updating address book live - The controversy of using radioactive dating

Radiometric dating methods are the strongest direct evidence that geologists have for the age of the Earth.When I first became interested in the creation-evolution debate, in late 1994, I looked around for sources that clearly and simply explained what radiometric dating is and why young-Earth creationists are driven to discredit it.Contents: The half-life of a radioactive isotope is defined as the time it takes half of a sample of the element to decay.

(Note that this doesn't mean the half-life of an element is a constant.

Different isotopes of the same element can have substantially different half-lives.) It's important to understand that the half-life is a purely statistical measurement. A sample of U238 ten thousand years old will have precisely the same half-life as one ten billion years old.

When I first got involved in the creationism/evolution controversy, back in early 1995, I looked around for an article or book that explained radiometric dating in a way that nonscientists could understand. Young-Earth creationists -- that is, creationists who believe that Earth is no more than 10,000 years old -- are fond of attacking radiometric dating methods as being full of inaccuracies and riddled with sources of error.

All these methods point to Earth being very, very old -- several billions of years old.

Because it's a statistical measurement, there's always a margin of error in the age figure, but if the procedure is done properly, the margin is very small. We must know the original quantity of the parent isotope in order to date our sample radiometrically. In order to do so, we need an isotope that's part of a mineral compound. Because there's a basic law of chemistry that says "Chemical processes like those that form minerals can't distinguish between different isotopes of the same element." This is because an element's chemical behavior depends only on the number of electrons it has, which is the same as its number of protons.

Obviously, the major question here is "how much of the isotope was originally present in our sample? So to a chemical process, U235 and U238 are identical.

That's all you really need to know to understand radiometric dating techniques. In the next part of this article, I'll examine several different radiometric dating techniques, and show how the axioms I cited above translate into useful age measurements. Common Methods of Radiometric Dating This section describes several common methods of radiometric dating. C14 is radioactive, with a half-life of 5730 years.

To start, let's look at one that almost everyone has heard of: radiocarbon dating, AKA "carbon-14 dating" or just "carbon dating." Method 1: Carbon-14 Dating The element carbon occurs naturally in three isotopes: C12, C13, and C14. C14 is also formed continuously from N14 (nitrogen-14) in the upper reaches of the atmosphere.

When we know how much has decayed, we know how old the sample is.

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