Is carbon dating accurate or not?

I was talking to my creationist friend and he insists carbon dating is a farse. He said, “dude, they tested peanut butter and jeally sandwich and it said it was 100 million years old.” He believes the earth is only 10,000 years old. I think he’s crazy, but everybody is entitled to their b…yada yada…

Now, when it comes to evolution and creationism, I think the two can co-exist. Maybe something higher started everything and then evolution took over.

But I lean more towards agnostic in the creation and evolution department. I don’t know or care too much.

But is carbon dating accurate?

W. Libby invented the method of carbon dating in the the mid 1900s, and was awarded the Noble prize in chemistry for that work in 1960. I guess that’s a pretty good stamp of approval. But no one uses carbon dating for anything older than about 60,000 years*, so tell your peanut butter friend he or she doesn’t not know what he or she is talking about.

*with a half-life of 5730 years, there isn’t much C-14 left after that amount of time

After 100 million years there would be about 2.66 x10[sup]-5252[/sup]% of the original C14 present. Considerably less than an atom in any reasonably-sized sample. After 60,000 years, there’s only about .07% left, and that’s right at the edge of detectability.

Here’s the Wikipedia article on the mechanics of Carbon dating. It points out some of the time periods when the dating may not be as accurate as others.

This article , by Michael Benton, a PH.D in Palentology, offers a calm and patient explination of why the creationists arguements against carbon dating and the fossil record are wrong. Calm and reasoned debate between these two camps is rare, so I thought I’d throw it in.

More stuff as I find it.


Up to certain limits, of course. Beyond a certain length of time, say 40,000 years or so, you have to use other decay cycles, like Uranium.

But, in particular, H. Kitagawa and J. van der Plicht, in their 1998 article in Science on calibrating the Radiocarbon methods discus the accuracy of the method back to 45,000 years, by comparisons of Radiocarbon dates, versus direct annual counts of varves, and tree rings.

Many others have done similar works, in the decades since the first Radiocarbon estimates were made. In fact, in recent years, a fortuitous find of timber buried by a landslide in a fjord which could be dated exactly, and matched with known tree rings allowed the direct dendrochronology to reach beyond 15,000 years for samples from the northern hemisphere.

You will often hear that “They” have disproven, or proven this that and the other thing. I would ask who they were. “They” tested lots of things. “They” don’t have a source for you to read, though, or a date when the study was done, or a name for the guy who did it, or the methodology used to obtain the data. In fact, you can’t even get a look at the data itself. Only the bald assertion that “They” tested it, and all of science turned out to be a vast conspiracy of idiots.


Finally read far enough down the article I cited above. As others have pointed out already, Carbon dating only takes you so far. The research now rests on radiometric dating, which relies on the much longer have lives of multiple elements, and drawing family trees (known as phylogenies) based on morphological and molecular characteristics.

I knew about the other techniques, but still thought carbon dating was the main tool. Damn, I don’t know everything. Guess I have to apologize to the husband.

Just to be clear, Carbon-14 dating is a radiometric technique, too. Radiometric techniques all use naturally occuring isotopes, like C-14, that decay over time. To date older fossils using radiometry, you need to pick an isotope with a longer half-life. But, say you want to date something in the 1-2M year territory, you don’t want an isotope that decays too slowly, or you’ll end up with the same problem you had with Carbon-14. So, different isotopes are used, depending on the need.

Also, keep in mind that there are lots of non-radiometric techniques that are used to determine the age of fossils, too.

However, having personally performed [sup]14[/sup]CO[sub]2[/sub] assays in a defective fume hood, I expect carbon dating of my bones to show I lived 20,000 years in the future.
Anyone want to buy some stock tips? :wink:

In any case there’s no real point in debating it since we all know that modern science is an atheist conspiracy to deny God. :rolleyes: :rolleyes: :rolleyes:

The Earth was created last Thursday. God planted all our memories to test our faith.

The Bible must be literal. If it isn’t, fundamentalist Christianity will collapse.
Since the Bible states the Earth is about 6,000 years old, evolution must be wrong (plus astronomy and many other sciences).
Did God create dinosaur fossils? How else can evolution and creationism ‘co-exist’?

No, he wasn’t. Nobel. Nobel. N-o-b-e-l.

Sorry to nitpick, but in this kind of debate, you don’t want to be giving ammo to the Creationists by making simple factual mistakes.

Furthermore, if ‘they’ were stupid enough to perform radiometric tests on a PBJ sandwich, then publish the results, it’s a fairly safe bet ‘they’ weren’t exactly mainstream scientists.
I’ve heard of quite a few supposed falsifications of radiometric dating; they invariably include one or more of the following factors:
-The test was performed on something inappropriate (PBJ sandwich, live molluscs, freshly-cooled volcanic lava with charred wood inclusions)
-The test was perfomed in someone’s garage
-The sample was collected/transported/stored inappropriately; in one video ‘debunking’ of carbon dating I saw, coal or shale was collected from the surface of an exposed outcrop in the earth embankment of a road cutting - five yards away from a busy road - at least some of the carbon in the sample will have been from vehicle exhaust particulates and from living micro organisms from the surrounding soil.
-The data was cherry-picked so as to focus on the statistical outliers and completely ignore the main volume of concordant results.

Could you elaborate on why those things are not suitable for radiometric dating? I imagine the volcanic lava example would show the age of the wood and not the lava itself, but I’m not sure about your other exmaples.

Mostly, the problem is either:

  • That the margin of error is greater than the measurable age of the sample; so you can’t expect to get a meaningful date on your PBJ sandwich, or rather, a date of, say, 50 years old for a fresh sandwich is not particularly inaccurate.

-That the sample was not appropriate for testing; most carbon dating is calibrated for samples that have been exchanging carbon with the atmosphere until they died; take a sample that was exchanging carbon with, say, the ocean (as in Kent Hovind’s famous mollusc), and test it as if it wasn’t, and you’ll get meaningless results.

Of course the creationists know this full well, which is why they set out to purposely conduct tests that they know will produce a higher level of meaningless results. Think about the implications of that; they know how to finagle the system, because they do actually understand that it works, with certain limitations - IMO, they are not just earnestly following their convictions, they are setting out to deliberately deceive.

To do radiometric decay dating there has to be enough time elapsed for a significant amount of atoms to decay. As was said earlier, the half-life for 14C is 5,730 years. You can probably get decent results with a fairly long timespan even before the first half-life (say 1000+ years) with good equipment, but there is no way that you could carbon date anything recent because of the statistics. Remember, all half-life means is that at X time (whatever X is for the particular isotope) half the sample has decayed. It doesn’t tell you anything about when a particular atom decayed or what atom will decay. It’s not like it hits 5,730 years and then half the 14C spontaneously decays all at once. So, for instance, we could probably radiocarbon date an illuminated manuscript. We could definitely date an Egyptian mummy. We might even be able to get enough sample to date something like this if we can get data above the background radiation. But there is no way we could date your lunch. The statistics don’t work that way.

As for the other things he mentioned, that’s just bad science (and that can be putting it politely.)