Noise in Resistances and Electron Streams

ECHNICALLY correct results in a field are achieved initially in diverse and often confusing and complicated ways. Sometimes, such results are later brought together to give them a more unified form and a sounder basis; such critical summary and exposition is of great value. In quite another way, a worker who uses results established in a field will discover many plausible reasons for believing the results, and he will find eventually that an air of inevitability and "understanding" pervades the subject. Such "understanding" is not to be confused with the process of rigorous proof carried out step by step, but it can help in organizing and making use of a body of related material. The field of "noise", especially as it affects electron devices and communi-. cations in general, is one particularly troublesome to engineers. The sound work on the subject has commonly involved mathematics and especially statistical ideas unfamiliar to many who must deal with the practical problems of noise. In early papers on noise, a great deal of heat was generated in acrimonious controversy between two schools, one of which assigned a uniform noise spectrum to certain noise sources, while the other held this to be inadmissible and got identical answers by more recondite means. Happily, a recent paper by S. 0. Rice 1 clearly presents both approaches. Rice's paper further provides a fine broad summary of noise problems together with considerable original material. It does not extend far into the field of electronics.