David Kestenbaum

David Kestenbaum is a correspondent for NPR, covering science, energy issues and, most recently, the global economy for NPR's multimedia project Planet Money. David has been a science correspondent for NPR since 1999. He came to journalism the usual way — by getting a Ph.D. in physics first.

In his years at NPR, David has covered science's discoveries and its darker side, including the Northeast blackout, the anthrax attacks and the collapse of the New Orleans levees. He has also reported on energy issues, particularly nuclear and climate change.

David has won awards from the American Association for the Advancement of Science, the American Physical Society and the Institute of Electrical and Electronics Engineers.

David worked briefly on the show This American Life, and set up a radio journalism program in Cambodia on a Fulbright fellowship. He also teaches a journalism class at Johns Hopkins University.

David holds a bachelor's of science degree in physics from Yale University and a doctorate in physics from Harvard University.

President Obama has called for increasing the minimum wage, saying it will help some of the poorest Americans. Opponents argue that a higher minimum wage will lead employers to cut jobs.

Figuring out the effect of raising the minimum wage is tough. Ideally you'd like to compare one universe where the minimum was raised against an alternate universe where it remained fixed.

In 1895, legislators in New York state decided to improve working conditions in what at the time could be a deadly profession: baking bread.

"Bakeries are actually extremely dangerous places to work," says Eric Rauchway, a historian at the University of California, Davis. "Because flour is such a fine particulate, if it gets to hang in the air it can catch fire and the whole room can go up in a sheet of flame."

This famous bet — between a biologist and an economist — was over population growth. It started three decades ago, but it helped set the tone for environmental debates that are still happening today.

The biologist at the heart of this bet was Paul Ehrlich at Stanford. He wrote a best-selling book in 1968 called The Population Bomb. It was so popular he appeared on The Tonight Show with Johnny Carson.

We recently published a story about how used clothes that get donated in the U.S. often wind up for sale in markets in Africa. As part of the story, we published some photos of used T-shirts we found in a couple of markets in Kenya.

One shirt in particular caught our eye:

For more on what Bitcoin is and how it works, see our story "What Is Bitcoin?"

Gavin Andresen is chief scientist at the Bitcoin Foundation. I first talked with him about Bitcoin, the virtual currency, back in 2011. I checked back in with him this week, because so much has been going on with Bitcoin lately.