As we gazed up at the heavens, we asked where we had come from, how all the stars were created, how all the elements were made, even how the universe itself had begun. One of mankind's greatest achievements is that we've answered these questions. What is truly remarkable is that this understanding has come through the study of the smallest building blocks of matter - atoms. As we peered inwards, we realised we could explain what we saw when we peered outwards. The atom has helped us solve the greatest mysteries of existence. Everything in the world we see is made out of tiny objects called atoms and yet we only proved their existence at the beginning of the 20th century. The first shock was to discover how small they were, less than a millionth of a millimetre across, there are trillions in a single grain of sand. Amazingly, we now have a pretty good idea of the number of atoms in the known universe. Now, given the vastness of the universe and the minuteness of the atom, it's not surprising that this is a mind-numbingly huge number, it's one followed by over 70 zeros, that's a trillion, trillion, trillion, trillion, trillion, trillion atoms.