A Mine for Dark Matter
by Marcus Y. Woo
Researchers have built an experiment 230 stories underground in search of dark matter, the mysterious stuff that makes up a quarter of the universe.
Cassini's Ringside Seat
by Linda Doran
As Cassini explores Saturn, its moons have grabbed most of the headlines.
But we're finding out a lot about its rings, as well.
Recommend a Movie, Win a Million Bucks
by Joseph Sill
Can a computer learn to choose movies you're sure to like? Artificial intelligence took on this real-world problem in the Netflix contest. A Caltech alum recounts his adventures in the quest for the million-dollar grand prize.