I would like to recall some of my previous encounters with him. The first encounter was when he delivered the Rouse Ball lecture in Cambridge when I was a first year undergraduate. Abdus Salam had been invited to deliver this prestigious lecture. He had come down from London. He talked basically about the non-conservation of parity. If you look at an event and its mirror image you normally expect that the event and its mirror image are both possible in nature. However, basic interactions tell us that this symmetry is not necessarily respected in nature. This discovery had been made just around mid-1950's. He himself had been one of the major players in the field. So it was a matter of great excitement to hear him first hand and even today I recall his ebullient way of presenting the subject and the response that he received at that time.
Another episode I remember was in Italy when I had gone for a summer school. He had come to lecture at the school where I had also gone to lecture. We were together for some time. I remember him asking me a question. ``In Hinduism you have reincarnations. If there is reincarnation the total number of human beings in the world should be conserved. But the population is growing. How do you account for this?" I told him that the soul number is certainly conserved but the religion does not say that it should all go into human beings. There are so many different species. There is a large number specified. It is not necessary that human beings go into human beings. So you had to look at a broader conservation law. Such type of things happen in particle physics. Earlier people thought that baryon number was conserved and then that law was relaxed and you had baryon minus lepton number conservation. So he could appreciate the argument.
When the Inter-University Centre for Astronomy and Astrophysics was set up we were trying to pattern some of its activities on Abdus Salam's International Centre for Theoretical Physics and I had written to him on two or three occasions. Once we had also sent someone from IUCAA to observe close at hand how the ICTP was being run administratively so that we could pattern some of our administration on that. He had been very receptive to this kind of interaction. We had of course elected him one of our founder honorary fellows and in that capacity also he used to correspond. My lasting regret is that we could never persuade him to visit IUCAA. He had on two or three occasions promised to come but his visit never materialised.
What I want to do
in my talk here today is to highlight the impact of Salam's work
on bringing together two extreme ends of human perceptions
of the universe. Two extreme ends in the sense that if you go down to
the smallest physical size you talk of the scale of 
centimetres.
It is an extremely small
number. So you are talking about a very short length scale. On the large size you
can go to cosmology where the large scale structure of the
universe has a length scale of 
cm.
That is a very large number. So you are trying to bring
physicists who are dealing with very very small systems
in touch
with physicists who are dealing with extremely large systems. You might
wonder what kind of dialogue will that be. Thanks to Abdus Salam's contributions, and in fact he was a leader in the field,
this became a reality in just two to three decades. I want to go
over that exciting history
and also say something about the future prospects of
such an interdisciplinary study.