The Biggest Number in the World

From the number of cells in our bodies to the size of the universe, big numbers have more to do with the real world than you might suspect. We all know that numbers go on forever, that you could spend your life counting and never reach the end of the line, so there can't be such a thing as a biggest number. Or can there? An epic quest into unfathomably large numbers. A journey to the edge of mathematics.