Turing test Kurzweil (optimist) about whether a computer will pass a lengthy Turing test by the year 2029. During the Long Now Turing Test, each of three Turing test judges will conduct online interviews of each of the four Turing test candidates (i.e., the computer and the three Turing test human foils) for two hours each for a total of eight hours of interviews. The bet specifies the conditions in some detail. 1990 marked the fortieth anniversary of the first publication of Turing's "Computing Machinery and Intelligence" paper, and, saw renewed interest in the test. Two significant events occurred in that year:
Church–Turing thesis three formally-defined classes of computable functions coincide with the "informal" notion of an effectively calculable function. Since, as an informal notion, the concept of effective calculability does not have a formal definition, the thesis, although it has near-universal acceptance, cannot be formally proven. Since its inception, variations on the original thesis have arisen, including statements about what can physically be realized by a computer in our universe (physical Church-Turing thesis) and what can be efficiently computed (Church–Turing thesis (complexity theory)). These variations are not due to Church or Turing, but arise from later work in complexity theory and digital physics.