The thermal rays of mice and men often go awry. An invisibility cloak built for a mouse could hide warm bodies from predators with thermal vision – and could scale up to hide humans from heat-seeking missiles.
Invisibility cloaks, which harness the unusual properties of light-bending metamaterials, have shown theoretical promise for years. But outside of dramatic illusions made with lenses, these haven’t been cloaks that would fool your eye. To redirect the short wavelengths of visible light requires tiny structures, so instead early designs deflected longer wavelengths like microwaves. Cloaks have also struggled to handle many wavelengths of light at once.
Now, a team at Zhejiang University in Hangzhou, China, has taken a significant step forward by making a cloak for infrared radiation, whose wavelengths are only just too long to see. All animals – including humans – emit infrared as heat. Snakes can sense this radiation even in darkness, using it to hunt down their prey.
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