Theory of Information and its Value pp 391-408 | Cite as

# Information theory and the second law of thermodynamics

## Abstract

In this chapter, we discuss a relation between the concept of the amount of information and that of physical entropy. As is well known, the latter allows us to express quantitatively the second law of thermodynamics, which forbids, in an isolated system, the existence of processes accompanied by an increase of entropy. If there exists an influx of information *dI* about the system, i.e. if the physical system is isolated only thermally, but not informationally, then the above law should be generalized by substituting inequality *dH* ≥ 0 with inequality *dH* + *dI* ≥ 0. Therefore, if there is an influx of information, then the thermal energy of the system can be converted (without the help of a refrigerator) into mechanical energy. In other words, the existence of perpetual motion of the second kind powered by information becomes possible.

## References

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