Dating the rainbow

Buttermere Lake, with Part of Cromackwater, Cumberland, a Shower

The truth is beautiful in Buttermilk Creek. That was the Texas site of a recent major archaeological find. In the village of Salado, just a couple hundred metres downstream from an important cache of artifacts of the early American Clovis people, anthropologists uncovered something just a few centimetres deeper1. In geological terms, that usually means older – and the assortment of stone tools found by Mike Waters and his team might be the definitive evidence needed to overturn the longstanding “Clovis first” theory.

“Clovis first” is the idea that North America was initially populated by a group of big game hunters known for their interchangeable fluted spear tips – a portable tool that fit well with the nomadic lifestyle. I won’t get into the details (see elsewhere), but many researchers now believe that other migrant groups arrived from the north well before Clovis domination. For example, fishing tools found in California’s Channel Islands provide evidence that a seafaring clan made its way south by hopping along the coastline2.

I also won’t cover the Buttermilk Creek find (again, see elsewhere for this). But there is a poetic element to this discovery worth sharing. The proof that the Buttermilk Creek people arrived ahead of Clovis hunters comes, not from the usual radiocarbon dating methods, but from dating the rainbow.

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Employed science

It’s when applied science gives back, contributing a piece to the basic research puzzle.

Jaded grad students like me get a warm fuzzy feeling when we hear about people reaping unexpected benefits – economic or social – from the results of pure science. Last night I was reminded that this can work in the opposite direction.

Matthew Mecklenburg and Chris Regan, two physicists from UCLA with interests in quantum theory and its applications for sustainable energy, wanted to design a better transistor. Instead, they discovered something fundamental about the structure of the universe1. Hidden from our eyes and our finest instruments, the space that surrounds us might be more like a chessboard than a continuous expanse.

Mecklenburg, a grad student, was investigating graphene as a potential material to make more efficient transistors – the little bits of silicon that allow computers and essentially all modern electronic devices to function. He needed some precise measurements of the way light interacts with graphene at the nanoscale, to assess feasibility of the new design. These experiments gave Mecklenburg a quantitative picture of the way electrons hop around in the lattice of carbon atoms in graphene. And that’s when the chessboard struck.

Mecklenburg and Regan realized that the hopping behaviour of electrons in graphene was formally equivalent to what happens when an electron flips its “spin” – a theoretical concept that has remained an enigma since it was described in the early 20th century.

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