  Chalmer's famously identified pinpointing an explanation for our subjective
experience as the "hard problem of consciousness". He argued that subjective
experience constitutes a "hard problem" in the sense that its explanation will
ultimately require new physical laws or principles. Here, we propose a
corresponding "hard problem of life" as the problem of how `information' can
affect the world. In this essay we motivate both why the problem of information
as a causal agent is central to explaining life, and why it is hard - that is,
why we suspect that a full resolution of the hard problem of life will, similar
to as has been proposed for the hard problem of consciousness, ultimately not
be reducible to known physical principles.
