Radiometric Dating

Radiometric dating is a procedure that aims to assess the date or age of a material sample. Radiometric dating is misunderstood: Evolutionists often assume it gives a definite age of tested samples and creationists often misunderstand it, claiming that the process is inaccurate.

The technology used in Radiometric dating is not inaccurate. It is certainly based on wrong assumptions, but it is not inaccurate. We need to understand what exactly is being measured during a radiometric dating test. One thing that is not being directly measured is the actual age of the sample.

It needs to be remembered that observational science can only measure things in the present using scientific method of repetition and verifying. Historical science is concerned with trying to work out what may have happened in in the past. Historical science is not capable of repeating, verifying or falsifying a historic event. Determining the age of a rock sample falls under the heading of historical science, not observational science. The rock sample will be subjected to observational scientific methods and then using historic science, the data will be extrapolated into the past. An educated guess.

Radioactive isotopes are unstable and will decay (break down) into more stable isotopes of other elements. One common radiometric dating method is the Uranium-Lead method. This involves uranium isotopes with an atomic mass of 238 that decays by a 14-step process into lead-206, which is stable.

The half-life (measured in time) is when statistically half of the available atoms have decayed.

For example, if an element had a half-life of 100 days and we started off with 1kg, then after 100 days we would have 0,5kg. After another 100 days half of that which would be 0.25kg, and after another 100 days half of that which would be 0.125kg. In theory the element would halve every 100 days until it would be infinitesimally small.

By observing how fast U-238 decays into lead-206, we can calculate the half-life of U-238. This is a theoretical calculation, and gives the half-life of U-238 as 4.5 billion years. Granite contains U-238 and if we look at the zircon crystals in granite, we can accurately measure how much U-238 and Pb-206 the crystal contains presently. In order to calculate the age of the rock, we need three other pieces of information:

1. We need to know how fast the U-238 turns into Pb-206. The half-life gives us this value, provided the half-life has never altered during the lifetime of the zircon crystal.
2. We need to know how much Pb-206 there was in the original rock. This is clearly impossible. It is usually assumed that the original quantity of Pb-206 in the rock was zero.
3. We need to be sure that no lead compounds have been added to or taken away from the rock. Lead compounds are fairly soluble in water.

Using the above assumptions, it is calculated that the zircon crystals have an age of about 1.5 billion years. One of the by-products of the radioactive decay process is Helium. The rate of at which the Helium escapes from a zircon crystal can be measured giving the zircon an age of about 5,000 years, not 1.5 billion years. Assumptions 2 and 3 are not provable, therefore, it seems that the first assumption must be wrong. The measurement of U-238 and Pb-206 is accurate and is therefore unlikely that the laboratory technicians have made a mistake in their measurements of U-238 or Pb-206. The only possible conclusion, therefore, is that the half-life of U-238 has not been constant throughout the lifetime of the granite and its zircon crystals.

Other radiometric dating methods are based on similar assumptions. If the assumptions cannot be trusted, then the calculations based on them are unsound. It is for this reason that young earth creationists question radiometric dating methods and do not accept their results.

Carbon dating is used to estimate shorter dates, specifically matter that was once living and organic - containing carbon-14. The half-life of Carbon-14 has a relatively short lifespan compared with Uranium. However this method has similar pitfalls because assumptions have to be made about how much isotope existed when the life form was alive.

Some anomalies of carbon and radiometric dating:

Shells from living snails were carbon dated as being 27,000 years old. Living mollusk shells were dated up to 2,300 years old. A freshly killed seal was carbon dated as having died 1,300 years ago. “One part of the Vollosovitch mammoth carbon dated at 29,500 years and another part at 44,000 years. Material from layers where dinosaurs are found carbon dated at 34,000 years old. A rock from the 11-year-old Mount St. Helens volcanic eruption was sent in for K-Ar radiometric dating. Tests gave 350,000 ± 50,000 years. The minerals in the sample were dated as 2.8 million years old. Since it is known that these samples were only a few years old, these results are clearly wrong.