Monday, August 10, 2009
"Imagine you're a water molecule in a glass of ice water, and you're floating right on the boundary of the ice and the water," proposes physicist Eric Weeks. "So how do you know if you're a solid or a liquid?"
Weeks' lab recently captured the first images of what's actually happening in this fuzzy area of the crystal/liquid interface. The lab's data, to be published this week in the Proceedings of the National Academy of Sciences (PNAS), make the waves between the two states of matter visible for the first time. "What we've done is found a way to take a picture of the intrinsic interface, measure it, and show how it fluctuates over time," Weeks says.
The experiment took a great deal of trial and error, says Jessica Hernández-Guzmán, a graduate student in physics and the lead author of the PNAS article. "I was looking for that transition," she says. "I knew what the colloids looked like in a crystal state, and I knew what they looked like as a liquid, but I didn't know what they looked like in-between. When I finally saw (the transition), I felt like I had won the lottery."
Read more about how the experiment was done.