For those unfortunate enough to be trapped in a caved-in mine or under the rubble of a collapsed building, the chance of being rescued largely depends upon trained humans and dogs. The equipment they may be outfitted with—thermal imaging sensors, carbon dioxide detectors and flexible video cameras—may also provide some limited help.
But those buried too deeply for searchers to detect them must put all hope of rescue upon the slim possibility that first responders uncover them by chance. For this reason, researchers are trying to develop search and rescue robots that could vastly improve the odds for victims trapped underground.
“The dream and goal in this field is to turn a robot into a multifunctional device capable of moving everywhere,” says Daniel Goldman, a physicist at the Georgia Institute of Technology. “We’re seeking inspiration for how teams of little robots could self-organize to create structures that allow them to efficiently and effectively move around in nasty environments.”
Alterations to the usual glass production process, such as putting the material under stress, can introduce effects that linger even after the material hardens. While manufacturers have long exploited this phenomenon to strengthen glass, a new theory aims to get closer to understanding why it happens.
Glass is not as well understood as most materials, because it straddles the line between liquid and solid. In typical crystalline materials, molecules assemble into a set structure over the span of the entire material as the substance solidifies from a disordered liquid form. Glass, on the other hand, retains a liquid-like disorder even after it hardens.
Without a set architecture, these disordered molecules are particularly vulnerable to outside forces. If you push or pull on a substance, you create internal forces, or stress, in the material itself. Once you remove that force, you’d expect the molecules to return to equilibrium, removing the stresses. But glassy materials “remember” the long-gone force.