In a 1939 letter to Vannevar Bush, Claude Shannon said he was working on a theorem, which states that for any transmitter and receiver the length of an arbitrary message multiplied by its essential spectrum and divided by the distortion of the system is less than a certain constant times the time of transmission of the message multiplied by its essential spectrum width or, roughly speaking, it is impossible to reduce bandwidth times transmission time for a given distortion. Relate the theorem to Equation (3.1).