Adventures with Carbon-14

Carbon-14 dating, also called radiocarbon dating, is commonly used to date objects containing carbon that are not considered extremely old. For example, the Shroud of Turin was dated to 1260-1390 A.D. using radiocarbon dating.

This is how Carbon-14 (C-14 for short) dating works. The normal atomic isotope of carbon is carbon-12 (C-12). However, nitrogen (nitrogen-15) in the atmosphere receives radiation from the sun, and this radiation causes a very small percentage of the nitrogen to lose a proton, forming C-14. The ratio of C-14 to C-12 is very small, about one to a trillion. Every living thing interacts with the atmosphere, so as long as an animal breathes or a plant lives, that animal or plant also has about one part per trillion of C-14 in every cell. C-14 is radioactive and decays exponentially with a half life of 5730 years. When an animal dies, it no longer breathes, and the C-14 in its body begins to decay. By measuring the ratio of C-14 to C-12, it is possible to determine how long ago the animal died. This process works for plants and animals, and can usually be used to also find the formation date of anything that contains carbon, such as petroleum, coal or diamonds.

Because the half-life is 5730 years, C-14 dating cannot be used to date things that are more than about 100,000 years old. The already tiny percentage of C-14 will have decayed to a percentage too small to be detected. Therefore, scientists will not usually try to date something like a dinosaur bone with C-14, since the conventional timeline has dinosaurs dying out 65 million years ago. The expectation is that if one dated a dinosaur's bone using C-14, no C-14 would be present and the age of the bone would be calculated to be infinite. Now here is where the fun begins. One of the nasty little secrets of C-14 dating is that whenever anything containing carbon is tested, C-14 is always found. When the sample is supposed to be extremely old, like a dinosaur bone, it will contain some C-14 and date to say, 50,000 years old. This produces one kind of problem for young earth creationists, who do not believe the earth is 50,000 old, meaning the date has to be off by a factor of 10 or so. It creates a more serious problem for evolutionists, who expect the dinosaur bone to be more than 65 million years old, meaning the date is off by a factor of more than 1000. What to do with this conundrum? Let's come back to it in a minute. Before we go further we need to discuss dating methods in general.

Dating Methods in General - An Example and Four Assumptions
All dating methods work in essentially the same way: they measure the rate a process operates, then calculate how long that process would take to arrive at the current state from some projected initial state. An example will help. Suppose we saw Chris peeling apples, and noticed that he took one minute to peel one apple. We then looked and saw a barrel of unpeeled apples on his left and a barrel of peeled apples on his right, with ten peeled apples in the right barrel. How long has the Chris been peeling apples? The answer is ten apples divided by one apple per minute, equalling ten minutes. So Chris has been peeling apples for ten minutes. Or has he? Perhaps he has improved his technique, having peeled the first few apples more slowly. Or perhaps he is tired and has slowed down, having peeled the first apples more quickly. We have been making an assumption, the first assumption in any dating method: (1) The rate of the process has remained constant. Here's another point - are we sure we counted the peeled apples correctly? If not, we will get the wrong answer. Therefore, the second assumption in any dating method is that (2) we have accurately measured the current state of the system. Also, what would have happened if just before we looked at Chris, Naomi's cheerleading squad arrived and they all ate some peeled apples? This illustrates the third assumption, (3) we are looking at a closed system, with no external contamination of inputs or outputs. Finally, are we sure that Chris peeled all ten apples? Perhaps Anne peeled eight apples before Chris sat down to peel his first one. This illustrates the fourth assumption: (4) We know what the initial state of the system is.

These four assumptions should be considered when we evaluate any dating method. (1) Has the rate of the process always remained constant? One might suppose with C-14 dating that it has, although we can't prove it beyond all doubt. It at least appears to be constant today even in varieties of temperatures, pressures, etc. However, there are dating methods where we are less confident about the rate. For example, one can calculate the age of the ocean by measuring the rate at which salt is swept into the ocean by erosion, but that rate probably has changed some as earth's climate and geography changed. (2) Have we accurately measured the current state of the system? Of all the assumptions, this is usually the most solid. Certainly with C-14 dating we can expect to get an accurate measurement, barring any incompetence in the labs. However, there are some dating methods where an accurate measurement of the current state of the system is questionable. For example, some models for estimating the age of the universe rely on estimates of the total mass of the universe. Whether we have accurate readings of universal mass is doubtful. (3) The assumption that we have a closed system is often dicey. In fact, when C-14 is present in samples thought to be too old, like a dinosaur bone, the evolutionary explanation will be that the sample has been contaminated, i.e., the system was not closed. (4) Do we know the initial state of the system? For young earth creationists, a 50,000 year old date for a dinosaur bone is still too old. The young earth explanation is that the initial state of the system is not what the C-14 labs believe; the atmosphere when the dinosaur died was not the same as it was today. Instead, there was less C-14 in the atmosphere, and anything that died at that time would date older than it really was.

Some C-14 Dating Results
C-14 dates seem to be pretty reliable going back to 1000 B.C. or so. C-14 accurately dated the Dead Sea Scrolls, scrolls which can be dated in several other ways. These scrolls were written at about the time of Christ. The Bible and Egyptian chronology agree on the date for an invasion of Judah by Pharaoh Shishak (Egyptian: Shoshenq) during the reign of Rehoboam around 925 B.C. C-14 dates at Tel Rehov (Rehov is mentioned in the Egyptian account) seem to match this date. However, moving back before 1000 B.C., problems emerge. Renown archeologist Katherine Kenyon verified that Jericho was destroyed and lay ruined for many years, as the Bible says. However, multiple C-14 tests put its destruction at about 1550 B.C, around 150 years before Joshua got there (my best estimate for the fall of Jericho using a Bible chronology would put it at 1406 B.C.). Similarly, Egyptologists were confident that the date of the eruption of the Thera volcano, the largest volcanic eruption in the Mediterranean in recorded history, was about 1500 B.C. However, C-14 dates pushed it back to a range between 1600-1627 B.C. Notice what has happened here: Recorded history for these two events, near in time to each other, give dates more recent than C-14 dates by 100-150 years. Something has begun to go wrong with the C-14 dates.

Moving back in time to events before this, but which a young earth creationist would place after the flood of Noah, the C-14 dates get older at an exponential rate. Many mammoth bones are frozen in the permafrost of Siberia and a few other locations in the far north. Permafrost must be post-flood. And these Mammoths often date around 12,000 years old or so, with dates ranging from around 40,000 B.C. to as recent as 1700 B.C. Now one wonders how mammoths, which need to ingest a massive amount of green food, can survive in Siberia, which is frozen for seven months a year. Of course they can't - they would go extinct. Yet somehow they once did, and during the ice age!? but that is a subject for another paper. For now let us just note that Mammoth dates and similar post-flood artifacts often date between 4000-40,000 years old.

Finally, what about samples which evolutionists would state are millions of years old, and which creationists would claim are pre-flood? As I mentioned before, it's a dirty little secret that all samples containing carbon also have some C-14, implying an age less than 100,000 years old. These samples have included dinosaur bones, diamonds, coal, and petroleum. At first glance, these samples seemed to measure with random very old but not infinite ages, ages that no one believes, so they have not until recently been analyzed systematically. Recently though, Rick Sanders wrote an article in the Creation Research Society Quarterly (Winter 2011 edition) that showed that the ages of these samples follow the lognormal model, with a mean age of 51,155 years and a standard deviation of 6997 years. The results are meaningful. They imply a "C-14 flood date" of 51,155 years before present.

So what does all this mean? I suggest that prior to the flood, the C-14 concentration in the atmosphere was only about one tenth of its present concentration. There can be several reasons why this may have been so - perhaps less radiation from the sun due to a slightly different atmosphere, more carbon in the biosphere, etc. This would calibrate the C-14 flood date from 51,155 years before present to a date about ten times more recent than that. After the flood, C-14 concentration in the atmosphere increased over a period of around a thousand years, reaching its modern equilibrium some time prior to 1000 B.C. I believe it was not quite at equilibrium at the time of the Thera eruption or the destruction of Jericho, explaining why those C-14 dates are a little too old. In between the flood and Jericho there were mammoths, whose bones have dates spanning the time period between the two.

I believe this is an area that would benefit from more study.