Radiocarbon dating - Wikipedia
At a very steady rate, unstable carbon gradually decays to carbon The ratio of these carbon isotopes reveals the ages of some of Earth's. Radiocarbon dating is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of. The use of carbon, also known as radiocarbon, to date organic materials has been an important method in both archaeology and geology. The technique.
Thus, the mere fact that the present rate of water coming in exceeds that of the water leaking out cannot be extrapolated back to a starting time. And, that destroys the entire argument. Figure 1 Lingenfelter's paper was written inbefore the cycles of C variation we described had been fully documented.
The point is that fluctuations in the rate of C production mean that at times the production rate will exceed the decay rate, while at other times the decay rate will be the larger. Strahler,p. Henry Morris chose not to mention that portion of the paper! Creationists don't want their readers to be distracted with problems like that -- unless the cat is already out of the bag and something has to be said.
Tree-ring dating see Topic 27 gives us a wonderful check on the radiocarbon dating method for the last years. That is, we can use carbon dating on a given tree-ring the year sequence having been assembled from the overlapping tree-ring patterns of living and dead trees and compare the resulting age with the tree-ring date.
A study of the deviations from the accurate tree-ring dating sequence shows that the earth's magnetic field has an important effect on carbon production.
When the dipole moment is strong, carbon production is suppressed below normal; when it is weak, carbon production is boosted above normal. What the magnetic field does is to partially shield the earth from cosmic rays which produce carbon high in the atmosphere. Contrary to creationist Barnes' totally discredited claims, which I've covered in Topic 11the earth's magnetic field dipole moment has, indeed, increased and decreased over time.
Strahler presents a graph of the earth's dipole moment going back years. The curve is roughly fitted to mean values determined about every to 1, years The curve is roughly degrees out of phase with the C curve.
Bucha, who has been able to determine, using samples of baked clay from archeological sites, what the intensity of the earth's magnetic field was at the time in question.
Even before the tree-ring calibration data were available to them, he and the archeologist, Evzen Neustupny, were able to suggest how much this would affect the radiocarbon dates. Therefore, as already noted, Dr. Hovind's claim that carbon has been slowly building up towards a 30, year equilibrium is worthless. You now have the technical reason for the failure of Morris' model. It may interest the reader to know that within this year period, where the radiocarbon method can be checked by tree-ring data, objects older than BC receive a carbon date which makes them appear younger than they really are!
An uncorrected carbon date of years for an object would actually mean that the object was years old. Seven hundred years or so is about as far as the carbon method strays from tree-ring dating on the average. Individual dates given on a correlation chart Bailey,p.
As it turns out, we have a check on the carbon production which goes back even further than years: Evidence of past history of C concentration in the atmosphere is now available through the past 22, years, using ages of lake sediments in which organic carbon compounds are preserved. Reporting before a conference on past climates, Professor Minze Stuiver of the University of Washington found that magnetic ages of the lake sediments remained within years of the radiocarbon ages throughout the entire period.
He reported that the concentration of C in the atmosphere during that long interval did not vary by more than 10 percent Stuiver,p. Thus, the available evidence is sufficient to validate the radiocarbon method of age determination with an error of about 10 percent for twice as long a period as the creation scenario calls for.
The dipole moment of the earth's magnetic field, sunspot activity, the Suess effect, possible nearby supernova explosions, and even ocean absorption can have some effect on the carbon concentration. However, these factors don't affect the radiocarbon dates by more than about percent, judging from the above studies. Of course, when we reach the upper limit of the method, around 40, years for the standard techniques, we should allow for much greater uncertainty as the small amounts of C remaining are much harder to measure.
Tree-ring data gives us a precise correction table for carbon dates as far back as 8, years.
The Age of the Earth - Radiocarbom Dating as a Current Scientific Clock: Jonathan Ring
The above study by Stuiver shows that the C fluctuations in the atmosphere were quite reasonable as far back as 22, years ago. The earth's magnetic field seems to have the greatest effect on C production, and there is no reason to believe that its strength was greatly different even 40, years ago.
For a refutation of Barnes' argument see Topic Therefore, atmospheric variation in C production is not a serious problem for the carbon method. The evidence refutes Dr. Hovind's claim that the C content of our atmosphere is in the middle of a 30,year buildup. Thus, we can dismiss this young-earth argument. The C decay rate is not constant. Several factors, including the year sunspot cycle, affects its rate of decay. It is painfully obvious that Dr.
Hovind knows next to nothing about carbon dating! Changes in the sunspot cycle do have a noticeable, short-term effect on the rate of C production inasmuch as sunspots are associated with solar flares, which produce magnetic storms on Earth, and the condition of the earth's magnetic field does affect the number of cosmic rays reaching the earth's upper atmosphere. Carbon is produced by energetic collisions between cosmic rays and molecules of nitrogen in the upper atmosphere.
Sunspots have absolutely nothing to do with the rate of C decay, which defines the half-life of that radioactive element. Hovind has confused two completely different concepts.
Quantum mechanics, that stout pillar of modern physics, which has been verified in so many different ways that I couldn't begin to list them all even if I had them at hand, gives us no theoretical reason for believing that the C rate of decay has changed or can be significantly affected by any reasonable process. We also have direct observation: That radiocarbon ages agree so closely with tree-ring counts over at least years, when the observed magnetic effect upon the production rate of C is taken into account, suggests that the decay constant itself can be assumed to be reliable.
We also have laboratory studies which support the constancy of all the decay rates used in radiometric dating. A great many experiments have been done in attempts to change radioactive decay rates, but these experiments have invariably failed to produce any significant changes.
It has been found, for example, that decay constants are the same at a temperature of degrees C or at a temperature of degrees C and are the same in a vacuum or under a pressure of several thousand atmospheres.
Measurements of decay rates under differing gravitational and magnetic fields also have yielded negative results. Although changes in alpha and beta decay rates are theoretically possible, theory also predicts that such changes would be very small [ Emery, ] and thus would not affect dating methods. There is a fourth type of decay that can be affected by physical and chemical conditions, though only very slightly. This type of decay is electron capture e. Because this type of decay involves a particle outside the nucleus, the decay rate may be affected by variations in the electron density near the nucleus of the atom.
For example, the decay constant of Be-7 in different beryllium chemical compounds varies by as much as 0.
The only isotope of geologic interest that undergoes e. Measurements of the decay rate of K in different substances under various conditions indicate that variations in the chemical and physical environment have no detectable effect on its e. Dalrymple,p. Harold Slusher, a prominent member of the Institute for Creation Research, claimed that "Experiments have shown that the decay rates of cesium and iron 57 vary, hence there may be similar variations in other radioactive decay rates.
How Good Are Those Young-Earth Arguments?
This statement merely reveals Slusher's ignorance of nuclear physics. Gamma decay of an excited state of iron 57 has been studied, but this has nothing to do with the kinds of decays used in radiometric dating. Brush,p. These changes are irrelevant to radiometric dating methods. They will switch tracks faster than you can say "tiddlywinks. Morris claimed that free neutrons might change the decay rates. However, Henry Morris, that icon of creationism, only demonstrated that he knew no more about radiometric dating than does Dr.
Free neutrons might change one element into another, but the decay rates all remain true to their elements. Another attempt by Morris invokes neutrinos. Morris [ ] also suggests that neutrinos might change decay rates, citing a column by Jueneman 72 in Industrial Research.
The subtitle of Jueneman's columns, which appear regularly, is, appropriately, "Scientific Speculation. Jueneman describes a highly speculative hypothesis that would account for radioactive decay by interaction with neutrinos rather than by spontaneous decay, and he notes that an event that temporarily increased the neutrino flux might "reset" the clocks. Jueneman, however, does not propose that decay rates would be changed, nor does he state how the clocks would be reset; in addition, there is no evidence to support his speculation.
Those mysterious neutrinos seem to be a hot topic! Slusher and Rybka also propose that neutrinos can change decay rates, citing an hypothesis by Dudley 40 that decay is triggered by neutrinos in a "neutrino sea" and that changes in the neutrino flux might affect decay rates. This argument has been refuted by Brush 20who points out that Dudley's hypothesis not only requires rejection of both relativity and quantum mechanics, two of the most spectacularly successful theories in modern science, but is disproved by recent experiments.
Dudley himself rejects the conclusions drawn from his hypothesis by Slusher and Rybkanoting that the observed changes in decay rates are insufficient to change the age of the Earth by more than a few percent Dudley, personal communication,quoted in 20, p.
Thus, even if Slusher and Rybka were correct--which they are not--the measured age of the Earth would still exceed 4 billion years. Judging from the above, it is easy to see that creationists are indulging in wild fishing expeditions.
Compare their flighty arguments to the solid support provided by theoretical work, laboratory testing, and, for the shorter half-lives, actual observation, and add to that the statistical consistency of the dates obtained, including numerous cross-checks between different "clocks," and only one conclusion is left. The radiometric decay rates used in dating are totally reliable. They are one of the safest bets in all of science. The initial C content cannot be known. Various living samples give very different ratios.
With at least one notable exception on the books, plants and animals get their carbon from the atmosphere. Plants take it in directly, and animals eat the plants. Thus, it gets passed up the food chain. It is not surprising, therefore, to find that the carbon in living plants and animals is in reasonable equilibrium with the atmospheric carbon Some creationists, however, have claimed that certain plants can reject carbon in favor of carbon Because of the chemical similarity of carbon and carbon, it is unlikely that such plants could deviate much from the ratio of C to C found in the atmosphere.
Neither freak cases nor small deviations pose much of a problem for radiocarbon dating, which, after all, works well with a wide variety of plant and animal species. Hence, we only have to worry about the initial concentration of C in the atmosphere.
Topic R1 shows that the level of C in the atmosphere has not varied appreciably over tens of thousands of years. Therefore, the initial C content is known for any reasonable sample! The notable exception involves certain mollusks, which get much of their carbon from dissolved limestone. Since limestone is very old it contains very little carbon Thus, in getting some of their carbon from limestone, these mollusks "inherit" some of the limestone's old age!
That is, the limestone carbon skews the normal ratio between C and C found in living things. If one dates such mollusks, one must be extra careful in interpreting the data. Not every mollusk shell presents such problems, and the dating of other material might yield a cross-check.
Further study might even allow correction tables. The discovery has strengthened the carbon method, not weakened it! By the way, shouldn't the creationist be worried over the old, carbon age of the limestone?
Why is it that limestone has so little C in it? Partial contamination, say of a block of wood, may affect its different parts to different degrees. Insect burrows, cracks, and partial decay may allow contamination later on to affect those portions of the sample unequally.
However, there are laboratory techniques, often ingenious, for dealing with such problems. If the sample shows evidence of being hopelessly contaminated it is pitched.
Some samples, such as a section of a tree trunk, may well contain material of considerably different ages. The interior portion of a tree trunk could easily be several hundred years older than the outer portions. In summing up this point, we do know within good limits what the initial C was for any reasonable sample.
A sample will not have different ratios of carbon unless it has been contaminated or reflects a genuine range of ages. It is very difficult or impossible to prove that a given sample has not been contaminated. Parent or daughter products could have leached in or out of the sample.
In the case of carbon dating, the daughter product is ordinary nitrogen and plays no role in the dating process. We are only interested in tallying the original C still present in the sample, the surviving "parent" isotope. The C that is incorporated in the carbon structure of cellulose and the other structural materials of living plants and animals is not going to do much migrating after burial. If structural carbon migrated easily there soon wouldn't be any cellulose, lignin, chitin or other structural carbon compounds left in the soil!
A piece of wood, for example, would soon turn into a formless cloud of graphite or soot in the soil, with perhaps a little ash marking the original shape! Clearly, that is not something which normally happens. In order to function properly, natural clocks need an irreversible process that occurs at a constant and known rate.
How Good are those Young-Earth Arguments: Radiocarbon Dating
Nuclear decay has a constant rate of decay, but as it turns out, the formation of 14C in the atmosphere is not always constant.
However, cross-checking techniques such as tree ring dating and coral analysis, 14C has been reliably calibrated to tens of thousands of years. The newest limit using cross-checking methods is around 26, years Dotinga Carbon isotopes are generally measured through the use of a machine called the accelerated mass spectrometer. A small portion of the sample is put into the machine which then vaporizes it. Taking advantage of the distinct mass of individual isotopes, the machine distinguishes the 14C from all of the other atoms and molecules present and is able to count the individual atoms.
Charcoal, cloth, bone, or any other material that contains organic carbon can be dated using an accelerated mass spectrometer. In conjunction with other creationist organizations, the Institute for Creation Research has assembled a team of researchers to challenge existing notions about the age of the Earth.
The RATE team Radioisotopes and the Age of the Earth have studied a variety of subjects pertaining to the age of the Earth including radiocarbon dating. In the traditional model of science, radiocarbon has little to do with the age of the Earth, since its lifespan is so short. However, RATE is attempting to fit all radiometric dating into a young earth model. The RATE research in the area of radiocarbon has focused on the "blank" sample date.
According to the science behind radiocarbon dating, very old samples should have no measurable 14C left. However, conventional scientific research projects, as well as RATE research on coal beds and diamonds, have found samples which should no longer have any 14C but actually contain very small amounts of it.
Since the accelerated mass spectrometer can detect 14C to a higher precision than what was found in the samples, the 14C is thought to exist because of some sort of unexplained phenomenon or contamination. Therefore, the RATE team has identified a valid anomaly in radiocarbon research which deserves further research.
Before proposing their alternate theory about the residual 14C found in very old samples, the Rate team first discusses the possibility of contamination. Besides the cosmic rays creating 14C in the atmosphere, other ways to create 14C have been identified. Alpha particle emissions from uranium and thorium decay can convert 14N into 14C just as it is formed in the atmosphere. However, as Baumgardner discusses the possible contamination through these processes, he concludes that "production of 14C by thermal neutrons at presently observed levels in unable, by several orders of magnitude, to account for the 14C levels we measure" Baumgardner The RATE team has used this anomaly to advance an alternative theory.
Noting that 14C exists in samples which should be 14C dead and thus providing an age for the samples around 50, years, the RATE team has come up with a theory for how such an inconsistency could occur. After rejecting contamination as a possibility for the presence of background radiocarbon, the team has come up with a model in which the accounts outlined in the Bible, specifically Noah's flood, explains the observed 14C.
All of the individuals who participated in the research began with the same view on the age of the earth: This means that we regard the bible as a uniquely inspired book given to mankind from the Creator" DeYoung In creating their 14C model, that premise is used as the foundation.
The logic for the theory is as follows: This means that radiocarbon dating actually proves the fossils are 5, years old, not 50, The RATE team has applied an inverse system of logic to the standard. They begin with the same assumption that they are trying to prove.
Broken down, the logic holds that the Bible says that the earth is very young; therefore the earth is very young. Without such a beginning claim, the logic would be extremely bizarre.
Basically, the claim made by the RATE team is that the maximum date of 50, years given by radiocarbon dating actually equals 6, years. However, the entire idea is based on an arbitrary, unproven assumption.
Without the Bible, there is no reason to believe that all of the life represented in the fossil record was alive at the same time, creating a different ratio of 14C to carbon than we see now. There is also no reason, other than the Bible, to assume that there was a world-wide flood. The only plausible way to create a theory about how the background 14C found in old samples is evidence that the Earth is 6, years old is to begin with the Bible.
This creates what is called circular, or cyclical, reasoning.Radiometric or Absolute Rock Dating