HS
I spent the year at Rockefeller on sabbatical. Where my best production
was my son. (laughter) I was closer to Columbia University.
My wife was teaching at Columbia then. Ok, where were we? I
mentioned to Sam that these episodes, that I told you about,
changing of direction, I've changed direction a lot of times.
And I wrote an essay on what I called 'Crucial calculations
in theoretical physics, and contrasted them to crucial experiments.
I never wrote the essay up. I just gave it at public talks,
one at Sam's course at Harvard, one at a public lecture here
[Brandeis]. It was intended as rebuttal to the people who said
particle physicists were ambulance chasers. Oh, a new idea comes
along and everybody wants to write a lot of papers. And this
bothered me a lot. The rebuttal was that there were well-defined
reasons for changing directions. I didn't have much sympathy
for the people, which I called the ergodic theory people, who
every five years the subject passed in their neighborhood made
a contribution. Like the group theory specialists who spend
their life on group theory, and of course when the orbit came
in their direction they were great heroes, and between that
they were irrelevant. I had no respect for that. The people
I respected were the ones who were always trying to solve the
hard problems. I was not an initiator, but when something convinced
me there was a new direction, damn it, I wanted to know. It
annoyed me not to know what people were doing.
PoS
So those episodes were when you learned what?
HS
Well, one episode was current algebra. The other episode was...
PoS
Can you be more specific? Gell-Mann's papers? The lectures by
Fubini?
HS
...and Adler-Weisberger which was a little bit earlier.
PoS
Adler-Weisberger was the crucial calculation...
HS
That convinced me that the subject was coming into its own. I
was knowledgeable about dispersion relations, which was my Rochester
experience. I also had worked on pion physics, which was part
of the Chew-Low stuff, so a good marriage. The Adler-Weissberger
stuff, which is just forward dispersion relations, married the
two things that I knew about and absolutely convinced me that
was the right area.Fubini andGell-Mann provided me the tools
to work on it. I think the next really crucial thing for me
was J/Psi, the discovery of quarks. That really changed a lot
of people's world-views. I also met [Gerard] t'Hooft in Amsterdam.
[Martinus] Veltmann had introduced Ben Lee to t'Hooft -- probably
it was at the Amsterdam conference. He said 'here's my graduate
student, he's done something great.'
Then we went off and did all these theories on renormalization,
that point of view. I tried some renormalization in those days.
People were interested in scale-invariance, in which I had to
do counterterms. But my view of renormalization was counter
terms to make things finite. You know, very pragmatic.
PoS
So where did you pick up renormalization?You say J/Psi changed
lots of people's points of view, to what?
HS
This was a time to do phenomenology, time to find the quantum
numbers of the quarks, doing spectroscopy, -- the jargon. Some
people said that the charmonium was going to be the hydrogen
atom of the strong interactions. What emerged, from the stuff
that I did, were properties ofthe confining forces.. I was interested,
heavily interested, in the spin-dependence of charmonium, I
learned spectroscopy as a tool to learn the phenomenology of
effective quark interactions. That occupied me for a long time.
PoS
Let's go back to this notion of crucial calculations.
HS
PoS
Charmonium is really an experimental crucial experiment. But in
terms of your training, if one were to look back, you'd say
Chew-Low was a crucial calculation.
HS
Yes. A little bit earlier, i.e., before I entered physics, but
it was a cornerstone of my thinking.
PoS
Right, you would characterize it as a crucial calculation. More
than a model because it was specific in terms of showing you
how to use that approach in a particular way that would extend
to other kinds of interactions, more than two-particle scattering,
...It's a nice notion, in terms of your own lifetime trajectory,
and your own life skills. Would current algebra, as you've characterized
it, and with Steve, effective Lagrangian approaches be likewise
characterized as crucial calculations?
HS
That was not my thing. I was more of a spectator. It superceded
the current algebra approach. It convinced us that the local
Lagrangian densities, Langrangians, were-effective tools.They
were crucial calculations in the march towards local field theory.
PoS
That's what convinced you towards Lagrangians?
HS
Yes. I was very comfortable with current algebra using Ward Identities,
superceded by other people's phenomenological Lagrangians, if
you will. And I would say, in retrospect, that it pushed the
community toward a belief in local Lagrangians. I mean, there
weren't form factors; there weren't black boxes; all there was
was the correct symmetries and low energies. In retrospect,
everything that was done there was correct.
PoS
But at the time, what were the successes and the promises that
convinced people?
HS
Well, first Adler-Weisberger. Then Weinberg, for example.
PoS
The low-energy scattering lengths?
HS
Low-energy scattering lengths, s-wave scattering lengths. Weinberg
could also relate, say, K-two-pi-e-nu to K-pi-e-nu, because
the extra pi was a soft pion, and he had a whole bunch of soft
pion theorems which had phenomenological verification. So the
whole machinery was being checked, not just an isolated thing.
The machinery convinced people that it was going in the right
direction.
PoS
As historians of science the notion of a crucial calculation is
particularly interesting when referring to the community. But
you're saying that there were some crucial calculations which
you would characterize as crucial calculations for the community
as a whole, that were such that you didn't necessarily feel
that that was your particular thing to do at that particular
time, to change your own personal direction.
HS
Or maybe I wasn't good enough to do it. You know, people say you
do what you could do. There are some things you can't do, not
because you don't respect it or think it's
right; some things one can't do.
PoS
But it's not so much that you can't do. You can think of Steve
Weinberg as a big fast tank, and he was going to go ahead.
HS
Working with him, knowing him very well, I've always thought that
Steve Weinberg was on my continuum. Every thing he did, I could
understand where it came from. Except everything he did was
better. He would work harder, he was smarter, his tools were
better, etc., etc., etc., but there was nothing that was unfamiliar
there; just twenty different processes, every one put together,
every one which was better. There are people around who I can't
understand where they come from. I mean, like [Ed] Witten. Witten's
a true Martian. But Weinberg was not a mystery. Every single
qualityyou could recognize, he was just better than everybody
at it. And he used it in a coherent way.
PoS
All I was trying to say is that if Weinberg would have shown youthese
things, and then decided to do something else, you might very
well have picked up on that trail. But given as how you just
characterized Weinberg, competing with him on this particular
battlefield would not be very fruitful.
HS
Yes. Also, regarding crucial calculations, personal crucial calculations
If you were doing an essay for the public, you'd recognize changes
of direction which you may not have participated in. You know,after
the very last thing I did with Steve he disappeared and did
this strange stuff on electroweak theory. Shelly and I and Steve
had done something with Rho Mesons and A Mesons, which must
have rang a bell and said, 'Oh, maybe this is the way weak interactions
work,' or something. You could see some parallels there. But
then we didn't see Steve, and then his paper came out, which
I, frankly, didn't understand at that time, and a lot of other
people didn't understand. So then there was some real field
theory, because Steve worked with Roman Jackiw to do radiative
corrections. I don't know how much counter terms is on that
stuff, a lot of that stuff is finite, anyway.
PoS
Thus Steve coming to Boston, in '66, '67, is a major change in
your life.
HS
PoS
And effective Lagrangians make you a field theorist in some sense.
HS
PoS
And when you talk of Ward Identities, where do they come from?
How do you look upon Ward Identities?
HS
In those days I looked at it as time-ordered products of vector
and axial-vector currents, whose divergences would give you
local versions of the algebra of charges that Gell-Mann had
proposed. First we had algebra of charges, that was my Fubini
experience; then local currents. If you take the divergence
of the time-ordered products of two currents, you get an equal
time-commutator, and that's where Gell-Mann comes in. Gell-Mann
would tell you what that current there is. And then the remaining
stuff would be Pions or conserved currents.
PoS
What would the Ward identities be from the current algebra viewpoint?
HS
Time-ordered products of currents! As many as you need. If you
want to take a 10 point function, you have time-ordered products
of ten currents. You grind away, and you get a proposal for
what the answer is: A lot of interlocking amplitudes.
PoS
So now when you work with Ira Gerstein, Gerald Guralnik, on magnetic
mass difference of zero mass pions, calculating to 4th order...
HS
What was the motivation for that? There were counter terms there
just to make things finite.
PoS
So that's your first practical application?
HS
In fact the motivation was to hopefully find that the thing was
finite without counter terms. There was a Francis Low calculation,
Low and who else, Mathur? Francis Low did a calculation of Pi
plus Pi Zero mass difference using current algebra.
PoS
[ ] Das, Guralnik, [ ] Mathur, and A. P. Young.
HS
in which you had two currents, axial currents, you had a radiative
correction. There was an anomalybut he actually was able to
calculate andget a very good number for the Pi plus Pi Zero
mass difference. So there weretwo calculations that we did.
Thefirst calculation to answer the question : is it finite when
the Pion has a finite mass? Answer: no. Was it possible that
current algebra is a solution to the divergence problems? So
the first exercise was to put in finite Pion masses, but still
lowest order electromagnetism. That answer was no. That we did
by sum rules. That way to do that is you do the same PCAC, except
that the divergence of the axial vector current is N * Pi squared
Phi (N*Pi^2*Phi), the Pion field appears, and so there's more
stuff to do. The fourth order calculation was with zero mass
pions. So then we said: Well, maybe current algebra is finite
to all orders of electromagnetism with zero mass Pions; zero
mass Pions are special. So we did the calculation and found
it diverged, so the exercise there was not to find an actual
number, and do a counter term, but to show that this was no
better than standard electrodynamics. It was a fortuitous accident
that the lowest order Low calculation at Pi equals zero, lowest
order alpha was zero. It was just fortuitous that it was finite.
The rest just had all the problems. So, the main exercise there
was to correctly organize fourth order graphs.By then the tools
were phenomenological Lagrangians. Gerstein and I worked with
Ward identities -- I knew how to do Ward identities to fourth
order -- and Ben Lee and a graduate student did phenomenological
Lagrangians. We compared and we got the same answer.
PoS
Ira Gerstein at that time was at MIT.
HS
Yeah, he would have gotten tenure at MIT. He dropped out, became
a sociology graduate student at Brandeis, got a PhD, from Marcuse,
and teaches, perhaps still teaches, sociology at U-Mass Boston.
Taught for a long time at U-Mass, became a complete drop-out
and very left wing. George Salzman went the same way. George
Salzman, my first advisor at Rochester, went to Colorado, then
came back to U-Mass Boston again. And he completely dropped
physics to be extremely left.
PoS
It was due both because of Vietnam and probably also because his
wife had just died.
HS
There wasa great deal of political ferment in this area around
those times. I think it affected people's work. At least the
more sensitive of them.
PoS
How much did you know of Gell-Mann-Levy and the Sigma model?
HS
I knew that. When I went to Paris I tried to do some stuff. But
often from a dispersion relation point of view.
PoS
Well, but that's part of your...
HS
Yeah. I did the Lee model, and some variants of the Lee model.
I could make a living doing Born approximations.
PoS
So you just had a sense of the usefulness of toolkits and what
tools you could effectively use, and tools and things that you
were not quite so adept with.
HS
Yeah. Things I had to learn. Except for the current algebra, the
Ward Identities, I was an innovator. And likewise in some of
the phenomenology and quark potentials, but in some of these
other big areas I was not an innovator at all.
PoS
Sofrom the time you became acquainted with Jauch and Rohrlich
you didn't look at renormalization again until you started doing
effective Lagrangians.
HS
It wasn't needed. In fact, I would say it was illegal to do radiative
corrections, because there's no fundamental way to do so. Phenomenological
Lagrangians in theirvertices already contained, in my opinion,
all the renormalizations to make up the dressed vertex. I would
have argued that it was not proper to do hadron radiative corrections.
It is appropriate to do electromagnetic corrections because
they are outside of the realm of the subject matter: they are
an additional perturbation.
PoS
And on a personal note, at what stage do you become aware of this
notion of crucial calculations?
HS
PoS
When Steve talked about effective Lagrangians was it clear to
you that here is some bifurcation?
HS
No....I think it's a view of my middle age. Having gone through
several, several changes of direction, we debated and talked,
and we often had different interpretations of what went on.
But I tried to get started getting interested in a world view
of what you know, I've spent my life on this subject since I
was less than twenty years old. So I wanted to get some overview.
What hashappened? What motivated people to choose the research
directions they did was one of the things I was interested in.
And this was a response. And this was also self-analysis. What
motivated me to choose directions? Well, limitations of skill.
But within that, I always wanted to be on the frontier subjects,
and do what I could do. And as you heard remarks of my disdain
for the 'ergodic' theory people, I would rather work in the
most important areas, and make a contribution even if I wasn't
a leader, rather than be the expert on something that's irrelevant.
I found that was tasteless to me. Still is tasteless to me.
PoS
Do you have a manuscript of these talks on crucial calculations?
HS
No. When we're finished, I might have the transparencies, but
I doubt it.
PoS
May I ask you some more personal questions, and then we'll come
back to some of the more specific issues. You're clear about
wanting to be at the frontiers of physics. What kinds of philosophical
questions do you ask along the road? What kinds of answers satisfy
you? What are the metaphysical rewards of the enterprise. Given
the struggles that you have gone through, what is it that motivates
you to work so hard?
HS
Well, let's see. You know, it's an increasing distillation towards
more fundamental issues. Starting with mechanical engineering,
where I knew a lot about steam turbines, to the phenomenology,
towards fundamental issues. As far as the psychology, you know,
I was in a room in Rochester with 10 Japanese graduates and
it annoyed the hell out of that I didn't understand their language.
Blah blah blah blah sodeska, blah blah blah blah sodeska, and
I said, damnit, I'm gonna try and learn Japanese. I failed.,
I learned a few hundred words, and I can do tourist Japanese
when I'm in Japan, but just that people could be talking about
things that I didn't understand, was and still is a tremendous
annoyance to me. So part of the motivation is, I'm not gonna
have these young guys talk about physics and I haven't got the
faintest idea what they're talking about. I don't have to be
up front, but at least I have to understand what they're doing
and why they're doing it. The most crucial calculation in my
life, most recently, was the Green-Schwartz anomaly calculation
in string theory, which absolutely convinced me that string
theory had something to say about nature. And nothing since
then has changed my mind. And that required a major retooling,
because I was not trained in it mathematically. So when was
it? In '84, now 17 years ago. So how old was I? 50 when I started
from scratch learning topology, differential geometry, a little
bit of algebraic geometry, a little algebraic topology. Wasn't
in my bones the way that field theory was. If I had to do a
current algebra calculation today, I would do a better job than
I do on the string theory. But that's not the point, the point
is that I was absolutely convinced that was the right view of
the world. It wasn't a miracle. Things fit together like a glove,
and nothing has changed my mind. Also, Witten's charisma, his
packaging of it. And a lot of the smartest people working on
it. And it's challenging to keep up with the young, smart people.
Even if it was wrong, it's fun to try to chase them. You know,
my analogies, to be a 67-year-old athlete and try to compete
with 30-year-old athletes on a level playing field, I think
it's just personally fun.
PoS
Ok. That's at the psychological level. At the metaphysical level?
HS
At the metaphysical level what always annoyed me is that I didn't
know what the first principles were. To get deeper and deeper.
And a lot of it was my own limitation, so I don't have the skills
of a Weinberg or a Schwinger, so I'm dependent on what information
other people could provide, because I couldn't create it for
myself primarily. But, I made judgments. Yah, this was an insight
to something more fundamental, and I was convinced by people
that a marriage of quantum mechanics and gravity was an important
issue. I guess I didn't pay attention to other stuff.
[Abdus] Salam was always coming up with a hair-brained scheme
of something or other. Relativistic SU-6, and others, indefinite
metric,.... So there was a lot of stuff. There was a lot of
stuff out there that I didn't believe, and you have to make
a judgment. Do you believe it or do you not believe it? Once
you believe it, then you have to make a judgment, 'Do I want
to work in it or not to work on it?' So those are the personal
things, but I think the sequence of things was towards more
fundamental issues. More reductionist issues.
PoS
Ok, you essentially talk of a road to ever-greater fundamentality.
How do you view that it has changed you personally?
HS
You know I haven't had thirty seconds of conflict with what I'm
doing since I started in physics in 1954. I don't think I've
changed one damn iota. I'm the same person. Physically, the
body's not there, but I have the same feeling for the stuff
I do that I did when I started out. I haven't changed. I have
an enormous respect for the great minds of the subject, and
a great feeling of privilege that I got to know a lot of them.
Either personally, or very up close. I didn't ever know Schwinger
personally, but I know Shelley personally, and Steve, of course.
I had a great privilege to be part of the game when it really
started, in '54, '55. My feeling about the subject hasn't changed,
the subject has an enormous amount of integrity to it.
PoS
What I'm really asking is: Having learned more deeply about how
the world is put together has it changed the way you look at
the meaning of your own life, or the meaning of things? You
could certainly argue that owing to the level of reality that
physicists have penetrated with quarks and with the standard
model, you have a deeper understandings of the workings of nature.
Do you agree to that?
HS
I have a deep respect for the rationalist view of the world, saying
it slightly differently. I have a deep respect for the logical
positivist view of the world--which is probably not what one
would say currently, but I still believe in it. I have a deep
disdain for the post-modern view, a gut antithesis to that point
of view. My wife debates me a little bit on this point. My wife
is a psychologist. She says: 'Well you know the problems that
people pose are culturally determined.' I say, 'Yeah, ma'am,
that's true, but the answers are not.' You can't convince me
that special relativity is a construct of western civilization
at the time we live. If I could give tools to a headhunter in
New Guinea, he would come up with the same damn answer. I don't
believe it's culturally determined. Maybe, the reason he's not
asking the question is cultural. I'm strongly on the Weinberg
side on that thing. Straight rationalist view of the world.
We're doing an honest job and not deceiving people.
PoS
Would you be on the same side when he says the deeper, the more
I understand about the world, the more absurd it seems. Would
you come out on that same side?
HS
No, I get very puzzled. Namely, our subject is going on to the
first three minutes, the first few seconds, the Planck time.
And I am deeply puzzled and don't know what to make of it. And
then, why did that happen? How did that happen? Did it happen
by itself? That doesn't make sense. And I wrestle with it. You
almost have a doorway open to a religious point of view, and
I can't cross the threshold. But on the other hand, it's an
unanswerable question which I don't think string theory, or
big bang, or anybody else is going totell me. Because nothing
should have happened. Why did this happen? And I don't see anything
in my rational life that's ever going to answer the question,
there's no tools that are ever going to be there. I don't know
whether formal religion is. I mean, I'm culturally a Jew, but
not a religious Jew.
PoS
But you would not come out with Weinberg?
HS
No, because of this deep puzzle of t = 0 You can't just say it
just happened, it doesn't make sense to me. And I don't see
the tools of science are going toanswer the question. Unless
I'm missing something.
PoS
Maybe we'll come back to that, when we talk about string theory.
Part of your investment in string theory brings you closer to
the epsilon.
HS
Epsilon is still epsilon.
PoS
Yes, right, but the epsilon has changed. The epsilon, you can
make it a little smaller than...
HS
You know, there's a philosophical debate of people who view God
as everything else you can't explain. And religious people should
say, that's a lousy debate because every time science makes
an advance, it makes the domain of God smaller and smaller.
So that's a very shaky philosophical position. You say, oh,
you can't explain this, and God gets the rest of the package.
There's always the epsilon. This epsilon that I'm worrying about,
I don't think will go away. I don't know what the answer is,
but agnostic maybe may be the right word. I don't think that's
a scientific question.
PoS
Regarding your view of crucial calculations and the role they
played in your life. Is it that you look backwards and say, this
is what I've been doing, or would you say that in the late
'60's and 70's you had a sense of the crucial calculations to
watch for?
HS
I didn't watch for it: I was deeply affected by it. You can't
look for it, cause if you knew what to look for, you could
do it yourself, perhaps. But, I think you have to be open to
it, and as I got more mature, I could probably recognize the
changes of direction in the field, get some overview. I think
when I was a kid, I just did my job, basically. But then if
youve gone through three or four directions in your life, you
say, hey something's going on here. And it's not all foolishness,
not all ambulance-chasing. Why do people change direction? Not
just why did I, why'd the subject change direction? You also
ask the question: 'Whats the psychological makeup of the people
who didn't change direction, got left behind?' I think it's
lack of courage.
PoS
I wonder what youmake of renormalization not being important in
your work, in the different phases of your work?It does seem
tobecome important after gauge theories come up.
HS
PoS
What about your work with Bert Ovrut?
HS
Yeah, with Bert, effective Lagrangians, running coupling constant,
renormalization group.
PoS
At some stage, presumably between sometime around the early 70's,
what happens is that you become convinced that field theory
is the explanation for your current algebra work and everything
else.
HS
PoS
But that's the question. Up until your work in current algebras,
it just wasn't something important.
HS
It was not a tool that I used.
PoS
OK. And thenwhen you were looking at current algebras and effective
field theories, it wasn't interesting.
HS
Well, the first place it really shows up is the stuff I did in
1/N expansion.
PoS
HS
Yeah, a little bit earlier. My own contribution was '74, by myself,
and then more. the more cited andrecognized one with [Larry]
Abbott and J. S. Kang, '76. And there we had counter terms,
and renormalization group. At the one loop level, again, I think
pragmatically.
PoS
HS
Had to make the damn thing finite. And that was the way you made
it finite. And then later with Marc Grisaru and our student,
Larry Abbott, we talked about anomalies and supersymmetries.
There it's another version of the Bell-Jackiw and Adler anomaly.
But we were co-discoverers of anomaly insupersymmetric theory.
There was a triangle anomaly where, let me think, you had a
gauge field, you had a fermion, and you had a supercurrent.
And you couldn't have everything conserved at once. We made
the bad interpretation that the supercurrent was broken symmetrically,
which was incorrect. There was something else going on. We learned
that you could cancel the anomalies by adding matter at one-loop,
and I gave a problem to my post-doc, Enrico Poggio, who worked
with Pendleton. They worked that same model, where the anomaly
was canceled at two-loops, they worked out Yang-Mills theory.
With two loops, though, the Beta function was zero. And that
was a subject which actually showed that N equals 4 Super Yang-Mills
theory was finite in two orders of perturbation theory. So,
we were sort of at the bottom of that subject, but didn't pursue
it completely. But by that time, we had a good idea of why there
are anomalies in field theory. And what you could do with them,
how to cancel them by changing the matter content. So certainly
by the mid-70's I understood that.
PoS
So how did you come to this new view of renormalization by the
mid-70's? How did that arise for you?
HS
I was learning supersymmetry, supersymmetry looked important.
PoS
That's how you came to renormalization?
HS
PoS
Can you tell us a little bit more about your constraint and anomalies
paper in QED?
HS
Which one was that? What year are we talking about?
PoS
1973, at the end of the QED paper in '73.
HS
I wonder if I even remember. Oh, that's the Ken Wilson, Ken Johnson
program. And to be honest, I don't remember that much about
it. I don't recall the details anymore.
PoS
They were worried about Z1, Z2, Z3, being finite, and how you
could make them finite
HS
I read Ken's paper, and if I remember, I tried to find a problem.
Sometimes I just found problems so I could learn somebody else's
work. Not a deep commitment to a program. That's another strategy.
The way to learn a subject is to set yourself a complicated,
homework problem. Hopefully make a contribution. I didn't think
that was going anywhere. Marshall Baker spent a lot of his time
on it.
PoS
But you certainly knew by then....
HS
I knew the tools of the trade. Z2, Z3 and power series.
PoS
So the couple of previous papers to that, the '71 paper on Chiral
Symmetry, the current algebra paper, those are all current algebras
ones?
HS
Scale-Transition Broken Symmetry, 1971. Those were calculating
the renormalization at one loop through the stress-energy tensor
with the counter terms. We had to figure out the appropriate
counter terms.
PoS
And this is now stimulated by the work of Jackiw and Coleman?
HS
Yeah, I think so. If I remember correctly.
PoS
That's interesting. Were these your earliest renormalization calculations?
These are the real consequences of anomalies.
HS
Yeah, we were looking for scale anomalies. I guess I was influenced
in those times. I was talking to Roman, and people were debating
anomalies. We had a summer school here, so I was learning anomalies.
I think the anomalies were all very much on people's minds in
those days. I don't know what the dates are but... These are
also exercises in learning multi-loop field theory.
PoS
This is also the time of the big explosion of Ken Wilson.
HS
Yeah, but you know, from '73 on I was going back and forth between
field theory and Hadron phenomenology. I had the energy to do
both simultaneously in those days. I had a strong feeling that
phenomenology was important because of the Charmonium business,
and as I told you, I thought that would be a window on Hadron
physics. Strong-coupling Hadron physics.
PoS
And this work on Reggetrajectories and field theory. The Regge
paper is a very complicated paper, huh?
HS
Yeah, that one I did with Marc Grisaru and H. S. Tsao.
Well, you know, it started out from a very simple concept, to
be found in the paper that was the first version of string theory,
the Veneziano stuff. And then people made multi-point functions,
and wrote down Lagrangians, Andre Neveu and some other people.
And they said: 'you take these effective Lagrangians which capture
the oldest string theory, take the zero-slope limit and you
get local Lagrangian.' So I said to Marc, 'You know, the local
Lagrangian should remember its parents.' This local field theory
should remember where it came from. We should be able to reconstruct
the Regge trajectories because it was a zero-slope limit of
the trajectories. So I should be able to go the other way. So
that's how that program started. It started from a very simple
concept. Marc was very much technically more able than I am.
I've always been a very intuitive person, so we had a good complimentary
contribution. Lot of hairy calculations. There is a personal
anecdote. My wife, after our son was born, in '70, got gall
bladder disease, and had a gall bladder operation. It was not
uncommon, after pregnancy. So we went to Puerto Rico over Christmas
and New Year. I was obligated to Marc to do this calculation,
and I had a notebook like that. So this is in San Juan, I'm
sitting in the hotel, everybody's celebrating New Year, and
Christmas. My wife went to bed cause she was sick, my son was
a young kid, toddler, and I was sitting in the lobby not to
disturb her, doing these calculations. People thought I was
from Mars. So, I remember some old dame coming along, saying
'What're you doing?' 'Oh, leave him alone, he's doing his homework.'(laughter) But I came back from Puerto Rico with a stack of calculations
like that.
PoS
Now you had identified yourself as a field theorist.
HS
Field theorist/phenomenologist. because I now could comfortably
go back and forth to both.
PoS
So where did you learn, how did you learn, a new point of view
on renormalization, specifically?
HS
My handbook was Bjorken and Drell.
PoS
HS
Both volumes. The combination tothe toolkit is the Weinberg theorem
and the Heine-Borel theorem of organizing that, and very clear
pragmatic calculations of how to do renormalization. I don't
think I did much ever with renormalization group. So the effort
consistedof the following:you had something in mind, and you
try to make it finite with the best tools at hand. You had to
worry about the overlapping divergences if you think higher-order,but
that was a toolbox again. I don't think I was deeply motivated.It
became more interesting afterI startedworrying about effective
field theories. AndI was also affected by Steve Weinberg's point
of view. You know, there was a shift of point-of-view that theories
had to be renormalizable to be legally discussed, and then we
learned more that these were just a low-energy manifestation,
that we could have marginal, irrelevant operators which you
would not see at lower energies, which just masked a more 'fundamental'
theory.
PoS
So you studied [Joseph] Polchinskis paper, probably?
HS
I read the Polchinski paper. I didn't study it thoroughly. I knew
about the Polchinski paper. I knew about Ken Wilson's papers,
I studied the Callen-Symanzik's paper, Curt Callen's was a better
paper.
PoS
When do you learn things like Wilson? Integrating out the high
energy contributions? When do you learn functional integrations?
HS
Ken Wilson, I don't even remember when I learned that. Functional
integration, I certainly knew by the time I did the 1/N expansion,
I knew about functional integration.
PoS
And you learned it from whom?
HS
PoS
So you started with anomalies, and you started working with supersymmetric
anomalies, and by the end of the 70's you're looking at decoupling
theorems... (end of tape)
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