

American theoretical physicist. He
carried out graduate studies at the
California Institute of Technology. He
applied renormalization group
techniques to the fixed source theory
of Kparticles, and found exact
solutions at high energies. He obtained
his Ph.D. in 1961. Wilson worked on
quantum field theory. Trying to
understand the highenergy behavior of
momentum space, he reformulated the
problem in terms of position space. He
then sought a way to reduce infinite
degrees of freedom to a finite number,
by casting problems in forms that might
be solved by computers. He devised
procedures for eliminating degrees of
freedom, in terms of "momentum slices,"
each of a different scale. A lecture by
Ben Widom, at Cornell, turned
Wilson’s attention to critical
phenomena, to try to explain the
homogeneous equations of state that
Widom posited. At the critical
point the relation between scales
seemed to become simple. Leo Kadanoff
had introduced the concept of
block variables for distinguishing
scales where fluctuations matter
or where they may be disregarded.
Wilson then sought a conceptual and
mathematical approach to clarify
Kadanoff’s scheme, and hence to yield a
model for carrying out calculations.
Wilson set up computer programs for
calculating hightemperature
expansions. Also, he continued to
eliminate microscopic degrees of
freedom, replacing them by averages
over ever larger blocks or cells. Fixed
points seemed to constitute a universal
representation of the various stable
phases of matter. Wilson realized that
the behavior near the unstable fixed
points determines the exponents of the
phase transitions. He found how to
start from a microscopicallydescribed
system of forces (a Hamiltonian) to
produce macroscopic critical behavior
(that is, nonclassical critical point
exponents). He demonstrated why
ascribing a definite spin to each block
is a good approximation. Given the
dimensionality of the system, he
derived the universality class that
stands for all the phase transitions
that map one another. For example, the
critical points of all transitions from
liquid to gas have exactly the same
exponents. Wilson thus derived Widom’s
formulation of the singular part of the
free energy near critical points.
Wilson’s work was published in 1971. It
showed that exponents do not depend on
charges or on the intensity of forces.
Then, alongside Michael Fisher, Wilson
reformulated it as a perturbation
series technique based on the concept
of dimensionality as a continuous
variable. The perturbative technique
served for calculating exponents. Only
with this "epsilon expansion" could
physicists finally calculate critical
indices, especially for three
dimensional space. Subsequently, Wilson
applied the renormalization group
techniques to achieve an accurate
numerical solution of the Kondo problem
of magnetic impurities in nonmagnetic
metals. He then also developed methods
of working with gauge theories on a
lattice useful for analyzing the
behavior of quarks. In 1982, Wilson was
awarded the Nobel Prize in Physics, for
his discoveries in understanding phase
transitions. In 1985 Wilson became the
Director of the Center for Theory and
Simulation in Science and Engineering
(the Cornell Theory Center on
supercomputing). Wilson currently
codirects Learning By Redesign, and
develops approaches to reform
education.
Since 1988, Kenneth G. Wilson
is the Hazel C. Youngberg Trustees
Distinguished Professor of Physics at
Ohio State University.
Click here to view the INTERVIEW.

