More than 2,000 nukes could be fired on short notice.
A planet’s atmosphere can reveal alien life.
Eighty percent of people hospitalized with swine flu in the U.S. were under 50.
Something outside our visible universe is moving whole galaxies.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.