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What is Carbon Dating Good For? (Not Much.)
For whatever reason, carbon dating seems to be the main radiometric dating method that people know of. They know it is used for dating ancient things, so they presume that fossils, and even the age of the earth, are dated using carbon dating. Yet in the overall scheme of the earth, carbon dating is pretty much worthless. That's because it is only good for organic material up to about 50,000 years old. In contrast, Earth is about 4.5 billion years old.
I don't begrudge the fact that people don't know this; there are many things I am quite ignorant about. I do get a little annoyed when anti-evolutionists yammer on about the problems with carbon-14 dating (as if scientists are unaware of the problems and limitations) and claim that this represents a problem for determining the age of the earth or of fossils.
Anyway, for fun I decided to make a graph of the usefulness of carbon dating relative to the age of the earth, as well as a few other points of comparison.
The black lines of the y-axis are a little hard to resolve, but they represent 10 million year increments. The values for the comparisons are as follows:
Carbon Dating: 50,000 years
Age of the Earth: 4.5 billion years
Dinosaur Extinction: 65 million years
Life on Earth: 3.7 billion years
"Cambrian Explosion": 530 million years
As you can(not) see, carbon dating doesn't even show up. That's because the maximum usage of carbon dating is represented by 1/200th of the space between two lines. I think I've made my point.
So don't be hard on people who don't realize the vast time disparity between the age of the earth or dinosaurs and carbon dating usefulness. It's a simple and innocent mistake. But if they make that mistake while getting on their high horse about the problems of carbon dating, don't take them seriously either.
Note: if you would like to learn more about radiometric dating, start with Radiometric Dating: A Christian Perspective.
16 comments:
Good to know, I was unaware that carbon dating's usefulness was so limited. Why is it the most widely known radiometric dating method? Was it the first one developed?
Jared*:
Thanks for the graph. It makes a great point.
It is sort of fun to live in a time when people realize that the earth is round, not flat with four corners, and yet many of those same people argue that the earth is only six-thousand years old. Evolution and the ancient age of the earth are hard facts that some day will have the same level of acceptance as the roundness of the earth. In the meantime, it is nice to have scientists thinking of creative ways to explain basic facts to the public. Your graph is a good example.
"Fact" used to mean verifiable data, like "the fossil was in this stratum" and "the detector showed this number". Now it means "anything I think is true that I want to ridicule others for not believing".
The age of the Earth and mechanics of evolution are inferred from facts. No matter how much you don't want it to be true, this necessarily means there's a significant nonzero probability that the current estimates are very wrong. As such, they cannot be facts. It's just semantics, but it's important semantics.
(Personally, I put a good chunk of probability on the order of magnitude of the current estimates of the Earth's age and the general conclusions of evolution, but that doesn't change their nature.)
Now that we've both abused and defended the relatively uninformed: thanks, Jared. A graph like that really only works on a web page, doesn't it? :)
Austin: It looks like uranium-lead dating was developed around 1910, and used to determine the age of rocks. Dating by carbon-14 decay was first done decades after, in 1949 - for dating organic matter. It could be that people hear of radiocarbon dating in archeology, and assume that because they hear about it so much, that *must* be what's used to date fossils. That's just a guess, though. I'm interested in the real answer.
A scientist doing work counter to the consensus of his field will sometimes result in shifting consensus, but only rarely. Usually the unfortunate scoffing and derision is warranted.
When a layman criticises the scientific consensus, you can bet it is for ideological reasons having little to do with science and will most certainly provide a profane, frustrating form of entertainment for the rest of us.
As a layman, I can study outlying opinions that support my ideological views and perform the mental gymnastics that go with it, or I can study the consensus view and absorb and enjoy a beautiful world view so many people smarter than me have painstakingly pieced together. Even if the consensus happens to conflict with my ideological views, I have no basis to dismiss it other than to deceive myself.
On this topic, I like
'Bones, Rocks and Stars: The Science of When Things Happened'
by Chris Turney
So what happens when scientists find soft tissue in dinosaur bones suppose to be millions and millions of years old?
Rob:
Sequence and document the DNA to add a dino genome to our body of knowledge, then inject some viable DNA into a chicken embryo, incubate it while making sure some fat goofy guy doesn't disable the security system and steal it away in a Barbasol can, hatch it, nurture it to adulthood, strap it onto a modifyed jumbo jet and fly her to Seattle, leave her on the doorstep of the Answers in Genesis folks around feeding time. =:)
Seriously though, have they confirmed it is actual soft tissue of the fossilized animal yet? Last I heard they weren't sure. Even if it is, is there science showing that 65 million year old soft tissue is impossible?
Austin,
Along with Anonymous, I'm guessing that its use in archaeology is what makes carbon dating most prominent.
S. Faux,
Thanks for the support.
Anonymous,
I take your point, but I think I would contrast observation (instead of fact) with inference. I like Stephen J. Gould's definition: "In science, fact can only mean confirmed to such a degree that it would be perverse to withhold provisional assent."
At any rate, I bet if we thought about it we would find that many things that most people consider fact are technically inferences.
Stan,
I need to put that book on my to-read list.
Rob,
Your question deserves a post of its own. Maybe two. All I will say for now is that sometimes nature surprises us. And as Stan said: Why not?
Stan,
Yes, this year they independently confirmed dinosaur soft tissue. Here is the link-
http://news.nationalgeographic.com/news/2009/05/090501-oldest-dinosaur-proteins.html
The big question is- Obviously soft tissue would mean that carbon dating it is a reality. How does this effect carbon dating? For that matter, odes it effect all realms of scientific dating procedures?
NEUMAAAAAAAAANNNNN!
The time it takes half of a sample of C14 to decay is about 5700 years. Let's go with 6000 years. The dinosaurs went extinct about 65 million years ago, so we'll use that number as a minimum.
65000000 yrs / 6000 yrs = 10833 half lives
So 10833 half lives of C14 have transpired since the dinosaurs went extinct.
0.5^10833 = excel won't do the calculation, so we'll use a much smaller number that is the limit of what excel will do
0.5^1022 = 2.2251X10^-308
T. rex weighed up to 6.8 tons. Let's go with 7 tons. According to an online converter, 7 metric tons = 7000000 grams
The atomic weight of C14 is about 14 grams/mole
The number of particles in a mole (Avagadro's number) is about 6.02X10^23
OK, let's put this together. Let's assume that every atom of T. rex was C14.
7000000 grams / 14 grams/mole = 500000 moles of C14 in a T. rex.
500000 moles X 6.02X10^23 atoms/mole = 3.01X10^29 atoms
3.01X10^29 atoms X 2.2251X10^-308 = 6.7X10^-279 atoms remaining.
So if a T. rex consisting exclusively of C14 died 65 million years ago, then by now there would be much less than 0.[278 zeros]67 atoms remaining.
This all assumes that no new C14 is created. In reality, there can be trace amounts of C14 in such ancient materials, probably newly created due to existing radioactivity in the earth. We haven't even discussed the limit of detection of the instruments.
Anyway, simply on theoretical grounds it should be clear why C14 is useless for dating dinosaurs.
"Anyway, simply on theoretical grounds it should be clear why C14 is useless for dating dinosaurs."
I've found that flowers and candy work well. =:)
If one "assumes" that a dinosaur bone is too old, it will not get carbon dated. So what happens in the case of people who actually do carbon date dinosaur bones and get back numbers of a more recent past?
I use the term "carbon dating" as a simplistic form of referring to the long list of dating methods. So I confess guilt in that department.
But as to the dating methods themselves and your optomistic view of their accuracy, we greatly differ.
How can you make claim that you KNOW that something is approximately 3 billion years old?
I mean, pardon me!!!!
Science??????
Fairy tales. I know you are all wrapped up in this religion. But it is a false one.
Scientists are always wrong until they try many efforts to make a product work. Here no product needs to be demonstrated. How can you now claim they have definately got it right, in all seriousness?
They choose the answer that aligns with their assumptions--er, I mean...
Actually, there is truth to that. If you are C14 dating dinosaur bones, then you are probably trolling for an anomaly to support your assumptions.
Doug,
I don't think I claimed to KNOW anything. But how about this: the best estimate of the age of the earth, based on radiometric dating (which not only has a sound theoretical basis, but when used appropriately has given repeatable and sometimes independently verifiable results--and therefore seems to be reliable) is that it is about 4.5 billion years old.
How do you KNOW that is a fairy tale?
"Scientists are always wrong until they try many efforts to make a product work. Here no product needs to be demonstrated. How can you now claim they have definately got it right, in all seriousness?"
Can you re-phrase? I'm not sure what you mean (other than scientists are wrong; I got that).
Jared*:
Happy Mutability Day to you. I wish we could celebrate it every year.
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