The Invisibility Cloak
Written by Dr. Klaus L.E. Kaiser
The Khaleej Times reports that you’ll soon be able to hide – perhaps even make your shadow invisible – with the headline: Coming soon: Invisibility cloaks! But that’s not all. The article’s writer goes on to say the new research “may in the not too distant future protect a building from earthquakes by bending seismic waves around it.”
Some say that invisibility is next to invincibility. I presume the NSA will be interested in that and fostering the research. Canadian and US military are said to be in discussions already, but bending seismic waves? Isaac, as in Newton, and others may have a word to say about that.
What makes you Visible?
To solve the perennial problem of how to hide from whatever, you have to determine what makes you visible in the first place. In the case of (visible) light that is easy to answer. The light bestowed upon you from the sun or another light source in form of electromagnetic (EM) wave radiation is reflected by your body and seen by another eye. Therefore, in total darkness you will be invisible to a human eye. But an “eye” that can see EM radiation of other wavelengths would have no problem in seeing you.
Apart from any light reflected, anything with a temperature above the absolute minimum temperature (-273 C) will emit some form of heat (infrared) or shorter wavelength (ultraviolet) radiation. Some organisms, such as pit vipers, have special organs to “see” such and, therefore, can find their prey in what is total darkness for us.
The new invention by researcher at the University of Toronto claims to have made the first active “invisibility cloak” for radar type EM waves. It’s all part of the new scientific discipline of “metamaterials” that exhibit properties not found in nature. As Prof. George Eleftheriades explains it: “a device that can ‘correct’ or cancel that [electromagnetic wave] scattering would take the notion of a magic invisibility cloak from the realm of science fiction to reality.”
Of course, Mother Nature has developed such a device a long time ago. It’s commonly called “black holes” which are scattered throughout the universe. Their force fields are so strong that anything coming close by (though possibly even light years away) will be sucked in to never re-emerge, including EM waves. Now that’s true invisibility! So, let’s go on to metamaterials and photonics.
Metamaterials & Nanophotonics
Metamaterials and nanophotonics are some of the new catchy phrases bandied about. The KTH Royal Institute of Technology website explains the latter as “Nanophotonics are technologies where the flow of optical-frequency electromagnetic radiation is engineered in dimensions, or with function-enabling feature-sizes, smaller than the vacuum wavelength.” If that all sounds a bit mysterious to you, don’t worry, you are not alone.
Trying to follow up on some of the early leaders in the field is not successful either. For example, a 2009 press release says “Rayspan Corporation [then a company located in San Diego, CA], the world’s leading innovator of metamaterial air interface solutions for wireless communications is proud to announce that its licensees have now shipped over 20 million of its breakthrough metamaterial antennas. ” That company is now defunct but others appear to be doing well. The field of optics and optical electronics certainly has much to offer in terms of potential new developments. However, much of what is being touted falls into the realm of science fiction. Now, let’s go on to the seismic waves.
Seismic waves are not electromagnetic but acoustic waves of the kind coming from your radio’s loudspeaker. Similarly to the movements of the diaphragm in the loudspeaker moving back and forth, the seismic waves cause physical compression and relaxation of solid rock by the tectonic forces heaving large sections of the earth’s crust.
In earthquakes, the earth moves suddenly up or down, or sideways. Those sudden movements can be anywhere from a tiny fraction of an inch to several feet at a time. When such translocations come to a place where a building is standing, they don’t stop. In a sideways quake movement, you could say “the rug is pulled out from under it.” If the building’s structure is flexible enough to sway and bend without breaking apart it will dissipate the energy that way and will survive. If it is not flexible enough, it will crumble and collapse. That’s also why some ancient wooden structures still stand today while many stone and concrete buildings have collapsed in earthquakes.
The claim about the possibility of “bending seismic waves” appears to be more than just futuristic, at least to me. Entirely apart from the concept for which I cannot see any rational possibility, nature’s force can be overwhelming. For most earthquakes to have any significant impact they’ll have to be at an energy equivalent of 1,000,000 lbs of the high-power explosive TNT or higher; on the Richter scale that equates to the magnitude 5. The idea of “bending” that size of energy release to go around you seems preposterous.
I think building structures to withstand that kind of natural force is a better option.
Dr. Klaus L.E. Kaiser is author of CONVENIENT MYTHS, the green revolution – perceptions, politics, and facts
Dr. Kaiser can be reached at:firstname.lastname@example.org