Sigma is a podcast series seeking to showcase young people taking on extraordinary challenges. From scientists labouring at the frontier of knowledge, authors using their novels to question some of their societies' deepest held beliefs or entrepreneurs taking on antiquated and rusty industries, I'm looking to meet people determined to shape the future want to live in, whatever the medium and who are asking for no one's permission in doing so. They are, at heart, optimists; or at the very least a source of optimism for us all.