It's interesting that the author chooses to emphasize the distinction between extropy as an opposition to entropy, but instead as a metaphor. However, would extropy not be the opposite of entropy metaphorically as well? Scientific definition aside, entropy is defined as the universe's tendency towards chaos in all manners of the word meaning constant expansion and disorder. Extropy is the universe's tendency towards the idea of a 'singularity' (discussed in "The Technological Singularity") so essentially the exact opposite? The universe's tendency to follow "intelligence, functional order", etc. toward a single point of "posthuman" where we've gone beyond human capability?