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Basically, carbon saying sounds like it is counting tree rings: "Since the 1960s, researchers have mainly done this recalibration with trees, counting annual r

Basically, carbon saying sounds like it is counting tree rings: "Since the 1960s, researchers have mainly done this recalibration with trees, counting annual rings to get calendar dates and matching those with measured radiocarbon dates. The oldest single tree for which this has been done, a bristlecone pine from California, was about 5,000 years old. By matching up the relative widths of rings from one tree to another, including from bogs and historic buildings, the tree record has now been pushed back to 13,910 years ago." One question, how are they able to push trees ring counting back 13,910 years, if the oldest tree they have counted was 5000 years old. The limit is 5000, right? And another question, why was this tree only "about 5,000 years old"? They have the very tree, it is either possible to count the rings or not... So why are they rounding (up or down)?

pessimizer 5y ago
> By matching up the relative widths of rings from one tree to another, including from bogs and historic buildings, the tree record has now been pushed back to 13,910 years ago." This is exactly how they did it. edit: Imagine I have one 50 year old tree in the yard, and a house with a log in it that was cut 40 years ago from another 50 year old tree. They were both alive at the same time for 10 years. The relative thicknesses of the rings will match for the first 10 years of the tree and the yard and for the last 10 years of the log in the house, giving me a 90 year record.
- verisimi 5y ago
  Well, if you say so! But its a bit open to interpretation I would say! Are there that many trees from 10,000 years ago even around, so we can read their rings?
  - industriousthou 5y ago
    They’re in bogs and historic buildings.
  - ldng 5y ago
    Yes, of course it is subject to interpretation, but it is not the only source of truth. And no we don't have a vast quantity of 10,00 years trees but enough to be meaningful. We are not measuring in very precise years the further back we go.

pessimizer 5y ago

> By matching up the relative widths of rings from one tree to another, including from bogs and historic buildings, the tree record has now been pushed back to 13,910 years ago." This is exactly how they did it. edit: Imagine I have one 50 year old tree in the yard, and a house with a log in it that was cut 40 years ago from another 50 year old tree. They were both alive at the same time for 10 years. The relative thicknesses of the rings will match for the first 10 years of the tree and the yard and for the last 10 years of the log in the house, giving me a 90 year record.

verisimi 5y ago
Well, if you say so! But its a bit open to interpretation I would say! Are there that many trees from 10,000 years ago even around, so we can read their rings?
- industriousthou 5y ago
  They’re in bogs and historic buildings.
- ldng 5y ago
  Yes, of course it is subject to interpretation, but it is not the only source of truth. And no we don't have a vast quantity of 10,00 years trees but enough to be meaningful. We are not measuring in very precise years the further back we go.