In 1905, the father of nuclear physics, Ernest Rutherford, proposed a method for radioisotope dating by calculating the age of several uranium minerals. Since then, radioisotope dating has been widely used in geology, paleontology, archeology … However, is this technique infallible? Many scientists have doubts on this score.
Formula of the question
Radioisotope, or radiometric, dating is a method of determining the age of various objects that contain any radioactive isotope. This isotope (parent), as a result of decay, gives rise to a new (daughter). From the ratio of these elements, knowing the half-life of the parent isotope, the age of the sample is calculated.
Here are the three most famous dating methods for rocks and minerals:
Uranium-lead analysis: the decay of uranium gives rise to lead, the half-life of the isotope uranium-238 is 4.47 billion years. For uranium-lead dating, zircon is commonly used, a chemical-resistant mineral common in igneous rocks.
Potassium-argon method: argon is a decay product of potassium-40 (half-life 1.2 billion years). True, potassium minerals easily lose argon, so an adjustment is made. Nevertheless, the method is widespread in the dating of igneous and sedimentary rocks.
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Rubidium-strontium analysis is based on the conversion of rubidium-87 to strontium. The half-life of Rb87 reaches 49 billion years. This type of analysis is often used in rock dating.
To determine the age of organic (biological) materials, a radiocarbon method has been developed. When dating, the ratio of radioactive carbon (C14) and stable carbon (C12) in the sample under study is determined, taking into account that the half-life of C14 is approximately 5,730 years.
The radiocarbon method was proposed by the American Willard Libby, for which he was awarded the Nobel Prize (1960).
However, it is now known that this method is based on dubious postulates: the ratio of carbon isotopes in the atmosphere does not change in time and space, and the content of isotopes in living organisms corresponds to the state of the atmosphere.
Carbon accumulation picture
Plants, along with carbon dioxide, absorb radiocarbon, and through plants it gets to animals. Earlier it was believed that with the "death" of an organic object, new carbon-14 does not enter it, but the existing one decays at a constant rate, while stable carbon remains unchanged. Dating is based on these assumptions. But in reality, new carbon can penetrate into the biomaterial - from the atmosphere and soil, with temperature drops and volcanic phenomena …
It has now been established that the content of C14 in the atmosphere changes depending on cosmic radiation and the activity of the Sun, the latitude of the area, the state of the magnetosphere, from volcanic eruptions and the cycle of carbon dioxide. Plus nuclear testing and constant burning of fossil fuels. All this negatively affects the accuracy of dating, especially of modern samples.
On this issue it is worth referring to … the Bible. It is assumed that before the Flood (4.5 thousand years ago) one of the layers of the Earth's atmosphere was a protective "dome" of water or moisture (Gen. 1: 6-8). This dome could protect the planet (and the atmosphere) from cosmic radiation that generates radioactive C14. That is why, and not because of decay, the content of carbon-14 in antediluvian samples can be extremely low. This means that the number of C14 "remains" will not reflect the real age of the object.
Registration of "anomalies"
Theoretically, the carbon method made it possible to determine the remains of no more than 60 thousand years old, after this period C14 remained negligible, but the development of mass spectrometry improved the "sensitivity" of measuring the C14 / C12 ratio from 1% to 0.001%, therefore the range of measured time could expand to 90 thousand years.
However, until now, no materials have been found with such a small (0.001%) ratio. That is, they are far from the age limit of 90 thousand years. Moreover, mass spectrometry has made it possible to see traces of C14 in coal, oil, anthracite, dating back millions of years. And radiocarbon should disappear long ago!
Most scientists attributed this fact to the pollution of ancient rocks with modern carbon sources. And we have developed effective ways to cleanse. However, the C14 level still remained significant, approximately 100 times higher than the near-limit sensitivity of the instruments. So, maybe the age of the same coal "pulls" only a few thousand years?
Inconvenient questions
Other methods are based on arbitrary assumptions: uranium-lead, potassium-argon, rubidium-strontium. It is assumed that originally the rock consisted only of the parent element (for example, uranium), and the daughter (lead) did not exist. But on what basis? Especially if we are talking about millions of years.
As a result, when analyzing a rock with a predominance of lead over uranium, it is possible to draw a conclusion about its antiquity. However, this sample may be young, but with a high initial lead content. In addition, the content of elements can change under the influence of external factors, such as water.
The "sacred cow" of radiometry is a constant decay rate. “It was found that the decay rate of radioactive elements today does not change at any temperature, pressure and other physical and chemical influences,” writes geographer Yuri Golubchikov. - It was decided that it has always been. According to the information gathered in the present, they began to recreate the past.
However, recent experiments question the constancy of the decay rate. According to American professor John Baumgardner, experiments have shown that the rate of decay of uranium into lead and helium was much higher in the past. And if the speed is not constant, the whole dating system collapses …
Practice is the criterion of truth
It is quite easy to verify the accuracy of radiometric dating when the age of the materials is accurately known. Here are just a few examples.
Carbon-14 dating showed: a newly killed seal … died 1.3 thousand years ago, the shell of live snails was 27 thousand years old, the age of a shell of a live mollusk was 2 thousand years.
Six laboratories performed 18 age analyzes of timber from Shelford, Cheshire, England. Estimates range from 26 thousand to 60 thousand years. That's so accurate!
The age of organic material in the mortar of one English castle was more than 7 thousand years, although the age of the castle is about 8 centuries. Probably very ancient eggs were used in the solution …
We decided to check the age of five lava flows from the Ngauruhoe volcano in New Zealand. It was known that lava flowed once in 1949, three times in 1954, and again in 1975. However, according to the potassium-argon method, the age of the lava flows was … from 0.2 to 3.5 million years.
And here are the results of the analyzes "rubidium-strontium" and "potassium-argon". Geologist Stephen Austin has sampled basalt from the lower layers of Colorado's Grand Canyon and from lava flows at the edge of the canyon. However, analysis has shown that the relatively recent lava flow is 270 Ma older than basalt from the bowels of the Grand Canyon!
In the 1990s, the same Steve Austin and his colleagues took samples from the lava of the San Helen volcano (USA, 1986 eruption), which they gave to the laboratory for potassium-argon analysis. The results exceeded all expectations: the instruments showed the age of fresh lava … from 0.3 to 2.8 million years.
Here are some more miracles: the Hualalai basalt (Hawaii, eruption of 1801) dates from 1.6 million years or more, the lava of Mount Etna (Sicily, the eruption of 1792) dates from 1.4 million years.
The age of freshly cut grass measured by radiocarbon at Moscow State University turned out to be thousands of years. It turned out that this is the age of gasoline from cars: plants absorb carbon dioxide released during its combustion, and it is depleted in C14. Since there is little carbon-14, then the age is large. Here is such a nonsense.
Problems remain
“In fact, we do not have such objects, the age of which would be known to us for sure … The only exceptions are the youngest volcanic objects, the formation time of which is recorded historically” - this is the opinion of the geologist Alexander Lalomov.
“Behind the back of a layman is the fact that we do not have a reliable method for determining the initial amount of isotopes in a sample,” said Archpriest Georgy Neifakh, Candidate of Physical and Mathematical Sciences.
So, the problems of radioisotope dating remain: this is the exchange of matter between the object and the environment, as well as the uncertainty of the initial isotopic composition. And therefore, the "accrued" age of ancient samples is doubtful.
Irina Gromova