US researchers for the first time made a three-dimensional object invisible.
The feat does not make a Harry Potter-style invisibility cloak a reality, but it brings the research a big step forward.
The scientists at the University of Texas at Austin said they coated an 18-centimetre-long cylinder with plasmonic metamaterials, which made it invisible from every angle.
Metamaterials, which redirect light around an object, have been used in the past to cloak objects, but only two-dimensional ones. The 3D breakthrough was made with plasmonic metamaterials, which cancel out the light rays bouncing off objects.
Humans and animals are able to see objects because of the light striking and rebounding off them to our eyes.
The breakthrough, however, rendered the cylinder invisible only in microwave wavelengths. It was still visible to the human eye, the scientists said in their research published Wednesday in the New Journal of Physics.
"Realistic and robust plasmonic metamaterial cloaks may be realized for elongated 3D objects with moderate transverse cross-section at microwave frequencies," the study said.
The world's armies were unlikely to be able to issue invisibility fatigues for their soldiers anytime soon, but the research could be put to military use.
Objects of any size could be masked, including warplanes, which could be made invisible to radar with plasmonic metamaterial, the scientists said.
The technology could also be used to hide objects from visible light but would work only if they are extremely small, they said.
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