Later On

A blog written for those whose interests more or less match mine.

Take a look at how weird glass is

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Some good videos in this article by Steph Yin at Motherboard:

Soon after I met Tarun Chitra, he shattered all of my illusions about glass.

It was a Friday evening in early September, the air was still summery, and we were hanging out at a friend’s house before going out dancing.

Chitra works with one of my roommates at a biochemistry research company called D.E. Shaw Research​ based in New York City. He is trying to figure out how glass molecules behave, but doing so on a level beyond the typical models and simulations physicists use.

Rather than using simplified models that essentially treat molecules like balls in a ball pit, Chitra uses a custom-built supercomputer to run intricate simulations of glass molecules that represent actual atoms bonded together with springs.

In addition to furthering physicists’ understanding of how glass works, Chitra’s research could inform the production of better glass technologies in everything from tough gorilla glass to better optical lenses to strong, ultra-thin glasses that can be used in fiber optics and nanotechnology.

In my experience, asking someone to talk about their research can either be immensely rewarding or immensely tedious, but I was on the prowl for good science stories, so I figured I’d give it a shot. Plus, I liked Chitra’s style: scruff and disheveled hair that I decided meant he prioritized thinking over grooming, a subtly nasal voice that I felt would pair well with explaining physics, and socks featuring colors not made by Crayola, which I coveted for myself.

Right off the bat, Chitra threw down a couple facts that surprised me. First, glass isn’t solid (which I knew)—but it’s not quite liquid either (which is what I thought it was). Secondly, glass doesn’t just refer to the silica-based material that we use to make bottles and windows. In fact, pretty much any liquid, including water, can be made into a glass if it is cooled past its melting point fast enough.

Then Chitra started talking about movies and contra-dancing. And that’s when I knew for sure that I was in for a good science lesson. By the end of it, it was clear to me that glass is freakishly weird, and scientists know relatively little about it.

***

We might mistake glass for a solid because it’s hard and retains its shape when we pick it up, Chitra said. But if we were to zoom in on a glass, down to a microscopic level, we’d see something different. “Glass is surprising because it’s so rigid, but when you measure its molecular properties, it looks exactly like a liquid,” he told me. The molecules in a glass are scattered all over the place rather than packed into the neat lattice structure that gives solids their stiffness.

Part of the confusion about where glass stands in relation to solids and liquids has to do with timescale, according to Chitra. Think of it in terms of frame rates for a movie, he suggested. “A solid is a single frame that never changes. A liquid is a movie at normal speed. And a glass is a movie that moves so slowly that it takes your whole lifetime to move one second.”

So even though a single frame of glass molecules looks the same as a single frame of liquid molecules, the frame rates for the two are very different. The frame rate of glass is so slow that it appears to act like the static single frame of a solid. “It’s as if I gave you a single picture and said, ‘Tell me whether this was taken by a still camera or a video camera,’” said Chitra. “Glass is like watching a movie so slowly that it basically looks like the frame doesn’t change.”

But it’s not like glass is just a really slow-moving liquid either. In fact, glass departs from liquid is some key ways. . .

Continue reading for more info and the videos.

Written by LeisureGuy

12 March 2015 at 1:08 pm

Posted in Science

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