If you were to ask physicists who
the greatest living physicist is,
I think Steven Weinberg's name
would rise right to the top.
It's not just that he has won a Nobel
prize, although he has, even in that
select group, he stands out. In 1967,
he published a paper that set down
for the first time, one of the key 
equations that describes the way
the world works, unifying
the electromagnetic and weak forces
that led straight to the standard model,
which is now the most comprehensive
general theory we know to be right
of how the world operates.
That's quite an accomplishment
but there is so much more.
You've heard of the big bang theory, right?
But why do we all know that mean
that thing, the big bang? Well it's 
because there have been great popularizers
of science and Steven Weinberg is 
one of the best. His book, the First
Three Minutes, was one of the very first
to lay out the modern view of cosmology.
But that's not all. If we are even here
to talk about it, it's because the world
has control of nuclear weapons and 
in the sixties and seventies and after,
Steven Weinberg was one of the key
people who brought the dangers of
nuclear weapons to the world's attention
and made sure that the world leaders
put measures in effect to help control
them. So it's quite remarkable I think
that he's taken the time to speak to you 
and help you get started on your journey
in physics and I hope you appreciate
what he has to say.
>> My name is Steven Weinberg.
I am a professor in both the physics
and the astronomy departments
at the University of Texas at Austin.
My research is in the theory of elementary
particles and cosmology, in other words,
physics and astronomy.
Well, I am not sure that any one person's
experiences are useful to anyone else,
but I was asked to describe how I got
into physics research, so I am going to
cast modesty aside and tell you my
story. It started with a toy,
a chemistry set that was handed down
to me by my older cousin, Bobbie.
And playing with chemicals, I began
to read about chemistry and I learned
that there were rules that told you
what kind of chemical reactions
were possible and that these rules
were understood in terms of
a deep science called physics, which
underlies everything in our experience.
And in particular there was a branch
of physics that was mysterious and
difficult called quantum mechanics
and that if you knew quantum mechanics,
you could understand why atoms and 
molecules behave the way they did
in chemical reactions and no one I knew
knew anything about this stuff and
I thought "well, this is what I have to
learn." So when I went off to college,
it was with the intention of learning
about all this stuff, about physics
and in particular, quantum mechanics.
So it was a little bit like Harry Potter
going off to Hogwarts to learn about
spells. At the time when I had gotten
excited about chemistry, I was also
reading popular books about science
and I remember there was one book
by a famous astronomer, Sir James
Jeans. It didn't have many equations
in it. It wasn't just serious treatise
on physics and astronomy but he
displayed a few equations.
And then there was one equation 
I remember, (chair scraping)
that went like this. Can you see
what I write?
xp - px = ihbar. Now I had no idea
what these symbols meant.
But I didn't know what x was or
p was. I certainly didn't know
what this h with a bar across it
was. But I knew there was something
strange about this because if 
x and p are numbers, any number,
any product of numbers is the same
whatever order you multiply them.
If you take 7 times 3, it's the same
as 3 times 7. So how can xp - px
be anything other than 0. 
But it wasn't 0. It was this thing
ihbar. I didn't know what that was.
And I thought this is really mysterious.
It wasn't clear. It wasn't that I was
turned on because I understood
this stuff. I was turned on because
I didn't understand it. I thought it was
something obscure and esoteric
and if I learn this, it would be something
that no one else I knew understood
and that was a great draw for me.
Another time, in a library, a public
library in New York where I live,
I went to the library to borrow books
about detectives and science fiction
and things like that, along with a few
of these popular science books.
Open on a library table, there was
a book, whose title was Heat.
Alright, there was a scientific book
about heat and there was a symbol
in it, that looks like this.
Now I knew that this symbol was 
something you learned about in calculus,
in mathematics and I had just begun
to learn calculus on my own.
Calculus wasn't offered as a course
in my high school and
with a number of my friends, we were
busy learning calculus by ourselves,
buying books and reading about it.
And I had seen this symbol, although
I didn't really know what it meant.
But it suddenly occurred to me that
this was really something wonderful,
that something as familiar and physical
as heat is encompassed, is explained
by higher mathematics and that you
could really learn about heat by using
this mysterious mathematics that
I was just then learning, calculus.
That gives me a sense of the power of
mathematics and in particular,
of mathematical physics that I hadn't
realized that all of common human
experience was somehow governed
by laws and that the language in which
these laws were expressed was 
the language of higher mathematics,
including the calculus 
that I was learning.
