In debates and speeches, interviews and a book, Republican presidential hopeful Newt Gingrich is ringing alarm bells over the threat of what experts call the electromagnetic pulse (or EMP), a poorly understood phenomenon of the nuclear age. The idea is that if a nuclear weapon, lofted by a missile, were detonated in outer space high above the American heartland, it would set off a huge and crippling shockwave of electricity. Gingrich warns that it would fry electrical circuits from coast to coast, knocking out computers, electrical power and cell phones. Everything from cars to hospitals would be knocked out. Experts dismiss the threat, however. America’s current missile defense system would thwart such an attack, they say, and the nations in question are at the kindergarten stage of developing nuclear arms.Learn more from the NY Times.