Cells in the placenta have an unusual trick for activating gentle immune defenses and keeping them turned on when no infection is present. It involves crafting and deploying a fake virus.

Scientists have recently discovered scores of free-floating worlds that defy classification. The new observations have forced them to rethink their theories of star and planet formation.

The discovery that the brain has different systems for representing small and large numbers provokes new questions about memory, attention and mathematics.

In the rumbles and groans of underwater volcanoes, Jackie Caplan-Auerbach finds her favorite harmonies — and clues to the Earth’s interior.

High-dimensional spheres can have a much wider variety of structures than mathematicians thought possible.

Three researchers have found a long-sought way to pull information from large databases secretly, moving us closer to fully private internet searches.

The moons orbiting Jupiter and Saturn appear to have subsurface oceans — tantalizing targets in the search for life beyond Earth. But it’s not clear why these seas exist at all.

Quadratic reciprocity lurks around many corners in mathematics. By proving it, number theorists reimagined their whole field.

New research in social bats raises the intriguing possibility that evolution can reprogram the brain’s “place cells,” which are typically associated with location, to encode all kinds of environmental information.