"The Computer Within," by Bennett Daviss. New Scientist, 8 January 2000, pages 18-22.
Although the Turing machine provided a theoretical basis for the field of computer science, one has never been built. Now Ehud Shapiro, of the Weizmann Institute of Science in Rehovot, Israel, has come up with a scheme to build a Turing machine using simple building blocks, such as amino acids. One day, tiny Turing machines could operate as "doctors" inside every cell in our bodies, looking for symptoms of disease and prescribing the appropriate drugs. While no one can yet build such a machine, and some doubt the possibilities, others speculate that the technology could be in place within fifty years.
--- Benjamin Stein