Long Time Intervals

Series: PSSC Physics Series

Duration: 24

Genre: Educational

Year Published: 1959

Creator: EDUCATION DEVELOPMENT CENTER

Format: 16mm

Color: B&W

Sound: sound

Description: Portrays various methods of measuring long time intervals including the ordinary clock, the movement of the earth about the sun, growth rings of trees, deposition of layers of sedimentary rocks and radioactive decay of uranium with special emphasis on the latter. Indicates the difference between "clocks" which record the number of time intervals measured and those which merely measure time intervals. Shows in some detail how the radioactive "clock" is used to determine the age of rocks on the earth, the age of the earth itself, and the age of the elements from which the earth was formed. Stresses the lack of knowledge concerning the exact nature of time.

Complete Record: Portrays various methods of measuring long time intervals including the ordinary clock, the movement of the earth about the sun, growth rings of trees, deposition of layers of sedimentary rocks and radioactive decay of uranium with special emphasis on the latter. Indicates the difference between "clocks" which record the number of time intervals measured and those which merely measure time intervals. Shows in some detail how the radioactive "clock" is used to determine the age of rocks on the earth, the age of the earth itself, and the age of the elements from which the earth was formed. Stresses the lack of knowledge concerning the exact nature of time. Harrison Brown discusses the significance of long time intervals and describes how radioactive dating arrives at an estimate for the age of the earth. For more info on PSSC, its history, and films, visit http://www.afana.org/psscfilms.htm