Researchers Spot Fake Ancient Pottery Using the Earth's Magnetic Field

userbinator•about 1 hour ago

Because the location of the pole is constantly shifting, the TRM of ancient pottery points in a slightly different direction than that of pottery made today.

Did anyone else have a strong "WTF?" reaction upon reading that sentence? Yes, the pole has moved. No, it's completely irrelevant given that not every piece of pottery even manufactured at the same time is going to be fired in the exact same orientation relative to the pole.

The researchers determined that any sample older than a millennium had to be heated to at least 234 degrees Fahrenheit before its VRM was erased. New pottery samples’ VRMs, meanwhile, could be wiped at lower temperatures.

That's a more useful difference which I would attribute to the ceramics having different Curie points in their compositions, and of course it's not something too difficult to change: https://en.wikipedia.org/wiki/Curie_temperature#Changing_a_m...

Incidentally, this effect of temperature on magnetism is how the https://en.wikipedia.org/wiki/Magneto-optical_drive media records data.

MadnessASAP•21 minutes ago

We should probably assume that the authors are aware of ceramics, Curie points, and the earth magnetic field. While the article isn't very clear on what effect causes the change in temperature needed to erase the VRM. I suspect is has something to do with how long the object has spent stationary with respect to the earth's field. At least that's my takeaway from having to periodically rotate magnetometers to prevent them from acquiring a bias.

thangalin•about 1 hour ago

https://impacts.to/downloads/lowres/impacts.pdf#page=23

Quoting my book:

"Studying these layered strata is known as magnetostratigraphy and can be used to verify radioactive dating methods. Geologists used magnetostratigraphy to cross-check the dates of the Nakali Formation, where Nakalipithecus nakayamai’s jaw was found."

flimflamm•about 2 hours ago

What prevents forgers from generating such magnetic fields? That might be worth while if people start to blindly believing that "pottery frozen magnetic fields are not possible to counterfeit". Note that "not possible to counterfeit" is not a claim in the article.

po1nt•about 2 hours ago

I would love to see such counterfeiting. The gear they would need to get and the scientists.

adrian_b•about 1 hour ago

From TFA:

> “So it’s hard for us to be ahead of the forgers since they can read our papers and figure out ways to trick our methods.”

mayneack•about 2 hours ago

The method of seems to involve hearing the artifacts which seems plausibly risky for an ancient artifact.

profsummergig•about 2 hours ago

can this clue be circumvented by using magnets oriented in a certain way around the workshop while constructing the pottery?

comrade1234•about 2 hours ago

There are two fields. The second very weak field is acquired over centuries, I assume when the piece is not moved. The primary stronger field is created when it's first formed. I think what you're talking about would orientate the primary field, not the weak field.

skew-aberration•about 1 hour ago

The second field can probably be created by changing the first field while the piece is still cooling down.

Researchers Spot Fake Ancient Pottery Using the Earth's Magnetic Field

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