Unification Theorist Who Brought Together Third World Scientists

The Sixth BCSPIN Summer School on "Current Trends in High Energy Physics and Cosmology" held in Kathmandu in early June owes its origins to the inspiration of the late Professor Abdus Salam, Nobel Laureate in Physics. Abdus Salam´s legacy was not just his outstanding contributions to particle physics but also the ceaseless championing of the cause of young and talented scientists of the developing world. A few years back, some of these young people gathered at the institute established by Abdus Salam, the International Centre for Theoretical Physics in Trieste, Italy, and decided to start a Summer School in Physics to help train and expose young physicists from the Asian region. This school has held classes in Kathmandu every two years since 1989, with lectures by many renowned physicists, including a few Nobel Laureates. The acronym of the summer school, BCSPIN, refers to the six countries from where young physicists are drawn for training: Bangladesh, China, Sri Lanka, Pakistan, India and Nepal.

The burning passion of Abdus Salam´s life was using science and technology to alleviate poverty. As he said at a science conference in Dhaka in 1961: "It is a new concept that not merely sections of the society, but entire societies can be lifted out of the quagmire of poverty and that entire peoples can now crash through the poverty barrier."

Abdus Salam carried his message to kings, presidents and prime ministers. When he visited Nepal in 1989 to inaugurate the First BCSPIN Summer School, during a meeting with King Birendra he forcefully pleaded for one percent of Nepal´s GDP to be spent on the development of science and technology for the benefit of the people.

If Mr Salam did not achieve as much success as he might have in this personal crusade, it is because he was ahead of his time. But Mr Salam had greater success in his other mission in life: the unification theory to better understand the divine design in Nature.

When he started his research career in Cambridge University as a young man from Punjab, we knew that there were really four forces of Nature: the strong nuclear force, the weak nuclear force, electromagnetism and gravity. Thanks to his life-long research, we now know that there is only one unified force combining the first three and with a strong indication about how the fourth could also be eventually unified.

Garden of Eden
Abdus Salam was born in Jhang, Punjab, on 26 January 1926 to a deeply religious family. He himself remained a liberal but religious man all his life, with implicit faith in the words of the Creator as enshrined in the Holy Book of Islam. Those of us who had the good fortune of knowing him over 30 years will always cherish the memory of a cosmopolitan man who loved his fellow human beings because he loved the Creator above everything else.

Young Abdus Salam was educated at Government College, Lahore. At the age of 21, he wrote a paper extending some work of the great Indian mathematical genius, Ramanujan. He took his PhD degree from Cambridge in 1952, working on a very difficult problem of mathematical physics known as "overlapping divergences" which occurs in the quantum theory of fields. The young man´s outstanding work made an immediate impact and he came to be recognised as an authority on the quantum field theory.

But Mr Salam´s magnum opus was really the unification theory and very soon he, along with his colleague John Ward, took the first steps towards explaining it as far back as 1954, when he was only 28. The idea was revolutionary and beautiful. Mr Salam was one of the very first few who immediately understood the great importance of the concept of "gauge variance" when it was first published by C.N. Yang and R. Mills.

It was of course not easy to make use of this principle in the quest for unification, principally because of a problem which Mr Salam called the "Serpent in the Grass". As soon as we make a theory using the gauge invariance principle, a zero mass particle makes its appearance out of nowhere, and nobody knew how to deal with this beast in the Garden of Eden.

But physicists are nothing if not resourceful, and very soon fine works of Peter Higgs, Thom Kibble and others gave us an elaborate prescription of generating mass for the Yang-Mills vector particles. This was the last important ingredient still missing, and very soon Sheldon Glashow, Abdus Salam and Steven Weinberg, working independently, were able to construct a Unified Theory of Weak and Electromagnetic Interactions, now called the Standard Theory. Hundreds of tests were made on the Standard Theory to confirm it, and the three great physicists were awarded the Nobel Prize for Physics in 1979.

Bosons, Fermions, Hadrons
Perhaps guided by the great mystique of Asian religions like Buddhism, which look for unity and harmony in everything, Abdus Salam had always searched for symmetry in physics. During the 1960s, he, along with some Japanese physicists and Murray Gell Mann, repeatedly emphasised the importance of symmetry principles as encoded in the mathematical theory of groups. This theory soon found its numerous applications in the classification of strongly interacting particles called hadrons.

But the elementary particles of Nature are broadly divided into two groups called bosons and fermions, and physicists soon discovered an abstract form of symmetry known as supersymmetry, placing bosons and fermions on the same footing. Incidentally, bosons are particles of even spin named after the great Bengali physicist S.N. Bose, and fermions are particles of half-integral spin named after the great Italian physicist, Enrico Fermi.

In 1974, Abdus Salam and John Strathdee invented a mathematical framework for supersymmetry known as "superspace", which every student of physics must now learn. It is this work of Mr Salam on supersymmetry and its numerous applications and enlargements which are at the centre of current research in physics, and it is this type of research all over the world which was reviewed, discussed and analysed in the Sixth BCSPIN Summer School in Kathmandu.

In a myriad of ways, Mr Salam touched the lives of tens of thousands of young men and women all over the world and it is fitting that every two years some of them should come together in Kathmandu to learn, and in doing so to pay homage to this great man.

A.M. Harun ar Rashid teaches physics at university of Dhaka