“A complex system is one where the properties of the building blocks, when they interact, can create phenomena that are very different from the building blocks themselves. The human brain is a great example. You take a neuron, which is a cell – you put an electrochemical signal in, electrochemical signal comes out – but somehow you hook 80 billion of them together and you get a brain. You have to hook them together just right, of course, but the result is completely fundamentally different than what you started with.”