A huge congratulations to Sara Walker for winning fourth prize in FQXi's "Wandering Towards a Goal" essay contest.
Understanding the origin(s) and nature of life poses a perplexing problem for physics. On the one hand our approaches to physics are incredibly adept at describing the material world. On the other hand abstractions such as what we commonly describe as information are important in biology, but their role in the physical world is not yet fully understood. In this essay I discuss how information (as we understand it in biology) is a window into causal structures that bridge counterfactual histories (and futures) and allow the possible for transitions between histories. It is this multiple realizability that is one of the most distinctive properties of living systems. It also leads to some of their most interesting – and difficult to explain – features, such as their apparent goal directedness.