Before Present (BP) years is a time scale used in archaeology, geology, and other scientific disciplines to specify when events in the past occurred. Because the "present" time changes, standard practice is to use 1 January 1950 as the origin of the age scale, reflecting the fact that radiocarbon dating became practicable in the 1950s. The abbreviation "BP", with the same meaning, has also been interpreted as "Before Physics"; that is, before nuclear weapons testing artificially altered the proportion of the carbon isotopes in the atmosphere.
Read more about Before Present: Usage of "BP", Radiocarbon Dating, Radiocarbon Calibration
Famous quotes containing the word present:
“Open the envelope quickly,
O this is not our son’s writing, yet his name is sign’d,
O a strange hand writes for our dear son, O stricken mother’s soul!
All swims before her eyes, flashes with black, she catches the main
words only,
Sentences broken, gunshot wound in the breast, cavalry skirmish, taken to hospital,
At present low, but will soon be better.”
—Walt Whitman (1819–1892)