  I begin with some memories of Abdus Salam who was my PhD supervisor. After
reviewing the theory of non-linear realisations and Kac-Moody algebras, I
explain how to construct the non-linear realisation based on the Kac-Moody
algebra E11 and its vector representation. I explain how this field theory
leads to dynamical equations which contain an infinite number of fields defined
on a space time with an infinite number of coordinates. I then show that these
unique dynamical equations, when truncated to low level fields and the usual
coordinates of space time, lead to precisely the equations of motion of eleven
dimensional supergravity theory. By taking different group decompositions of
E11 we find all the maximal supergravity theories, including the gauged maximal
supergravities, and as a result the non-linear realisation should be thought of
as a unified theory that is the low energy effective action for type II strings
and branes. These results essentially confirm the E11 conjecture given many
years ago.
