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Iron Age Potters Accidentally Recorded the Strength of Earth's Magnetic Field (npr.org)
Solandri writes: We've only been able to measure the Earth's magnetic field strength for about two centuries. During this time, there has been a gradual decline in the field strength. In recent years, the rate of decline seems to be accelerating, leading to some speculation that the Earth may be losing its magnetic field -- a catastrophic possibility since the magnetic field is what protects life on Earth from dangerous solar radiation. Ferromagnetic particles in rocks provide a long-term history which tells us the poles have flipped numerous times. But uncertainties in dating the rocks prevents their use in understanding decade-scale magnetic field fluctuations.
Now a group of archeologists and geophysicists have come up with a novel way to produce decade-scale temporal measurements of the Earth's magnetic field strength from before the invention of the magnetometer. When iron-age potters fired their pottery in a kiln to harden it, it loosened tiny ferromagnetic particles in the clay. As the pottery cooled and these particles hardened, it captured a snapshot of the Earth's magnetic field. Crucially, the governments of that time required pottery used to collect taxed goods (e.g. a portion of olive oil sold) to be stamped with a royal seal. These seals changed over time as new kings ascended, or governments were completely replaced after invasion. Thus by cross-referencing the magnetic particles in the pottery with the seals, researchers were able to piece together a history of the Earth's magnetic field strength spanning from the 8th century BCE to the 2nd century BCE. Their findings show that large fluctuations in the strength of the magnetic field over a span of decades are normal. The study has been published in the journal PNAS.
Now a group of archeologists and geophysicists have come up with a novel way to produce decade-scale temporal measurements of the Earth's magnetic field strength from before the invention of the magnetometer. When iron-age potters fired their pottery in a kiln to harden it, it loosened tiny ferromagnetic particles in the clay. As the pottery cooled and these particles hardened, it captured a snapshot of the Earth's magnetic field. Crucially, the governments of that time required pottery used to collect taxed goods (e.g. a portion of olive oil sold) to be stamped with a royal seal. These seals changed over time as new kings ascended, or governments were completely replaced after invasion. Thus by cross-referencing the magnetic particles in the pottery with the seals, researchers were able to piece together a history of the Earth's magnetic field strength spanning from the 8th century BCE to the 2nd century BCE. Their findings show that large fluctuations in the strength of the magnetic field over a span of decades are normal. The study has been published in the journal PNAS.
From TFA: ''' "When dealing with such large-scale phenomena, we don't usually think it can occur within a few decades. We usually think it would take thousands or tens of thousands of years," Forman says. The finding, he adds, "opens up a big can of worms" because researchers just don't know how or why that would happen. So there's something missing about scientists' concept of goings on in the Earth's core.''' But hey, at least now we know we don't know :)
+Raider of the lost BBS
How do we boost the strength far enough to eliminate cancer?
In short: you can't. Cosmic radiation is just a small part of the complex system that can trigger cancer. Other aspects include: genetic make-up, environment (carcinogens) and the inherent error rate in the DNA copying machinery (missense, frameshifts, slippage, etc) [to name a few off the top of my head - I don't treat cancer]. And before you go down there....those imperfect copies are what leads to genetic variation (important to fend off predators both macro and microscopic) and evolution. Cancer is just about inevitable in any DNA based system
. . . . back in my Geophysics days (early 1980s), we already knew that the current planetary magnetic field was in decline, and we were approaching a pole reversal "real soon now" (in Geologic timeframe, not human timeframe. . ).
Heck, we were routinely measuring fossilized magnetic remnant fields in far older rocks, not just strength, but orientation as well. And finding the proper orientation of the sample was always difficult, generally required microscopic examination of a thin slice of the sample. The advantage of pottery for recent sampling, is that it is far easier to determine the orientation of the sample. . .
no news to anyone in the field.
I see what you did there. Also, thanks to Slashdot's no editing policy, we now have a record of pun field strength for future paleocomedians.
Escher was the first MC and Giger invented the HR department.
"... to some speculation that the Earth may be losing its magnetic field -..."
Since the data ultimately suggests that fluctuations are completely normal, I submit that this also starts to explain why people are taking scientists less and less seriously.
Don't blame this on the researchers; blame this on the "science writers" (including the author of the summary here on Slashdot). The actual study - at least the abstract and the supplemental material, which was all I could read without a PNAS subscription - says no such thing and that particular wording is just a click-bait addition in order to garner more views. Science journalism - like so much journalism this day - has gone on a real decline over the past twenty years and tries to "spice up" every study rather than simply reporting the science. The end result is that scientists end up sounding inconsistent and hyperbolic ("Coffee Cures cancer!", no wait, "Coffee Causes Cancer"), when they usually are neither; it is the people reporting on their work that are to blame.
Also see for a more graphic comment on the same problem.
It's in the actual paper - unfortunately it seems paywalled, I don't know if there's an arXiv equivalent for this stuff but the table on page 4 is pretty conclusive - about 100 samples split into age categories based on their stamps.
Are you sure that the Curie point was named after Marie?
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Just checked. It's named after Pierre Curie
https://en.wikipedia.org/wiki/...
If you're scared of your govt then you need to further restrict its powers
Vote 3rd Party in 2016 and beyond
BCE/CE has been a standard in discussing historical time periods for a while now. There's nothing impolite about it, just as there's nothing impolite about using Before Christ/Anno Domini, or using a Hebrew calendar, or using a Chinese calendar, or using an Islamic calendar, or a Hindu one, etc.