Ice can be hard to get a handle on, literally and figuratively. It can be cloudy or clear, as hard as concrete or as soft as a snowflake. Ice experts Erland Schulson, head of the Ice Research Lab at Dartmouth College, and Shintaro Okamoto, founder of Okamoto Studio in Queens, New York, have staked their livelihoods on the slippery material. We asked them what fascinates them about frozen water.