Archive for January 2009

PBS film on Oppenheimer

January 27, 2009

I accidentally came to know about this film about Oppenheimer on American Experience on PBS yesterday. It was a 2 hour piece, a docu-drama, with David Strathairn playing Oppenheimer during his infamous trial. The trial was an opportunity for Oppenheimer to recapitulate his life, and this is what the docu-drama does. It would undoubtedly be repeated and I would strongly encourage those unfamiliar with the man and the period in this country’s history to watch it. It shows the rise of a truly brilliant and iconic character, followed by his fall that was orchestrated by a vindictive and self-serving government.

Given my long interest in Oppenheimer, there wasn’t much in the film that was new for me. It was highly informative, poignant and fortunately well-grounded in facts and consensus. Interviewed among others were historians Richard Rhodes, Martin Sherwin, Priscilla McMillan and veteran scientists Harold Agnew, Herbert York, Nobel Laureate Roy Glauber and Marvin Goldberger. Prudently, the film does not speculate on Gregg Herken’s belief that Oppenheimer was a member of the communist party; to my knowledge only Herken holds this opinion, and to be honest it does not even matter. But as the record shows, 30 years of constant investigation by the FBI turned up nothing that indicated party membership, and that says a lot.

The disturbing thing about the trial of course is that it is a poster boy case for how disagreement and dissent are equated with disloyalty by the government, a tale for our times even as its essential unlawful scare tactics have been repeated in numerous administrations, and most recently in the Bush administration when opposition to the Iraq war was often deemed “unpatriotic”. The Oppenheimer story, one of the most shameful episodes in this country’s history in my opinion, is a cautionary tale that should always be remembered as an example of how we need to be constantly alert and aware in a democracy and watch out for abuse of power by the government. The film does a good job of demonstrating this.

Obama’s threat reduction priorities

January 16, 2009

Others should embrace them in their own self-interests

I sincerely believe that because of its utterly devastating and game-changing implications, nuclear terrorism is one of the greatest threats the world faces. Even a crude nuclear weapon detonated in Mumbai, London, Tokyo or Los Angeles will cause the kind of destruction and havoc that would be every citizen’s worst nightmare. Such an event will significantly change the political and social landscape of a country for a long time to come, and probably for the worse. That’s all everybody would talk about. In case of nuclear terrorism, the adage about us having to succeed every single time while them having to succeed just once rings resoundingly true.

A recent Nature article emphasizes the steps that President-elect (for only 5 more days) Obama should take to keep nuclear weapons from falling into the hands of terrorists. Political leaders all over the world especially in sensitive countries should join him in this endeavor, because their cities might be the first casualties of nuclear terrorism. According to the article, something like only 0.2% of US defence spending is devoted to practical non-proliferation, an amount that has remained virtually unchanged for a decade. The new President’s chief science advisor John Holdren has worked on these issues, having already alerted the non-proliferation community to them back in 2002.

What needs to be paid very close attention to is highly-enriched uranium (HEU) and not plutonium. Building a plutonium implosion weapon involves many intricate steps and would likely be beyond the reach of a terrorist outfit. Plutonium is a hideous element that is extremely difficult to work with. The explosives arrangement around it needs to be machined to the finest dimensions in order to work as expected. By contrast, simple firing mechanisms can be used to detonate a uranium bomb (although I don’t share the article’s predilection for calling it “child’s play”). One of the topics of discussion between Pakistani scientists and Osama Bin Laden in August 2001 apparently involved such firing mechanisms. As the article correctly notes, even a uranium weapon fizzle that delivers 1-5 kT in a place like Manhattan would be devastating.

Given this scenario, it is more than disconcerting that some 272 HEU reactors in 56 countries remain unsecured. Feedstock balances for many of these reactors are not meticulously accounted for. Some uranium can even be scraped from the insides of centrifuges or gaseous diffusion tubes and declared as wasted or not produced. Quiet and gradual extraction of tiny amounts could lead to the accumulation of tens of kilograms, a quantity sufficient for a crude explosive device.

Clearly the focus of the new administration should be to try to secure such reactors in hot spots; in Pakistan, Iran and the former Soviet Union among other countries. Leaders all over the world should join in the effort; to provide secure technology, sensors, anti-terrorist safeguards. They should make sure their own reactors are sufficiently guarded. Fortunately, one of the foremost policy actions that Barack Obama was involved in as a Senator was non-proliferation. He worked with Senator Richard Lugar to continue securing nuclear material from the former Soviet Union. Non-proliferation was always one of Senator Obama’s special concerns. Let’s hope it stays that way and gets bolstered by international support.

Pakistan’s Nuclear Arsenal

January 11, 2009

And what woe it could breed

The New York Times has a very interesting, lengthy article by David Sanger on problems with Pakistan’s nuclear arsenal. Although Pakistani officials repeatedly suggest that their weapons are safely secured, they would not allow American or other officials to verify this; thus we are basically left with their reassurances, and unfortunately there’s not much in the past that would help us accept their reassurances. On the other hand, it’s not just the safety of the arsenal that’s the only matter of concern.

Among other things, the article profiles Khalid Kidwai, a general who is in charge of the Pakistani arsenal. Kidwai is a man who knows a lot but will not say much. He was essentially put in charge of the security of the complex after the 1998 nuclear tests. Although Pakistan’s nuclear secrets were supposed to be secure after this, it was just one month before 9/11 in August 2001 that one of Pakistan’s most prominent and eccentric nuclear scientists, Sultan Mahmood, had a meeting with Osama Bin Laden. Mahmood was a chilling emblem of the conflation of advanced technology and religious fundamentalism. Even more than A Q Khan he wanted to build an “Islamic bomb” and was more than glad to await the day of reckoning. Nuclear weapons were undoubtedly discussed in his meeting with the Al Qaeda leader, although the details remain vague. The fact that such a meeting even took place calls into question how safe Pakistan’s nuclear secrets are. Plus, nobody is going to allow American authorities to directly inspect the nuclear complex. Mahmood and A Q Khan have long since been kept incommunicado. We have to take the Pakistanis’ word for accounting of nuclear material and personnel checks.

The article has other troubling details. While the warheads and missiles are apparently kept separate by the authorities, specs on Permissive Action Locks (PALs) are not known. PALs essentially disable a warhead if someone tries too hard to tamper with it. The Pakistanis would not allow American personnel to inspect their weapons and installs PALs. Apparently there was some exchange of design information between the two countries, but nobody would say how effective that exchange was and whether its recommendations were put into effect. More exchange has been thwarted by one of those ironically absurd and ridiculous policies where the US cannot divulge details of PALs to Pakistan because then it would be ostensibly selling nuclear technology to a failed state. Muddle-headed bureaucracy does not get any better than this.

The principal problem as always is that it’s just difficult to trust anything that the Pakistanis say for two reasons. Firstly nothing that they say can be actually verified. But more importantly, Pakistan’s past pronouncements have turned out to be false so many times either because of inside complicity or ignorance that it’s hard to believe them when they say they are a responsible nuclear power. Consider the A Q Khan and the Mahmood debacles. Consider the radicalization of the universities from where the nuclear programs draws its talent. There are 2000 Pakistani personnel with advanced nuclear knowledge and even 1 percent of these wiling to offer their expertise to terrorists is a huge liability. The article also talks about Prime Minister Yousef Gilani’s 2008 trip to Washington where he wanted to assure Bush that he had ordered a raid on a radical Madrassa school in tribal areas where Islamic radicalization was part of the daily curriculum. Apparently the NSA had already intercepted messages from insider elements which warned the school about the raid before it took place so that targeted personnel could possibly leave. Bush knew about this, and yet Gilani tried to assure Bush that it was evidence of how the Pakistani government is trying to weed out radical elements.

As long as there is a total lack of control from Islamabad over fundamentalists in the ISI, in the general populace and in the defence forces, no assurances that the Pakistani government gives the US or the world can be taken too seriously. There are just too many non-state players sometimes in collusion with state players who run amok in the country. Neither the president nor the prime minister nor any single authority controls them; even the more authoritarian Musharraf could not keep them in check. Official promises are not going to stop unofficial actions. And as long as these anarchic elements continue to be part of the unofficial and official outfits of Pakistan, the threat of its nuclear arsenal falling into the wrong hands will always have to be taken seriously. Even if directly pilfering a nuclear weapon may be hard, there are many other ways in which the love of Pakistan’s nuclear weapons can be spread around. When it comes to assessing Pakistan’s nuclear weapons, it is important to err on the safer side.

But an even more important lesson to be learnt is that US policy towards Pakistan needs to be significantly changed. For 50 years the US has supported the country in hopes of first fighting communists and then of fighting terrorists. Both these objectives have bred unwanted repercussions. During this process the government has also turned a blind eye toward Pakistan’s nuclear activities in the hope that their neglect will be compensated for by a greater victory. But there has been scant success in this endeavor. In addition, instead of the US dangling carrots in front of Pakistan, it’s been Pakistan who has inevitably dangled carrots in front of the US. Pakistan’s carrots have been simple and very effective; give us money otherwise we will descend into chaos. Perhaps now the mantra of the US should be- give us the terrorists or we will replace the carrot with a stick. The buck needs to stop here.

Boulevard of Broken Dreams

January 5, 2009

The brilliant and tragic history of nuclear fusion

Sun in a Bottle: The Strange History of Fusion and the Science of Wishful Thinking
Charles Seife
Viking Adult, October 2008

Among all of humanity’s great quests to wrest control of nature and its own destiny, few quests have been as grand in scale and optimism as nuclear fusion. The fascinating history of nuclear fusion shows man’s relentless efforts to first understand and then gain power over the source of energy that makes the stars shine. This history has also been dotted with some of the most brilliant, colorful and tragic figures in scientific history. Most importantly, fusion also demonstrates the dangers and pitfalls inherent in trying to seize nature’s greatest secrets from her.

In this engaging and informative history, Charles Seife tells us the story of trying to put the sun in a bottle, the singular personalities which permeated this history, the monumental mistakes made in understanding and harnessing this awesome source, and the wishful thinking that has pervaded the dream ever since its conception. Seife who has bachelor’s and master’s degrees in mathematics from Princeton and is now a journalism professor at NYU does a great job of clearly explaining the science behind fusion, and sprinkles his narrative with wit and gripping human drama.

These days fusion is mostly associated with hydrogen bombs that can obliterate entire cities and populations. And yet its story begins with a quest to understand one of the oldest and most profound questions that man has pondered; what makes the sun shine? Quite early on, it was quickly recognized that chemical rections couldn’t sustain the tremendous power of the sun for so long. After many decades of efforts, it was the great physicist Hans Bethe who finally cracked the secret of the stars’ luminous glow. Bethe found out a set of reactions catalysed by carbon that achieved the transformation of four hydrogen atoms into helium atoms. This central mechanism was soon shown to underlie the production of energy in all so-called main sequence stars like the sun.

It was with the entry of the United States into the Second World War however, that a more sinister use for nuclear fusion was envisioned by the volatile, brilliant Hungarian physicist Edward Teller, a dark character whose shadow looms large over the history of fusion and nuclear weapons. Teller proposed setting off a then still conceptual atomic bomb to generate the immense temperatures of tens of millions of degrees at the center of the sun that would ignite and hopefully propagate a fusion reaction in deuterium and tritium, isotopes of hydrogen that would be easier to fuse compared to hydrogen itself. Achieving fusion is an enormously difficult endeavor; one has to overcome the intense repulsive barrier between nuclei that keeps them from approaching one other. Only temperatures of tens of millions of degrees can get these nuclei hot enough to fuse. And yet as Seife explains, there is a fundamental paradox here; the very temperatures that can overcome the repulsive barrier between nuclei also blow them apart. It seems that in achieving nuclear fusion, we are constantly working against ourselves.

The history of the US and Soviet thermonuclear weapons program has been well documented in other sources. I have a summary in my last post. Seife succintly enumerates this history and narrates the development of genocidal megaton yield hydrogen bombs which are now part of almost every nuclear arsenal.

It is however in life and not in death that fusion promises mankind eternal glory. Efforts to attain this glory bear the stamp of the quintessential Faustian bargain for knowledge, where men gambled their careers and reputations, not to mention billions of government dollars, in trying to secure their place in history and free mankind of the burden of energy sources.

These efforts, while they taught us a lot about the workings of nuclei and electrons, have been riddled with tall claims and monumental failures. Seife recounts one program after another starting in the early 1950s that promised working fusion reactors in about twenty years. In Argentina and Britain, in Russia and the United States, claims about fusion regularly appeared and were hungrily lapped up by the popular press until a few months later, when the premature optimism came crashing down in the light of further investigations. In the first UN conference organized to discuss peaceful uses for atomic energy, Indian physicist Homi Bhabha talked about fusion becoming the practical solution to all our energy needs in three decades. And yet, effort after effort exposed fundamental problems in the system, hideously recalcitrant barriers that nature seemed to have erected to thwart us in our quest. The barriers still seem insurmountable.

On one hand, grandiose schemes using hydrogen bombs to excavate harbors, to carve out canals, to analyze moon dust and to solve almost every conceivable problem were imagined by Edward Teller and his followers. None of them worked, and all of them would produce dangerous radioactive fallout. On the other hand, early on scientists recognized a basic mechanism for taming fusion; by keeping fusing deuterium or tritium nuclei confined within a magnetic field in an extremely hot plasma of electrons and nuclei. The field of plasma physics emerged. This is the famous inertial confinement approach for harnessing fusion. This approach was developed and tested throughout the 50s and 60s. Some schemes looked as if they were working. Later it was found that not only were they producing less energy than what went in, but sometimes fusion was not even taking place and the neutrons that are a signature of the process were coming from elsewhere. The first condition, a net gain of energy, is called breakeven and is a fundamental condition for any energy-generating source to be satisfied. You have got to get more energy than what you put in. Ever since then, fusion has been achieved on smaller scales, but breakeven has never been attained.

Apart from inertially confined plasma fusion, Seife also describes the second major approach called laser fusion, which gradually arose as a competitor to plasma fusion in the 1970s. In this process, intense lasers shine on a small pellet of a deuterium or tritium compound from many directions. In the center of the pellet where unearthly temperatures and pressures are achieved, fusion takes place. This approach has been pursued in many grand schemes. One is called Shiva and involves 20 laser beams from 20 different directions squeezing a fusile pellet. The latest approach is called Nova which uses even more lasers. Both Shiva and Nova are closely guarded secrets. A computer program called LASNEX which helps their operation by simulating different fusion scenarios based on hundreds of variables and conditions is highly classified. Billions of dollars were spent on both these developments. And yet, as practical energy producing devices, both Shiva and Nova now look like dead ends.

Why is this the case? Why has almost every attempt to tame fusion failed? The answer has to do simply with the magnitude of the problem, and with how less we still understand nature. Both laser fusion and inertial fusion suffer from some fundamental and extremely complex problems that were discovered only when the experiments were underway. One problem has already been stated; the difficulty of confining such a hot plasma of particles. Another problem has to do with instability. As a hot plasma of deuterium and tritium circulates in an intense magnetic and electric field, local inescapable defects and asymmetries in the fields get quickly amplified and cause ‘kinks’ in the flow. The kinks gradually grow bigger like cracks in weak concrete and finally bring the entire structure down, quickly dissipating the plasma and halting fusion. While impressive progress has been made in controlling the fine parameters of the magnetic and electric fields, the problem still persists because of its basic nature. The other problem was that the electrons were getting heated much faster than the nuclei so that the nuclei- the real target- would stay relatively cool. A third serious problem was the initiation of Rayleigh-Taylor instabilities, little whirlpools and tongues that develop when a less-dense material presses against a more-dense material. Interestingly it’s Rayleigh-Taylor instabilities and not gravity that is the reason why water from an overturned glass escapes. Rayleigh-Taylor instabilities developed in laser fusion when less dense photos of light tried to compress a denser pellet of deuterium. These instabilities quickly destroyed the fine balance of the fusion process. The process is exquisitely sensitive to the finest of defects, like nanoscopic dimples of the surface of the pellet. Solving this problem requires the best of physics and engineering.

All these problem still plague fusion, and billions of dollars, thousands of brilliant scientists and hundreds of innovative ideas later, fusion still remains a dream. It has been achieved many times, neutrons have been observed, but breakeven still is a land that’s far, far away.

But scientists don’t give up. And while legitimate scientific efforts on the two ‘hot fusion’ approaches continue, there have been cases where some scientists believed they were observing fusion a tad too easily under circumstances that were too good to believe. These events saw their careers being destroyed and the promise of fusion again mangled. The events refer to the infamous cases of ‘cold fusion’ which constitute the last and most important part of Seife’s book. Seife weaves a riveting tale around these events, partly since he was a participant in one of the debacles.

The story of Pons and Fleischmann’s 1989 cold fusion disaster at the University of Utah is well known. The two took the unusual step of announcing their results in a press conference before getting them peer-reviewed and published. Later their experiments were shown to be essentially irreproducible. Seife recounts in details the developments that gradually cast a black cloud over this claim. One of the characters in this story is Steve Jones, a physicist who has recently gained notoriety for becoming a 9/11 denier.

But I was particularly interested in the next story since I had actually met and talked to one of the characters in the cold fusion catastrophe many years ago. Rusi Taleyarkhan, an Indian scientist, happened to come to our University in 2002 to give a talk. Just a few months before, he and his colleagues had published a paper in the prestigious journal Science, which if true would herald one of the greatest breakthroughs in scientific history. Taleyarkhan and his group claimed to have observed fusion in the most disarmingly simple experiment. They had taken a solution of deuterated acetone (acetone with its hydrogen atoms replaced by deuterium) and had bombarded it with neutrons that caused giant bubbles to form in the solution. They had then exposed the solution to intense acoustic waves, thus causing the bubbles to violently collapse. The phenomenon was well known and is called sonoluminescence, a name alluding to the light that is often given off because of these violent collapses. But what was Taleyarkhan’s claim? That the immense pressures and temperatures generated at the center of the bubbles caused nuclear fusion of the deuterium in the acetone, essentially in a tabletop apparatus at room temperature. Why acetone? This was the question I asked Taleyarkhan when I met him in 2002. He did not know, and he sounded sincere about it.

But this was before the storm was unleashed and the controversy erupted. In this case unlike the previous one, the work had been peer reviewed by one of the most famous and stringent journals in the world. But curiously, further investigation by Seife and others revealed that the paper had been published by Science’s editor in spite of objections by the reviewers. This was highly unusual to say the least. What was more disturbing was that concomitant experiments done at Oak Ridge National Laboratory, Taleyarkhan’s home turf at the time, revealed negative results. Once the results were announced, researchers across the world including some at prestigious institutions scurried around to repeat the experiments using more sophisticated detectors and apparatus. Fusion produces very signature neutrons of specific energy. The more sophisticated apparatus failed to detect these neutrons. In the earlier cold fusion debacle, there had been doubt about the energy peaks of the neutrons. Similar doubts started surfacing in this case. Questions were also raised about the possibly shoddy nature of the experiments, including the absence of control experiments. Later Taleyarkhan moved to Purdue, and Purdue initially defended the experiments. But the story remained murky. Some ‘independently’ published later articles turned out to not be so independent after all. Gradually, just like it had previously, the great edifice turned into a crumbling structure and came down. As a reporter for Science then, Seife personally covered these events. Purdue reinvestigated the matter and as of 2008, Taleyarkhan is forbidden from working as a regular PhD. student advisor at Purdue. Even though he was not convicted of deliberate fraud, his reputation has come crashing down.

This then is the history of fusion, episode after episode of wishful thinking to solve the biggest problem in the history of mankind. A fusion reactor may someday be possible, but nothing until now suggests that it would be so. It’s hard to trust a technology if it has consistently failed to deliever on its promise time after time. After all this, even the mention of the statement ‘cheap, abundant and universal energy’ should raise our eyebrows. In the afterword, Seife discusses the rather harsh nature of the scientific process where skepticism is everyone’s best friend and results are intensely vetted, a fact that’s necessary though to keep science and scientists in line. Fusion seems to be one of those endeavors where tall claims have been more consistently proclaimed than perhaps in any other branch of science. This has been undoubtedly so because of the earth-shattering implications of a true practical nuclear fusion reactor and the fame that it will bring its inventor. Even with such a reactor, our problems may not be over. First of all fusion is not as clean as it is made out to be; copious amounts of neutrons, gamma rays and other forms of radiation are released in the process. Secondly, even with mass production fusion reactors may cost no less than tens of millions of dollars. Even as Seife writes, the world’s economies have pooled their resources together into ITER, an international thermonuclear project that promises to be the biggest of its kind until now. The United States did not support the project earlier and it had to be scaled back. Now the US seems to be contributing again to a more modest version of the vision. As with other matters, the politics of fusions seems to be even more elusive than the science of fusion. Gratifyingly, Seife thinks that our best current bet to solve the energy problem is nuclear fission. It emits no carbon dioxide, provides the biggest bang for your buck, and most importantly unlike fusion is already here. Compared to the will-o-wisps of fusion, the very real strands of fission can solve many of our real problems. Ironically, controlled fusion is still a distant dream while very tangible thermonuclear bombs sit securely in the arsenals of so many nations.

In the end, one factor which Seife should have appreciated more in my opinion is the immense knowledge that has been gained from so many years of fusion research. That is one of the great virtues of science, that even failed endeavors can contribute key insights into the workings of nature and uncover new principles. Fusion might be wishful thinking, a grandiose and tragic scheme to put the sun in a bottle, but science always wins. And if not for anything else, for that we should always be grateful.