Computing · 1936

Turing machine

A thought experiment that defined what it means to compute.

Alan Turing described an abstract machine reading and writing symbols on a tape, and showed a single universal machine could simulate any other. It settled Hilbert's decision problem and became the theoretical foundation of computer science.

See it in the living tree Wikipedia

Arcs above join it to what it stood on, arcs below to what it led to. The bar places this stretch on the tree's whole timeline.

What it built on 2

Godel's incompleteness 1931
Boolean logic 1854

What it led to 6

McCulloch-Pitts neuron 1943
Stored-program architecture 1945
Information theory 1948
Turing test 1950
NP-completeness 1971
Quantum computing proposal 1982

Related measurements

The dashed line marks when it first worked.

Computation per constant dollar, 1850-2006 Latest: 7.3B million units of computer power per 2006 $ (2003) Source: Nordhaus 2007, Two Centuries of Productivity Growth in Computing, J. Econ. Hist. 67(1), Table 6

Fastest computer in the world Latest: 2.2×10¹⁸ operations per second (2026) Source: Wikipedia: List of fastest computers; Wikipedia: History of supercomputing