- If the half-life of carbon-14 is 5730 years and a wooden artifact from an ancient tomb contains 50% of the carbon-14 that is present in living trees, how long ago (in years) was the artifact made?
- Hans-Georg Lundahl
- Thorough, but not fast or even always bright in maths.
- Answered just now
- “If the half-life of carbon-14 is 5730 years and a wooden artifact from an ancient tomb contains 50% of the carbon-14 that is present in living trees, how long ago (in years) was the artifact made?”
As others have noted : the artifact may be made after the tree was felled and we don’t know how long, and the tree may have lived long and have carbon 14 levels reflecting a medium, not just the younger parts.
However, people normally, unless Young Earth Creationists, count on it being made one half life, that is 5730 years, ago, since they count on its coming from an atmosphere having roughly same amount of C14 as today.
I am a Young Earth Creationist. If at a point the atmosphere contained only half the present amount of carbon 14 and an object of organic material then “took one half life to arrive to” our time, that object would not have 50 % but only 25 % of the carbon 14 that is present in recent organic material.
This is how I see Göbekli Tepe, except it was really more recent than one half life ago, and its lowest levels contain less than 25 % the carbon recent material does. Or organic material from its lowest levels contain that.
Now, if a little less than one half life ago the carbon 14 level was such that organic material from then carbon dates to roughly two half lives, this means, if it carbon-dates to one half life, it is more recent than one half life and if it is more recent than one half life, the carbon level was higher than 50 % and lower than 100 %.
One could in pure theory imagine, it could have half a half life ago been 70.7 % - but half a half life ago is 2865 “BP” - 2018 AD = 847 BC.
In 847 BC, carbon levels were if not 100 % like modern carbon at least not too far off, so, while we have 70.7 % of something which ceased to breathe in 847 BC, the original carbon level was so close to 100 % that the remaining carbon is if not 70.7 % at least not very far below.
So, things carbon dated to 1 half life old, or to 5730 years ago or to 3712 BC are less recent than 847 BC and more recent than 2511 BC (the Babel date for Göbekli Tepe’s end, if I get St Jerome’s chronology correct).
When it comes to Abraham being 75 to 80 years old, between Genesis 12 and Genesis 14, we seem to deal with sth like early dynastic Egypt, carbon dated to 3200 BC or sth. So, 1935 or even 1940 BC is carbon dated 3200 BC.
This means a carbon date of 3712 BC could be from either Abraham’s childhood or a little earlier (2015 BC or a little back toward 2511 BC).