Better than Kevlar: Silk could stop jets

Q: What's the strongest material made by an animal a) turtle shell b) rhino horn c) oyster pearl d) spider silk? –Charlotte Webster

 A: d. The story here begins in old Tombstone days of the Wild West, 1881, when physician George Emery Goodfellow noticed upon examining the body of a man gunned down that his silk handkerchief protruded from the wound, says Science News. When Goodfellow removed the handkerchief, tugging it through ripped-out flesh and broken ribs, there lay the bullet wrapped within the untorn cloth, he wrote in his Notes on the Impenetrability of Silk to Bullets.

 Early on, silkworms spinning cocoons provided tough materials for parachutes, pantaloons, and the like. But recent research indicates spider silk is even superior for tasks such as warding off projectiles. "Dragline silk is the strongest animal-stuff there is," says University of Wyoming molecular biologist Randy Lewis. These are the threads spiders dangle from, and use in their outer-web framework. (The inner web is cushier, to snare prey.)

Dragline silk is at least three times stronger than Kevlar, which is used in bulletproof vests, says Lewis. A one-inch diameter "rope" of this silk, if it could be woven using millions and millions of strands, could stop a jet landing on an aircraft carrier. But since spiders are hard to farm (they tend to eat each other), it is not possible to collect enough of this silk for commercial use. "Through the marvels of genetic engineering, a company in Canada is now producing the dragline protein in goat's milk!"


Q: Don't try this, but it's said you could take a key and scratch a deep radial groove in a CD (compact disc) from center to perimeter and on playback you wouldn't notice the difference. Can this be true? ­M. Jagger

 A: Yes, because the info is burned onto the disc in a spiral from the inside out, so the scratch would leave only small gaps that can be compensated by the error detection algorithms, says Iowa State University's Ben Graubard. Redundancy is the key, with the same information stored many times in many places on the CD. More difficult to fix would be curved scratches running along the recording direction.

For even more CD-defacement fun, try drilling 1/8-inch holes all around one and see if it still plays. It will, says Penn State physicist Julian Maynard, because the data is widely dispersed rather than placed sequentially. Two tests Maynard hasn't yet run: What happens when you run over a CD with your SUV or drop one from an airplane.


Q: Some blind people "see" again in their dreams. Do deaf people "hear" in their dreams? ­S. Wonder

A: Depends on when the hearing loss occurred, how profound it is, whether the person grew up with hearing or deaf parents, and a host of other factors, says Gallaudet University psychologist Robert Lee Williams. There is no "typical" deaf person. "Given that caveat, I can tell you some of my deaf students report hearing and talking in their dreams. Others use sign language. I might add that as a hearing person, I have had dreams in sign language, too. Apparently in dreams, all things are possible."

If a person is born deaf and never hears, there will be no sounds or voices stored in memory for conjuring in the dream world, paralleling the experience of the blind. But having once heard, David Wright, in his book Deafness describes how he continued to hear "phantasmal voices" for the first year or two, just as the adventitiously blind continue to dream in images for a time, until these start to fade in vividness.

Yet, quite marvelously, when a vital sensory input is cut off, says neurologist Oliver Sacks in The New York Review of Books, other parts of the brain may seem heightened in function, with enhancement of the visual cortex (or reallocation of auditory centers) in the deaf.

Send your strange questions to brothers Bill and Rich at their email address.