Carbon dating margin of error naughty fish dating
The most common isotope is carbon-12 (or 12 C), which (according the article) makes up 98.89 percent of the naturally occurring carbon.There's carbon-13, or 13 C, which is much rarer, accounting for only 1.11 percent, and then there's carbon-14, or 14 C, which makes up a ridiculously tiny fraction of existing carbon. Living organic matter will have steady and predictable concentrations of each isotope of carbon, pretty much the percentages mentioned above. After something dies, the 14 C decays over time (because it is radioactive) and doesn't replenish as it would in a live specimen because the dead thing isn't eating and breathing or otherwise exchanging molecules with the outside world anymore).Consequently, carbon-dating within the past (say) thousand years or so can be adjusted fairly accurately.(There could still be local variation in the amounts of C-14, etc.) Carbon dating for much older samples has a greater margin of error, since we have have no way of knowing the variation in rate of C-14 absorption prior to the tree-ring era.Well, before it was shroud, it was, like, wool or something, and before it was wool or somethnig, it was hairs on a sheep's back, right? Sunlight (cosmic radiation) strikes the upper atmosphere and converts a small amount of nitrogen (element 7, atomic mass of 14) into the unstable radioactive iostope carbon-14.Blah, blah, blah (you can see where I'm going with this). Randy The broad principles behind carbon dating are fairly simple to explain. The C-14 then gets bound into carbon dioxide gas molecules in the atmosphere, and thus absorbed into plant life.So, with that all in the back of your head, carbon-dating the Shroud of Turin tells us that the linen (it’s linen, not wool, and we refrain from any comments about woolly thinking) was made from flax that was cut around the year 1325 AD, plus or minus 65 years.SDStaff Ken, Straight Dope Science Advisory Board Send questions to Cecil via [email protected]
Carbon dating tells us how long ago an organism died (that is, stopped absorbing C-14.) For dating the remains of a short-lived plant or animal, such as flax or sheep, this is not a problem.Each ring is examined for the amount of C-14 absorbed that year.Thus, carbon-daters know the precise adjustments, year by year, to make to an initial radiocarbon dating to account for fluctuations in absorption rates over time.STAFF REPORTS ARE WRITTEN BY THE STRAIGHT DOPE SCIENCE ADVISORY BOARD, CECIL' S ONLINE AUXILIARY.THOUGH THE SDSAB DOES ITS BEST, THESE COLUMNS ARE EDITED BY ED ZOTTI, NOT CECIL, SO ACCURACYWISE YOU' D BETTER KEEP YOUR FINGERS CROSSED.
So at what point does something's carbon b-day start? The plants are consumed by animals, and thus C-14 appears in all living creatures on Earth.