Extropy Extropy is neither wave nor particle, nor pure energy. It is an immaterial force that is very much like information. Since extropy is defined as negative entropy — the reversal of disorder — it is, by definition, an increase in order. But what is order? Despite our intuitive sense, we lack a good operational definition of order, which seems to be tied up with complexity (see Ordained Becoming). For simple physical systems, the concepts of thermodynamics suffice, but for the real world of cucumbers, brains, books, and self-driving trucks, we don't have useful metrics for extropy. The best we can say is that extropy resembles, but is not equivalent to, information.