2017-10-05 09:50:02
Trilobites: Electric Honeycombs Form When Nature Gets Out of Balance

09:50, October 05 66 0

This is an electric honeycomb. It’s what happens when certain kinds of electrically charged particles travel between a pointy electrode and a flat one, but bump into a puddle of oil along the way.

The polygonal pattern that emerges is what some physicists also call the rose-window instability, because it resembles the circular, stained-glass designs found in Gothic churches. It’s what happens as natural forces work to keep an electric charge moving in an interrupted circuit.

This visualization reveals fundamental principles about how electricity moves through fluids that engineers can use to develop technology for printing, heating or biomedicine. But it also reminds us that humans aren’t the only ones seeking stability in an unstable world. Even tiny, unconscious objects need balance. You can see similar patterns in wax honeycombs, fly’s eyes and soap bubbles.

Physicists knew of this phenomenon decades before Muhammad Shaheer Niazi, a 17-year-old high school student from Pakistan met the electric honeycomb. In 2016, as one of the first Pakistani participants in the International Young Physicists’ Tournament, he replicated the phenomenon and presented his work as any professional scientist would. But he also developed photographic evidence of charged ions creating the honeycomb, and published his work Wednesday in the journal Royal Society Open Science.

But first: How does the honeycomb form?

Just about every electronic device in your home contains capacitors, which store electricity, a bit like a battery. Electricity travels from the top electrode, through the insulator, to the bottom, or ground electrode.

An electric honeycomb behaves like a capacitor. In this case, the top electrode is a needle that delivers high voltage to the air just a few centimeters above a thin layer of oil on the other flat, grounded surface electrode.

The high voltage strips molecules in the air of their electrons, and creates what’s called a corona discharge, pouring down these electrically charged particles, or ions, like water from a fountain, onto the surface of the oil. Just as lightning strives to strike the ground, these ions want to hit their ground electrode. But because oil is an inefficient conductor, they can’t get through it.

“We can say this is frustrated lightning,” said Alberto T. Pérez Izquierdo, a physicist at the University of Seville in Spain whose 1997 work on the subject inspired Mr. Niazi’s project.

The ions start accumulating on top of the oil until their force is too much. They sink down, forming a dimple in the oil that exposes the bottom electrode, allowing them to find their ground.

But now, the surface of the oil is no longer even. Within milliseconds, dozens of hexagonal shapes form in the layer that help maintain the equilibrium nature demands. The polygons keep the amount of energy flowing into and out of the system equal, and balance two forces — gravity, which keeps the oil’s surface horizontal, and the electric field pushing down on top of it.

To prove that the ions were moving, Mr. Niazi photographed images of the shadows formed by their wind as they exited the needle and recorded the heat presumed to come from the friction of their travel through the oil. Heat appeared to originate at the needle, and dissipate outward, increasing with time — even five minutes after the honeycomb formed.

The thermal images puzzled Dr. Pérez Izquierdo. Neither he nor others had previously explored temperature changes on the oil’s surface, and he would have expected a smaller and more even heating effect than Mr. Niazi observed. Determining the heat’s origin is an interesting question that requires more study, he said, while also praising Mr. Niazi’s experimental skill.

“I think it’s outstanding for so young a scientist to reproduce these results,” Dr. Pérez Izquierdo said.

Mr. Niazi hopes to further explore the mathematics of the electric honeycomb, and in the future, dreams of earning a Nobel Prize. In nature — and in the electric honeycomb — Mr. Niazi points out, “nothing wants to do excess work,” but he’s getting started early anyway.