Trilobite Eyes: Ultimate Optics

What do physicists and paleontologists have in common? One analyzes equations while the other digs fossils. But when it came to discovering God's complex design for trilobite eyes, expertise from both fields was required. As a child in Italy, Riccardo Levi-Setti started collecting fossilized trilobites, an extinct group of sea creatures somewhat similar to horseshoe crabs. This interest led to curiosity about rocks, then to crystals in rocks, then to the chemistry of crystals, and finally to the physics behind chemistry! Though he eventually earned his doctorate in physics, his love for trilobites never died.

That's why a physicist showed up at a talk about trilobite eyes, given one fateful day in the early 1970s by renowned paleontologist Euan Clarkson.

Soft tissues are not usually preserved in fossils. But since the lenses of trilobite eyes were made of the mineral calcite, they are often preserved. Clarkson had cut through trilobite lenses to study their design. To his surprise, he told the audience, one group of trilobites had lenses unlike any others he had ever seen. Not only that, but there were two different unique shapes, and different trilobite species had one or the other shape.

Clarkson admitted he didn't know why. But Levi-Setti did.

An Old Fix to a Modern Problem

Like flies, undersea creatures known as trilobites had "compound eyes" made of dozens of tiny lenses. Each individual lens usually produces a blurry image. But certain trilobites (order Phacopida) had special lenses that produced crystal-clear images, even on the murky seafloor.

Levi-Setti immediately recognized these as solutions to a problem that had long vexed early lens makers, known as "spherical aberration." The problem arises because solid lenses, like those made of glass (or calcite), aren't flexible. This prevents the lens from focusing well along the edges. The lens shapes were the only two solutions that humans have ever devised — one by René Descartes in 1637 and another by Christian Huygens in 1690. Trilobite eyes had the ideal lenses to see clearly!

[Read the rest of the article at Answers in Genesis.]