Information storage density of magnetic recording and other systems

Information storage density in bits per cubic centimeter are compared for various media including magnetic tape, phonograph records, photographic film, the human nervous system, and biological genetics. Magnetic recording is on a par with other man-made systems; but all of these are poorer by many orders of magnitude than genetics. An analogy between contact printing of tapes and genetic replication shows the superiority of the latter. Factors which limit the ultimate density of magnetic recording are discussed: gap-length, straightness, shunt effect, azimuth; tape surface, stability, particle size; head-tape contact, drive stability; amplifier noise, and demagnetization.