A time capsule is a historic cache of goods or information, usually intended as a method of communication with future people and to help future archaeologists, anthropologists or historians. Time capsules are sometimes created and buried during celebrations such as a World's fair, a cornerstone laying for a building or at other events.
The 1939 New York World's Fair time capsule was created by Westinghouse as part of their exhibit. It was 90 inches (2.3 metres) long, with an interior diameter of 6.5 inches (16 cm), and weighed 800 pounds (360 kg). Westinghouse named the copper, chromium and silver alloy "Cupaloy", claiming it had the same strength as mild steel. It contained everyday items such as a spool of thread and doll, a Book of Record (description of the capsule and its creators), a vial of staple food crop seeds, a microscope and a 15-minute RKO Pathé Pictures newsreel. Microfilm spools condensed the contents of a Sears Roebuck catalog, dictionary, almanac, and other texts.
George Edward Pendray is responsible for coining the term "time capsule." During the socialist period in the USSR, many time capsules were buried with messages to a future communist society.
Currently, four time capsules are "buried" in space. The two Pioneer Plaques and the two Voyager Golden Records have been attached to spacecraft for the possible benefit of spacefarers in the distant future. A fifth time capsule, the KEO satellite, which is scheduled to be launched in 2015, carrying individual messages from Earth's inhabitants addressed to earthlings around the year 52,000, when it is due to return to Earth. The International Time Capsule Society was created to maintain a global database of all existing time capsules.
According to time capsule historian William Jarvis, most intentional time capsules usually do not provide much useful historical information: they are typically filled with "useless junk", new and pristine in condition, that tells little about the people of the time. Many time capsules today contain only artifacts of limited value to future historians. Historians suggest that items which describe the daily lives of the people who created them, such as personal notes, pictures, and documents, would greatly increase the value of the time capsule to future historians.
Historians also concede that there are many preservation issues surrounding the selection of the media to transmit this information to the future. Some of these issues include the obsolescence of technology and the deterioration of electronic and magnetic storage media, and possible language problems if the capsule is dug up in the distant future. Many buried time capsules are lost, as interest in them fades and the exact location is forgotten, or they are destroyed within a few years by groundwater.
Archives and archival materials, including videos, might be the best types of time capsules, as long as the medium can still be used, or the data can be read by the latest technologies and software.
