 
Well, from the point
of view of somebody
who did theoretical work in
the early '60s, a lot of this
is jumping ahead
in time, rather.
If I go back to the
early '60s, there
were difficulties in the
theory, for which we now
have solutions, but no
coherent theoretical framework
for dealing with them.
The situation
which had developed
was that, first of all,
when quantum field theory
ideas, which had been so
successful in electrodynamics,
were applied to
the strong forces,
they didn't give
good predictions.
The agreement between theory and
experiment was always very bad.
Some people thought
that this was simply
because the coupling strength,
in terms of which you make
a series expansion,
was too big for you
to be able to do this at all.
We now know that we
simply had the wrong model
of strong interactions.
We thought that protons and
neutrons and other strongly
interacting particles that
we observe were elementary.
And that meant that the theory
that was based on those ideas
was almost bound to
give the wrong answers.
Quarks didn't really
arrive as being something
with an experimental basis
until about 1970, which
was several years after
the theoretical work
that I've been involved in.
And in fact, it took
several years, I think,
for the idea of quarks
to be generally accepted,
despite the strength of
the experimental evidence.
 
Both Weinberg and
I remained sceptics
for several more years.
I'm prepared to admit it.
He's embarrassed about it.
 
I was finally convinced in
1974 by the J/Psi discovery.
But that was one
kind of difficulty
which was not being coped
with in the early '60s.
The other was that the
theory of weak forces
was just-- it wasn't just wrong.
It was ridiculous.
It led to infinite answers
that people did not know how
to sweep under the carpet,
unlike quantum electrodynamics.
By then, a number of people
had categorised simple quantum
field theories of
various sorts according
to whether they would be
renormalizable or not.
And the candidate theories
for the weak force
was simply not renormalizable.
And that was a real headache.
 
