Category: History

50 years of limits to growth

In my closest scientific surrounding, The Limits to Growth is surprisingly unknown, so at its 50th anniversary, this blog post is an intro + my reflections. For short, it’s a fascinating story of what happens when computational social science makes a splash. If we interpret computational social science literally—not just meaning social media data mining—its […]

Using networks to design an Indian village

Notes on the Synthesis of Form by maverick architect/mathematician Christopher Alexander belongs to the canon of design theory. In 150 pages of youthful enthusiasm, Alexander brings together D’Arcy Thompson, cosmology, modernist architecture, anthropology, and his own algorithm to hierarchically decompose a graph. In 1962, two years before the publication of Notes on the Synthesis of Form, […]

Faraway, so close! Nobel prize to complex systems

Yesterday, it was announced that Syukuro Manabe, Klaus Hasselmann, and Giorgio Parisi get to share the 2021 Nobel prize in physics. Woo hoo! I had a smile on my lips running through the night streets of Tokyo (my usual exercise). The best part is the motivation: “For groundbreaking contributions to our understanding of complex physical […]

Universality: Stronger than logic

I was re-reading some old universality papers. You know, universality in the stat-mech sense—the critical exponents that characterize phase transitions are insensitive to details of your model or crystal structure of your material. This insight matured in the 1950s and 60s and culminated with Kenneth Wilson’s development of the renormalization group in the first few […]

Do you believe in ghosts?

I do. In the sense of phantom traffic jams—traffic jams without a bottleneck, that just emerge spontaneously (and with peculiar density characteristics—more below). The most fundamental feature of highway traffic is the “inverse-λ shape” flow-density diagram. Flow is the number of vehicles that pass a point along the road. Density is how many cars there […]