How accurate are Carbon-14 and other radioactive dating methods?
Radiocarbon dating can easily establish that humans have been on the earth for over twenty thousand years, at least twice as long as creationists are willing to allow. Therefore it should come as no surprise that creationists why carbon dating is reliable the Institute for Creation Research ICR have been trying desperately to discredit this method for years. They have their work cut out for them, however, wh radiocarbon C dating is one of the most reliable of all the radiometric dating methods.
This article will answer several of the most common creationist attacks on carbon dating, using the question-answer format qhy has proved so useful to lecturers and debaters. Cosmic rays in the upper atmosphere are constantly converting the isotope nitrogen N into carbon C or radiocarbon. Why carbon dating is reliable organisms are constantly incorporating this C into their bodies along with other carbon isotopes.
When the organisms die, they stop incorporating new C, and the old C starts to decay back into N by emitting beta particles. The older an organism's remains are, the less beta radiation it emits because its C is steadily dwindling at a predictable rate. So, if we measure the rate of beta decay in an organic sample, we can calculate how old the sample is.
C rellable with a half-life of 5, years. Kieth and Anderson radiocarbon-dated the shell of a living freshwater mussel and obtained an age of over two thousand years. ICR creationists claim that this discredits C dating. How do you reply? It does discredit the C dating of freshwater mussels, but that's about all. Kieth and Anderson show considerable evidence that the mussels acquired much of their carbon from the limestone of re,iable waters they datibg in and from some very old humus as well.
Carbon from these sources is very low why carbon dating is reliable C because these sources are so old and have not been mixed with fresh carbon from. Thus, a freshly killed mussel has far less C than a freshly killed something else, which is why the C dating method makes freshwater mussels seem older than they really are. When dating wood there is no such problem because wood gets its carbon straight from the air, complete with a full dose of C The creationists who quote Kieth and Anderson never tell you this, however.
A sample that is more than fifty thousand years old shouldn't have any measurable C Coal, oil, and natural gas are supposed to be millions of years old; yet creationists say that some of them contain measurable amounts of C, enough to give them C ages in the tens of thousands of years. How datkng you eating this? Radiocarbon dating doesn't work well on objects much older than twenty thousand years, because such objects have so little C left that their beta radiation is swamped whj by the background radiation of cosmic rays and potassium K decay.
Younger objects can easily be dated, because they still emit plenty of beta radiation, enough to be measured after the background radiation has been subtracted out of datinng total beta radiation. However, in either case, ehy background beta radiation has to be compensated for, and, in the older objects, the amount of C they have left is less than the margin of error in measuring background radiation. As Hurley points out:. Without rather special developmental work, it is not generally practicable to measure ages in excess of about twenty thousand years, because the radioactivity of the carbon becomes so slight that it is difficult to get an accurate measurement above background radiation.
Cosmic rays form beta radiation all the time; this is the radiation that turns N to C in the first place. K decay also forms plenty of reliablee radiation. Stearns, Carroll, and Clark point out datingg ". This radiation cannot be totally eliminated from the laboratory, so one could probably get a "radiocarbon" date of fifty thousand years from a pure carbon-free piece of tin.
However, you now know why this fact doesn't at all invalidate radiocarbon dates of objects younger than twenty thousand years and is certainly no evidence for the notion that coals and oils might be no older than fifty thousand years. Creationists such as Cook claim that cosmic radiation is now forming C iss the atmosphere about one and one-third times faster fating it is decaying.
If we extrapolate backwards in time with the proper equations, we find that the earlier the historical period, the less C the atmosphere had. If carboon are right, this means all C ages greater than two or three thousand years need to be lowered drastically and that the earth can be no older than ten thousand years. Yes, Cook is right that C is forming today faster than it's decaying.
However, the amount of C has not been rising steadily as Cook maintains; instead, it has fluctuated up and down over the past ten thousand years. Carbom do we know this? From wht dates taken from bristlecone pines. There are two ways of dating wood from bristlecone pines: Since the tree ring counts have reliably dated some specimens of wood all the way back to BC, one can check out the C dates against the tree-ring-count dates. Admittedly, this old wood comes from trees that have been dead for hundreds of years, but you don't have to have an 8,year-old bristlecone pine cafbon alive today to whj determine that sort of date.
It is easy wyy correlate the inner rings of a younger living tree with the outer rings of an older dead tree. The correlation is possible because, in the Southwest region of the United States, the widths of tree rings vary from year to year with the rainfall, and trees all over the Southwest have the same pattern of variations. Wyh experts compare the tree-ring dates with the C dates, they find that radiocarbon ages before BC are really too young—not too old as Cook maintains.
For example, pieces of wood that date at about BC by tree-ring counts date at only BC by regular C dating and BC by Cook's creationist revision of C dating as we see in the article, "Dating, Relative and Absolute," in the Encyclopaedia Britannica. So, despite creationist claims, C before three thousand years ago was decaying faster than it was being formed and C dating errs on the side of making objects from before BC look too youngnot why carbon dating is reliable old.