
Evidence of Ancient Solar Storms in Tree Rings Could Pinpoint Historical Events - curtis
http://www.pbs.org/wgbh/nova/next/ancient/evidence-of-solar-storms-in-tree-rings-could-help-pinpoint/
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rl3
> _... they’ll be able to piece together more precise time stamps for
> history’s uncertainties: the construction of Egypt’s Great Pyramid of Giza,
> the collapse of the Mayan civilization, and maybe even the arrival of the
> Vikings in the Americas._

That should require some really old trees, no? Wikipedia puts the The Great
Pyramid of Giza for example at 2580–2560 BC. That's about 4600 years ago.

[https://en.m.wikipedia.org/wiki/List_of_oldest_trees](https://en.m.wikipedia.org/wiki/List_of_oldest_trees)

According to that, there's only three known trees on the planet that were
alive at the time.

Of course, maybe I'm misunderstanding; perhaps it's the case that by
accounting for the past few thousand years of solar events, carbon dating will
become far more accurate even for periods in which no tree alive at the time
is available today.

~~~
shagie
While the oldest _living_ trees are there, its not living trees that are being
dated. If you find a timber used in the construction of the pyramid, you can
then match its tree rings up with another set of tree rings that overlap, and
so on back to the present age. In theory.

See
[https://www.crowcanyon.org/index.php/dendrochronology](https://www.crowcanyon.org/index.php/dendrochronology)

The challenge is there are gaps and spots where it doesn't quite match up. A
bad few years and it throws the tree rings off. However, if you can pinpoint
some reference event that spans the globe, you can line the samples back up
again. This is known as cross dating (
[http://www.ltrr.arizona.edu/lorim/basic.html](http://www.ltrr.arizona.edu/lorim/basic.html)
) - it doesn't need to have a living tree.

Radiocarbon dating will never be precise (being able to pin down a specific
year) because of the probabilistic nature of decay and the errors on that are
on the sample. Carbon dating only gives a one sigma. Something that is 3500 BP
(before present) can have a +/\- 60 year error on it. Give
[https://en.wikipedia.org/wiki/Calculation_of_radiocarbon_dat...](https://en.wikipedia.org/wiki/Calculation_of_radiocarbon_dates)
a read.

~~~
tabs_masterrace
That's very cool, could be a interesting problem for using machine learning.
Train it with all the pictures of tree rings with known age, and then see if
it can reliably guess the age of something it hasn't seen.

~~~
willvarfar
Its much more efficiently solved with the naive 'represent the distance
between each adjacent ring as a number' and slide the array of numbers
representing the sample along the known line and for each possible offset,
calculate the error. Then you're left with some shortlist of candidate dates
and their probabilities.

It reminds me of the algorithms for locating reads on the genome.

