Quick question on carbon dating

Please excuse my ignorance but I am somewhat confused on how this works. I understand that carbon decays at a specific rate and this ammount of decay is measured to give a date. Right?How is it that two objects can have a different "age" if the same matter that is in them has been around since the beginning of time or the big bang? Is the carbon created at different times?For instince I have a chicken bone that is only 1 year old but, the carbon that is in the bone should be as old as the earth. Wouldnt it? Shouldnt everything have the exact same age? Sorry for the dumb question I just dont understand.

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Originally posted by Jonathan:
Please excuse my ignorance but I am somewhat confused on how this works. I understand that carbon decays at a specific rate and this ammount of decay is measured to give a date. Right?

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How is it that two objects can have a different "age" if the same matter that is in them has been around since the beginning of time or the big bang? Is the carbon created at different times?

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For instince I have a chicken bone that is only 1 year old but, the carbon that is in the bone should be as old as the earth. Wouldnt it? Shouldnt everything have the exact same age? Sorry for the dumb question I just dont understand.

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There are three major variants-- isotopes-- of carbon. Carbon-14 is unstable. That is it slowly decays via radiation. Carbon-12 and Carbon-13 are stable. Carbon-14 is created at a (somewhat) constant rate in the upper atmosphere. As living organisms do what they do they absorb the various carbon isotopes in amounts proportional to the proportions in the atmosphere. When an organism dies, it stops absorbing carbon. This is when the clock starts. As time passes the proportions of the various carbons change as C-14 decays. That change give us a means of dating the death of the organism. C-14 only works on organic remains and care has to be taken to avoid contaminations, etc.The following link will give you more detail on C-14 ( and other radio-decay based dating methods as well). No webpage found at provided URL: http://my.erinet.com/~jwoolf/rad_dat.html------------------
http://www.hells-handmaiden.com

It should also be mentioned that Carbon 14 dating only works for things tens of thousands of years old.Really old things use other methods.

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Originally posted by schrafinator:
It should also be mentioned that Carbon 14 dating only works for things tens of thousands of years old.

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Really old things use other methods.

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Really young things don't work either. Recent events-- nuclear testing-- have skewed the ratios of c14 toward the high concentrations. And fossil fuel burning starting a couple hundred years ago has dumped a lot of old carbon into the atmosphere. This latter effect is pretty minimal I believe.------------------
http://www.hells-handmaiden.com

That is good to know, thanks.

[QUOTE][B]How is it that two objects can have a different "age" if the same matter that is in them has been around since the beginning of time or the big bang?[/QUOTE][/B]The matter that is in the object is thought to have been around since the beginning. The atoms may not have been. [QUOTE][B]Is the carbon created at different times?[/QUOTE][/B]Yes, it is. ¹⁴C is being generated in the atmosphere of Earth when a particular isotope of Nitrogen is bombarded by alpha particle radiation and undergoes a nuclear reaction. Since the rate of production is fairly constant we can extrapolate how old something is, or more to the point, how much time has elapsed since the organism died (and 14C was no longer being added to its body).Some of the posts above mention complications with carbon dating. One that they haven't mentioned yet is that it is useless with sea shells or marine life that accrete carbon from an aquatic environment, because the major source of dissolved carbon for water is from the geologic environment, so nearly all the carbon used there is millions of years old. It also becomes useless above 40,000 years of sample age because the existing 14C on such old materials is too low to measure. Also carbon dating cannot be used on true fossils because the organic material has been replaced with minerals. So 14C is commonly used in archeaology and anthropology but rarely used in paleontology. [QUOTE][B]Sorry for the dumb question I just dont understand.[/QUOTE][/B]I ask questions, I don't mind answering questions, and I encourage other people to ask as many as they like. After all, the best part of the debate is learning.[This message has been edited by gene90, 08-02-2002]