Experts say that after childbirth, intrusive thoughts are common and mostly benign. Lindsay Clancy’s story provides a disturbing exception.

Conservationists set up a colony of white storks in southern England, touching off a debate over whether they truly belong there.

“Recursive self-improvement” is the idea that artificial intelligence could learn to build and train itself, creating exponential new progress — and risk.

Troy E. Meink’s comments were the first public acknowledgment of American weapons in orbit. The Pentagon has been preparing for potential conflict in space with Russia or China.

Models of the insect’s nervous system have been trained to solve a Rubik’s Cube, play video games and even parallel park a car.

Kent Hups, a high school science teacher in Colorado, discovered a 23-foot trackway of fossilized dinosaur footprints, which offer a glimpse of how the apex predator moved 66 million years ago.

Birds are drawn to lights, and more than a billion die each year after crashing into buildings, experts said.

We found grace, humanity and friendship in the stories of disparate Americans hit by climate chaos.

Scientists simulated what happens when the pipes and tunnels that divert rainwater fail. In one scenario, 30 percent of local residents couldn’t reach an E.R.

He developed a program that became a model for hospitals around the world, making it easier for poor Black patients to navigate an onerous bureaucratic system.

A plan to halve the agency’s sprawling work force was illegal, a judge ruled. But the court is not blocking other FEMA cuts.

Thousands of planets have been discovered beyond our solar system, offering clues to where life might thrive and whether Earth is truly unique.

The Times’s Science section is introducing new columns, projects and more as part of its online relaunch.

The New York Times is soliciting readers’ questions about the dangers — and benefits — posed by artificial intelligence.

Today’s chatbots aren’t likely to help lone actors invent a deadly pathogen, experts say. But newer models, trained in biology, may need stronger safeguards.

New estimates using the planet’s surface wrinkles show that our smallest planet is growing even smaller, at a faster clip than expected.

A researcher surveying a San Mateo County creek stumbled upon a preserved Pacific mastodon molar estimated to be at least 10,000 years old.

Cardiologists are struggling to figure out why a drug that should have prevented heart attacks didn’t work at all.

Tribes and scientists are mounting an urgent trapping effort to keep European green crabs from devastating a corner of Puget Sound.

The technology is far from the only existential risk our species faces. But weighing such cosmic fears can become a mind-bending exercise.