Ohio State’s Nuclear Experimental Group reports on atom smashing
Professors Tom Humanic, Mike Lisa, and Evan Sugarbaker are members of the STAR collaboration. On
June 12, 2000, the operators in the main control room of the Relativistic Heavy Ion Collider (RHIC)
announced that the STAR detector captured the first spectacular images of particles streaming from a
head-on collision point. Beams circulate in the collider’s twin rings on a collision course at an energy of 30
billion electron volts (GeV) per
nucleon. Later, events indicated
that PHOBOS also detected the
collisions.
The result is great news to
the thousands of physicists,
engineers, and support staff who
have been working since 1991 to
get RHIC up and running, and
to physicists everywhere who
have been anticipating RHIC’s
debut. These spectacular subatomic collisions are the
culmination of many years of hard work, and they mark
the beginning of a new era of discovery in nuclear physics.
The kinds of high-energy collisions produced by this extraordinary machine should further enhance our
understanding of the fundamental nature of matter.
For the full news release, see the web site of the
American Institute of Physics at www.aip.org.releases/
2000/rhic.html.
For more information and to follow RHIC’s progress,
go to www.rhic.bnl.gov/.
String Theory at Ohio State
By Fernand Hayot
T
he popular scientific press has
dubbed string theory the so-called
“theory of everything.” “Everything”
is a lot. What researchers seek is a theory
that would encompass both quantum
mechanics and gravitation, thus unifying
two great developments of the 20th century,
Einstein’s classical theory of general
relativity and the quantum mechanics of
Bohr and Schroedinger.
Since autumn of 1999, the Department
of Physics has built a string theory group
starting with two senior people: Arkady
Tseytlin, born in Moscow, and Samir
Mathur, born in Allahabad. Tseytlin holds a
Ph.D. and D.Sc. from the Lebedev Institute
in Moscow and was a reader in Theoretical
Physics at Imperial College in London
before joining the Ohio State physics
department as a professor. Mathur has a
Ph.D. from the University of Bombay and
was an associate professor at M.I.T. before
coming to Ohio State as an associate
professor. Mathur and his collaborator S.
Das did the “near extremal” black hole
calculation, which sheds light on the black
hole information paradox.
The story of black holes is fascinating.
We know that an object too close to a black
hole is swallowed, pulled in by the enormous
gravitational force. Is the information
the object carries irretrievably lost or can it
be reconstructed from the radiation, the so-called
Hawking radiation, which a black
hole emits as it evaporates? This is the black
hole information paradox. This paradox
suggests that in any theory that incorporates
general relativity there must be a breakdown
of usual quantum mechanics.
Because we know of the existence of
black holes in our galaxy and others, black
holes have become the theoretical laboratories
of string theory. If quantum mechanics
holds for a black hole, information can be
retrieved because of the reversibility of
quantum mechanics. If not, quantum
mechanics fails at distances where gravitation becomes infinitely
strong. This
would be strong
medicine.
The public’s
fascination with string
theory was evident
last summer with the
large turnout at Brian
Greene’s public lecture
about string theory (see page 6 for details).
Professor Tseytlin’s notes that “the
development of string theory underwent
rapid progress during the last six years with
the introduction of new extended states
called ‘D-branes,’ which are membrane-like
excitations in higher dimensions, and also
because of the unifying role played by the
11-dimensional formulation called M-theory.
D-branes represent a special class of
black holes in string theory and provide a
theoretical laboratory to study quantum
properties of black holes using string-theory
or gauge-theory methods.”
An impressive set of ideas is rapidly
emerging that suggests how properties of
ordinary quantum field theories, particularly
Yang-Mills gauge theory, are linked to
string theory. There is now growing hope
for understanding how field theories may
be described non-perturbatively. This may
have very intriguing repercussions for a
wide range of applications in particle
physics.
Tseytlin’s work was at the center of these
new advances. His main areas of research
include: black holes and extended brane
solutions in string theory and M-theory;
relations between gauge theory and gravity
descriptions of D-branes of superstring
theory; and string theories in curved
backgrounds and their gauge-theory
connections.
Professor Mathur notes that string
theory has so far provided remarkable
evidence that the black hole information
paradox can be bypassed and general
relativity and string theory can be made
consistent with each other. But the physical
mechanism for bypassing the paradox is not
understood in any explicit way.
“There must be a clear mathematical
formulation of the theory that makes its
symmetries manifest, but we have not yet
found the right variables for such a
description,” said Mathur. “It is likely that
new mathematical tools will be needed to
obtain such a description. In addition,
strings must make contact with the physics
of the low energy world that we observe
around us.”
In addition to their research, Professors
Tseytlin and Mathur are also developing
graduate level courses in string theory.
“I am very pleasantly surprised by the
interest among the students and faculty in
courses related to string theory,” said
Mathur. “The material is fast developing,
and thus not available in books for the most
part. It has been an interesting project to
develop courses that are accessible to every
graduate student and explore the current
work in the field. So far, I have taught a
course in general relativity showing its links
to string theory, and another course
explaining the details of the black hole
information paradox.”
Professor Tseytlin taught a
supersymmetry course spring quarter and
plans to teach string theory in the near
future.
1999 Nobel
Laureate gives
38th Annual
Smith Lecture
T
he Alpheus Smith lecture for the year
2000 was given on May 1 by
Gerardus ’t Hooft, the fourth
consecutive year that the lecture has been
given by a new Nobel laureate. The 1999
Nobel Prize in Physics was awarded by the
Royal Swedish Academy of Sciences jointly
to Gerardus ’t Hooft and Martinus J.G.
Veltman. The Academy’s citation was “for
elucidating the quantum structure of
electroweak interactions in physics.” In his
visit to Ohio State, ’t Hooft displayed
humor, brilliance, and a genuine affection
for sharing his knowledge. An impression of
his warm sense of humor can be obtained
from a view of his web site at
www.phys.uu.nl/~thooft/.
In his Smith lecture entitled “A Confrontation
with Infinity,” ’t Hooft described
the early attempts at constructing realistic
models for the elementary particles. Most of
these models resulted in infinite and
therefore meaningless expressions. Even
something as basic as the mass of the
electron appeared infinite. The extremely
successful modern models of elementary
particles are based on Yang-Mills theories,
which were co-invented by the late Ohio
State professor Bob Mills. Professor ’t Hooft
was awarded the Nobel prize for showing
that the symmetries of these theories cause the infinities to cancel. While the
cancellations
may appear to be due to “mathematical
sorcery,” ’t Hooft explained in his lecture
that they are actually based on physical
insights. Professor ’t Hooft met the
challenge of describing this phenomenon to
a lay audience with seeming ease. The wide
variety of audience members at the well-attended
lecture demonstrated a broad
interest in the subject.
Gerardus ’t Hooft is also well-known for
a long standing debate with Stephen
Hawking over one of the deepest problems in theoretical physics: the conflict between
quantum mechanics and Einsteins’s theory
of gravity. The debate between Hawking
and ’t Hooft is described in an entertaining
article by Leonard Susskind that appeared
in Scientific American in April 1997.
Hawking argued that information must be
lost in the evolution of black holes, which
would violate one of the basic principles of
quantum mechanics. Not so, said ’t Hooft.
Black holes must abide by the laws of
quantum mechanics, and it must be our
understanding of gravity that is incomplete.
Recent results in superstring theory have
strongly tipped the balance of scientific
opinion in favor of ’t Hooft.
In addition to the Smith Lecture,
’t Hooft met with graduate students and
also with colleagues to discuss black holes and quantum mechanics. In a special
seminar, he described a new theory, “The
Holographic Principle,” that is emerging
from his studies of the quantum mechanics
of black holes. He believes that quantum
mechanics itself must ultimately be replaced
by a completely deterministic theory.
According to ’t Hooft, nature is a big jigsaw
puzzle, and he sees his task as trying to fit
pieces of it together. You can read more
about that in his book In Search of the
Ultimate Building Blocks from Cambridge
University Press.
Robert Laurence Mills
The Department of
Physics expresses
condolences to the
family of Robert
Laurence Mills,
Professor Emeritus
in the department,
upon his death in
October 1999.
Professor Mills received his A.B. from
Columbia University in 1948, a B.A. and an
M.A. from Cambridge University in 1950
and 1954 respectively, and his Ph.D. in
physics from Columbia University in 1955.
He was a research associate at the
Brookhaven National Laboratory from 1953
to 1955, and a member of the Institute of
Advanced Study in 1955-56. In 1956 he
joined the Department of Physics at Ohio
State as an assistant professor, and rose to
professor in 1962. He served as vice chair for
Undergraduate Studies from 1992 until his
retirement in 1995. Following his retirement
he lectured as a Fulbright Scholar at St.
Patrick’s College near Dublin, Ireland.
His research and that of his graduate
students was in quantum field theory, many-body
theory, and the theory of alloys.
He
was the author of two books: Propagators for
Many-particle Systems: an Elementary
Treatment (Gordon and Breach 1969) and
Space, Time, and Quanta: an Introduction to
Contemporary Physics (W.H. Freeman 1994).
Professor Mills shared the Rumford
Premium of the American Academy of Arts
and Sciences with C.N. Yang. This award
honored the seminal work on the gauge field
theories now known as Yang-Mills theories,
which to quote The Scientist, have emerged
as “the foundation for current understanding
of how subatomic particles interact, a
contribution which has restructured modern
physics and mathematics.”
He and his wife, Lee, were very active in
community affairs, and in 1991 they shared
the International Community Service Award
of The Ohio State University Office of
International Affairs. He also received the
Rosalene Sedgewick Faculty Service Award
for outstanding service to undergraduates in
the College of Arts and Sciences. Professor Mills was a member of the
American Physical Society, the American
Physical Society Forum on Physics and
Society, the American Association of
University Professors, and the Federation of
American Scientists. His broad interests and
activities were well characterized by C.N.
Yang, who said, “Bob had a brilliant mind.
He was very quick at grasping new ideas.”
A gentleman of unfailing good humor
and sincere and active concern for helping
others, Robert Mills will be long remembered
with great respect and affection.
K. Narahari Rao
The Department of
Physics extends
condolences to the
family of K.
Narahari Rao,
Professor Emeritus
of the department,
upon his death in
May 2000.
Professor Rao received his Ph.D. from
the University of Chicago in 1949 under the
direction of Dr. Gerhard Herzberg (Nobel
laureate, 1971). He was at the National
Physical Laboratory in Delhi, India from
1950 to 1952, then Duke University and the
University of Tennessee from 1952 to 1954.
He came to the Department of Physics at
Ohio State in 1960 as a research associate,
became associate professor in 1960, and was
promoted to professor in 1963. In 1992 he
retired as Professor Emeritus of Physics.
His research was centered in the field of
high resolution infrared spectroscopy.
Throughout his career, he addressed a need
for better wavelength standards in this region,
which culminated in the publication with Dr.
Guy Guelachvili of the Handbook of Infrared
Standards (Academic Press 1986 and later
editions). He also led in the development of
improved methods of studying infrared
spectra at higher and higher resolution. These
methods were applied to the determination of
molecular constants, studies of intra-molecule
interactions, and observations of transitions
normally considered to be unavailable for
study. These research activities resulted in
over 300 publications, including six books
and six major review articles. He worked
with 43 students who received Ph.D.
degrees, 36 students who received M.S.
degrees (with thesis), 10 postdoctoral
fellows, and 34 visiting scientists from nine
countries, many of whom returned on
several occasions.
Professor Rao was involved in the
development of the Journal of Molecular
Spectroscopy from its inception in 1957,
when he served as assistant editor to
Harald H. Nielsen. In 1973, he became
editor of the journal. When he stepped
down in 1995, the journal had increased in
size by a factor of six, and he had processed
nearly 10,000 articles essentially
singlehandedly.
During the same period he also played
a similar role as director and organizer of
the international “Symposia on Molecular
Structure and Spectroscopy.” These
conferences are held annually at Ohio State
and are attended by 400-500 scientists
from around the world. His role with the
journal and the symposium led to a special
recognition in 1992 at his retirement, as
well as the creation of the annual “Rao
Prizes” given to three young scientists for
outstanding first presentations at the
symposium.
Professor Rao was elected to the
Cosmos Club in 1967, received the Asian
Indians in North America Prize for Basic
Research in 1980, the Indian National
Science Academy Endowment Lecture in
Spectroscopy in 1982, the Marcus Marci
Medal of the Czechoslovak Spectroscopy
Society in 1985, The Ohio State University
Distinguished Scholar Award in 1986, the
Faculty Service Award from the National
University Continuing Education Association
in 1987, the Pittsburgh Spectroscopy
Award in 1988, The Ohio State University
International Outstanding Faculty Award
in 1992, and the William Fowler Award
from the Ohio Section of the American
Physical Society in 1993. He is also a
fellow in the American Physical Society
and the Optical Society of America.
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