Using Spectral Cloaking for Object Invisibility

An example of when science fiction becomes science fact. This advance could be used in many different ways, including in digital security, with out of sight possibly meaning out of mind.


Researchers and engineers have long sought ways to conceal objects by manipulating how light interacts with them. A new study offers the first demonstration of invisibility cloaking based on the manipulation of the frequency (color) of light waves as they pass through an object, a fundamentally new approach that overcomes critical shortcomings of existing cloaking technologies.

The approach could be applicable to securing data transmitted over fiber optic lines and also help improve technologies for sensing, telecommunications and information processing, researchers say. The concept, theoretically, could be extended to make 3D objects invisible from all directions; a significant step in the development of practical invisibility cloaking technologies.

Most current cloaking devices can fully conceal the object of interest only when the object is illuminated with just one color of light. However, sunlight and most other light sources are broadband, meaning that they contain many colors. The new device, called a spectral invisibility cloak, is designed to completely hide arbitrary objects under broadband illumination.

The spectral cloak operates by selectively transferring energy from certain colors of the light wave to other colors. After the wave has passed through the object, the device restores the light to its original state. Researchers demonstrate the new approach in Optica, The Optical Society’s journal for high impact research.

“Our work represents a breakthrough in the quest for invisibility cloaking,” said José Azaña, National Institute of Scientific Research (INRS), Montréal, Canada. “We have made a target object fully invisible to observation under realistic broadband illumination by propagating the illumination wave through the object with no detectable distortion, exactly as if the object and cloak were not present.”


While the new design would need further development before it could be translated into a Harry Potter-style, wearable invisibility cloak, the demonstrated spectral cloaking device could be useful for a range of security goals. For example, current telecommunication systems use broadband waves as data signals to transfer and process information. Spectral cloaking could be used to selectively determine which operations are applied to a light wave and which are “made invisible” to it over certain periods of time. This could prevent an eavesdropper from gathering information by probing a fiber optic network with broadband light.

The overall concept of reversible, user-defined spectral energy redistribution could also find applications beyond invisibility cloaking. For example, selectively removing and subsequently reinstating colors in the broadband waves that are used as telecommunication data signals could allow more data to be transmitted over a given link, helping to alleviate logjams as data demands continue to grow. Or, the technique could be used to minimize some key problems in today’s broadband telecommunication links, for example by reorganizing the signal energy spectrum to make it less vulnerable to dispersion, nonlinear phenomena and other undesired effects that impair data signals.

Removing C02 from the Atmosphere — Most Efficient Process Yet Found

With climate change’s dangers looming, it would be sensible for more people to try to lower the cost of direct air capture demonstrated here. Estimating that humans put 50 billion tons of C02 in the atmosphere every year, with the cost of removing one ton of C02 being at maybe $100, it would cost approximately $5 trillion (5-6% of world GDP) a year to offset the new C02 being added yearly. It isn’t clear to me how much value would be able to be generated by the tons of C02 captured, but I am aware that there are good catalysts for recycling C02 into valuable chemicals available.

Even so, it’s troubling that governments around the world don’t join forces to reduce the costs of this direct air capture and contribute money towards using it more. Eventually, my guess is that something similar to this technology is going to have be used much, more in the future. I don’t think humanity is moving fast enough to ditch fossil fuels for clean energy, and the next ten years are going to be especially crucial in what happens with climate change. The problem with C02 removal is going to continue to revolve around the high cost to do it though — if the cost could be further lowered significantly, much of the warming this century could be prevented.

By removing emitted carbon dioxide from the atmosphere and turning it into fresh fuels, engineers at a Canadian firm have demonstrated a scalable and cost-effective way to make deep cuts in the carbon footprint of transportation with minimal disruption to existing vehicles. Their work appears June 7 in the journal Joule.

“The carbon dioxide generated via direct air capture can be combined with sequestration for carbon removal, or it can enable the production of carbon-neutral hydrocarbons, which is a way to take low-cost carbon-free power sources like solar or wind and channel them into fuels that can be used to decarbonize the transportation sector,” says lead author David Keith, founder and chief scientist of Carbon Engineering, a Canadian CO2-capture and clean fuels enterprise, and a professor of applied physics and public policy at Harvard University.

Direct air capture technology works almost exactly like it sounds. Giant fans draw ambient air into contact with an aqueous solution that picks out and traps carbon dioxide. Through heating and a handful of familiar chemical reactions, that same carbon dioxide is re-extracted and ready for further use — as a carbon source for making valuable chemicals like fuels, or for storage via a sequestration strategy of choice. It’s not just theory — Carbon Engineering’s facility in British Columbia is already achieving both CO2capture and fuel generation.

The idea of direct air capture is hardly new, but the successful implementation of a scalable and cost-effective working pilot plant is. After conducting a full process analysis and crunching the numbers, Keith and his colleagues claim that realizing direct air capture on an impactful scale will cost roughly $94-$232 per ton of carbon dioxide captured, which is on the low end of estimates that have ranged up to $1,000 per ton in theoretical analyses.


Centuries of unchecked human carbon emissions also mean that atmospheric carbon dioxide is a virtually unlimited feedstock for transformation into new fuels. “We are not going to run out of air anytime soon,” adds Steve Oldham, CEO of Carbon Engineering. “We can keep collecting carbon dioxide with direct air capture, keep adding hydrogen generation and fuel synthesis, and keep reducing emissions through this AIR TO FUELSTM pathway.”


“After 100 person-years of practical engineering and cost analysis, we can confidently say that while air capture is not some magical cheap solution, it is a viable and buildable technology for producing carbon-neutral fuels in the immediate future and for removing carbon in the long run,” says Keith.

Availability of 3D-Printed Weapons Present Risks, and 3D Printers Present Other Opportunities

The main cause of violent street criminality is poverty. Having many of the same societal problems today — poverty, despair, isolation — exist at similar levels world where 3D-printed weapons are widely accessible is a recipe for more disasters.

While advances in additive manufacturing offer potential breakthroughs in prosthetic arms or jet engine parts, 3D printing, as it is known, may also accelerate weapons proliferation.

A new RAND Corporation paper suggests additive manufacturing could benefit military adversaries, violent extremists and even street criminals, who could produce their own weapons for use and sale.

3D printing technology is also susceptible to hacking, which could allow sabotage by hackers who maliciously instruct 3D printers to introduce flawed instructions or algorithms into mission-critical parts of airplanes, according to the paper.


Additive manufacturing may also indirectly support the survival and rise of pariah states like North Korea, which could avoid the costs of withdrawing from the international community by producing complex items domestically, skirting international sanctions.

From an economic perspective, by decentralizing manufacturing individuals and firms may choose to produce locally rather than importing goods. 3D printing could therefore weaken international connections currently sustained by complex, multi-country supply chains, the authors conclude. That in turn may create upheaval in labor markets — and subsequent social conflict.

“Unemployment, isolation and alienation of middle and low-skilled laborers may be exacerbated by additive manufacturing, potentially leading to societal unrest in both developed and developing countries,” said Troy Smith, an author on the paper and an associate economist at RAND. “The potential security implications of large masses of unemployed, disconnected people are substantial.”


The paper, “Additive Manufacturing: Awesome Potential, Disruptive Threat,” is part of a broader effort to envision critical security challenges in the world of 2040, considering the effects of political, technological, social and demographic trends that will shape those security challenges in the coming decades.

Artificial Mole as Early Cancer Detection in Development

For those of you who aren’t enthused about some of the other modern methods of cancer screenings, this artificial mole will possibly provide another avenue sometime in the next several years or so.

Alongside cardiovascular disease, cancer has become the top cause of death in industrialised countries. Many of those affected are diagnosed only after the tumour has developed extensively. This often reduces the chance of recovery significantly: the cure rate for prostate cancer is 32 percent and only 11 percent for colon cancer. The ability to detect such tumours reliably and early would not only save lives, but also reduce the need for expensive, stressful treatment.

Researchers working with Martin Fussenegger, Professor at the Department of Biosystems Science and Engineering at ETH Zurich in Basel, have now presented a possible solution for this problem: a synthetic gene network that serves as an early warning system. It recognises the four most common types of cancer — prostate, lung, colon and breast cancer — at a very early stage, namely when the level of calcium in the blood is elevated due to the developing tumour.

The early warning system comprises a genetic network that biotechnologists integrate into human body cells, which in turn are inserted into an implant. This encapsulated gene network is then implanted under the skin where it constantly monitors the blood calcium level.

As soon as the calcium level exceeds a particular threshold value over a longer period of time, a signal cascade is triggered that initiates production of the body’s tanning pigment melanin in the genetically modified cells. The skin then forms a brown mole that is visible to the naked eye.


The researchers used calcium as the indicator of the development of the four types of cancer, as it is regulated strongly in the body. Bones serve as a buffer that can balance out concentration differences. However, when too much calcium is detected in the blood, this may serve as a sign for one of the four cancers.

“Early detection increases the chance of survival significantly,” says Fussenegger. For example, if breast cancer is detected early, the chance of recovery is 98 percent; however, if the tumour is diagnosed too late, only one in four women has a good chance of recovery. “Nowadays, people generally go to the doctor only when the tumour begins to cause problems. Unfortunately, by that point it is often too late.”

The implant also has an additional advantage: “It is intended primarily for self-monitoring, making it very cost effective,” explains the ETH professor.


So far, this early warning implant is a prototype; the associated work recently published in the journal Science Translational Medicine is a feasibility study. The researchers have tested their early warning system in a mouse model and on pig skin. It functioned reliably during these tests. Moles developed only when the calcium concentration reached a high level.


The concept of the “biomedical tattoo,” as Fussenegger describes this new finding, would also be applicable to other gradually developing illnesses, such as neurodegenerative diseases and hormonal disorders. In principle, the researchers could replace the molecular sensor to measure biomarkers other than calcium.