Remember that dizzying, quarter-mile-high glass observation deck that opened on the 103rd story of Chicago's Sears Tower recently? Well, the New York Times now has an interesting article about the science of making the damn thing work without killing anyone.

Basically the designers had to make the glass five layers thick, using various new polymers and whatnot to ensure that the whole structure wouldn't crumble and send people plummeting to their dooms. The firm that built The Ledge and another group, who made big inroads in the glass architecture field by building all of the glass stairs that bedeck Apple stores across the nation, both have an end goal for all this alchemy: "Ultimately what we're all striving for is an all-glass structure." Sounds like fun! But, um, count us out.