  For decades the number of scientific publications has been rapidly
increasing, effectively out-dating knowledge at a tremendous rate. Only few
scientific milestones remain relevant and continuously attract citations. Here
we quantify how long scientific work remains being utilized, how long it takes
before today's work is forgotten, and how milestone papers differ from those
forgotten. To answer these questions, we study the complete temporal citation
network of all American Physical Society journals. We quantify the probability
of attracting citations for individual publications based on age and the number
of citations they have received in the past. We capture both aspects, the
forgetting and the tendency to cite already popular works, in a microscopic
generative model for the dynamics of scientific citation networks. We find that
the probability of citing a specific paper declines with age as a power law
with an exponent of $\alpha \sim -1.4$. Whenever a paper in its early years can
be characterized by a scaling exponent above a critical value, $\alpha_c$, the
paper is likely to become "ever-lasting". We validate the model with
out-of-sample predictions, with an accuracy of up to 90% (AUC $\sim 0.9$). The
model also allows us to estimate an expected citation landscape of the future,
predicting that 95% of papers cited in 2050 have yet to be published. The
exponential growth of articles, combined with a power-law type of forgetting
and papers receiving fewer and fewer citations on average, suggests a worrying
tendency toward information overload and raises concerns about scientific
publishing's long-term sustainability.
