A prejudice characterizing chaotic systems as “bad” and periodic systems as “good” is giving way as the function of chaos in systems, especially biological systems, becomes evident. For example, epileptic seizures and cardiac arrhythmias may reflect pathological periodicity where there should be chaos. William Ditto, et al., of the Georgia Institute of Technology have come up with a practical scheme for supporting chaos, “anti-control,” in which precisely timed jolts force a system with a penchant for periodicity to continue to be chaotic. Chaos control has actually been achieved, including maintaining chaos in brain tissues. In the May 29th Physical Review Letters, Ditto, et al., showed how a computer can learn to recognize that a system is approaching areas of phase space called “lost regions” where it slips into periodic behavior. Researchers can then make small, precisely timed perturbations to the system to avoid periodic traps. The system does not require full knowledge of the chaotic system, but only observation that identifies lost regions.