Less is most definitely more. The vital ingredient responsible for endowing mundane metals with a range of valuable new properties is not a new compound or a new material—it is the holes. Scientists are taking ordinary metals like aluminium and frothing them up to create amazing metal foams. Lightweight, fireproof, sound and heat absorbent, foamy metals could soon be cropping up in cars, ships and aeroplanes. They are already damping down noise in road tunnels, and even orbiting the planet aboard the space shuttle. The foams use less material to fill the same space, saving metal as well as weight. And yet they retain a lot of the strength of the original materials. Nature realised the benefits of such a design a long time ago. Many natural materials, such as bone, have a foamy kind of structure, making them light but tough.
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