I’ve been reading a little bit tonight on carbon dating, and I have one question. Everything that I’ve seen says that it is a “fact” that the half-life of C14 is 5,730 years.
I’m sure someone, at some point, had to figure out that the number 5,730 was the stick by which to measure the age of really old stuff. Anyone care to point me in the direction of how the half-life of C14 was determined?
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I know what carbon dating is but I haven’t got a clue how it really works. I did find this article about the guy why came up with the “half-life” method. maybe it will help?………..
http://www.c14dating.com/int.html
you know I am a news, discovery, national geographic junkie, I still have no clue how they can date items back that many years.
Carrie, I saw that source – unless I missed something this is what is referenced for “how they got the number”, and it’s a different number from the standard measure, even:
“Libby, Anderson and Arnold (1949) were the first to measure the rate of this decay. They found that after 5568 years, half the C14 in the original sample will have decayed and after another 5568 years, half of that remaining material will have decayed, and so on (see figure 1 below). The half-life (t 1/2) is the name given to this value which Libby measured at 5568±30 years. This became known as the Libby half-life. After 10 half-lives, there is a very small amount of radioactive carbon present in a sample. At about 50 – 60 000 years, then, the limit of the technique is reached (beyond this time, other radiometric techniques must be used for dating). By measuring the C14 concentration or residual radioactivity of a sample whose age is not known, it is possible to obtain the countrate or number of decay events per gram of Carbon. By comparing this with modern levels of activity (1890 wood corrected for decay to 1950 AD) and using the measured half-life it becomes possible to calculate a date for the death of the sample. ”
That’s all fine and good if you can accept that as fact, but if you accept it as fact you are accepting that they have been alive for that period of time to witness and record that data.
That’s why I’m so curious to know how they picked that magic number! 😛
I don’t think it’s fact, just a rough estimate at best. They must of had some way to accelerate the decay process in the lab that they were able to time as so many hours or whatever = so many years? If that’s possible? Oh, I noticed that too, If you go down a little further it says in the early 60’s they revised the formula, the paragraph and the one above where it says “Cambridge half-life”. Ok it’s way too early for me to be thinking all scientifically! I need my coffee 😀 …………………………
C14 is one of the most stable compounds on earth. You don’t have to be alive for that long to understand that it decays at a very stable, very definite rate. The rate of decay for a molecule of C14 does not vary over 10 years, 50 years, 100 years or otherwise. Nothing is introduced to accelerate or slow the process because they aren’t looiking at a chunk of it, just a single molecule (unless you happen to have a supercollider on hand). I’m very analytical in nature (surely you kinow this about me by now) and I do not accept as fact things I can’t see the logic in. At least this is the way that I understand it. You also have to keep in mind that we measure a year as one revolution around the sun. Now accepted as absolute, indisputable fact, in the late 1500’s the mere idea was grounds for persecution of Galileo. Now, how did they measure a year before that? Anyway, I love the debate of it all and I love hearing other people’s ideas on it all. Hugs, Hope your back is better! CLARA
http://www.answersingenesis. org/ docs2002/ carbon_dating.asp
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