Von Neumann’s War

Shane looked at the bench, then around the cluttered laboratory for a place to set the papers. He carefully picked them up and set them on the floor. Forrester had already turned away from him and was erasing a whiteboard across the room. Shane chuckled to himself again and sat down.

“You see, a few years ago some fellows at Berkeley and at Carnegie Mellon had the idea that being able to emulate a gecko and walk up walls and across ceilings might, and I’m sure you’d agree, be a fun and useful thing.” Forrester stopped long enough to grin from ear to ear at Gries. “Think about it. If we could create a material that enabled us to have the nimble little lizard’s incredible grip, wow, the applications would be endless.

“The efforts of those fellows made the idea a step closer to reality because they were clever and worked out how to make a material coated with synthetic gecko hairs. Uh, I’m getting ahead of myself. Let me see…” Dr. Forrester ran his fingers through his unruly hair.

“Ah yes, the hairs on gecko feet. Biologists call them ‘setae.’ These little setae are the key to its remarkable grip on just about any surface, rough or smooth, wet or dry, and the things are so sticky that the little lizards can hang from a ceiling with their entire weight held up by a single toe. Isn’t that just marvelous?”

“Yes, I’ve seen little geckos do that trick before. The ones they call leopard geckos are all over Iraq,” Shane added.

“Iraq, yes indeed, leopard geckos, hmm, marvelous.” Forrester chuckled and his belly jiggled like Santa Claus’s. “Well, it wasn’t until as recently as last year that we understood how these little guys can do such a nifty thing. In fact, there was some very, shall I dare say, heated, debate about why geckos’ setae were so fantastically sticky.”

“Really,” Shane asked, trying not to let his eyes glaze over or to check his watch.

“Oh, indeed. There was one school of thought that there was some gluey chemical interaction taking place between their feet and the surface they walked on. But that didn’t pan out. This really clever fellow, uh, named Ron Fearing, and a few of his colleagues at the University of California at Berkeley finally figured it out. Can you believe that it turns out to be an electromagnetic interaction between a gecko’s feet and the surface molecules, wow!” Forrester said excitedly.

“Oh, yes, believe it or not, the adhesion is in fact due to very weak intermolecular attractive forces called van der Waals forces. Amazing, isn’t it?” He chuckled again and spent the next few minutes drawing a diagram of the gecko setae and explaining the van der Waals attraction.

While Forrester’s back was turned, Shane stifled a yawn and did check his watch. He had no more than an hour he could spend here and it was airport food for sure. If he didn’t make it through security, fast, it would be soggy sandwich time.

“The way it works is that the gecko setae measure tens of microns across and at their tiny ends they split into lots of even more tiny, thinner, extremely flexible hairs, each just hundreds of nanometers in diameter; now, isn’t Mother Nature just incredible?” the scientist added, looking over his shoulder at his audience and apparently failing to notice that Shane’s eyes were creeping closed.

“These little hairs then broaden out into flat spatulas, just like egg turners, at their tips. The wonderful little buggers can bend and conform to the surface of the wall at the molecular level and believe it or not again, this maximizes the surface area contact between the spatula and the surface, which in turn maximizes the van der Waals attractive force. I just can’t hardly believe it, can you?” Forrester seemed almost giddy.

“Uh, no?” Shane added uncertain if the question had been rhetorical or not. He restrained the desire to check his watch again. The guy wouldn’t be hurried by it, he was sure.

“Finally, these other fellows I’ve been talking about figured out how to synthesize the gecko skin. Wonderful ingenuity, wonderful,” Dr. Forrester said enthusiastically. “Modern vacuum deposition, lithography technology, and some other materials technology allowed them to build synthetic gecko setae made from a material called Kapton that you see there in those orange rolls behind you. They made little gecko hairs that measure about two microns in height and about a tenth that in diameter. That is about the same dimensions as gecko hairs are. They made tape that was covered with this gecko hair with a mold created by a lithographic process. And the most wonderful part is that a piece of tape one centimeter square holds around a hunderd million of these little artificial gecko setae and can actually support a weight of one kilogram. Wow! That suggests that a pair of gloves made of this stuff is all it would take to support the weight of a human being!”