Time dating history of bc ad
Thermolumiscence dating, on the other hand, has a unique situation.
Unlike radiocarbon dates, TL dates are calculated in straight calendar years—and the dates measured range from a few years to hundreds of thousands of years.
However, a major disadvantage of using BP is that the present year, of course, changes every twelve months.
If it was a simple matter of counting backward, what was accurately measured and published as 500 BP today in fifty years would be 550 BP.
Long after the Gregorian calendar was established throughout most of the world, atomic clocks have allowed us to adjust our modern calendars with leap seconds to correct for the slowing spin of our planet and other corrections.
But, perhaps the most interesting outcome of all this investigation is the wide variety of modern mathematicians and programmers who have taken a crack at perfecting the matches between ancient calendars using modern technology.
The problem is, of course, that CE and BCE still use the estimated date of the birth of Christ as the reference points for its numbering system: the two years 1 BCE and 1 CE are numerically equivalent to 1 BC and 1 AD.
P.), when placed after a number (as in 2500 BP), means "years Before the Present." Archaeologists and geologists generally use this abbreviation to refer to dates that were obtained through the radiocarbon dating technology.
While BP is also used generally as an imprecise estimate of an age of an object or event, the use of it in science was made necessary by the quirks of the radiocarbon methodology.
Radiocarbon dating was invented in the late 1940's, and within a few decades, it was discovered that while the dates retrieved from the method have a sound, repeatable progression, they are not a one-to-one match with calendar years.
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).
We need a fixed point in time as a starting point so that all the BP dates are equivalent no matter when they are published.