All Kinds of Behavior are Possible in Chemical Kinetics: A Theorem and Its Potential Applications to Chemical Computing

Until the late 1950s, it was believed that the processes described by the equations of chemical kinetics are simple: in the course of each chemical reaction, concentrations of some chemical substances decrease while concentrations of other substances increase. This belief was shattered when the first periodic reaction -- the famous Belousov-Zhabotinsky reaction -- was discovered. Since then, it was shown that many other types of unusual behavior are possible for chemical systems. This discovery led to the possibility of finding chemical reactions that emulate non-trivial transformations that occur during computations -- and thus, perform computations "in vitro", by actually performing the corresponding chemical reactions. The potential advantages of such chemical computing are numerous; the main advantage is that with 10^{23} molecules performing computations in parallel, we have a potential for an unheard-of-parallelization -- and thus, of an unheard-of speed-up. The possibility of computing "in vitro" was at first only theoretically conjectured, but then, in 1994, L. Adleman has actually performed successful chemical computations. This started a current boom in chemical computing, with many new ideas and devices appearing all the time.