creationist rebuttal of evolution

[lifertexan]

Hello,this is my first time here.I am here to ask a question about carbon dating.I understand that it is not accurate over about 60,000 years in the past,but I am seeing creation sites trumpeting a situation in which supposed dino bones were given to Oak Ridge lab without telling them what they were and they came back dated at 16,000 years.Every site seems to be repeating this one incident verbatim.I have looked on the net for an evolutionary response to this,but have not found it.Anyone know about this?Was it really dino bones,or did they hoax the lab?Does trying to use a method that only works back to 60K years ago give whacky results when tried on things millions of years old?

 

What is the scientific response to this Oak Ridge incident that creationists hang so much importance on in rebutting evolution?

[Mr Skeptic]

The reason carbon dating stops working is because of the way radioactive decay works: half of the material decays within the half-life. After 10 half-lifes, there's 1/1000th the material. In the case of carbon dating, the half-life of carbon 14 is 5,730 years, and the starting concentration of C-14 is 1 part per trillion of the carbon. So if you have a sample that is 57,000 years old, you can tell because the C-14 makes up 1 part per 1,000,000,000,000. Or rather, you could if your equipment were absurdly accurate and you were completely certain that your sample was uncontaminated.

 

Any contamination of the sample would introduce new C-14, whether from the CO2 in the atmosphere or from the oils of your skin, or really anything organic. This will increase the amount of C-14 and make the sample appear much younger (which in fact is true because the contamination is younger). Since even the air has C-14, at some point most of the C-14 in the sample would be due to contamination, making carbon dating beyond that point extremely unreliable and inaccurate.

 

Likewise, it is also possible (but much harder) to contaminate in the opposite direction. To make a sample appear older, you can contaminate it with old carbon, like from a tar pit or from coal. I've heard this used to decry carbon dating as well, where creationists created a contaminated fossil by putting a sample in a tar pit, and then acting all surprised when the ratio of C-14 in it was very low.

 

In addition, the ratio of C-14 is different in the atmosphere and in the ocean, so that lying about whether a sample is aquatic or not will result in the C-14 measurement being translated to the wrong date.

 

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In short, C-14 dating does not give the date, it gives the ratio of C-14 in the sample. Given certain assumptions (uncontaminated sample, original carbon source as atmosphere or ocean), this can be translated into a date. Under false assumptions, it will translate to the wrong date. And it won't work past a given age.

Edited April 17, 2010 by Mr Skeptic