![]() Radioactive dating no problem for the Bible by Photo iStockphoto What about radioactive dating? Doesn’t that prove the world is millions of years old? Radioactive dating may be one of the big questions looming in your mind. But the idea of an unimaginably old earth did not come from radioactive dating. It was popular long before radioactivity was discovered (see ). It came from a geologic philosophy, not a scientific measurement. Note too that radioactive dating is something that most people don’t understand. Normal people are not familiar with isotopes, mass spectrographs, rubidium, strontium or half lives. We find ourselves in the position where we are being asked to trust the specialists, of not being able to check the facts first hand. But it’s not difficult to understand the basic principles to realize that alleged ages of millions of years have not been measured objectively, but derived from subjective assumptions. Scientists estimate that the Earth is about 4.5 billion years old, based on radioisotope dating techniques. To understand how this process works, you need to know a little bit about atoms and isotopes. Often, any one atom has several different forms, called isotopes. Atoms are made up of electrons, protons, and neutrons, and. What is radioactive decay? Radioactive dating begins by carefully measuring the concentrations of radioactive isotopes in rocks. Everything is composed of elements and there are about 90 naturally occurring ones, such as hydrogen, carbon, oxygen and iron. Each element comes in different forms, called isotopes, most of which are stable and do not change. Some isotopes, however, are unstable and decay radioactively into other elements. There are many different radioactive isotopes that are used for radiometric dating. For example, there is a radioactive form of potassium (potassium-40) that decays into argon (argon-40). The unstable potassium isotope is called the parent while the argon product is called the daughter. There are a couple of different radioactive forms of uranium that decay into lead. There is a radioactive form of thorium that also decays into lead. There is an isotope of samarium that decays into neodymium, and one of rubidium that decays into strontium. How does radioactive dating work? We do not know how much of each isotope was in the rock in the beginning Radioactive dating is often illustrated with an hour glass. The sand grains at the top of the sealed glass are like the atoms of the parent isotope in the rock, and those at the bottom like the atoms of the daughter. Radioactive decay is where the parent atoms change as a result of radioactive decay into daughter atoms, like the individual grains of sand falling from the top to the bottom of the glass. The hourglass depends on the sand falling at a regular rate. Like an hour glass, it is said, you simply measure the parent and the daughter elements and you can calculate the age. What was the starting amount? However, an hour glass is only useful if we saw it turned over and observed that the bottom glass was empty. In other words, the hourglass only works when we know its initial condition. Unlike the hourglass, we do not know how much of each isotope was in the rock in the beginning. That’s because we did not observe what happened in the past when the rock formed. Neither can we travel into the past to make the necessary measurements. All we can do is guess. This is the fatal problem that essentially makes radioactive dating useless as a primary method for determining age. Each dating method uses different kinds of assumptions to get around this problem for radiometric dating—the deadly problem caused by the fact that we cannot make measurements in the past. Geologists don’t like to assume the amount of daughter directly (perhaps that sounds like cheating), but they often do, and they call it a ‘model’ age. Geologists prefer to make indirect assumptions. They may assume that different minerals in the rock originally had the same isotopic ratios to start with. Or they may assume that different rock samples from the same geographical area had the same ratio. Each dating method uses different kinds of assumptions to get around this problem for radiometric dating—the deadly problem caused by the fact that we cannot make measurements in the past. Has the rock been disturbed? Photo iStockphoto Apart from the fatal problem of not knowing the initial conditions, there is another problem that is just as deadly. We don’t know what happened to the rock during its ‘lifetime’. An hour glass is only useful if it is not disturbed. But after rocks crystallize from molten magma, they can be heated and cooled; they can be affected by metamorphic events and groundwater. These geologic events can cause elements to be gained and lost to the rock. It’s like cracking the hourglass and having some of the sand leak out, or other sand leak in. How can we know what disturbances have affected the elements in our rocks? Again, we can only guess. Every date has to be interpreted Did you hear about the old wood cutter who was bragging about his axe? ‘I’ve had this trusty axe for fifty years,’ he said. ‘It’s only had two new heads and three new handles.’ The question is: how old was his axe? It’s much the same with rocks. When a geologist hammers off a sample of rock he needs to know its history. Different minerals would have crystallized at different times depending on the way the molten magma cooled. Some small pieces of other rock, or even some foreign minerals, may have been carried along by the magma and existed long before the rock crystallized. Other minerals may have grown inside the rock much later, during a time when the area was heated and metamorphosed. Some minerals may have crystallized even later still when ground waters in the area percolated through the pores of the rock. So the age of a rock is quite a complicated question, and we first need to know its entire history before we can develop a story to explain the isotopic measurements. This means that, on its own, a radioactive ‘date’ is meaningless. Geologists recognize this. You may be surprised to learn that a geologist would never collect a rock at random and send it off for radioactive dating on its own. The result would mean nothing. Every radioactive date has to be interpreted before anyone can say what it means. What happens is that the geologist will carefully record exactly where he collected the rock. He explores the geology of the area so he can understand the geological history, and where his particular sample fits into the sequence of geological events. He checks out the ages other geologists have assigned to the different rocks in the region. He studies samples of his rock under the microscope looking for clues of how it crystallized, whether it was later heated, deformed, altered or weathered. Then, when the laboratory sends him the ‘date’ for his rock, he can decide what the date refers to. Does it represent the time the rock crystallized or when it cooled? Or perhaps the date refers to the time when the rock was heated or deformed or altered, or somewhere between two of these. Or maybe the date refers to an earlier time, a time when the magma melted before the rock even formed. So the geologist has a lot of options he can choose from as he develops a story to explain the meaning of the date for his rock. He can even combine a number of different explanations to explain his result. Radiometric dating never has the final word. It’s not objective like the lay-person is led to believe. And even after the geologist has interpreted his date and published his interpretation in a journal, another geologist may later decide that there is a problem with that interpretation, and say the date should be disregarded or reinterpreted. So radiometric dating never has the final word. It’s not objective like the lay-person is led to believe. Has the decay rate ever changed? An hourglass is only useful for telling time if the sand always falls at the same rate. An hourglass can be disturbed if it tips over, is shaken, or gets moisture inside. Likewise, radioactive dating will only be reliable if the radioactive decay rate of the isotopes has never been disturbed. Each different kind of isotope decays at a regular, repeatable rate called its ‘half life’. It is generally believed that the decay rates for isotopes would never change, even under the sorts of conditions that could be experienced deep inside the earth, or even inside other planets. However, there is one survey of the scientific literature that refers to more than two dozen experiments where changes in decay rates were reported. Laboratory experiments have quantified, for certain radioactive decay processes, how much the rate is affected by the chemical and physical conditions, but in these cases the changes observed are small. On the other hand, it has been demonstrated in the laboratory that under certain conditions the radioactive decay rate can be accelerated a billion fold. Some may argue that these sorts of conditions would not apply on the earth, or that the changes are only small in most cases. But in recent years, a group of seven creationist research scientists, called the RATE group, has identified examples in the field that point toward accelerated nuclear decay. They have also developed a theoretical basis for how accelerated decay could occur. The fact is that we cannot travel into the past so we cannot know all the different conditions that have existed on Earth and to which rocks may have been subject. So, the idea that decay rates have remained absolutely constant over all time is a belief, not a fact. And even secular scientists have sometimes proposed that the decay rate changed in the past in order to resolve a disagreement between the age of the earth and the age of the universe. Not objective measurement, but subjective assumption We are all familiar with measuring time so we should easily see that radioactive dating is not everything it’s claimed to be. In an Olympic race, for example, the official starts his stopwatch when the starting gun sounds. He stops his watch when the athlete touches the finish line. He reads the time from his watch. But what would happen if he missed the beginning of the race and only saw the finish? It would be impossible for him to measure the time, no matter how accurate his watch. We all know that, so we should all see the inherent problems with radioactive dating. Every ‘scientific’ dating method, including radioactive dating, needs to know the initial conditions of the rock. But, unlike the Olympic official, we were not present at the beginning so we can only assume how the rock formed and what the conditions were. Not only that, but we must also assume what happened to the rock during its lifetime. Clearly, radioactive ‘dates’ are not independently-determined objective measurements of age. Rather, all dates are based on subjective assumptions. And because long-age researchers don’t take the Bible’s history seriously they make assumptions that are inconsistent with it. That’s why their answers contradict the Bible. But the numbers they quote are all based on assumptions and don’t disprove the biblical timescale at all. Related Articles • References • Hahn, H.-P., Born, H.-J. And Kim, J.I., Survey on the rate perturbation of nuclear decay, Radiochimica Acta 23:23–37, 1976.. • Huh, C.-A., Dependence of the decay rate of 7Be on chemical forms, Earth and Planetary Science Letters 171:325–328, 1999.. • Woodmorappe, J.,, Journal of Creation 15(2):4–6, 2001.. • RATE stands for Radioactivity and the Age of The Earth.. • Snelling, A.A.,, Creation 27(3):44–49, 2005.. • Chaffin, E.F., Accelerated decay: theoretical considerations; in: Vardiman, L. (Eds.), Radioisotopes and the Age of the Earth Vol. II, ICR, El Cajon, CA, CRS, Chino Valley, AZ, pp. 525–586, 2005.. Published: 30 April 2008(GMT+10). Uses of Radioisotopes Smoke Detectors and Americium-241 Ionization smoke detectors use an ionization chamber and a source of ionizing radiation to detect smoke. This type of smoke detector is more common because it is inexpensive and better at detecting the smaller amounts of smoke produced by flaming fires. Inside an ionization detector is a small amount (perhaps 1/5000th of a gram) of americium-241. The radioactive element americium has a half-life of 432 years, and is a good source of alpha particles. Another way to talk about the amount of americium in the detector is to say that a typical detector contains 0.9 microcurie of americium-241. A curie is a unit of measure for nuclear material. If you are holding a curie of something in your hand, you are holding an amount of material that undergoes 37,000,000,000 nuclear transformations per second. Generally, that means that 37 billion atoms in the sample are decaying and emitting a particle of nuclear radiation (such as an alpha particle) per second. One gram of of the element radium generates approximately 1 curie of activity (Marie Curie, the woman after whom the curie is named, did much of her research using radium). Food Irradiation Food irradiation is a method of treating food in order to make it safer to eat and have a longer shelf life. This process is not very different from other treatments such as pesticide application, canning, freezing and drying. The end result is that the growth of disease-causing microorganisms or those that cause spoilage are slowed or are eliminated altogether. This makes food safer and also keeps it fresh longer. Archaeological Dating Significant progress has been made in this field of study since the discovery of radioactivity and its properties. One application is carbon-14 dating. Recalling that all biologic organisms contain a given concentration of carbon-14, we can use this information to help solve questions about when the organism died. It works like this. When an organism dies it has a specific ratio by mass of carbon-14 to carbon-12 incorporated in the cells of it's body. (The same ratio as in the atmosphere.) At the moment of death, no new carbon-14 containing molecules are metabolized, therefore the ratio is at a maximum. After death, the carbon-14 to carbon-12 ratio begins to decrease because carbon-14 is decaying away at a constant and predictable rate. Remembering that the half-life of carbon-14 is 5700 years, then after 5700 years half as much carbon-14 remains within the organism. Geological Dating U-238 is used for dating rocks. U-238 (half-life of 4.5 billion years) decays to lead-206. The ratio of U-238 to Pb-206, present in a rock, can be used to determine the age of a rock. Tracing Chemical Vitamin B 12 can be tagged with a radioisotope of cobalt to study the absorption of the vitamin from the gastrointestinal tract. Compounds tagged with Fe-59 and Fe-55 are used to study the absorption of iron. Glucose tagged with carbon-11 (half-life, 20.3 minutes and positron decay mode) circulates through the body, and the positrons emitted in the heart, brain or some other organ are monitored by a PET detector. A computer uses this information to construct an image (called a PET scan) of the organ that is being examined. PET scans have been used to study the effects of drugs on cancers, to measure damage in victims of stroke or heart attack, and to study chemical changes that occur during epileptic seizures. Melvin Calvin, a biochemist, labeled CO 2 with C-14 and worked out the process by which plants photosynthesize carbohydrate from CO 2 and H 2O from- Detection of Disease Iodine-131, a beta emitter, is taken as sodium iodide in drinking water. Almost all of it will find its way to the thyroid. The rate of iodine-131 uptake, determined with a Geiger counter or other scanning device, indicates whether the thyroid glands are functioning properly. Sodium chloride containing sodium-24, can be injected into the bloodstream to study blood circulation. The beta particles emitted by the sodium-24 are followed and an impaired circulation is immediately detected. A thallium-201 compound injected into the bloodstream will concentrate in normal heart muscle but will not remain in damaged tissue. A photograph with a nuclear scintillation camera allows the physician to locate the damaged areas. Technetium-99m is used for locating brain tumors and damaged heart cells.Technetium-99m is probably the most widely used radioisotope in medicine today; it is a decay product, of molybdenum-99. From- Treatment of Disease Radium-226 and cobalt-60 are used in cancer therapy. From- Past Regents Questions- Usually #49 or #50 Jan 2010- 49 Which radioisotope is used to treat thyroid disorders? (1) Co-60 (3) C-14 (2) I-131 (4) U-238 June 2007- 50 Which radioisotope is used in medicine to treat thyroid disorders? (1) cobalt-60 (3) phosphorus-32 (2) iodine-131 (4) uranium-238 June 2009- 50 Which nuclide is used to investigate human thyroid gland disorders? (1) carbon-14 (3) cobalt-60 (2) potassium-37 (4) iodine-131 August 2008- 50 Which nuclide is paired with a specific use of that nuclide? (1) carbon-14, treatment of cancer (2) cobalt-60, dating of rock formations (3) iodine-131, treatment of thyroid disorders (4) uranium-238, dating of once-living organisms Jan 2006- 50 The decay of which radioisotope can be used to estimate the age of the fossilized remains of an insect? (1) Rn-222 (3) Co-60 (2) I-131 (4) C-14 Jan 2009- 50 Cobalt-60 and iodine-131 are radioactive isotopes that are used in (1) dating geologic formations (2) industrial measurements (3) medical procedures (4) nuclear power Aug 2010- 50 Which isotope is used to treat cancer? (1) C-14 (3) Co-60 (2) U-238 (4) Pb-206 June 2008- 50 Which radioactive isotope is used in treating cancer? (1) carbon-14 (3) lead-206 (2) cobalt-60 (4) uranium-238 June 2003- 39 Which isotope is most commonly used in the radioactive dating of the remains of organic materials? (1) 14-C (2) 16-N (3)32-P (4)37-K.
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