Scientists who have long wondered why the polarity of the Earth's magnetic field occasionally reverses may finally have their answer. Also, a look at how the online industry is stepping up its measures to thwart electronic junk mail, a new way of approaching long-term problems that focuses on flexibility rather than cost-benefit analysis; and surprising similarities between humans and animals when it comes to dealing with personal economics.
(Tags : Scientific American, April 2005 Scientific American Audiobook, Scientific American Audio CD )
