Is the world facing a population explosion? Or a birth dearth? Or both at the same time? The two-hour documentary "World in the Balance" on "NOVA" (7 p.m., PBS) shows how the birth rates and population levels of developing-world and industrialized societies are moving in radically different directions. In places like Japan, old people are plentiful and babies rare. At the same time, India, where families of eight children or more are considered normal, is projected to have a population exceeding one and a half billion people.
And what effect will a projected world population of 9 billion have on the Earth's environment? The second half of "Balance" looks at China's rapid industrialization. Dust clouds from eroded soil in Mongolia now regularly darken the skies over Asia and occasionally drift as far as California. As "Balance" makes clear, the old line about dark clouds on the horizon may not be such a cliche.
- Did Hitler die in a bunker? Or in the closet? "The Hidden Fuhrer" (6 p.m., Cinemax) explores controversial theories about Hitler's sexuality. The documentary "Blind Spot: Hitler's Secretary" (7:30 p.m.) follows.
- The three-part documentary "Off to War" (7 p.m., Discovery Times) follows members of an Arkansas National Guard unit and their families as they depart for duty in Iraq. Unlike regular soldiers who undergo boot camp and combat training, these guard troops are just recently removed from civilian life. Many are out of shape and woefully unprepared for life under hostile fire. Tonight's installment focuses on the home front. In upcoming episodes, cameras follow detachment members as they make their way from Kuwait to Iraq in a truck outfitted only with planks of plywood because there were not enough armored cars to go around.
Tonight's other highlights
- The remaining seven perform on "American Idol" (7 p.m., Fox).
- News leaks about Lorelai and Jason on "Gilmore Girls" (7 p.m., WB).
- Jack finds a new angle to deal with Saunders on "24" (8 p.m., Fox).
- The backstage train wrecks never stop on "Showbiz Moms" (8 p.m., Bravo).
- A bullet to the head causes amnesia, television's most prevalent disease, on "NYPD Blue" (9 p.m., ABC).
Jim Carrey and Steve Winwood appear on "Late Show with David Letterman" (10:35 p.m., CBS) ... Jay Leno welcomes Lindsay Lohan and David Bowie on "The Tonight Show" (10:35 p.m., NBC) ... The Darkness appear on "Jimmy Kimmel Live" (11:05 p.m., ABC).