Had he done so, I am quite sure he would have become curious about just what the threshold for his concept of universality would be, and just how simple a Turing machine would suffice. In the mid-1990s, I searched the space of simple Turing machines, and found the smallest possible candidate. And after I put up a $25,000 prize, in 2007 Alex Smith showed that indeed this Turing machine is universal.
