Sometime next summer, on the second floor of a research building on the Case Western Reserve University campus, scientists hope to record something the world has never witnessed: The moment of impact when an 18-millimeter-diameter projectile hits a wall of water at 9,000 miles per hour. What will occur in that instant and in the subsequent milliseconds—expected to be captured in detail by high-speed cameras—is a tantalizing mix of “knowns, unknowns and what-if’s,” according to Bryan Schmidt, the project’s lead researcher.