Hedonium is the arrangement of the universe's resources optimized for the production of pleasurable experience.
The term was introduced by Carl Shulman in a 2012 essay. Shulman also defined dolorium as the arrangement of the universe's resources optimized for the production of pain. Sometimes the term utilitronium is used to express this same concept, though that expression may instead be understood more broadly as referring to whichever state is regarded as the ultimate bearer of value, such as preference satisfaction on preference utilitarianism.
Armstrong, Stuart (2015) Hedonium’s semantic problem, LessWrong, April 9.
Shulman, Carl (2012) Are pain and pleasure equally energy-efficient?, Reflective Disequilibrium, March 24.