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Allegedly, in the fall of 1943 a U.S. Navy destroyer was made invisible and teleported from Philadelphia, Pennsylvania, to Norfolk, Virginia, in an incident known as the Philadelphia Experiment. Records in the Operational Archives Branch of the Naval Historical Center have been repeatedly searched, but no documents have been located which confirm the event, or any interest by the Navy in attempting such an achievement.
In theory, an invisibility cloak could be built using available technology, according to an international team of scientists.
The scientists, from Duke University's Pratt School of Engineering in the U.S. and Imperial College London have developed the blueprint for an invisibility cloak. Once devised, the cloak could have numerous uses, from defense applications to wireless communications, they said.
In principle, their invisibility cloak could be realised with exotic artificial composite materials called "metamaterials", they said.
The British Ministry of Defence captured the attention of the global media in October 2007, when it announced that it had successfully made a tank invisible to the human eye. Although the British government is keeping the details to itself, it released the basic idea behind the technology.
The tank is coated in silicon, effectively turning the vehicle into a highly reflective movie screen. Video cameras positioned on the tank take real-time footage of the surrounding environment, and projectors show the images on the surface of the tank. To observers at secret trials conducted by the British army in October 2007, the only thing visible was the images of the terrain projected onto the tank.
"The next stage is to make the tank invisible without [cameras and projectors]," physicist Sir John Pendry tells the Daily Mail, "which is intricate and complicated, but possible."
Scientists, however, have made huge strides in the past few years in the rapidly developing field of cloaking. Cloaking involves making an object invisible or undetectable to electromagnetic waves.
A paper published in the March 2009 issue of SIAM Review presents an overview of the theoretical developments in cloaking from a mathematical perspective. One method involves light waves bending around a region or object and emerging on the other side as if the waves had passed through empty space, creating an "invisible" region which is cloaked. For this to happen, however, the object or region has to be concealed using a cloaking device, which must be undetectable to electromagnetic waves. Manmade devices called metamaterials use structures having cellular architectures designed to create combinations of material parameters not available in nature.
A group of researchers from the Department of Physics at UAB have designed a device, called a dc metamaterial, which makes objects invisible under certain light – very low frequency electromagnetic waves - by making the inside of the magnetic field zero but not altering the exterior field. The device, which up to date has only been studied in theoretical works, thus acts as an invisibility cloak, making the object completely undetectable to these waves. The research is based on an initial idea of the British Ben Wood and John Pendry – the latter considered the father of metamaterials - and is a step forward in the race to create devices which could make objects invisible at visible light frequencies.
"The theoretical work provides the details for constructing a real dc metamaterial and represents another step towards invisibility," says Àlvar Sánchez, director of the research. He goes on to state that "now comes a very important stage: building a prototype in the laboratory and applying this device to improving magnetic field detection technology".
Electromagnetic metamaterials are artificially structured materials that are designed to interact with and control electromagnetic waves. Electromagnetic waves might be any type of wave in the electromagnetic spectrum (shown here on the figure to the right). Most of us are familiar with light waves in the visible, which occupy a rather small portion of the electromagnetic spectrum. Visible light waves have wavelengths from 400 to 700 nanometers (a nanometer is one-billionth of a meter), yet electromagnetic waves can have wavelengths of thousands of kilometers to trillionths of a meter!
While the researchers can't promise delivery to a parallel universe or a school for wizards, books like Pullman's Dark Materials and JK Rowling's Harry Potter are steps closer to reality now that researchers in China have created the first tunable electromagnetic gateway.
n the research paper, the researchers from the Hong Kong University of Science and Technology and Fudan University in Shanghai describe the concept of a "a gateway that can block electromagnetic waves but that allows the passage of other entities" like a "'hidden portal' as mentioned in fictions."
The gateway, which is now much closer to reality, uses transformation optics and an amplified scattering effect from an arrangement of ferrite materials called single-crystal yttrium-iron-garnet that force light and other forms of electromagnetic radiation in complicated directions to create a hidden portal.
In the absence of a magnetic field, such nanoparticles would simply float around in the water, but if a field were introduced, the particles would self-assemble into chains whose lengths depend on the strength of the field, and which can also attract one another to form thicker columns.
The chains and columns would lie along the direction of the magnetic field. If they were oriented vertically in a pool of water, light striking the surface would refract negatively – bent in way that no natural material can manage.
This property could be exploited for invisibility devices, directing light around an object so that it appears as if nothing is there, or be put to use in lenses that could capture finer details than any optical microscope.
Originally posted by axiomuser
Great post, good sited information. I too like that Riker narrated. Sounds like he still has the beard. Along these lines, I have also read ideas about manipulating a persons optical nerve and their ability to convert light into an electrical signal to the brain to achieve a type of invisibility. Really, you are blinding them, not allowing them to see you when they look in your direction. I for one think that invisibility is the best superpower.