Dating innacurate

26 Jun

Scientists at the Lamont-Doherty Geological Laboratory of Columbia University at Palisades, N.

Y., reported today in the British journal Nature that some estimates of age based on carbon analyses were wrong by as much as 3,500 years.

An image of your fetus will appear on an accompanying computer screen and while looking at this image, the technician will take some standard measurements from different angles and listen for a heartbeat.

Don't worry: This type of exam is painless and risk-free, and seeing your baby for the first time will likely be an enjoyable experience.

The technique hinges on carbon-14, a radioactive isotope of the element that, unlike other more stable forms of carbon, decays away at a steady rate.

dating innacurate-35dating innacurate-76dating innacurate-72

If you can't remember your last menstrual period date or if you have consistently irregular cycles, the doctor can use an early ultrasound to give you a fairly reliable due date.Naturally, one of the most common questions asked about ultrasound accuracy is: Just how accurate are the due dates that are predicted by an ultrasound?Evidence suggests that, in the first 20 weeks of pregnancy, the first ultrasound may be the most accurate tool for predicting when your baby will be born.Based on a discipline of geology called stratigraphy, rock layers are used to decipher the sequence of historical geological events.Relative techniques can determine the sequence of events but not the precise date of an event, making these methods unreliable.Today, many different radioactive elements have been used, but the most famous absolute dating method is radiocarbon dating, which uses the isotope C.This isotope, which can be found in organic materials and can be used only to date organic materials, has been incorrectly used by many to make dating assumptions for non-organic material such as stone buildings.They arrived at this conclusion by comparing age estimates obtained using two different methods - analysis of radioactive carbon in a sample and determination of the ratio of uranium to thorium in the sample.In some cases, the latter ratio appears to be a much more accurate gauge of age than the customary method of carbon dating, the scientists said.By measuring the ratio of the radio isotope to non-radioactive carbon, the amount of carbon-14 decay can be worked out, thereby giving an age for the specimen in question.But that assumes that the amount of carbon-14 in the atmosphere was constant — any variation would speed up or slow down the clock.