Studying the material remains of past human life and activities may not seem important or exciting to the average Joe unlike the biological sciences.
But archaeology’s aim to understand mankind is a noble endeavor that goes beyond uncovering buried treasures, gathering information, and dating events.
It is calculated on the assumption that the atmospheric radiocarbon concentration has always been the same as it was in 1950 and that the half-life of radiocarbon is 5568 years.
For this purpose `present' refers to 1950 so you do not have to know the year in which the measurement was made.
P.), when placed after a number (as in 2500 BP), means "years Before the Present".
Archaeologists generally use this abbreviation to refer to dates that were obtained through the radiocarbon dating technology, although not exclusively; it was certainly made necessary by the quirks of the radiocarbon methodology.
Most importantly, researchers discovered that radiocarbon dates are affected by the amount of carbon in the atmosphere, which has fluctuated greatly in the past for both natural and human-caused reasons (such as the invention of iron smelting, the Industrial Revolution and the invention of the combustion engine). The problem is, of course, that CE and BCE still use the putative date of the birth of Christ as the reference points for its numbering system: the two years 1 BCE, 1 CE are equivalent to 1 BC, 1 AD.
If we have a tree that is 500 years old we can measure the radiocarbon in the 500 rings and see what radiocarbon concentration corresponds to each calendar year.
Using very old trees (such as the Bristlecone Pines in the western U. A.), it is possible to make measurements back to a few thousand years ago.
That methodology has been refined and improved several times over the last few years. The date was chosen because radiocarbon dating was invented in the late 1940s.
BP was first established as a way to clarify the relationship between calendar years and radiocarbon dates. C., with their explicit references to Christianity, or to use the alternatives C. At the same time, atmospheric nuclear testing, which throws huge amounts of carbon into our atmosphere, was begun in the 1940s.