Cloak of invisibility: Fact or fiction?

Scientists boldly go where only science fiction has been before

The Associated Press
Updated: 11:46 a.m. ET Oct 19, 2006

WASHINGTON - Harry Potter and Captain Kirk would be proud. A team of American and British researchers has made a Cloak of Invisibility.

Well, OK, it’s not perfect. Yet.

But it’s a start, and it did a pretty good job of hiding a copper cylinder. In this experiment the scientists used microwaves to try and detect the cylinder. Like light and radar waves, microwaves bounce off objects making them visible and creating a shadow, though it has to be detected with instruments.

If you can hide something from microwaves, you can hide it from radar — a possibility that will fascinate the military. Cloaking differs from stealth technology, which doesn’t make an aircraft invisible but reduces the cross-section available to radar, making it hard to track. Cloaking simply passes the radar or other waves around the object as if it weren’t there, like water flowing around a smooth rock in a stream.

The new work points the way for an improved version that could hide people and objects from visible light. Conceptually, the chance of adapting the concept to visible light is good, cloak designer David Schurig said in a telephone interview. But Schurig, a research associate in Duke University’s electrical and computer engineering department, added, “From an engineering point of view it is very challenging.”

Nonetheless, the cloaking of a cylinder from microwaves comes just five months after Schurig and colleagues published their theory that it should be possible. Their first success is reported in a paper in Friday’s issue of the journal Science.

"We did this work very quickly ... and that led to a cloak that is not optimal,” said co-author David R. Smith, also of Duke. “We know how to make a much better one.”

Casting a shadow

The first working cloak was in only two dimensions and did cast a small shadow, Smith acknowledged. The next step is to go for three dimensions and to eliminate any shadow. Viewers can see things because objects scatter the light that strikes them, reflecting some of it back to the eye.

“The cloak reduces both an object’s reflection and its shadow, either of which would enable its detection,” said Smith.

In effect the device, made of meta-materials — engineered mixtures of metal and circuit board materials, which could include ceramic, Teflon or fiber composite materials — channels the microwaves around the object being hidden.

When water flows around a rock, Smith explained, the water recombines after it passes the rock and people looking at the water downstream would never know it had passed a rock. The cloaking has to be designed for specific bandwidths of radiation. In this case it’s microwaves, and someone measuring them wouldn’t be able to tell they had passed around an object. The hope is to do the same for light waves. Looking at a cloaked item, Smith explained: “One would see whatever is behind the cloak. That is, the cloak is, ideally, transparent. Since we do not have a perfect cloak at this point, there is some reflection and some shadow, meaning that the background would still be visible just darkened somewhat.

The ideal cloak would have nearly negligible reflection and virtually no shadowing, Smith said.

“This first experiment has provided a confirmation that the mechanism of cloaking can be realized, we now just need to improve the performance of cloaking structures.”

Other possibilities

In addition to hiding things, redirecting electromagnetic waves could prove useful in protecting sensitive electronics from harmful radiation, Smith commented. In a very speculative application, he added, “one could imagine ’cloaking’ acoustic waves, so as to shield a region from vibration or seismic activity.”

Natalia M. Litchinitser, a researcher at the University of Michigan department of electrical engineering and computer science, said this appears to be the “first, to the best of my knowledge, experimental realization of the fascinating idea of cloaking based on meta-materials at microwave frequencies.”

“Although the invisibility reported in this paper is not perfect, this work provides a proof-of-principle demonstration of the possibility,” said Litchinitser, who was not part of the research team. She added that the next breakthrough is likely to be an experimental demonstration of the cloaking in visible light. “These ideas represent a first step toward the development of functional materials for a wide spectrum of civil and military applications.”

Joining Schurig and Smith in the work were researchers at Imperial College in London and SensorMetrix, a materials and technology company in San Diego, Calif. The research was supported by the Intelligence Community Postdoctoral Research Fellowship Program and the United Kingdom Engineering and Physical Sciences Research Council.

© 2006 The Associated Press. All rights reserved.
URL: http://www.msnbc.msn.com/id/15329396/

Blackwater: Shadow Army

Blackwater

The Smear This Time

By ANITA HILL
Published: October 2, 2007

ON Oct. 11, 1991, I testified about my experience as an employee of Clarence Thomas’s at the Equal Employment Opportunity Commission.

I stand by my testimony.

Justice Thomas has every right to present himself as he wishes in his new memoir, “My Grandfather’s Son.” He may even be entitled to feel abused by the confirmation process that led to his appointment to the Supreme Court.

But I will not stand by silently and allow him, in his anger, to reinvent me.

In the portion of his book that addresses my role in the Senate hearings into his nomination, Justice Thomas offers a litany of unsubstantiated representations and outright smears that Republican senators made about me when I testified before the Judiciary Committee — that I was a “combative left-winger” who was “touchy” and prone to overreacting to “slights.” A number of independent authors have shown those attacks to be baseless. What’s more, their reports draw on the experiences of others who were familiar with Mr. Thomas’s behavior, and who came forward after the hearings. It’s no longer my word against his.

Justice Thomas’s characterization of me is also hobbled by blatant inconsistencies. He claims, for instance, that I was a mediocre employee who had a job in the federal government only because he had “given it” to me. He ignores the reality: I was fully qualified to work in the government, having graduated from Yale Law School (his alma mater, which he calls one of the finest in the country), and passed the District of Columbia Bar exam, one of the toughest in the nation.

In 1981, when Mr. Thomas approached me about working for him, I was an associate in good standing at a Washington law firm. In 1991, the partner in charge of associate development informed Mr. Thomas’s mentor, Senator John Danforth of Missouri, that any assertions to the contrary were untrue. Yet, Mr. Thomas insists that I was “asked to leave” the firm.

It’s worth noting, too, that Mr. Thomas hired me not once, but twice while he was in the Reagan administration — first at the Department of Education and then at the Equal Employment Opportunity Commission. After two years of working directly for him, I left Washington and returned home to Oklahoma to begin my teaching career.

In a particularly nasty blow, Justice Thomas attacked my religious conviction, telling “60 Minutes” this weekend, “She was not the demure, religious, conservative person that they portrayed.” Perhaps he conveniently forgot that he wrote a letter of recommendation for me to work at the law school at Oral Roberts University, in Tulsa. I remained at that evangelical Christian university for three years, until the law school was sold to Liberty University, in Lynchburg, Va., another Christian college. Along with other faculty members, I was asked to consider a position there, but I decided to remain near my family in Oklahoma.

Regrettably, since 1991, I have repeatedly seen this kind of character attack on women and men who complain of harassment and discrimination in the workplace. In efforts to assail their accusers’ credibility, detractors routinely diminish people’s professional contributions. Often the accused is a supervisor, in a position to describe the complaining employee’s work as “mediocre” or the employee as incompetent. Those accused of inappropriate behavior also often portray the individuals who complain as bizarre caricatures of themselves — oversensitive, even fanatical, and often immoral — even though they enjoy good and productive working relationships with their colleagues.

Finally, when attacks on the accusers’ credibility fail, those accused of workplace improprieties downgrade the level of harm that may have occurred. When sensing that others will believe their accusers’ versions of events, individuals confronted with their own bad behavior try to reduce legitimate concerns to the level of mere words or “slights” that should be dismissed without discussion.

Fortunately, we have made progress since 1991. Today, when employees complain of abuse in the workplace, investigators and judges are more likely to examine all the evidence and less likely to simply accept as true the word of those in power. But that could change. Our legal system will suffer if a sitting justice’s vitriolic pursuit of personal vindication discourages others from standing up for their rights.

The question of whether Clarence Thomas belongs on the Supreme Court is no longer on the table — it was settled by the Senate back in 1991. But questions remain about how we will resolve the kinds of issues my testimony exposed. My belief is that in the past 16 years we have come closer to making the resolution of these issues an honest search for the truth, which, after all, is at the core of all legal inquiry. My hope is that Justice Thomas’s latest fusillade will not divert us from that path.

Anita Hill, a professor of social policy, law and women’s studies at Brandeis University, is a visiting scholar at the Newhouse Center for the Humanities at Wellesley College.