"Does Dark Energy Really Exist?": Dark energy's existence could have another explanation - that our galaxy lies at the center of a giant cosmic void.
"Saving the Honeybee": A disease called "colony collapse" is killing millions of bees and could affect the future of our food supply.
"The Post-Traumatic Stress Trap": A growing number of experts believe that the concept of post-traumatic stress disorder is severely flawed - and that soldiers are suffering as a result.
"Preventing the Next Pandemic": An international network for monitoring virus transmission from animals to humans might help scientists head off global epidemics.