Stephen Wolfram
Computation · Cellular automata · Hypergraph physics
Kernel
Wolfram is the figure who has spent four decades arguing that computation is the substrate of physical reality. The 2002 A New Kind of Science classified simple computational systems and proposed that the universe at sufficient depth is one of them; the 2020 Wolfram Physics Project offers candidate rule-systems and shows that general relativity and quantum mechanics emerge as statistical limits.
Contribution
Mathematica (1988) and Wolfram Alpha (2009) as working knowledge engines. The classification of 1-dimensional cellular automata. The 2020 hypergraph-rewriting model of fundamental physics. A research program that treats computation as the discipline most likely to contain physics' next opening.
Civilization-scale significance
Whether Wolfram's specific hypergraph proposal turns out to be correct, the position that physics is fundamentally computational — heterodox in 2002 — is now defensible enough that the Wolfram Physics Project's papers appear in serious journals. The shift is partly his.