Posted on 8:13 AM
Experts test cloaking technology
By Paul Rincon
Science reporter, BBC News
Invisibility cloak Image: Duke University
The cloak is constructed from advanced "metamaterials"
A US-British team of scientists has successfully tested a cloak of invisibility in the laboratory.
The device mostly hid a small copper cylinder from microwaves in tests at Duke University, North Carolina.
It works by deflecting the microwaves around the object and restoring them on the other side, as if they had passed through empty space.
But making an object vanish before a person's eyes is still the stuff of science fiction - for now.
We've opened the door into the secret garden
Prof John Pendry, Imperial College London
The cloak consists of 10 fibreglass rings covered with copper elements and is classed as a "metamaterial" - an artificial composite that can be engineered to produce a desired change in the direction of electromagnetic waves.
Like visible light waves, microwaves bounce off objects, making them apparent and creating a shadow. But at microwave frequencies, the detection has to be made by instruments rather than the naked eye.
New chapter
Water behaves differently. When water in a river flows around a smooth rock, the water closes up on the opposite side. Someone looking at the water downstream would never guess it had passed around an obstacle.
The metamaterial cloak channelled the microwaves around the object like water flows around the rock.
Laboratory at Duke University Image: Duke University
Scientists were able to watch waves bending around the cloak
"These metamaterials have opened a new chapter in electromagnetism. We've opened the door into the secret garden," co-author Professor John Pendry, from Imperial College London, told BBC News.
In the experiment, the scientists first measured microwaves travelling across a plane of view with no obstacles. Then they placed a copper cylinder in the same plane and measured the disturbance, or scattering, in the microwaves.
Next, the researchers placed the invisibility cloak over the copper cylinder. The cloak did not completely iron out the disturbance, but it greatly reduced the microwaves being blocked or deflected.
Hidden from view
Posted on 8:10 AM
Experts test cloaking technology
By Paul Rincon
Science reporter, BBC News
Invisibility cloak Image: Duke University
The cloak is constructed from advanced "metamaterials"
A US-British team of scientists has successfully tested a cloak of invisibility in the laboratory.
The device mostly hid a small copper cylinder from microwaves in tests at Duke University, North Carolina.
It works by deflecting the microwaves around the object and restoring them on the other side, as if they had passed through empty space.
But making an object vanish before a person's eyes is still the stuff of science fiction - for now.
We've opened the door into the secret garden
Prof John Pendry, Imperial College London
The cloak consists of 10 fibreglass rings covered with copper elements and is classed as a "metamaterial" - an artificial composite that can be engineered to produce a desired change in the direction of electromagnetic waves.
Like visible light waves, microwaves bounce off objects, making them apparent and creating a shadow. But at microwave frequencies, the detection has to be made by instruments rather than the naked eye.
New chapter
Water behaves differently. When water in a river flows around a smooth rock, the water closes up on the opposite side. Someone looking at the water downstream would never guess it had passed around an obstacle.
The metamaterial cloak channelled the microwaves around the object like water flows around the rock.
Laboratory at Duke University Image: Duke University
Scientists were able to watch waves bending around the cloak
"These metamaterials have opened a new chapter in electromagnetism. We've opened the door into the secret garden," co-author Professor John Pendry, from Imperial College London, told BBC News.
In the experiment, the scientists first measured microwaves travelling across a plane of view with no obstacles. Then they placed a copper cylinder in the same plane and measured the disturbance, or scattering, in the microwaves.
Next, the researchers placed the invisibility cloak over the copper cylinder. The cloak did not completely iron out the disturbance, but it greatly reduced the microwaves being blocked or deflected.
Hidden from view