As you may know, crafting a katana is a delicate process that involves carefully constructing a razor-sharp high-carbon edge around a soft shock-absorbent core. One day though, smiths and forging fires could be replaced by electrode-wielding mad-scientists, with the technology to selectively harden and soften metal at will. At least that's what we envisioned when we read about Jörg Weißmüller's breakthrough research in the field of nanomaterials
. The German scientist discovered that by placing precious metals in acid he could create tiny ducts through corrosion. Once those channels are flooded with a conductive liquid, electrical currents can be used to harden the material and, if you change your mind about the brittle results, the effect can easily be reversed to make it soft again. The tech could eventually lead to self-healing vehicle armor or scratch-resistant cellphones -- but, really, we just want to zap our way to a high-quality samurai sword.