The Church-Turing thesis is not a proof - it is a definition of computability. (The thesis is that it is the reasonable definition. For all I know someone could come up with a new kind of computation that is stringer then turing machines and then we would have to redefine our notions.)
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And the number of companies still using COBOL and FORTRAN prove what? As Dr. Turing's proof demonstrates, they're both swiss army knives too.
The Church-Turing thesis is not a proof - it is a definition of computability. (The thesis is that it is the reasonable definition. For all I know someone could come up with a new kind of computation that is stringer then turing machines and then we would have to redefine our notions.)