They've traveled 500 miles underground, passing through soil and rock as easily as Casper the Friendly Ghost glides through walls. They've gone straight through the Earth, reaching their destination without needing any guidance—no tunnels, no cables—along the way. What are these little ghosts? They're neutrinos, particles scientists created at the Fermi National Accelerator Laboratory near Chicago and then aimed at a 14,000-ton detector located in Ash River, Minnesota, near the Canadian border. Fermilab announced today it saw its first neutrinos arriving at Ash River.