Metal 100x lighter than styrofoam

World's lightest metallic substance We know about aerogels, substances so light they are called "frozen smoke." But the boffins (I like that old british word) at the University of California have something more: a metallic substance composed of minitubes and so light the photo here shows it sitting on top of a dandelion puff. Where will this kind of research lead? Well, a kilogram of payload bound for Mars costs $1M to ship. Aerospace engineers might be the first users, but contruction engineers and carmakers also come to mind. We'll just have to see.