Communications between people were in written or oral and transmitted via the
transportation available at the time until 1835, when
telegraphy was invented. From that time, information
exchange between people could be made without transportation, thus making it immeasurably
faster and cheaper, which increased the productivity of
all industries and, consequently, American living standards.
Later inventions in telephony
and computer networks increased communications still more.
Radio and television
are not only entertainment media. They supply information regarding safety and
health and therefore contribute directly to living standards.
Radar and sonar contribute to
plane safety by communicating location and position.
Sonar also is used in medical diagnostics.