Explained

Explained: SigmaHow do you know when a new finding is significant? The sigma value can tell you — but watch out for dead fish.

Explained: Measuring earthquakesHow do scientists measure jolts such as the recent disaster in Japan? Hint: They don’t use the Richter scale.

Explained: Ad hoc networksDecentralized wireless networks could have applications in distributed sensing and robotics and maybe even personal communications.

Explained: Transiting exoplanetsHow astronomers learn whether a planet is habitable by observing slight changes in light emanating from its parent star.

Explained: Currency warsCountries are clashing over their currency prices. Why?

Explained: Defining recessionsIt’s not what conventional wisdom holds, as an MIT economist — who heads the bureau charged with identifying U.S. downturns — makes clear.

3 questions: P vs. NPAfter glancing over a 100-page proof that claimed to solve the biggest problem in computer science, Scott Aaronson bet his house that it was wrong. Why?

Explained: the Doppler effectThe same phenomenon behind changes in the pitch of a moving ambulance’s siren is helping astronomers locate and study distant planets.

Explained: BandgapUnderstanding how electrons get excited is crucial to creating solar cells and light-emitting diodes

Explained: PhononsWhen trying to control the way heat moves through solids, it is often useful to think of it as a flow of particles.