Picture in 500 words

Since the 1940s, there has been a broad shift away from public transit across the U.S., and service has declined in many cities, including New York, Boston, Denver, Orlando and St. Louis. A look back at the last national mass transit boom helps explain the challenges that confront modern transit agencies. Starting in the 19th century, transit companies worked closely with real estate developers to develop “streetcar suburbs” for a growing population. The companies kept fares low, thanks to corporate consolidation, government regulation and thrifty management. During World War II, producing weapons and supplies for troops fighting abroad became the nation’s top priority. Gasoline, tires and autos were strictly rationed, so most commuters had few ways to get to work other than public transit. In Baltimore, for example, people could ride a streetcar anywhere in the city in 1943 for 10 cents. With wartime production booming, the city’s Baltimore Transit C...

The Himalayas stand as Earth’s highest mountain range, possibly the highest ever. How did it form? Why is it so tall? You might think understanding big mountain ranges requires big measurements – perhaps satellite imaging over tens or hundreds of thousands of square miles. Although scientists certainly use satellite data, many of us, including me, study the biggest of mountain ranges by relying on the smallest of measurements in tiny minerals that grew as the mountain range formed. These minerals are found in metamorphic rocks – rocks transformed by heat, pressure or both. One of the great joys in studying metamorphic rocks lies in microanalysis of their minerals. With measurements on scales smaller than the thickness of a human hair, we can unlock the age and chemical compositions hidden inside tiny crystals to understand processes occurring on a colossal scale. Measuring radioactive elements Minerals containing radioactive elements are of special interest...

The Southern Ocean encircling Antarctica is the world’s largest feeding ground for baleen whales – species like humpbacks that filter tiny organisms from seawater for food. In the 20th century, whalers killed roughly 2 million large whales in the Southern Ocean. Some populations, like the Antarctic blue whale, were reduced by more than 99% and have been struggling to recover, even though most nations ended commercial whaling in the mid-1980s. Today a new threat is emerging: industrial fishing for Antarctic krill – tiny swimming crustaceans, roughly 2 inches (60 millimeters) long. In a newly published study, colleagues and I found that competition with this burgeoning fishery may impede whales’ recovery. I first learned about this issue in early 2022, when a colleague working aboard a cruise ship told me that he had seen approximately 1,000 fin whales feeding on krill near the South Orkney Islands, just north of Antarctica. This was probably the largest a...