Shannon , in 'A Mathematical Theory of Communication ', proposed a linear schematic model of communications, defining the fundamental problem of communication as the task of reproducing at one point in space a message created at another point.  He worked out how such a message could be reliably sent, the theoretical limit of the amount of information it could contain, and contributed the notion of negentropy as a measure of information, thereby creating 'information theory.' The word 'bit,' short for binary digit, and credited to John Tukey , was used in print for the first time.