October 2009

The explosive C4, a favorite for everything from demolition to terrorism to action movies, is in fact one of the safest explosives. How can an explosive be safe? If it’s hard to set off by accident. C4 is so stable that you can light it with a match (it burns but does not explode) or shoot it (it splatters but does not explode). To go bang, it requires a detonator that produces both heat and shock.

At the other end of the spectrum are mixtures that ignite simply from being scratched or knocked. There are obvious challenges in mixing, storing, and handling these substances so that they explode only when intended, yet they’re surprisingly common.

As if the universe weren’t strange enough, scientists have recently discovered that entire galaxy clusters—the largest known structures in the universe, consisting of thousands of galaxies—are moving toward the same area. And we have no idea what mysterious phenomenon is drawing them along. Whatever it is, it’s huge. So far, cosmologists’ best guess is that it’s the gravitational pull from something beyond the visible universe. NASA scientist Alexander Kashlinsky and a team of researchers discovered the mystery motion, dubbed “dark flow,” last year.

Flu season in the Southern Hemisphere is almost over—and now it’s heading back our way. At the time this issue went to press, there were more than 162,000 confirmed cases and 1,154 deaths worldwide from “novel H1N1,” a.k.a. swine flu, but the Centers for Disease Control and Prevention believes this figure is a gross underestimate, especially since only a fraction of people who have the flu go to the hospital.

When Nintendo debuted its DSi game console earlier this year, it closed the loopholes hackers had used to run homebrew applications—unofficial software distributed freely on the Internet—on its predecessor, the DS Lite. But hackers soon found holes in the DSi’s software too, and now DSi-compatible “flash carts,” specially modified cartridges that allow you to run custom code, are coming to market.