With the rise of the entertainment culture, with its movie houses and dance halls and their universal appeal across class lines, dating quickly moved up the socio-economic ladder to include middle- and upper-class men and women, as well as the new urbanites.When one tries to understand how dating has changed over time, and most importantly, how we arrived at the system of courtship and dating we have today, one must realize the monumental cultural shift that occurred during the 1940s, primarily due to World War II."Radiocarbon ages" are calculated from f M using the exponential decay relation and the "Libby half-life" 5568 a.The ages are expressed in years before present (BP) where "present" is defined as AD 1950.
However, by the turn of the 20th century we find the word being used to describe lower-class men and women going out socially to public dances, parties and other meeting places, primarily in urban centers where women had to share small apartments and did not have spacious front parlors in their homes to which to invite men to call.
The method was developed by Willard Libby in the late 1940s and soon became a standard tool for archaeologists.
Libby received the Nobel Prize in Chemistry for his work in 1960.
The abbreviation "BP", with the same meaning, has also been interpreted both of which requested that publications should use the unit "a" for year and reserve the term "BP" for radiocarbon estimations. A large quantity of contemporary oxalic acid dihydrate was prepared as NBS Standard Reference Material (SRM) 4990B. This value is defined as "modern carbon" referenced to AD 1950.
Some archaeologists use the lowercase letters bp, bc and ad as terminology for uncalibrated dates for these eras. Beginning in 1954, metrologists established 1950 as the origin year for the BP scale for use with radiocarbon dating, using a 1950-based reference sample of oxalic acid. Currie Lloyd: The problem was tackled by the international radiocarbon community in the late 1950s, in cooperation with the U. Radiocarbon measurements are compared to this modern carbon value, and expressed as "fraction of modern" (f M).