首字母BP（或bp和很少B.P.），当放在一个数字后（如2500 BP），意味着“现在之前的年份”。考古学家和地质学家通常使用这个缩写来指代通过放射性碳测年技术获得的日期。虽然BP通常也被用作对象或事件年龄的不精确估计，但是放射性碳方法的怪癖使得在科学中使用它是必要的。放射性碳测年是在20世纪40年代后期发明的，并且在几十年内，人们发现虽然从该方法中检索到的日期具有良好的，可重复的进展，但它们与日历年不是一对一的匹配。最重要的是，研究人员发现放射性碳日期受到大气中碳含量的影响，过去由于自然和人为原因（例如铁冶炼的发明，工业革命和发明），大气中的碳大量波动。内燃机）。树木年轮在创建时记录大气中的碳含量，用于校准或微调放射性碳日期到其日历日期。学者们使用树木年代学，将那些环形环与已知的碳波动相匹配。在过去的几年里，这种方法已经多次改进和改进。首先建立BP是为了澄清日历年与放射性碳年代之间的关系。使用英国石油公司的一个优点是它避免了偶尔激怒的哲学辩论，即在我们这个多元文化的世界中，使用AD和BC，更明确地引用基督教，或者使用相同的日历但是没有明确的参考文献：CE（共同时代）和BCE（在共同时代之前）。当然，问题是CE和BCE仍然使用基督诞生的估计日期作为其编号系统的参考点：公元前1年和公元前1年在数字上等同于公元前1和公元1年。
新加坡南洋理工论文代写：铁冶炼的发明
The initials BP (or bp and rarely B.P.), when placed after a number (such as 2500 BP), means “the year before the current”. Archaeologists and geologists often use this abbreviation to refer to dates obtained through radiocarbon dating techniques. Although BP is often used as an inaccurate estimate of the age of an object or event, the quirks of the radiocarbon approach make it necessary to use it in science. Radiocarbon dating was invented in the late 1940s, and within a few decades it was discovered that although the dates retrieved from the method have good, repeatable progress, they are not one-on-one with the calendar year. match. Most importantly, the researchers found that the radiocarbon date was affected by the carbon content of the atmosphere, which in the past was largely fluctuated by natural and human factors (such as the invention of iron smelting, industrial revolution and invention). internal combustion engine). The tree rings record the carbon content of the atmosphere at the time of creation and are used to calibrate or fine tune the radiocarbon date to its calendar date. Scholars use tree chronology to match those toroidal rings with known carbon fluctuations. This approach has been improved and improved many times over the past few years. BP was first established to clarify the relationship between the calendar year and the radiocarbon age. One of the advantages of using BP is that it avoids the occasional irritating philosophical debate that in our multicultural world, using AD and BC, more explicitly citing Christianity, or using the same calendar but without a clear reference: CE (common era) and BCE (before the common era). Of course, the problem is that CE and BCE still use the estimated date of birth as the reference point for their numbering system: 1 year BC and 1 BC are numerically equivalent to 1 BC and 1 year AD.