For much of history, human beings needed to be physically active every day in order to hunt or gather. They didn't do formal exercise

3.5 billion year-old stromatolites built the oxygen in Earth's atmosphere to 20%, giving the kiss of life to all that was to evolve

An astrophysicist argues signs of intelligent extraterrestrial life have appeared. What's the evidence? By Elizabeth Kolbert

Hot spots orbit just outside the black hole at the galaxy's center. Their motions give us a close look at that violent environment.

Regular ingestion of the drug alters your brain's chemical makeup, leading to fatigue, headaches and nausea if you try to quit.

Optical hardware performs massive parallel AI calculations. Two research groups do it by very different methods. By John Timmer

How an obscure British PC maker invented the Acorn Risc Machine (ARM) processor and changed the world. By Jason Torchinsky

The World Is Studded With Artificial Mountains. They're fake, but they can be spectacular (and hazardous). By Dylan Taylor-Lehman

Smart concrete could pave the way for high-tech, cost-effective roads. By Luna Lu and Vishal Saravade.

A renaissance in structural battery research aims to build energy storage into the structures of devices they power.