Matthew Cook is the man who proved that the Rule 110
cellular automaton is
Turing-complete, and presented this proof at a
Santa Fe Institute[?] conference. However,
Stephen Wolfram suppressed its publication with a court order. (Wolfram was the first to study this rule, and had concluded that it could not be Turing-complete.) Then Wolfram gave a general overview of the proof in
A New Kind of Science.