Mathematicians use Sudoku to understand a mysterious, powerful algorithm.

R.K. Pachauri, an engineer and economist by training, is director-general of The Energy and Resources Institute in New Delhi, India, and a corecipient of the 2007 Nobel Peace Prize for his role as chief of the Intergovernmental Panel on Climate Change. The IPCC periodically issues consensus reports on the science of climate change. Senior editor Janet Raloff spoke with him about changes he hopes to see from the Obama administration.

Two studies apply social networking ideas to data from health studies of thousands of people, and suggest different interpretations of how contagious happiness or other experiences can be.

Some game theory paradoxes can be resolved by assuming that people adopt multiple personae, and aren’t rational.

Edward O. Wilson of Harvard University has written and lectured widely in fields ranging from sociobiology and evolutionary psychology to conservation biology. He spoke recently on “sustainability” at Baldwin-Wallace College in Berea, Ohio. Wilson believes that too much emphasis has been placed on trying to reduce energy consumption and avert climate change—what he calls the “physical environment”—and too little on preserving habitat and biodiversity, or the “living environment.” For Wilson, preserving the living environment means protecting areas of the world...

Florence Nightingale pioneered the use of applied statistics to develop policy and developed novel ways of displaying them.

Planetary science is in the midst of a revolution. As recently as the early 1990s, “the planets” consisted of just nine famous objects in our solar system that every school kid learned to recognize by name and appearance. But then, advances in astronomical technology unleashed an explosion of new planetary discoveries on two fronts. One of these fronts involved a bewildering variety of planets discovered around other stars. In rapid succession, we learned about extrasolar pulsar planets, hot Jupiters, superEarths and more. And there is now a widespread scientific consensus that the 300...