Iran issued a threat to a U.S. aircraft carier, today, which further complicates the tense relationship between the two countries. The threat comes just a day after Iran performed naval maneuvers in the Strait of Hormuz.
Science writer Kitty Ferguson sits next to Stephen Hawking in this undated photograph. Ferguson is the author of several books about physics, including <em>Stephen Hawking: Quest for a Theory of Everything </em>and <em>Black Holes in Spacetime.</em>
Make a list of the world's most popular scientists, and Stephen Hawking's name will be near or at the very top of the list.
Hawking, the author of A Brief History of Time and a professor at the University of Cambridge, is known as much for his contributions to theoretical cosmology and quantum gravity as for his willingness to make science accessible for the general public, says science writer Kitty Ferguson.
"It's not dumbing down [science]; it's really making it accessible, hopefully, to a lot of people," she tells Fresh Air's Terry Gross.
Republican presidential candidates prepared Tuesday for their first major test of the primary season, making last-minute whistle-stops throughout Iowa in hopes of swaying many undecided caucus-goers.
Later tonight, Iowa Republicans will gather to cast ballots for the person they want to stand against President Obama in November. But after a bruising months-long campaign, more than a third of those participating in the caucuses say they still haven't made up their minds.