Technology

How Do Retroreflectors Give You Super Vision at Night?

The tiny optical devices turn up in lane markers, road signs, bike gear and even on the moon, helping us see under low-light conditions.

A Third of Shark and Ray Species May Face Extinction

Overfishing, habitat loss, and climate change are driving species collectively known as chondrichthyan fishes toward a global crisis.

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A Flawed, Strange Covid-19 Origin Theory Is Gaining Traction

A spate of studies claim that the disease was circulating in Italy long before the pandemic—but they struggle to support the theory.

Sweeping Mandates, New Vaccines Underway, and More News

Catch up on the most important updates from this week.

The Dark Asteroid Ryugu Finally Comes Into the Light

Using cameras aboard the Hayabusa2 spacecraft, Japanese scientists get a rare, close-up glimpse of a space rock’s structure.

As Covid Cases Rise, So Do Hospital-Related Infections

A decade of work helped limit the spread of dangerous pathogens in medical settings. Overcrowding from Covid care is allowing infections...

I’m Vaccinated. When Do I Need to Wear a Mask?

Mask guidance continues to change. Here’s what you need to know, depending on who you are, to protect yourself—and, most importantly,...

Dolphins Eavesdrop on Each Other to Avoid Awkward Run-Ins

The new finding underscores the complexity of marine mammals’ social life and cognition. It may also help save the snoopy cetaceans.

Better Data on Ivermectin Is Finally on Its Way

Studies have been small and often not great. The best info so far says don’t use it, get vaccinated, and hang in there for the more...

Pigeons, Curves, and the Traveling Salesperson Problem

Mathematician Ian Stewart explains the twisty history of combinatorial optimization.