Gravitation and Cosmology Group
Roberto Emparan
- ICREA Research Professor
- Fields of research: Classical and Quantum Gravity, String Theory,
Black Holes
- Publication list
from SPIRES
- Personal webpage: Myself at ICREA (Catalan Institution for Research and Advanced
Studies)
Research
In broad terms, my research aims at the
elucidation of problems of quantum gravity, and in particular at developing the
interface between string theory and gravity. My point of view, as well as
that of many other researchers in the field, is that black holes provide the
best theoretical laboratory for studying such problems.
Black holes pose a number of clear-cut questions in quantum gravity. Therefore,
they allow to focus on specific problems and to test new ideas and
techniques. Most of these problems are related to the fundamental basis of
Hawking radiation and black hole thermodynamics, and some of the deepest developments
in theoretical physics of the last decade, such as the AdS/CFT correspondence
and the holographic principle of quantum gravity, arose from the study of
quantum black hole physics. During the last years I have made several
contributions to this field, as you can see from my publication list.
A long-term line of research that I have initiated together with
collaborators in UK and USA aims at
unraveling the structure of General Relativity in dimensions higher than
four. The interest of this program is manifold: a primary motivation is that
string theory requires both additional spatial dimensions and
gravity. From a phenomenological perspective, much of the impetus in this
field has come from the possibility of experimental detection of extra
dimensions in the near future (see below), which makes the study of
higher-dimensional gravity particularly compelling and pressing. Higher-dimensional
gravity can also provide an extremely powerful tool to study the physics of four-dimensional
gauge theories, through the holographic AdS/CFT duality mentioned above. Furthermore,
a detailed comprehension of the dynamics of spacetime in higher dimensions is
likely to lead to clues to the question of why we only observe four
macroscopic dimensions. Finally, the study will illuminate the mathematical
aspects of General Relativity in higher dimensions. What little is known so
far about the dynamics of gravity in vacuo, and in particular about its black
holes in higher dimensions, indicates that a structure much richer than in
four dimensions is there to be discovered. Already our first results are
striking: we have found solutions (black rings) that exhibit entirely new qualitative features
Even if the initial studies of full-fledged higher-dimensional General
Relativity (and not just its Kaluza-Klein truncation) and its black holes
date back to at least the 1960's, the field has begun its development in
earnest only in recent years, with the formation of a compact and
well-connected community of energetic youngish researchers. As in every
budding and exciting field, unexpected discoveries are being turned up at
every corner. A recent highlight was the KITP workshop devoted to the subject. Other events are coming up.
In parallel with these lines, I've taken part in the investigation of
possible experimental verifications of string theory and quantum gravity
within the realm of high energy particle physics. If (and, admittedly, this
is a big 'if') the fundamental scale of quantum gravity is as low as a TeV,
then we may face the exciting prospect of studying quantum gravity in future
accelerators such as the LHC, presently in construction at CERN in Geneva. The
idea, which may have sounded almost preposterous only a few years ago, was
reexamined in 1998 by Arkani-Hamed, Dimopoulos and Dvali, who proposed a
general framework for theories of this kind, involving additional dimensions,
which isconsistent with all observations to date, and predicts
radically new phenomena at accessible energies. One of the most striking
consequences of these models, as well as a very robust one, is the prediction
of formation of black holes and other new states of matter at the LHC. That
these black holes can actually be detected was first proven in work I did with Gary Horowitz and
Rob Myers, and this
prompted the detailed investigation of the phenomenological signatures of
black holes at colliders.
Finally, I try to keep abreast of the exciting recent developments in
cosmology, and make some contributions to our theoretical understanding of
issues such as inflation and the current acceleration of the Universe.
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