Talk of the Nation on WAMC HD2

Apple CEO Timothy Cook made a rare appearance on Capitol Hill on Tuesday, testifying after congressional investigators revealed that Apple avoided billions in taxes. Reporter Charles Duhigg of The New York Times and guest host Jennifer Ludden talk about how, as Duhigg writes, "technology giants have taken advantage of tax codes written for an industrial age."

The National Transportation Safety Board has recommended reducing the legal limit for blood alcohol content for drivers from .08 to .05. Critics say it won't significantly help prevent drunken driving. Guest LZ Granderson argues that without more checkpoints, a lower threshold would do nothing.

Monday's tornado tore through parts of Oklahoma City at 200 miles per hour and killed at least 24 people. Many more are missing orinjured. Guest host Jennifer Ludden talks to KOSU reporter Michael Cross and to meteorologist Paul Douglas about why it's so hard to track tornadoes.

As the populations in big cities increase and more people choose to live alone, a new trend of living in very small spaces has emerged. But the tiny living movement is not without controversy as growth of these multi-unit buildings puts pressure on established neighborhoods.

As membership in private-sector labor unions has continued to nosedive, traditional labor groups have been forced to reevaluate — just as non-union worker groups have emerged. Guest host Jennifer Ludden talks to writer Josh Eidelson about what he calls 'alt-labor.'

During Argentina's so-called Dirty War, thousands were abducted and taken to secret prisons like a place known as "the little school," where many were tortured and killed. Guest host Jennifer Ludden talks to a former prisoner, Alicia Partnoy, about her disappearance and her time there.

Generations of physicists have claimed that time is an illusion. But not all agree. In his book Time Reborn: From the Crisis in Physics to the Future of the Universe, theoretical physicist Lee Smolin argues that time exists--and he says time is key to understanding the evolution of the universe.

Scientists reported this week in the journal Cell that they had used somatic cell nuclear transfer techniques to create a source of embryonic stem cells from the skin cells of a patient. George Daley, director of the stem cell transplantation program at Boston Children's Hospital, and Josephine Johnston of the Hastings Center discuss the research.

A report from the UN Food and Agriculture Organization says insects offer a huge potential for improving the world's food security. Peter Menzel, co-author of Man Eating Bugs, describes some insect-based cuisine and the western aversion to creepy-crawly snacks.

As the summer travel season approaches, air travel provides a barometer for the health of the U.S. economy — and airlines report they're having a good year. After years of financial troubles, industry representatives hope U.S. travelers are more willing to fly. NPR senior business editor Marilyn Geewax explains what summer travel tells us about the health of the economy.