Al-Khalili, professor of physics, takes the viewer into the world of quantum mechanics, the most accurate, yet always surprising theory ever in science. It begins in the nineteenth century, when perceptions of the behavior and nature of light change, revealing much more of how nature works. Of course Einstein will pass with his breakthroughs. The second episode takes a closer look at what has been suggested about quantum physics, namely that it could even solve biological mysteries: how birds navigate, how humans can smell, and how evolution can take place.