Darwin and Einstein Correspondence Patters

Human interaction in the e-mail and snail mail eras

Living before e-mail, Charles Darwin and Albert Einstein wrote and read prodigious volumes of snail mail, exchanging scientific ideas and opinions with their colleagues. Joao Oliveira and Albert-Laszlo Barabasi (Nature, October 27 2005, p1251 – subscription only) analyzed Darwin and Einstein’s letter writing patterns (particularly the intervals between their receipt of a letter and their responses).

They found that the delay followed a "power law," much like e-mail does today. Specifically, the probability of a response taking a time tau (in days) is well approximated by

P(tau) = tau^-alpha,

where alpha is 3/2 for the collected letters of Einstein and Darwin (individually, their scalings were each very close to 1.5). Modern e-mail has a similar scaling, only with alpha equal to 1.

Oliveira and Barabasi explain the scaling law as being due to Darwin and Einstein both having a "prioritization" system in place, whereby they can rank the importance of communications as the arrived, so they could answer the more important letters first (neither answered more than 1/3 of all the mail they received).

The authors point out that the similarity in scaling laws between electronic and written correspondence points to a "fundamental pattern in human dynamics", although the difference in the scaling parameter points to a new class phenomena brought about by the advent of e-mail.