Tag Archives: Sarah Gates

Fish gets invisibility cloak first, cat waits patiently

An invisibility cloak devised by researchers in Singapore and China is receiving a high degree of interest online with a June 14, 2013 news item on Nanowerk, a June 11, 2013 article by Philip Ball for Nature, and a June 13, 2013 article by Sarah Gates for Huffington Post.

The research paper, Natural Light Cloaking for Aquatic and Terrestrial Creatures by Hongsheng Chen, Bin Zheng, Lian Shen, Huaping Wang, Xianmin Zhang, Nikolay Zheludev, Baile Zhang was submitted June 7, 2013 to arXiv.org (arXiv is an e-print service in the fields of physics, mathematics, computer science, quantitative biology, quantitative finance and statistics. Submissions to arXiv must conform to Cornell University academic standards. arXiv is owned and operated by Cornell University, a private not-for-profit educational institution),

A cloak that can hide living creatures from sight is a common feature of mythology but still remains unrealized as a practical device. To preserve the phase of wave, the previous cloaking solution proposed by Pendry \emph{et al.} required transforming electromagnetic space around the hidden object in such a way that the rays bending around it have to travel much faster than those passing it by. The difficult phase preservation requirement is the main obstacle for building a broadband polarization insensitive cloak for large objects. Here, we suggest a simplifying version of Pendry’s cloak by abolishing the requirement for phase preservation as irrelevant for observation in incoherent natural light with human eyes that are phase and polarization insensitive. This allows the cloak design to be made in large scale using commonly available materials and we successfully report cloaking living creatures, a cat and a fish, in front of human eyes.

What they seem to be saying is that it’s possible to create an invisibility cloak perceptible to the human eye that is made of everyday materials.

I’ll show the fish video first. Pay attention as that fish darts behind its invisibility cloak almost as soon as the video starts (from the Nanowerk Youbube channel; June 14, 2013 Nanowerk news item),

Then, there’s the cat (also from the Nanowerk Youtube channel),


The June 11, 2013 article by Philip Ball for Nature describes the device which provides invisibility,

… This latest addition to the science of invisibility cloaks is one of the simplest implementations so far, but there’s no denying its striking impact.

The ‘box of invisibility’ has been designed by a team of researchers at Zhejiang University in Hangzhou, China, led by Hongsheng Chen, and their coworkers. The box is basically a set of prisms made from high-quality optical glass that bend light around any object in the enclosure around which the prisms are arrayed, the researchers describe in a paper posted on the online repository arXiv.

Ball suggests that this latest invisibility cloak is very similar to a Victorian era music hall trick,

As such, the trick is arguably closer to ‘disappearances’ staged in Victorian music hall using arrangements of slanted mirrors than to the modern use of substances called metamaterials to achieve invisibility by guiding light rays in unnatural ways.

As far as I know, the ‘metamaterial’ invisibility cloaks require very sophisticated equipment for their production, are incredibly expensive, and aren’t all that practical.

Gates’s June 13, 2013 article for the Huffington Post provides an overview of some of the recent work on invisibility cloaks and metamaterials, as well as, previous work done by Dr. Hongsheng Chen, an electromagnetics professor at Zhejiang University (China), and Baile Zhang, an assistant physics professor at Singapore’s Nanyang Technological University before they unveiled this latest invisibility cloak.

My most recent posting on the topic was a June 6, 2013 piece on a temporal invisibility cloak.