Why is invisibility cloak hard to come true?

New research by German and New Zealand scientists indicates that invisible coats are easy to detect when the relative speed between the shirt and the observer changes.

Two physicists, Jad Halimeh of the University of Munich, Germany, and Robert Thompson of the University of Otago, New Zealand, published a study on the limitations of invisibility cloaks in Physical Review A on March 10.

In principle, the invisibility cloak is capable of bending light to the incoming light and leading these rays through the human body without difficulty. However, according to Halimeh and Thompson, the best invisibility cloak can only help the body become part of the body. The rest will be exposed by movement.

Invisible cloak of the character Harry Potter in the movie of the same name. Photo: Get Daily Updates.

The direct light of the image behind the blouse comes to the observer's eyes in terms of distance and shorter time than the blazing blaze as it passes through the invisibility cloak. This difference can lead to noticeable distortions.

"Basically, our research shows that invisibility cloaks can not be invisible to all observers, " Phys.org quoted Halimeh. "Harry Potter stealth cloak exists only in novels. The invisible cloak, in fact, will reveal what lies behind when you move relative to it."

The cause of this phenomenon is due to the Fresnel - Fizeau effect . In the 19th century, scientists discovered that light transmitting in the shifting environment would also be dragged by the environment. Thus, for a stationary observer, the invisible coats move the light waves to different areas of space, causing the image to distort.

The image distortion caused by the Fresnel-Fizeau effect is proportional to the relative speed of the cloak and the observer. However, even at the slowest speed and distortion the image is difficult to see with the human eye, the light sensor can still detect abnormalities.

"Although our results may disappoint the magicians, the perception of the limitations of stealth devices is very important in the real world , " Thompson said. "With today's modern technologies, we will look for effects that can improve the functionality of invisibility cloak, or exploit it for some practical purposes in the future."