Explained

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.

Explained: Quark-gluon plasmaBy colliding particles, physicists hope to recreate the earliest moments of our universe, on a much smaller scale.

Explained: Knightian uncertaintyThe economic crisis has revived an old philosophical idea about risk and uncertainty. But what is it, exactly?

Explained: The Carnot LimitLong before the nature of heat was understood, the fundamental limit of efficiency of heat-based engines was determined

Explained: Monte Carlo simulationsMathematical technique lets scientists make estimates in a probabilistic world

Explained: Directed evolutionSpeeding up protein evolution in the lab can yield useful molecules that nature never intended.

Explained: ThermoelectricityTurning temperature differences directly into electricity could be an efficient way of harnessing heat that is wasted in cars and power plants.

Explained: Dynamo theoryRecent discoveries raise questions about how small planets can have self-sustaining magnetic fields

Explained: Climate sensitivityIf we double the Earth’s greenhouse gases, how much will the temperature change? That’s what this number tells you.

Explained: Regression analysisSure, it’s a ubiquitous tool of scientific research, but what exactly is a regression, and what is its use?

Explained: Radiative forcingWhen there’s more energy radiating down on the planet than there is radiating back out to space, something’s going to have to heat up

Explained: Linear and nonlinear systemsMuch scientific research across a range of disciplines tries to find linear approximations of nonlinear behaviors. But what does that mean?

Explained: Gallager codesIn 1993, scientists achieved the maximum rate for data transmission — only to find they’d been scooped 30 years earlier by an MIT grad student.

Explained: The Shannon limitA 1948 paper by Claude Shannon SM ’37, PhD ’40 created the field of information theory — and set its research agenda for the next 50 years.

Explained: The Discrete Fourier TransformThe theories of an early-19th-century French mathematician have emerged from obscurity to become part of the basic language of engineering.

Explained: RNA interferenceExploiting the recently discovered mechanism could allow biologists to develop disease treatments by shutting down specific genes.

Explained: P vs. NPThe most notorious problem in theoretical computer science remains open, but the attempts to solve it have led to profound insights.