Feature

  1. Math

    Logic in the Blocks

    Sliding-block puzzles can be surprisingly difficult to solve and can even serve as theoretical models of computation.

    By Ivars Peterson
  2. Materials Science

    Gems of War

    While international bodies grapple with regulatory schemes to stem the diamond trade that funds ongoing civil conflicts in African countries, scientists are attempting to develop methods for identifying gems from conflict zones.

    By John Pickrell
  3. Tech

    Shrinking toward the Ultimate Transistor

    Scientists demonstrate transistor action in an atom—or two.

    By Peter Weiss
  4. Health & Medicine

    Viral Survivor

    Epstein-Barr virus, the cause of diseases ranging from mononucleosis to several kinds of cancer, has begun to reveal how it enters human cells and protects itself from the immune system.