## Elasticity

In physics, elasticity (or stretchiness) is the physical property of a material that returns to its original shape after the stress (e.g. external forces) that made it deform or distort is removed. The relative amount of deformation is called the strain.

The elastic regime is characterized by a linear relationship between stress and strain, denoted linear elasticity. The classic example is a metal spring. This idea was first stated by Robert Hooke in 1675 as a Latin anagram â€œceiiinossssttuuâ€ whose solution he published in 1678 as â€œUt tensio, sic visâ€ which means â€œAs the extension, so the force.â€

This linear relationship is called Hookeâ€™s law. The classic model of linear elasticity is the perfect spring. Although the general proportionality constant between stress and strain in three dimensions is a 4th order tensor, when considering simple situations of higher symmetry such as a rod in one dimensional loading, the relationship may often be reduced to applications of Hookeâ€™s law.

Because most materials are elastic only under relatively small deformations, several assumptions are used to linearize the theory. Most importantly, higher order terms are generally discarded based on the small deformation assumption. In certain special cases, such as when considering a rubbery material, these assumptions may not be permissible. However, in general, elasticity refers to the linearized theory of the continuum stresses and strains.

Above a certain stress known as the elastic limit or the yield strength of an elastic material, the relationship between stress and strain becomes nonlinear. Beyond this limit, the solid may deform irreversibly, exhibiting plasticity. A stress-strain curve is one tool for visualizing this transition.

Furthermore, not only solids exhibit elasticity. Some non-Newtonian fluids, such as viscoelastic fluids, will also exhibit elasticity in certain conditions. In response to a small, rapidly applied and removed strain, these fluids may deform and then return to their original shape. Under larger strains, or strains applied for longer periods of time, these fluids may start to flow like a liquid, with some viscosity.

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## Cumran Vafa

By Syed Aslam

Cumrun Vafa was born in Tehran, Iran in 1960 and graduated from Alborz Boys School. He came to the US in 1977 and completed  his undergraduate degree from Massachusetts Institute of Technology with a major in physics and mathematics. He received his Ph.D. from Princeton University in 1985 under the supervision of Edward Witten. He then became a junior fellow at Harvard, where he later got a junior faculty position. In 1989 he was offered a senior faculty position, and he has been there ever since. Currently, he is the Donner Professor of Science at Harvard University.

Cumrun Vafaâ€™s primary area of research is string theory. String theory, a subject that is about four decades old, is at the center of efforts by theoretical physicists to find a unified fundamental theory of nature. String theory provides a framework to unify everything we know about nature, including all particles and the forces between them, in a consistent quantum theory. This is an ambitious goal, given that it aims to describe physical phenomena involving scales 1025times smaller than the atom, as well as the cosmology of our entire universe, which involves a scale of about 1037times bigger than the atom. In a single theory, one studies the mysteries of confinement of quarks inside atomic nuclei, as well as enigmatic properties of astrophysical objects such as black holes.

Such an all-encompassing theory necessarily requires a tremendous amount of mathematical skill. In fact, most of the mathematics needed for string theory is not even yet developed. String theorists thus have the exciting task of building new mathematics as tools to explore new laws of physics. It is therefore not surprising that string theory is at the cross roads of many fields, including mathematics, particle phenomenology and astrophysics. Cumrun Vafaâ€™s research has involved essentially all these aspects. Together with his colleagues he has worked on topological strings, trying to elucidate some new mathematics originating from string theory  and using these techniques to uncover some of the mysteries of black holes, particularly the Bekenstein-Hawking entropy. He has also applied these ideas to particle theories by geometrically engineering quantum field theories, as well as solving the strong coupling dynamics of confining theories  and geometrizing string theory defects.  His recent work involves applying these ideas to come up with stringy predictions about what the Large Hadron Collider (LHC) located at Franco â€“ Swiss border may potentially discover in the near future.

Dr. Cumrun Vafa,  was elected as a new member of The National Academy of Sciences on April 28, 2009. Members are elected in recognition of their distinguished and continuing achievements in original research.

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## Conspiracy Theory

By Paul Craig Roberts

While we were not watching, conspiracy theory has undergone Orwellian redefinition.

A â€œconspiracy theoryâ€ no longer means an event explained by a conspiracy. Instead, it now means any explanation, or even a fact, that is out of step with the governmentâ€™s explanation and that of its media pimps.

For example, online news broadcasts of RT have been equated with conspiracy theories by the New York Times simply because RT reports news and opinions that the New York Times does not report and the US government does not endorse.

In other words, as truth becomes uncomfortable for government and its Ministry of Propaganda, truth is redefined as conspiracy theory, by which is meant an absurd and laughable explanation that we should ignore.

When piles of carefully researched books, released government documents, and testimony of eye witnesses made it clear that Oswald was not President John F. Kennedyâ€™s assassin, the voluminous research, government documents, and verified testimony was dismissed as â€œconspiracy theory.â€

In other words, the truth of the event was unacceptable to the authorities and to the Ministry of Propaganda that represents the interests of authorities.

The purest example of how Americans are shielded from truth is the mediaâ€™s (including many Internet sitesâ€™) response to the large number of professionals who find the official explanation of September 11, 2001, inconsistent with everything they, as experts, know about physics, chemistry, structural engineering, architecture, fires, structural damage, the piloting of airplanes, the security procedures of the United States, NORADâ€™s capabilities, air traffic control, airport security, and other matters. These experts, numbering in the thousands, have been shouted down by know-nothings in the media who brand the experts as â€œconspiracy theorists.â€

This despite the fact that the official explanation endorsed by the official media is the most extravagant conspiracy theory in human history.

Letâ€™s take a minute to re-acquaint ourselves with the official explanation, which is not regarded as a conspiracy theory despite the fact that it comprises an amazing conspiracy. The official truth is that a handful of young Muslim Arabs who could not fly airplanes, mainly Saudi Arabians who came neither from Iraq nor from Afghanistan, outwitted not only the CIA and the FBI, but also all 16 US intelligence agencies and all intelligence agencies of US allies including Israelâ€™s Mossad, which is believed to have penetrated every terrorist organization and which carries out assassinations of those whom Mossad marks as terrorists.

In addition to outwitting every intelligence agency of the United States and its allies, the handful of young Saudi Arabians outwitted the National Security Council, the State Department, NORAD, airport security four times in the same hour on the same morning, air traffic control, caused the US Air Force to be unable to launch interceptor aircraft, and caused three well-built steel-structured buildings, including one not hit by an airplane, to fail suddenly in a few seconds as a result of limited structural damage and small, short-lived, low-temperature fires that burned on a few floors.

The Saudi terrorists were even able to confound the laws of physics and cause WTC building seven to collapse at free fall speed for several seconds, a physical impossibility in the absence of explosives used in controlled demolition.

The story that the government and the media have told us amounts to a gigantic conspiracy, really a script for a James Bond film. Yet, anyone who doubts this improbable conspiracy theory is defined into irrelevance by the obedient media.

Anyone who believes an architect, structural engineer, or demolition expert who says that the videos show that the buildings are blowing up, not falling down, anyone who believes a Ph.D. physicist who says that the official explanation is inconsistent with known laws of physics, anyone who believes expert pilots who testify that non-pilots or poorly-qualified pilots cannot fly airplanes in such maneuvers, anyone who believes the 100 or more first responders who testify that they not only heard explosions in the towers but personally experienced explosions, anyone who believes University of Copenhagen nano-chemist Niels Harrit who reports finding unreacted nano-thermite in dust samples from the WTC towers, anyone who is convinced by experts instead of by propaganda is dismissed as a kook.

In America today, and increasingly throughout the Western world, actual facts and true explanations have been relegated to the realm of kookiness. Only people who believe lies are socially approved and accepted as patriotic citizens.

Indeed, a writer or newscaster is not even permitted to report the findings of 9/11 skeptics. In other words, simply to report Professor Harritâ€™s findings now means that you endorse them or agree with them.

Everyone in the US print and TV media knows that he/she will be instantly fired if they report Harritâ€™s findings, even with a laugh.

Thus, although Harrit has reported his findings on European television and has lectured widely on his findings in Canadian universities, the fact that he and the international scientific research team that he led found unreacted nano-thermite in the WTC dust and have offered samples to other scientists to examine has to my knowledge never been reported in the American media.

Even Internet sites on which I am among the readersâ€™ favorites will not allow me to report on Harritâ€™s findings.

As I reported earlier, I myself had experience with a Huffington Post reporter who was keen to interview a Reagan presidential appointee who was in disagreement with the Republican wars in the Middle East. After he published the interview that I provided at his request, he was terrified to learn that I had reported findings of 9/11 investigators.

To protect his career, he quickly inserted on the online interview that my views on the Iraq and Afghanistan invasions could be dismissed as I had reported unacceptable findings about 9/11.

The unwillingness or inability to entertain any view of 9/11 different  from the official view dooms to impotence many Internet sites that are opposed to the wars and to the rise of the domestic US police state.

These sites, for whatever the reasons, accept the governmentâ€™s explanation of 9/11; yet, they try to oppose the â€œwar on terrorâ€ and the police state which are the consequences of accepting the governmentâ€™s explanation. Trying to oppose the consequences of an event whose explanation you accept is an impossible task.

If you believe that America was attacked by Muslim terrorists and is susceptible to future attacks, then a â€œwar on terrorâ€ and a domestic police state to root out terrorists become necessary to make Americans safe. The idea that a domestic police state and open-ended war might be more dangerous threats to Americans than terrorists is an impermissible thought.

A country whose population has been trained to accept the governmentâ€™s word and to shun those who question it is a country without liberty in its future.

Foreign Policy Journal

Paul Craig Roberts served as Assistant Secretary of the Treasury in the Reagan administration.

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