Tag: Steven Weinberg

The question of Abdus Salam ‘deserving’ his Nobel

Peter Woit has blogged about an oral history interview with theoretical physicist Sheldon Glashow published in 2020 by the American Institute of Physics. (They have a great oral history of physics series you should check out if you’re interested.) Woit zeroed in on a portion in which Glashow talks about his faltering friendship with Steven Weinberg and his issues with Abdus Salam’s nomination for the physics Nobel Prize.

Glashow, Weinberg and Salam together won this prize in 1979, for their work on the work on electroweak theory, which describes the behaviour of two fundamental forces, the electromagnetic force and the weak force. Glashow recalls that his and Weinberg’s friendship – having studied and worked together for many years – deteriorated in the 1970s, a time in which both scientists were aware that they were due a Nobel Prize. According to Glashow, however, Weinberg wanted the prize to be awarded only to himself and Salam.

This is presumably because of how the prize-winning work came to be: with Glashow’s mathematical-physical model published in 1960, Weinberg building on it seven years later, with Salam’s two relevant papers appeared a couple years after Glashow’s paper and a year after Weinberg’s. Glashow recalls that Salam’s work was not original, that each of his two papers respectively echoed findings already published in Glashow’s and Weinberg’s papers. Instead, Glashow continues, Salam received the Nobel Prize probably because he had encouraged his peers and his colleagues to nominate him a very large number of times and because he set up the International Centre for Theoretical Physics (ICTP) in Trieste.

This impression, of Salam being undeserving from a contribution-to-physics point of view in Glashow’s telling, is very at odds with the impression of Salam based on reading letters and comments by Weinberg and Pervez Hoodbhoy and by watching the documentary Salam – The First ****** Nobel Laureate.

The topic of Salam being a Nobel laureate was never uncomplicated, to begin with: he was an Ahmadi Muslim who enjoyed the Pakistan government’s support until he didn’t, when he was forced to flee the country; his intentions with the ICTP – to give scholars from developing countries a way to study physics without having to contend with often-crippling resource constrains – were also noble. Hoodbhoy has also written about the significance of Salam’s work as a physicist and the tragedy of his name and the memories of his contributions having been erased from all the prominent research centres in Pakistan.

Finally, one of Salam’s nominees for a Nobel Prize was the notable British physicist and Nobel laureate Paul A.M. Dirac, and it seems strange that Dirac would endorse Salam if he didn’t believe Salam’s work deserved it.

Bearing these facts in mind, Glashow’s contention appears to be limited to the originality of Salam’s work. But to my mind, even if Salam’s work was really derivative, it was at par with that of Glashow and Weinberg. More importantly, while I believe the Nobel Prizes deserve to be abrogated, the prize-giving committee did more good than it might have realised by including Salam among its winners: in the words of Weinberg, “Salam sacrificed a lot of possible scientific productivity by taking on that responsibility [to set up ICTP]. It’s a sacrifice I would not make.”

Glashow may not feel very well about Salam’s inclusion for the 1979 prize and the Nobel Prizes as we know are only happy to overlook anything other than the scientific work itself, but if the committee really screwed up, then they screwed up to do a good thing.

Then again, even though Glashow wasn’t alone (he was joined by Martinus J.G. Veltman on his opinions against Salam), the physicists’ community at large doesn’t share his views. Glashow also cites an infamous 2014 paper by Norman Dombey, in which Dombey concluded that Salam didn’t deserve his share of the prize, but the paper’s reputation itself is iffy at best.

In fact, this is all ultimately a pointless debate: there are just too many people who deserve a Nobel Prize but don’t win it while a deeper dive into the modern history of physics should reveal a near-constant stream of complaints against Nobel laureates and their work by their peers. It should be clear today that both winning a prize and not winning a prize ought to mean nothing to the practice of science.

The other remarkable thing about Glashow’s comments in the interview (as cited by Woit) is what I like to think of as the seemingly eternal relevance of Brian Keating’s change of mind. Brian Keating is an astrophysicist who was at the forefront of the infamous announcement that his team had discovered evidence of cosmic inflation, an epoch of the early universe in which it is believed to have expanded suddenly and greatly, in March 2014. There were many problems leading up to the announcement but there was little doubt at the time, and Keating also admitted later, that its rapidity was motivated by the temptation to secure a Nobel Prize.

Many journalists, scientists and others observers of the practice of science routinely and significantly underestimate the effect the Nobel Prizes exert on scientific research. The prospect of winning the prize for supposedly discovering evidence of cosmic inflation caused Keating et al. to not wait for additional, confirmatory data before making their announcement. When such data did arrive, from the Planck telescope collaboration, Keating et al. suffered for it with their reputation and prospects.

Similarly, Weinberg and Glashow fell out because, according to Glashow, Weinberg didn’t wish Glashow to give a talk in 1979 discussing possible alternatives to the work of Weinberg and Salam because Weinberg thought doing such a thing would undermine his and Salam’s chances of being awarded a Nobel Prize. Eventually it didn’t, but that’s beside the point: this little episode in history is as good an illustration as any of how the Nobel Prizes and their implied promises of laurels and prestige render otherwise smart scientists insecure, petty and elbows-out competitive – in exchange for sustaining an absurd and unjust picture of the scientific enterprise.

All of this goes obviously against the spirit of science.

Engels, Weinberg

Dialectics of Nature, Friedrich Engels, 1883 (ed. 1976):

… an acquaintance with the historical course of evolution of human thought, with the views on the general inter-connections in the external world expressed at various times, is required by theoretical natural science for the additional reason that it furnishes a criterion of the theories propounded by this science itself. Here, however, lack acquaintance with the history of philosophy is fairly frequently and glaringly displayed. Propositions which were advanced in philosophy centuries ago, which often enough have long been disposed of philosophically, are frequently put forward by theorising natural scientists as brand-new wisdom and even become fashionable for a while. It is certainly a great achievement of the mechanical theory of heat that it strengthened the principle of the theory of heat that it strengthened the principle of the conservation of energy by means of fresh proofs and put it once more in the forefront; but could this principle have appeared on the scene as something so absolutely new if the worthy physicists had remembered that it had already been formulated by Descartes? Science physics and chemistry once more operate almost exclusively with molecules and atoms, the atomic philosophy of ancient Greece has of necessity come to the fore again. But how superficially it is treated even by the best of natural scientists! Thus Kekulé tells us … that Democritus, instead of Leucippus, originated it, and he maintains that Dalton was the first to assume the existence of qualitatively different elementary atoms and was the first to ascribe to them different weights characteristic of the different elements. Yet anyone can read in Diogenes Laertius that already Epicurus had ascribed to atoms differences not only of magnitude and form but also of weight, that is, he was already acquanited in his own way with atomic weight and atomic volume.

The year 1848, which otherwise brought nothing to a conclusion in Germany, accomplished a complete revolution only in the sphere of philosophy. By throwing itself into the field of the practical, here setting up the beginnings of modern industry and swindling, there initiating the mighty advance which natural science has since experienced in Germany and which was inaugurated by the caricature-like itinerant preachers Vogt, Büchner, etc., the nation resolutely turned its back on classical German philosophy that had lost itself in the sands of Berlin Old-Hegelianism. Berlin Old-Hegelianism had richly deserved that. But a national that wants to climb the pinnacles of science cannot possibly manage without theoretical thought. Not only Hegelianism but dialectics too was thrown overboard—and that just at the moment when the dialectical character of natural processes irresistibly forced itself upon the mind, when therefore only dialectics could be of assistance to natural science in negotiating the mountain of theory—and so there was a helpless relapse into the old metaphysics. What prevailed among the public since then were, on the one hand, the vapid reflections of Schopenhauer, which were fashioned to fit the philistines, and later even those of Hartmann, and, on the other hand, the vulgar itinerant-preacher materialism of a Vogt and a Büchner. At the universities the most diverse varieties of eclecticism competed with one another and had only one thing in common, namely, that they were concocted from nothing but remnants of old philosophies and were all equally metaphysics. All that was saved from the remnants of classical philosophy was a certain neo-Kantianism, whose last word was the eternally unknowable thing-in-itself, that is, the bit of Kant that least merited preservation. The final result was the incoherence and confusion of theoretical thought now prevalent.

One can scarcely pick up a theoretical book on natural science without getting the impression that natural scientists themselves feel how much they are dominated by this incoherence and confusion, and that the so-called philosophy now current offers them absolutely no way out. And here there really is no other way out, no possibility of achieving clarity, than by a return, in one form of another, from metaphysical to dialectical thinking.

Dreams of a Final Theory, Steven Weinberg, 1992:

Even where philosophical doctrines have in the past been useful to scientists, they have generally lingered on too long, becoming of more harm than ever they were of use. Take, for example, the venerable doctrine of “mechanism,” the idea that nature operates through pushes and pulls of material particles or fluids. In the ancient world no doctrine could have been more progressive. Ever since the pre-Socratic philosophers Democritus and Leucippus began to speculate about atoms, the idea that natural phenomena have mechanical causes has stood in opposition to popular beliefs in gods and demons. The Hellenistic cult leader Epicurus brought a mechanical worldview into his creed specifically as an antidote to belief in the Olympian gods. When Rene Descartes set out in the 1630s on his great attempt to understand the world in rational terms, it was natural that he should describe physical forces like gravitation in a mechanical way, in terms of vortices in a material fluid filling all space. The “mechanical philosophy” of Descartes had a powerful influence on Newton, not because it was right (Descartes did not seem to have the modern idea of testing theories quantitatively) but because it provided an example of the sort of mechanical theory that could make sense out of nature. Mechanism reached its zenith in the nineteenth century, with the brilliant explanation of chemistry and heat in terms of atoms. And even today mechanism seems to many to be simply the logical opposite to superstition. In the history of human thought the mechanical worldview has played a heroic role.

That is just the trouble. In science as in politics or economics we are in great danger from heroic ideas that have outlived their usefulness. The heroic past of mechanism gave it such prestige that the followers of Descartes had trouble accepting Newton’s theory of the solar system. How could a good Cartesian, believing that all natural phenomena could be reduced to the impact of material bodies or fluids on one another, accept Newton’s view that the sun exerts a force on the earth across 93 million miles of empty space? It was not until well into the eighteenth century that Continental philosophers began to feel comfortable with the idea of action at a distance. In the end Newton’s ideas did prevail on the Continent as well as in Britain, in Holland, Italy, France, and Germany (in that order) from 1720 on. To be sure, this was partly due to the influence of philosophers like Voltaire and Kant. But here again the service of philosophy was a negative one; it helped only to free science from the constraints of philosophy itself.

Review: ‘Salam – The First ****** Nobel Laureate’ (2018)

Awards are elevated by their winners. For all of the Nobel Prizes’ flaws and shortcomings, they are redeemed by what its laureates choose to do with them. To this end, the Pakistani physicist and activist Abdus Salam (1926-1996) elevates the prize a great deal.

Salam – The First ****** Nobel Laureate is a documentary on Netflix about Salam’s life and work. The stars in the title stand for ‘Muslim’. The label has been censored because Salam belonged to the Ahmadiya sect, whose members are forbidden by law in Pakistan to call themselves Muslims.

After riots against this sect broke out in Lahore in 1953, Salam was forced to leave Pakistan, and he settled in the UK. His departure weighed heavily on him even though he could do very little to prevent it. He would return only in the early 1970s to assist Zulfiqar Ali Bhutto with building Pakistan’s first nuclear bomb. However, Bhutto would soon let the Pakistani government legislate against the Ahmadiya sect to appease his supporters. It’s not clear what surprised Salam more: the timing of India’s underground nuclear test or the loss of Bhutto’s support, both within months of each other, that had demoted him to a second-class citizen in his home country.

In response, Salam became more radical and reasserted his Muslim identity with more vehemence than he had before. He resigned from his position as scientific advisor to the president of Pakistan, took a break from physics and focused his efforts on protesting the construction of nuclear weapons everywhere.

It makes sense to think that he was involved. Someone will know. Whether we will ever get convincing evidence… who knows? If the Ahmadiyyas had not been declared a heretical sect, we might have found out by now. Now it is in no one’s interest to say he was involved – either his side or the government’s side. “We did it on our own, you know. We didn’t need him.”

Tariq Ali

Whether or not it makes sense, Salam himself believed he wouldn’t have solved the problems he did that won him the Nobel Prize if he hadn’t identified as Muslim.

If you’re a particle physicist, you would like to have just one fundamental force and not four. … If you’re a Muslim particle physicist, of course you’ll believe in this very, very strongly, because unity is an idea which is very attractive to you, culturally. I would never have started to work on the subject if I was not a Muslim.

Abdus Salam

This conviction unified at least in his mind the effects of the scientific, cultural and political forces acting on him: to use science as a means to inspire the Pakistani youth, and Muslim youth in general, to shed their inferiority complex, and his own longstanding desire to do something for Pakistan. His idea of success included the creation of more Muslim scientists and their presence in the ranks of the world’s best.

[Weinberg] How proud he was, he said, to be the first Muslim Nobel laureate. … [Isham] He was very aware of himself as coming from Pakistan, a Muslim. Salam was very ambitious. That’s why I think he worked so hard. You couldn’t really work for 15 hours a day unless you had something driving you, really. His work always hadn’t been appreciated, shall we say, by the Western world. He was different, he looked different. And maybe that also was the reason why he was so keen to get the Nobel Prize, to show them that … to be a Pakistani or a Muslim didn’t mean that you were inferior, that you were as good as anybody else.

The documentary isn’t much concerned with Salam’s work as a physicist, and for that I’m grateful because the film instead offers a view of his life that his identity as a figure of science often sidelines. By examining Pakistan’s choices through Salam’s eyes, we get a glimpse of a prominent scientist’s political and religious views as well – something that so many of us have become more reluctant to acknowledge.

Like with Srinivasa Ramanujan, one of whose theorems was incidentally the subject of Salam’s first paper, physicists saw a genius in Salam but couldn’t tell where he was getting his ideas from. Salam himself – like Ramanujan – attributed his prowess as a physicist to the almighty.

It’s possible the production was conceived to focus on the political and religious sides of a science Nobel laureate, but it puts itself at some risk of whitewashing his personality by consigning the opinions of most of the women and subordinates in his life to the very end of its 75-minute runtime. Perhaps it bears noting that Salam was known to be impatient and dismissive, sometimes even manipulative. He would get angry if he wasn’t being understood. His singular focus on his work forced his first wife to bear the burden of all household responsibilities, and he had difficulty apologising for his mistakes.

The physicist Chris Isham says in the documentary that Salam was always brimming with ideas, most of them bizarre, and that Salam could never tell the good ideas apart from the sillier ones. Michael Duff continues that being Salam’s student was a mixed blessing because 90% of his ideas were nonsensical and 10% were Nobel-Prize-class. Then, the producers show Salam onscreen talking about how physicists intend to understand the rules that all inanimate matter abides by:

To do this, what we shall most certainly need [is] a complete break from the past and a sort of new and audacious idea of the type which Einstein has had in the beginning of this century.

Abdus Salam

This echoes interesting but not uncommon themes in the reality of India since 2014: the insistence on certainty, the attacks on doubt and the declining freedom to be wrong. There are of course financial requirements that must be fulfilled (and Salam taught at Cambridge) but ultimately there must also be a political maturity to accommodate not just ‘unapplied’ research but also research that is unsure of itself.

With the exception of maybe North Korea, it would be safe to say no country has thus far stopped theoretical physicists from working on what they wished. (Benito Mussolini in fact setup a centre that supported such research in the late-1920s and Enrico Fermi worked there for a time.) However, notwithstanding an assurance I once received from a student at JNCASR that theoretical physicists need only a pen and paper to work, explicit prohibition may not be the way to go. Some scientists have expressed anxiety that the day will come if the Hindutvawadis have their way when even the fruits of honest, well-directed efforts are ridden with guilt, and non-applied research becomes implicitly disfavoured and discouraged.

Salam got his first shot at winning a Nobel Prize when he thought to question an idea that many physicists until then took for granted. He would eventually be vindicated but only after he had been rebuffed by Wolfgang Pauli, forcing him to drop his line of inquiry. It was then taken up and to its logical conclusion by two Chinese physicists, Tsung-Dao Lee and Chen-Ning Yang, who won the Nobel Prize for physics in 1957 for their efforts.

Whenever you have a good idea, don’t send it for approval to a big man. He may have more power to keep it back. If it’s a good idea, let it be published.

Abdus Salam

Salam would eventually win a Nobel Prize in 1979, together with Steven Weinberg and Sheldon Glashow – the same year in which Gen. Zia-ul-Haq had Bhutto hung to death after a controversial trial and set Pakistan on the road to Islamisation, hardening its stance against the Ahmadiya sect. But since the general was soon set to court the US against its conflict with the Russians in Afghanistan, he attempted to cast himself as a liberal figure by decorating Salam with the government’s Nishan-e-Imtiaz award.

Such political opportunism contrived until the end to keep Salam out of Pakistan even if, according to one of his sons, it “never stopped communicating with him”. This seems like an odd place to be in for a scientist of Salam’s stature, who – if not for the turmoil – could have been Pakistan’s Abdul Kalam, helping direct national efforts towards technological progress while also striving to be close to the needs of the people. Instead, as Pervez Hoodbhoy remarks in the documentary:

Salam is nowhere to be found in children’s books. There is no building named after him. There is no institution except for a small one in Lahore. Only a few have heard of his name.

Pervez Hoodbhoy

In fact, the most prominent institute named for him is the one he set up in Trieste, Italy, in 1964 (when he was 38): the Abdus Salam International Centre for Theoretical Physics. Salam had wished to create such an institution after the first time he had been forced to leave Pakistan because he wanted to support scientists from developing countries.

Salam sacrificed a lot of possible scientific productivity by taking on that responsibility. It’s a sacrifice I would not make.

Steven Weinberg

He also wanted the scientists to have access to such a centre because “USA, USSR, UK, France, Germany – all the rich countries of the world” couldn’t understand why such access was important, so refused to provide it.

When I was teaching in Pakistan, it became quite clear to me that either I must leave my country, or leave physics. And since then I resolved that if I could help it, I would try to make it possible for others in my situation that they are able to work in their own countries while still [having] access to the newest ideas. … What Trieste is trying to provide is the possibility that the man can still remain in his own country, work there the bulk of the year, come to Trieste for three months, attend one of the workshops or research sessions, meet the people in his subject. He had to go back charged with a mission to try to change the image of science and technology in his own country.

In India, almost everyone has heard of Rabindranath Tagore, C.V. Raman, Amartya Sen and Kailash Satyarthi. One reason our memories are so robust is that Jawaharlal Nehru – and “his insistence on scientific temper” – was independent India’s first prime minister. Another is that India has mostly had a stable government for the last seven decades. We also keep remembering those Nobel laureates because of what we think of the Nobel Prizes themselves. This perception is ill-founded at least as it currently stands: of the prizes as the ultimate purpose of human endeavour and as an institution in and of itself – when in fact it is just one recognition, a signifier of importance sustained by a bunch of Swedish men that has been as susceptible to bias and oversight as any other historically significant award has been.

However, as Salam (the documentary) so effectively reminds us, the Nobel Prize is also why we remember Abdus Salam, and not the many, many other Ahmadi Muslim scientists that Pakistan has disowned over the years, has never communicated with again and to whom it has never awarded the Nishan-e-Imtiaz. If Salam hadn’t won the Nobel Prize, would we think to recall the work of any of these scientists? Or – to adopt a more cynical view – would we have focused so much of our attention on Salam instead of distributing it evenly between all disenfranchised Ahmadi Muslim scholars?

One way or another, I’m glad Salam won a Nobel Prize. And one way or another, the Nobel Committee should be glad it picked Salam, too, for he elevated the prize to a higher place.

Note: The headline originally indicated the documentary was released in 2019. It was actually released in 2018. I fixed the mistake on October 6, 2019, at 8.45 am.

‘Nothing in the history of science is ever simple’

Once I finished Steven Weinberg’s book Dreams of a Final Theory, I figured I’d write a long-winding review about what I think the book is really about, and its merits and demerits. But there is a sentence in the seventh chapter – titled ‘Against Philosophy’ – which I think sums up all that the book essentially attempts to explain.

Nothing in the history of science is ever simple.

And Dreams of a Final Theory wants to make you understand why that is so. To Weinberg’s credit, he has done a good job – not a great one – with complexity as his subject. I say ‘not a great one’ because it has none of the elegance that Brian Greene’s The Elegant Universe did, and it laid out string theory from beginning to end. At the same time, it is still Weinberg, one of the towering figures of particle physics, at work, and he means to say, first, that there is no place for simplicity in his line of work and, second, even in all the terrible complexity, there is beauty.

The book, first published in 1992, is a discourse on the path to a ‘final theory’ – one theory to rule them all, so to speak – and the various theoretical, experimental, mathematical and philosophical challenges it presents. Weinberg is an erudite scientist and you can trust him to lay out almost all facets of all problems that he chooses to introduce in the book – and there are many of them. Also, I wouldn’t call the book technical, but at the same time it demands its fair share of intellectual engagement because the language tends to get (necessarily) intricate. And if you’re wondering: There are no equations.

In fact, I would be able to describe the experience of reading Dreams of a Final Theory using a paragraph from the book, and such internal symmetry is unmistakable throughout the book:

But why should the final theory describe anything like our world? The explanation might be found in what [Robert] Nozick has called the principle of fecundity. It states that the different logically acceptable universes all in some sense exist, each wit its own set of fundamental laws. The principle of fecundity is not itself explained by anything, but at least it has a certain pleasing self-consistency; as Nozick says, the principle of fecundity states ‘that all possibilities are realized, while it itself is one of those possibilities’.

Buy the book.

Debating the business of beauty in ‘Dreams of a Final Theory’

In his book Dreams of a Final Theory, Nobel-Prize-winning physicist Steven Weinberg discusses the various aspects of the journey toward a unifying theory in fundamental physics. One crucial aspect is the aesthetic of such a theory, and Weinberg’s principal contention is that a unifying theory must be beautiful because if it weren’t beautiful, it wouldn’t be final in every sense. However, thinking so presupposes all scientific pursuits are motivated by a quest for beauty – this may not be the case. More importantly, beauty in being a human construction can be fickle and arbitrary, and interfere with the pursuit of science.

We are trained to expect nature to be a certain way and we call that beauty. As a result, we strive for solutions that are beautiful, i.e. commensurate with the way we see nature to be. But if the physicist confesses to you that the problems he chooses to solve are so beautiful, then that implies he thinks the problem is beautiful in its own right and independently of its solution’s beauty. Does this mean problem-solving in fundamental physics is dominated by a selection bias: whereby scientists choose to solve some problems over others because of the way they appeal to their aesthetic sense? Weinberg thinks so, and presents an example of scientists going after an ‘ugly’ problem – the thermal demagnetization of iron and critical exponent associated with it (0.37) – in the hope that it will have a beautiful solution. He writes,

Why should leaders of condensed matter theory give the problem of the critical exponents so much greater priority? I think the problem of critical exponents attracted so much attention because physicists judged that it would be likely to have a beautiful solution.

The result of their selection bias is the emergence of a dividing line between what needs to be studied and what doesn’t, between what knowledge is codified in the form of principles and what knowledge remains as individual facts. There is an obvious conflict with objective rationality here, which guides the fundamental investigations of nature and excludes unreasonable judgments like those backed by one’s sense of beauty. It seems, according to Weinberg, we are all motivated only to discover a beautiful universe – one that appeals to our preexisting convictions of what the universe ought to be – as if we are defining the beauty we feel we are bound to abide by. What else are we doing when we reject ‘ugly’ solutions but rejecting a form of the truth that doesn’t appeal to our sense of beauty2? By Weinberg’s own admission, what constitutes beauty1 has been changing with the discovery of more truths: just as beauty was a universality among the dynamics of forces in the early 20th century, beauty in the 21st century seems to be the presence of symmetry principles.

Therefore, by making such decisions, we are actively precluding the ‘existence’ of certain kinds of beauty because we are also forestalling the discovery of certain truths. Weinberg defends this by saying that if aesthetic judgments are working increasingly well, it could be because they are applicable – but the contention he does not address at all is that it is an arbitrary mechanism with which to arrive at the truth. We are simply consigning ourselves to understand beauty in different eras as new deviations from previous definitions of beauty, and removing opportunities to understand other3 (i.e. seemingly unrelated) kinds altogether. For example, the physicist who decides that the ‘ugly’ critical exponent of 0.37 must belong to a more beautiful, overarching theory is immediately pigeonholing other seemingly random exponents to the same fate. What if such exponents are indeed ones of a kind – perhaps even part of a much larger renormalization framework that researchers are desperately seeking to make sense of the many ‘fine-tuned’ constants in high-energy physics, rather than buoys of apparently hidden symmetries themselves that lead nowhere?

There are three additions to this discussion (referenced in the paragraph above):

1. Has beauty always been the pursuit of science? Elegance is definitely a part of the pursuit – if not more – because the elegance of natural phenomena is sure to reflect in the natural sciences, to paraphrase Werner Heisenberg. At the same time, Weinberg goes to some length to mark a distinction between beauty and elegance: “An elegant proof or calculation is one that achieves a powerful result with a minimum of irrelevant complication. It is not important for the beauty of a theory that its equations should have elegant solutions.” That said, the answer to this question is unlikely to be short or general for it questions the motivations of scientists over many centuries. At the same time, some of the greatest scientists – typically Nobel Prize winners – have said the quest for beauty has constituted a significant part of their work simply as an abrogation of randomness. Here is Subrahmanyan Chandrasekhar writing about the work of Lord Rayleigh in his book, Truth and Beauty: Aesthetics and Motivations in Science:

… after a scientist has reached maturity, what are the reasons for his continued pursuit of science? To what extent are they personal? To what extent are aesthetic criteria, like the perception of order and pattern, form and substance, relevant? Are such aesthetic and personal criteria exclusive? Has a sense of obligation a role? I do not mean obligation with the common meaning of obligation to one’s students, one’s colleagues, and one’s community. I mean, rather, obligation to science itself. And what, indeed, is the content of obligation in the pursuit of science for science?

2. We started with the assumption that beauty is what we have learnt nature to be. Therefore, by saying a problem or a solution doesn’t appeal to our sense of beauty, it only means it doesn’t appeal to what we already know. This attitude is best characterized by the tendency of well-entrenched paradigms to not give way to new ones, to not surrender in the face of new knowledge that they can’t account for. An example I am particularly fond of in this regard is the story of Dan Shechtman‘s discovery of quasicrystals, which went against the grain of Linus Pauling’s theory of crystals at the time.

Before introducing the third point (which is optional): While it is clear that Weinberg is enamored by the prospect of beauty legitimizing the study of fundamental physics, all of science cannot afford to be guided by as fickle a metric because beauty is what we expect nature to be – according to him – and that signifies a persistence with ‘old knowledge’ while discovering ‘new knowledge’. That deprives the scientific method of its objectivity. Also, the classification of knowledge impedes what scientists choose to study and how they choose to study it as well, and judging the legitimacy of knowledge based on its beauty lends itself to a mode of classification that is not entirely rational. Finally, that scientists also wouldn’t reject new knowledge if it was ugly but that beautiful knowledge would find acceptance faster and scrutiny slower is not… proper.

3. Orson Scott Card’s Speaker for the Dead provides an interesting way to understand this ‘otherness’. It describes a so-called hierarchy of foreignness to understand how alien a person or object is relative to another, in four stages (quoted from the book): Utlänning, “the stranger that we recognize as being a human of our world, but of another city or country”; framling, “the stranger that we recognize as human, but of another world”; raman, “the stranger that we recognize as human, but of another species”; and varelse, “the true alien … which includes all the animals, for with them no conversation is possible. They live, but we cannot guess what purposes or causes make them act. They might be intelligent, they might be self-aware, but we cannot know it.” Similarly, the ‘other’ kinds of beauty we stand to lose, according to Weinberg, are varelse, while we stick to the more fathomable (utlänning, framling and raman) kinds.

 

The hunt for supersymmetry: Is a choke on the cards?

The Copernican
April 28, 2014

“So irrelevant is the philosophy of quantum mechanics to its use that one begins to suspect that all the deep questions are really empty…”

— Steven Weinberg, Dreams of a Final Theory: The Search for the Fundamental Laws of Nature (1992)

On a slightly humid yet clement January evening in 2013, a theoretical physicist named George Sterman was in Chennai to attend a conference at the Institute of Mathematical Sciences. After the last talk of the day, he had strolled out of the auditorium and was mingling with students when I managed to get a few minutes with him. I asked for an interview and he agreed.

After some coffee, we seated ourselves at a kiosk in the middle of the lawn, the sun was setting, and mosquitoes abounded. Sterman was a particle physicist, so I opened with the customary question about the Higgs boson and expected him to swat it away with snowclones of the time like “fantastic”, “tribute to 50 years of mathematics” and “long-awaited”. He did say those things, but then he also expressed some disappointment.

George Sterman is distinguished for his work in quantum chromodynamics (QCD), for which he won the prestigious J.J. Sakurai Prize in 2003. QCD is a branch of physics that deals with particles that have a property called colour charge. Quarks and gluons are examples of such particles; these two together with electrons are the proverbial building blocks of matter. Sterman has been a physicist since the 1970s, the early years as far as experimental particle physics research is concerned.

The Standard Model disappoints

Over the last four or so decades, remarkable people like him have helped construct a model of laws, principles and theories that the rigours of this field are sustaining on, called the Standard Model of particle physics. And it was the reason Sterman was disappointed.

According to the Standard Model, Sterman explained, “if we gave our any reasonable estimate of what the mass of the Higgs particle should be, it should by all rights be huge! It should be as heavy as what we call the Planck mass.”

But it isn’t. The Higgs mass is around 125 GeV (GeV being a unit of energy that corresponds to certain values of a particle’s mass) – compare it with the proton that weighs 0.938 GeV. On the other hand, the Planck mass is 10^19 GeV. Seventeen orders of magnitude lie in between. According to Sterman, this isn’t natural. The question is why does there have to be such a big difference in what we can say the mass could be and what we find it to be.

Martinus Veltman, a Dutch theoretical physicist who won the Nobel Prize for physics in 2003 for his work in particle physics, painted a starker picture, “Since the energy of the Higgs [field] is distributed all over the universe, it should contribute to the curvature of space; if you do the calculation, the universe would have to curve to the size of a football,” in an interview to Nature in 2013.

Evidently, the Standard Model has many loose ends, and explaining the mass of the Higgs boson is only one of them. Another example is why it has no answer for what dark matter is and why it behaves the way it does. Yet another example is why the four fundamental forces of nature are not of the same order of magnitude.

An alternative

Thanks to the Standard Model, some mysteries have been solved, but other mysteries have come and are coming to light – in much the same way Isaac Newton’s ideas struggled to remain applicable in the troubled world of physics in the early 20th century. It seems history repeats itself through crises.

Fortunately, physicists in 1971-1972 had begun to piece together an alternative theory called supersymmetry, Susy for short. At the time, it was an alternative way of interpreting how emerging facts could be related to each other. Today, however, Susy is a more encompassing successor to the throne that the Standard Model occupies, a sort of mathematical framework in which the predictions of the Model still hold but no longer have those loose ends. And Susy’s USP is… well, that it doesn’t disappoint Sterman.

“There’s a reason why so many people felt so confident about supersymmetry,” he said. “It wasn’t just that it’s a beautiful theory – which it is – or that it engages and challenges the most mathematically oriented among physicists, but in another sense in which it appeared to be necessary. There’s this subtle concept that goes by the name of naturalness…”

And don’t yet look up ‘naturalness’ on Wikipedia because, for once, here is something so simple, so elegant, that it is precisely what its name implies. Naturalness is the idea that, for example, the Higgs boson is so lightweight because something out there is keeping it from being heavy. Naturalness is the idea that, in a given setting, the forces of nature all act in equal measure. Naturalness is the idea that causes seem natural, and logically plausible, without having to be fine-tuned in order to explain their effects. In other words, Susy, through its naturalness, makes possible a domesticated world, one without sudden, unexpected deviations from what common sense (a sophisticated one, anyway) would dictate.

To understand how it works, let us revisit the basics. Our observable universe plays host to two kinds of fundamental particles, which are packets of some well-defined amount of energy. The fermions, named for Enrico Fermi, are the matter particles. Things are made of them. The bosons, named for Satyendra Bose, are the force particles. Things interact with each other by using them as messengers. The Standard Model tells us how bosons and fermions will behave in a variety of situations.

However, the Model has no answers for why bosons and fermions weigh as much as they do, or come in as many varieties as they do. These are deeper questions that go beyond simply what we can observe. These are questions whose answers demand that we interpret what we know, that we explore the wisdom of nature that underlies our knowledge of it. To know this why, physicists investigated phenomena that lie beyond the Standard Model’s jurisdiction.

The search

One such place is actually nothingness, i.e. the quantum vacuum of deep space, where particles called virtual particles continuously wink in and out of existence. But even with their brief life-spans, they play a significant role in mediating the interactions between different particles. You will remember having studied in class IX that like charges repel each other. What you probably weren’t told is that the repulsive force between them is mediated by the exchange of virtual photons.

Curiously, these “virtual interactions” don’t proliferate haphazardly. Virtual particles don’t continuously “talk” to the electron or clump around the Higgs boson. If this happened, mass would accrue at a point out of thin air, and black holes would be popping up all around us. Why this doesn’t happen, physicists think, is because of Susy, whose invisible hand could be staying chaos from dominating our universe.

The way it does this is by invoking quantum mechanics, and conceiving that there is another dimension called superspace. In superspace, the bosons and fermions in the dimensions familiar to us behave differently, the laws conceived such that they restrict the random formation of black holes, for starters. In the May 2014 issue of Scientific American, Joseph Lykken and Maria Spiropulu describe how things work in superspace:

“If you are a boson, taking one step in [superspace] turns you into a fermion; if you are a fermion, one step in [superspace] turns you into a boson. Furthermore, if you take one step in [superspace] and then step back again, you will find that you have also moved in ordinary space or time by some minimum amount. Thus, motion in [superspace] is tied up, in a complicated way, with ordinary motion.”

The presence of this dimension implies that all bosons and fermions have a corresponding particle called a superpartner particle. For each boson, there is a superpartner fermion called a bosino; for each fermion, there is a superpartner boson called a sfermion (why the confusing titles, though?).

Physicists are hoping this supersymmetric world exists. If it does, they will have found tools to explain the Higgs boson’s mass, the difference in strengths of the four fundamental forces, what dark matter could be, and a swarm of other nagging issues the Standard Model fails to resolve. Unfortunately, this is where Susy’s credit-worthiness runs into trouble.

No signs

“Experiment will always be the ultimate arbiter, so long as it’s science we’re doing.”

— Leon Lederman & Christopher Hill, Beyond the Higgs Boson (2013)

Since the first pieces of the Standard Model were brought together in the 1960s, researchers have run repeated tests to check if what it predicts were true. Each time, the Model has stood up to its promise and yielded accurate results. It withstood the test of time – a criterion it shares with the Nobel Prize for physics, which physicists working with the Model have won at least 15 times since 1957.

Susy, on the other hand, is still waiting for confirmation. The Large Hadron Collider (LHC), the world’s most powerful particle physics experiment, ran its first round of experiments from 2009 to 2012, and found no signs of sfermions or bosinos. In fact, it has succeeded on the other hand to narrow the gaps in the Standard Model where Susy could be found. While the non-empty emptiness of quantum vacuum opened a small window into the world of Susy, a window through which we could stick a mathematical arm out and say “This is why black holes don’t just pop up”, the Model has persistently puttied every other crack we hound after.

An interesting quote comes to mind about Susy’s health. In November 2012, at the Hadron Collider Physics Symposium in Kyoto, Japan, physicists presented evidence of a particle decay that happens so rarely that only the LHC could have spotted it. The Standard Model predicts that every time the B_s (pronounced “Bee-sub-ess”) meson decays into a set of lighter particles, there is a small chance that it decays into two muons. The steps in which this happens is intricate, involving a process called a quantum loop.

What next?

“SUSY has been expected for a long time, but no trace has been found so far… Like the plot of the excellent movie ‘The Lady Vanishes’ (Alfred Hitchcock, 1938)”

— Andy Parker, Cambridge University

Susy predicts that some supersymmetric particles should show themselves during the quantum loop, but no signs of them were found. On the other hand, the rate of B_s decays into two muons was consistent with the Model’s predictions. Prof. Chris Parkes, a British physicist, had then told BBC News: “Supersymmetry may not be dead but these latest results have certainly put it into hospital.” Why not: Our peek of the supersymmetric universe eludes us, and if the LHC can’t find it, what will?

Then again, it took us many centuries to find the electron, and then many decades to find anti-particles. Why should we hurry now? After all, as Dr. Rahul Sinha from the Institute of Mathematical Sciences told me after the Symposium had concluded, “a conclusive statement cannot be made as yet”. At this stage, even waiting for many years might not be necessary. The LHC is set to reawaken around January 2015 after a series of upgrades that will let the machine deliver 10 times more particle collisions per second per unit area. Mayhap a superpartner particle can be found lurking in this profusion by, say, 2017.

There are also plans for other more specialised colliders, such as Project X in the USA, which India has expressed interest in formally cooperating with. X, proposed to be built at the Fermilab National Accelerator Laboratory, Illinois, will produce high intensity proton beams to investigate a variety of hitherto unexplored realms. One of them is to produce heavy short-lived isotopes of elements like radium or francium, and use them to study if the electron has a dipole moment, or a pronounced negative charge along one direction, which Susy allows for.

(Moreover, if Project X is realised it could prove extra-useful for India because it makes possible a new kind of nuclear reactor design, called the accelerator-driven sub-critical reactor, which operates without a core of critical-mass radioactive fuel, rendering impossible accidents like Chernobyl and Fukushima, while also being capable of inducing fission reactions using lighter fuel like thorium.)

Yet another avenue to explore Susy would be looking for dark matter particles using highly sensitive particle detectors such as LUX, XENON1T and CDMS. According to some supersymmetric models, the lightest Susy particles could actually be dark matter particles, so if a few are spotted and studied, they could buffet this theory’s sagging credence.

… which serves to remind us that this excitement could cut the other way, too. What if the LHC in its advanced avatar is still unable to find evidence of Susy? In fact, the Advanced Cold Molecule Electron group at Harvard University announced in December 2013 that they were able to experimentally rule out that they electron had a dipole moment with the highest precision attained to date. After such results, physicists will have to try and rework the theory, or perhaps zero in on other aspects of it that can be investigated by the LHC or Project X or other colliders.

But at the end of the day, there is also the romance of it all. It took George Sterman many years to find a theory as elegant and straightforward as Susy – an island of orderliness in the insane sea of quantum mechanics. How quickly would he give it up?

O Hunter, snare me his shadow!
O Nightingale, catch me his strain!
Else moonstruck with music and madness
I track him in vain!

— Oscar Wilde, In The Forest