In How does carbon-14 dating work?, SDSTAFF Ken writes:
Sunlight is not the same thing as cosmic radiation! Sunlight is (obviously) light, i.e., electromagnetic radiation from the Sun. Cosmic radiation is particulate radiation (mostly, but not entirely, protons) from sources that probably include, but are not limited to, supernovae.
The Sun also boils off some particles (the “solar wind”), but these are far too low in energy to transmute [sup]14[/sup]N to [sup]14[/sup]C.
I recall hearing that the carbon-14 dating conducted on the Shroud of Turin a few years ago had been disputed by the Catholic Church and some in the scientific community. The results posted in 1997(?) showed that the flax used to make the linen in the Shroud was harvested in the 14 century.
But others dispute this, saying that a fire in the 14th century that almost consumed the Shroud (and gave it the scorch marks that it now has) skewed the result of the carbon-14 tested. Has there been any new information released? Does anyone know anything else?
The people who want to believe the Shroud was the real live honest-to-god (so to speak) wrapping cloth used around Jesus, aint gonna be discouraged by such flimsy evidence as Carbon 14 testing, lack of written record of the Shroud before the 1300s, similar fabrications (heh) of holy relics from that same time period, or any other evidence, scientific or not.
As far as I am aware, the Carbon-14 dating of the Shroud is believed to be accurate by almost everyone knowledgable. The small number of hold outs continue to raise arguments that are laughable pretty much laughable. “The shroud was actually underwater for several centuries, held by Nessie in the Loch Ness, and the tiny bacteria in the water got on the shroud and foiled the C-14 dating.”
Faith can move mountains, but I’ll vote for gravity, every time.
Hey, BTW, as a painting from the 1300s, the Shroud still has some intrinisic value.
On the sunshine vs cosmic radiation, I will dig into it and get back to you.
I think Akatsukami is right, except IIRC, cosmic radiation is electromagnetic, not particulate. I seem to remember seeing cosmic rays at the far end of an EM spectrum somewhere along my too-many years in college. But sunlight doesn’t qualify. In fact, I seem to remember that cosmic rays can be distinguished from everything else because they’re extremely redshifted, having originated really far away.
Cosmic rays are indeed particles, accelerated by the galaxy’s magnetic field. (How cool is that?)
Whoops!
Gotta correct myself! Some cosmic rays are particles accelerated by the galactic magnetic field. However, the term cosmic rays can also refer to high-energy EM radiation, and they can come from the Sun, and other places–as long as they aren’t earthly in origin.
Here’s the page that showed me the, er, light:
http://helios.gsfc.nasa.gov/cosmic.html
Roughly speaking, cosmic rays are anything high-energy that hits Earth from someplace else. As a practical matter, most of them are protons, as Akatsukami points out, but there’s also a few photons, electrons, antiprotons and positrons in there. They don’t seem to have any single origin in the sky; the distribution is fairly uniform. Supernovas are a good explanation, but really, we don’t know for sure where they come from. The Sun does produce a few hard gamma rays, and these could be considered cosmic rays, but they’re insignificant compared to the rays from everywhere else. A redshift can’t be determined from the cosmic ray photons, because we don’t know what their frequency was when they were produced. They’re distinguished by their high energy.
Please see the following thread, including a link to a column by Cecil.
http://boards.straightdope.com/sdmb/showthread.php?threadid=25479
Let’s keep this thread discussing how carbon-14 dating works, and what cosmic rays are.