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From Jürgen Schmidhuber, Dalle Molle Institute for the Study of Artificial Intelligence

I just read your interesting article about the possibility of a single formula underlying the fabric of the universe (21 June, p 32).

You mention Ed Fredkin and Stephen Wolfram. But did you know it was Konrad Zuse who was first to suggest that the physical universe is being computed on a discrete, deterministic cellular automaton? His first paper on this topic dates back to 1967 (Elektronische Datenverarbeitung, vol 8, p 336).

This is the same Zuse who built the world’s first working general-purpose computers from 1935 to 1941 (). His book on cellular aut omaton-based universes came out 2 years later. So Zuse’s book pre-dates those of Wolfram and Fredkin by three decades. Clearly Zuse is the man to cite.

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Lugano, Switzerland