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The development of new materials could see items such as invisibility cloaks, a key weapon in the trickery of Harry Potter and countless science fiction plots, become a reality within five years.

Two research groups have published technical blueprints for making "metamaterials" which can change how light and other forms of radiation bend around an object, in a way similar to water flowing around a rock.

An observer would see whatever was behind the object as if it were not there, said Professor Ulf Leonhardt of St Andrews University, whose research was published in the latest edition of the journal Science.

David Smith from Duke University in the United States, who has been independently pioneering the development of metamaterials with John Pendry of Imperial College London said the cloak would act "like you've opened up a hole in space."

"All light or other electromagnetic waves are swept around the area, guided by the metamaterial to emerge on the other side as if they had passed through an empty volume of space," Prof Smith told the Financial Times.

The developments have led to concerns about the ethics that might govern how such technology could be used. "Innovations such as these as fantastic, imaginative and useful as they might be would be disruptive to society today," said Patrick Lin, the research director of the US-based Nanoethics Group.

"For instance, the ability to become invisible will have profound implications for privacy as well as national security."

Lin insisted his group, which calls for open-mindedness and public debate about the development of new technologies, did not want to discourage scientists by slowing slow down their work.

"We're fans of technology and are excited about its possibilities just like everyone else," he said.

"Instead, we are encouraging ethicists, policymakers and the broader public to catch up on thinking through the enormous implications of new technologies in this case, before any privacy violations or security breaches may occur."

Smith's research has received funding from the US defence advance research projects agency, which sees possible applications for cloaking military hardware.

Experiments to demonstrate cloaking at microwave frequencies could give results within 18 months, Pendry said.

"But I don't think we will have cloaks for visible light for at least five years," he added.

David Schurig, another member of the Duke University research team, said there was no theoretical limit to the size of cloaking materials. They could be used to hide eyesores as large as refineries, he said.

Source:China Daily