Radiocarbon Dating and the Bible
Is carbon-14 dating (or radiocarbon dating) always reliable and beyond question? Are all radioactive dating methods unreliable? Have carbon-14 (C14) dates millions of years old been proven wrong? Is carbon-14 dating useless before 2,000 B.C.? Or are the above statements all false, and the truth is something else?
Since there are many misconceptions about carbon-14 dating, this paper will explain the principle, the method, some early problems with it, and its current trustworthiness. While many probably have not thought about it before, carbon-14 dating relates to Christianity and Judaism in interesting ways. This method addresses questions on the Shroud of Turin, the archaeological reliability of the Bible, reliable preservation of the Bible, and the Young Earth Theory.
All plants take in carbon from carbon dioxide in the atmosphere. All animals take in carbon by eating the plants. Now most carbon has a molecular weight of 12. However, solar radiation creates a small percentage of carbon with two extra neutrons and a molecular weight of 14. A carbon-14 atom is radioactive; it eventually loses an electron and a neutrino and changes to nitrogen-14. Its half-life is 5,730 ± 30 years, so it never has nor can be used to date carbon samples millions of years old.
When a plant or animal dies, it stops taking in carbon. Since the carbon-14 decays, comparing the current ratio to the predicted C14 / C12 ratio vs. time can tell exactly how long ago the organism died. This is the principle behind radiocarbon dating.
For any logical method, if the assumptions are right, and the reasoning is valid, then the conclusion is right. If not, then the conclusions are simply guesses. Carbon-14 dating assumptions used to be:
1. The atmospheric C14 / C12 ratio has never changed.
2. Nothing but radioactive decay would alter the ratio in a dead plant or animal.
3. We can measure the ratio accurately.
To sum up these assumptions, if you know the initial conditions, the final conditions, and everything in between, you will get the right answer. We will look at the method first, and then the assumptions.
There are three simple steps to getting a carbon-14 date: sample preparation, getting the ratio, and using a calibration chart to get the age from the ratio.
1. Before dating, samples are first soaked in an 8% HCL, and then an NaOH caustic solution to clean them of contaminants, such as dirt, microbes, and tree sap. While this soaking removes some good material too, it does not change the C14 / C12 ratio of the good material.
2. Next a small piece, often taken from the interior of the sample, is burned. Burning does very slightly alter the C14 / C12 ratio, but it is altered the same way in the calibration samples too. For example, while the Catholic Church was unwilling to let scientists burn a square inch piece of the Shroud of Turin, when mass spec technology advanced, it was willing to let them burn a thread, and that was all that was needed.
3. Finally, one reads the age from a calibration chart of age vs. ratio. In the Radiocarbon journal the ratio is reported, so readers can calibrate for themselves.
So if one does these three steps: prepare a valid sample well, run the test correctly, and read the right calibration, the date should be good. So while many date to dance, you might say scientists do the "three-step" to date. (On the other hand, if you don't like puns, you might not.)
So if you believe your assumptions, use good methods, what could go wrong? Well, it turns out the problems with early carbon-14 were so severe, that many historians were on the verge of abandoning it. Some clams were dated as having died 50,000 years ago, and they were still alive! Many Middle Eastern artifacts, preserved under ideal conditions, were consistently giving dates wrong by 20%. What happened?
Let's look critically at assumption 2, that nothing else affects the ratio in a dead organism. Now clams take in ocean carbonate, which contains almost no C14, so that it is no surprise today that a clam shell date appears ridiculously old. This phenomenon, now well understood, only gives ages that are "all wet" for some samples that have been in water for some time.
A more difficult to deal problem with radiocarbon dating came from Egyptian and Mesopotamian artifacts when the dates were already known. In Egypt, Assyria, Babylonia, and Sumeria, there are "king lists" of who reigned and for how long. When you have records dated by the scribes, as well as actual mummies and the carbon-14 dates are not off by hundreds of years but by thousands, you either have to throw away every historical record, or else there was a general failure with carbon-14 dating.
Let's look at assumption 1 again. Solar intensity, the earth's magnetism, and CO2 concentration all affect the C14/C12 ratio. Libby, who won a Nobel Prize in 1960 for C14 dating, failed to question his uniformitarian assumption, that the ratio had reached static equilibrium. This was the state of affairs with radiocarbon dating for many years.
To "face up" to the absolute age problem, scientists devised calibration scales based on tree rings, lake varves, and ice cores.
Oak trees can live for 200-300 years, and they grow a new tree ring every year. The ring is thick when the winter is short, and thin when the winter is long. Different trees growing at the same time in the same forest have very similar tree ring patterns. So, by comparing many different trees in a forest in South Germany, and performing radiocarbon dating on a large number of samples, a calibration scale was developed. Other researchers did similar work in a forest in Northern Germany. Still others did this in Ireland, and others in England. Finally American researchers did this with bristlecone pine trees in Arizona. Bristlecone pine is both worse and better to use than oak. It is worse, in that the rings are very thin, and roughly 5% of the time the tree either does not grow a ring in a year or else grows two rings. It is better in that an individual bristlecone pine can live for 2,000 years. Anyway, all these different calibrations from around the world agree with each other within about 5%. Using tree rings, the calibration of carbon-14 has been extended back to ~4,760 B.C. (Ralph et al. 1973, Stuiver & Pearson 1986, Stuiver & Reimer 1986, van der Plicht & Mook 1989 and others). Of course, they could all be wrong, but if enough independent studies agree with each other, then being wrong becomes a more remote possibility.
In addition to tree rings, scientists have looked at what are called lake varves in Northern Sweden. Now trees shed their leaves in the fall, and the leaves that fall in a lake form a thin layer at the bottom. This happens annually, and thus very thin annual layers are deposited. By counting lake varves, one has a cross-check for carbon-14 dating similar to tree rings. Lake varve calibration goes back to ~11,000 years.
A third cross-check is ice cores in Greenland. More snow is deposited in summer, when the air is wetter, than in winter. Thus there are annual rings in Greenland ice cores too. However, instead of dating organic matter, carbon-14 dating is performed on the minute amounts of carbon dioxide and methane gas in each layer. This method is less reliable than tree rings and lake varves, but it calibrates back to >15,000 years before present.
So, because of the triple testimony of tree rings, lake varves, and ice cores, carbon-14 dating works assuming:
1. We can measure the ratio very accurately.
2. We know the ways an organism's ratio is altered.
3. While the atmospheric C14 / C12 ratio has changed, we have calibration scales( ± 5%) back to 4,760 B.C, 11,000 B.C, and more than 15,000 B.C..
Relationship to Christianity and Judaism
Carbon-14 relates to Christianity and Judaism in four ways. First, we have New Testament manuscripts dated from <70 A.D. (Cave 7 of the Dead See Scrolls), 117-138 A.D. (John Ryland's Papyrii), 100-150 A.D. (the three Chester Beatty Papyrii), and 125-175 A.D. (the three Bodmer II Papyrii), to authenticate the reliable transmission of the New Testament. For the Old Testament we have 200 different Dead Sea Bible manuscripts) (Exodus 250 B.C, Isaiah 100 B.C.), all others before 70 A.D., as one means to show the reliable transmission of the Old Testament from the time of Christ to the present. On the Dead Sea scrolls, it should be mentioned that even without carbon-14 dating, it is certain that all scrolls were written before the site was abandoned 70 A.D., when the Romans reconquered Palestine. More information on Dead Sea scroll dating can be found in the journal Radiocarbon vol.3 1993.
Carbon-14 dating has verified hundreds of archaeological sites mentioned in the Bible. Over 57,000 readable clay tablets in Mesopotamia and many Egyptian Papyrii have shown that even many slaves could write in Abraham's time. Thus the liberal JEPD Theory, which assumed a long period of oral history before the Bible was even to be written down, is "outdated" so to speak.
Third, for years many wondered if the Shroud of Turin was actually Christ's burial covering. Scientists are so far been unable to find a process to duplicate the image on the Shroud of Turin. Nevertheless, carbon-14 dating gave a date from the Middle Ages.
Finally, carbon-14 dating relates to the Young Earth Theory. Greenland ice core gases show no major climac-tic changes since 11,500 years ago. (Major weather changes occurred 11,500 years ago, however.) Thus if Noah's flood had to be 11,500 years ago or earlier, then the earth must have been created before 9,500 B.C.
Modern carbon-14 dating is substantially accurate for the period over which there is a calibration scale. Our faith should not be based merely on Radiocarbon dating, but it is a strong witness to the accuracy and reliability of the Bible. It also shows the importance of using scientific and historical data as secondary authorities in interpreting the Bible.
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