Five hundred years ago, people looked at the dawn and thought that they saw the Sun going round the Earth. If that seems stupid, ask what it would look like if it did go round the Earth. Exactly the same. It's your knowledge that tells you what you're seeing. You are what you know. When your knowledge changes, you change, and so does the universe.From the US Air Defence Centre in Colorado to Mount Everest and the Greek Islands, the first of ten programmes illustrates this basic theme of the series. It shows how to read the present for clues about what the universe used to be. And each time the universe changed, it gave us a part of modern life - helping to make us the way we are.