Written by Luca D'Acci in 2010, this article has been referenced by NASA in one of their publications.


The happiness of people is formulized by an Underground Hedonic Theory taking into account several levels. A formal way to think of and measure Underground happiness passes through the idea of Hedonic Inertia. This is the ‘‘residual happiness’’, the ‘‘substratum of feeling’’ given by our experiences lived in each different moment of our days. The concept of happiness as the temporal integral of momentary utility is focused, pointing out the role that one or more events in our day can influence our mood throughout the entire day. We also refer to the underground happiness coming from our general situation (love, career, money, national politics, etc.), and from the underground scenario of our daily activities (urban beauty, noisiness, comfort, etc.). Finally we summarize the logical steps to design a certain Profile of Hedonic Response for a certain person, or personality typology, as a set of particular Curves of Hedonic Ponderation. This is also explained in a mathematical way by an ‘‘equation of happiness’’.