Now I want to tell some alternative ideas. I will only name them and not go into details. There are brane theories using ideas first proposed by Kaluza and Klein eighty years ago. In a Kaluza-Klein cosmology one talks of a higher dimensional universe (that is not just of four dimensions, three of space and one of time) whose extra dimensions have shrunk. So you don't experience them at the macroscopic level, but the fundamental particles do in the form of their internal degrees of freedom. Then there is `dark energy' which relates to this force of repulsion which I mentioned a while ago. Then there are different versions of inflation. How did the universe inflate for a very short period? People have different ideas. The fourth is creation of matter. If matter was not created in a big bang which violates conservation of matter and energy then how was it created? You have to have alternative scenarios of creation of matter. The Quasi Steady State Cosmology which was proposed by Fred Hoyle, Geoffrey Burbidge and myself gives an alternative description of cosmology through the path of creation of matter. In this we replace the unique and singular epoch of creation of matter which was the characteristic of the big bang model, by a series of regularly spaced events of matter creation which happens in finite space. You don't have any singular infinite amount of matter being created in a single point of time but regular creation of matter at the expense of the negative energy field. So mathematically one could write this as an equation respecting the law of conservation of matter and energy. All the cosmological observations can be explained and well understood in this theory including the present microwave background, light nuclei, dark matter etc. One can use particle physics ideas in this cosmology also.
To conclude I would say that it would be possible to bring particle physics and cosmology interface closer to a testable theory with prediction of repeatable events by going over to the alternative cosmology which I briefly mentioned because it gives us new means of testing cosmology. And because it gives us repeatable events for creation of matter it is not open to that criticism that this happened only once and so we cannot test it again and again. We have the creation events happening all the time in mini-explosions (like those in quasars and active galactic nuclei) to which we can apply particle physics at very high energies and try to understand both particle physics and cosmology in a more concrete fashion.
I once again say that this entire line of investigation of studying physics at very very high energies in the context of the whole universe would not have taken off as it did without the contribution which Abdus Salam made through the electroweak theory and gauge theories in general. This was the one aspect of Salam which I wanted to highlight today. I thank you for giving me this opportunity of paying my tributes to a great man and a great physicist.