies are racing away from us.

Simon says that scientist Albert Einstein did not accept these new ideas, instead backing the traditional view of an everlasting universe. “He liked the idea of a universe that had just been here forever,” he says.

Finally, in the 1960s, a pair of scientists convinced most doubting astronomers that the Big Bang theory was the correct one. Arno Penzias and Robert Wilson had a radio telescope, which they pointed up into space to get radio waves from galaxies and learn about what was going on inside a galaxy.

“When they pointed the telescope away from galaxies, they also got microwaves.
Somebody said to them that what they had was the echo of the Big Bang,” says Simon. They also had to deal with another possible explanation – that pigeon droppings in the telescope were making it malfunction. But the Big Bang won out over the pigeon theory.

Seeing back in time

The Hubble Space Telescope is travelling in orbit around the Earth - about 380 miles above the Earth’s surface - and can see a lot of the universe.

David Leckrone, senior project scientist for Hubble at NASA, has helped astronomers make some incredible discoveries about the universe.

“We’ve acquired hundreds of thousands of images of all kinds of astronomical objects,” says David. “We view out across the universe and back in time, almost to the very beginning of the universe itself, and everything in between – our own galaxy, nearby galaxies.”

Time machine

“Hubble is sometimes called a time machine because light doesn’t travel infinitely fast - it takes a while for a beam of light to get from one thing to another,” he says. "We believe, now based in part on work Hubble did, that the universe is about 13.7 billion years old. And so as we look across space, we’re looking back in time towards that origin.

David says that the most surprising and jaw dropping achievement by Hubble was the discovery that the universe is not only expanding, but the expansion isn’t slowing down, like everybody thought it would. “Gravity should be tugging at all the stuff in the universe and causing it to slow down, but in fact it’s speeding up,” he says.

Hubble is a medium sized telescope - it’s about as big as a single-decker bus, roughly 40 to 45 feet long and weighs about 12 tonnes. Scientists expect it to operate for at least five more years.

Visit the Hubble Space Telescope online

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Learn more about the Big Bang theory

Visit Simon Singh’s website [http://www.simonsingh.net/] or find out his favourite science books