When exactly did life begin? What really happened during the big bang - and before it? Is the universe expanding? Is dark matter real? Do we live in one of many worlds? What's more, how can we prove any of this? This book is all about how we - any of us - can gain an understanding of the Universe in all its awe-inspiring glory. Brian Cox and Jeff Forshaw take us on an epic journey of scientific exploration, revealing how the biggest questions - from the size of the earth to the distance to the stars - are answerable from our own back gardens.