Issues
Physics Update
Reference Frame
Letters
Teaching, Propaganda, and the Middle Ground
Search and Discovery
New Measurements of Hydroxyl in the Middle Atmosphere Confound Chemical Models
Nicknamed the atmospheric garbage disposal, the hydroxyl molecule is one of the most potent oxidizers throughout the atmosphere. Among its habitual targets is ozone.
Chandra X‐Ray Observatory Examines a New Kind of Black Hole
A surprising new class of middleweight black holes, perhaps 10 000 times more massive than the Sun, may have much to teach us about how galaxies form.
Articles
From Quantum Cheating to Quantum Security
For thousands of years, code‐makers and code‐breakers have been competing for supremacy. Their arsenals may soon include a powerful new weapon: quantum mechanics.
Technologies to Reduce Carbon Dioxide Emissions in the Next Decade
The prospects for meeting the Kyoto Protocol for greenhouse‐gas reductions will be brighter if the US can develop technologies to lower its energy use.
Diffusion‐Limited Aggregation: A Model for Pattern Formation
Recent insights from this well‐studied model have led to many new applications—from river networks to oil recovery, and from electrodeposition to string theory.
