David Eagleman describes a world in which a person only truly dies when they are forgotten.

Continued and shared attention to people and events is important because it can help to shape identity — how individuals see themselves as part of a group — and because the choice of what to commemorate, and so remember, influences the structures and priorities of society.

collective memory: the pattern of its decay follows a mathematical law (C. Candia et al. Nature Hum. Behav. http://doi.org/cxq2; 2018)

Using attention as a proxy for memory, the authors analysed online views of the Wikipedia profiles of around 1,700 sports stars, citations of almost 500,000 physics papers and 1.7 million patents, and online play counts of some 33,000 songs and 15,000 film trailers.

analysis of the new study data revealed that a better fit was a shape called a biexponential function, which has two phases. It shows that collective memory dropped quickly, but that the subsequent decline in attention slowed considerably, and went down a much gentler slope.

Music showed the shortest and sharpest initial decline in attention (taking 6 years) and the online biographies of the sports stars the longest (20–30 years).

The first, steep decline phase is dominated by the process of communicative memory, which is the direct word-of-mouth transfer of information. And the second, more enduring phase relies more on cultural memory, which is sustained by the physical recording of that same information.

The researchers compare their biexponential function of collective-memory decay to the more poetic description of a two-phase system from Chilean writer Pablo Neruda: “Love is so short, forgetting is so long.”