Graphene May Someday Power the World

Scientists have discovered an endless energy supply in the naturally occurring Brownian motion of graphene.

Graphene is a sheet of individual carbon atoms arranged in a chicken-wire-like pattern. It’s weird stuff, an electrically two-dimensional object in that its charge carriers — its electrons — are only capable of moving in two directions. It does have a little trick by which it gets a third dimension, though: Brownian motion, in this case, continuous, tiny, random movements in its atoms that ultimately cause the sheet to ripple upward and downward. Picture waves moving across a body of water. And now, a team of physicists from the University of Arkansas led by Paul Thibado have found it’s possible to capture energy from graphene’s ripples as an endless source of clean energy.


(VERITASIUM)

Brownian motion was first discovered way back, in 1827, and as a naturally occurring phenomenon, scientists ever since have wondered if there was a way to harness its energy. Leave it to weird graphene to make that possible by doing it on an atomic scale.

Thibado's microscope (RESEARCH FRONTIERS)

Thibado and his students were measuring the movement of graphene sheets, laid atop a copper grid for support, through a scanning tunneling microscope (or STM). The measurements didn’t make any sense, really, with each observation producing different data.

Thibado tells Research Frontiers, “The students felt we weren’t going to learn anything useful, but I wondered if we were asking too simple a question,” in thinking about the movement of the whole graphene sheet. So they studied measurements in smaller and smaller chunks, until they arrived at a single ripple, at which point things began to at least suggest some kind of governing logic.

When they zeroed in on measurements of a single point, “like looking at a buoy which only moves up and down in the ocean,” to use Thibado’s metaphor, they saw it: Tiny Brownian motion combined with larger, coordinated movements, a combination referred to as Lévy flights, that caused a sheet to flip up and down in ripples, similar to the motion produced by flexing a thin sheet of metal. It was the first time this had been observed at the atomic scale, and Thibado and his students published their research in Physical Review Letters.

The insight that graphene’s ripples are naturally occurring is the “key to using the motion of 2D materials as a source of harvestable energy,” says Thibado. Unlike other materials’ individual atoms moving randomly, the carbon atoms in graphene remain connected in their layer and thus move together, which allows the energy from those ripples to be captured using nanotechnology.

Thibado has invented the Vibration Energy Harvester, or VEH, for doing this, and he’s been awarded a provisional patent for his device that can run tiny motors.

While the amount of energy produced by each graphene layer is minuscule, it’s easy to see how it can scale upwards.

Graphene on copper from Thibado’s lab (RESEARCH FRONTIERS)

Thibado’s been working with pieces of graphene a mere 10 microns across, and whose Lévy flights measure only 10 nanometers by 10 nanometers to produce 10 picowatts of power.

Still, you can fit 20,000 such pieces on the head of a pin. A thin membrane of graphene layers could power a watch forever without the need for recharging, and imagine the possibilities for large “batteries” built from graphene: They could run indefinitely, never need recharging, and be absolutely clean. 

(UNIVERSITY OF ARKANSAS)

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Homo sapiens have been on earth for 200,000 years — give or take a few ten-thousand-year stretches. Much of that time is shrouded in the fog of prehistory. What we do know has been pieced together by deciphering the fossil record through the principles of evolutionary theory. Yet new discoveries contain the potential to refashion that knowledge and lead scientists to new, previously unconsidered conclusions.

A set of 8-million-year-old teeth may have done just that. Researchers recently inspected the upper and lower jaw of an ancient European ape. Their conclusions suggest that humanity's forebearers may have arisen in Europe before migrating to Africa, potentially upending a scientific consensus that has stood since Darwin's day.

Rethinking humanity's origin story

The frontispiece of Thomas Huxley's Evidence as to Man's Place in Nature (1863) sketched by natural history artist Benjamin Waterhouse Hawkins. (Photo: Wikimedia Commons)

As reported in New Scientist, the 8- to 9-million-year-old hominin jaw bones were found at Nikiti, northern Greece, in the '90s. Scientists originally pegged the chompers as belonging to a member of Ouranopithecus, an genus of extinct Eurasian ape.

David Begun, an anthropologist at the University of Toronto, and his team recently reexamined the jaw bones. They argue that the original identification was incorrect. Based on the fossil's hominin-like canines and premolar roots, they identify that the ape belongs to a previously unknown proto-hominin.

The researchers hypothesize that these proto-hominins were the evolutionary ancestors of another European great ape Graecopithecus, which the same team tentatively identified as an early hominin in 2017. Graecopithecus lived in south-east Europe 7.2 million years ago. If the premise is correct, these hominins would have migrated to Africa 7 million years ago, after undergoing much of their evolutionary development in Europe.

Begun points out that south-east Europe was once occupied by the ancestors of animals like the giraffe and rhino, too. "It's widely agreed that this was the found fauna of most of what we see in Africa today," he told New Scientists. "If the antelopes and giraffes could get into Africa 7 million years ago, why not the apes?"

He recently outlined this idea at a conference of the American Association of Physical Anthropologists.

It's worth noting that Begun has made similar hypotheses before. Writing for the Journal of Human Evolution in 2002, Begun and Elmar Heizmann of the Natural history Museum of Stuttgart discussed a great ape fossil found in Germany that they argued could be the ancestor (broadly speaking) of all living great apes and humans.

"Found in Germany 20 years ago, this specimen is about 16.5 million years old, some 1.5 million years older than similar species from East Africa," Begun said in a statement then. "It suggests that the great ape and human lineage first appeared in Eurasia and not Africa."

Migrating out of Africa

In the Descent of Man, Charles Darwin proposed that hominins descended out of Africa. Considering the relatively few fossils available at the time, it is a testament to Darwin's astuteness that his hypothesis remains the leading theory.

Since Darwin's time, we have unearthed many more fossils and discovered new evidence in genetics. As such, our African-origin story has undergone many updates and revisions since 1871. Today, it has splintered into two theories: the "out of Africa" theory and the "multi-regional" theory.

The out of Africa theory suggests that the cradle of all humanity was Africa. Homo sapiens evolved exclusively and recently on that continent. At some point in prehistory, our ancestors migrated from Africa to Eurasia and replaced other subspecies of the genus Homo, such as Neanderthals. This is the dominant theory among scientists, and current evidence seems to support it best — though, say that in some circles and be prepared for a late-night debate that goes well past last call.

The multi-regional theory suggests that humans evolved in parallel across various regions. According to this model, the hominins Homo erectus left Africa to settle across Eurasia and (maybe) Australia. These disparate populations eventually evolved into modern humans thanks to a helping dollop of gene flow.

Of course, there are the broad strokes of very nuanced models, and we're leaving a lot of discussion out. There is, for example, a debate as to whether African Homo erectus fossils should be considered alongside Asian ones or should be labeled as a different subspecies, Homo ergaster.

Proponents of the out-of-Africa model aren't sure whether non-African humans descended from a single migration out of Africa or at least two major waves of migration followed by a lot of interbreeding.

Did we head east or south of Eden?

Not all anthropologists agree with Begun and his team's conclusions. As noted by New Scientist, it is possible that the Nikiti ape is not related to hominins at all. It may have evolved similar features independently, developing teeth to eat similar foods or chew in a similar manner as early hominins.

Ultimately, Nikiti ape alone doesn't offer enough evidence to upend the out of Africa model, which is supported by a more robust fossil record and DNA evidence. But additional evidence may be uncovered to lend further credence to Begun's hypothesis or lead us to yet unconsidered ideas about humanity's evolution.