Our current description of the basic interactions in
nature, based on the standard model of particle physics and
general relativity, is in spectacular agreement with all known
experiments. However, it is almost certainly fundamentally
incomplete. In addition to difficulties associated with strong
quantum gravitational effects at the Planck length, sensible
quantum-mechanical theory of gravity, two striking facts about
nature clues suggest that we are missing a big part of the
picture. The extreme weakness of gravity relative to the other
forces, as well as the huge size and flatness of our observable
universe, require absurdly delicate adjustments of the parameters
of the theory. We expect that new physical principles will be
revealed to address these puzzles — the “hierarchy
problem” and the "cosmological constant problem.”
Fortunately, these mysteries are associated with length
scales—the electroweak scale and the Hubble
scale—which will be probed experimentally in the near
future with particle accelerators and cosmological observations.
Therefore theories which address these puzzles are likely to have
experimental consequences that will be checked in the next few
Nima Arkani-Hamed’s research in theoretical physics is
driven by attempting to address these mysteries. Much of his work
has centered around addressing the hierarchy problem. Together
with Savas Dimopoulos and Gia Dvali, he suggested that the
extreme weakness of gravity can be attributed to the existence of
large extra dimensions of space, perhaps as large as 100 microns
in size, with the scale of quantum gravity lowered to the
electroweak scale. This opens up the possibility that quantum
gravitational effects can be probed at accelerators and even in
table-top experiments. In a different direction, together with
Andy Cohen and Howard Georgi he has constructed models where
(non-gravitational) extra dimensions are generated dynamically
from purely four-dimensional models. This has also led to new
approaches to the hierarchy problem. He has also investigated the
possibility that gravity is modified at large distances and times
in an effort to address various cosmological problems. Most
recently, together with Dimopoulos, he has explored the
possibility that the fine-tunings for the cosmological constant
and hierarchy problems find a common explanation within a huge
landscape of possible low-energy worlds that may exist in string
theory, leading to a novel proposal for "split" supersymmetry at
the large hadron collider..
Public Lecture at Institute for advanced Study, October 26, 2012
2010 Messenger Lectures at Cornell University, October 4 - 8, 2010
- N. Arkani-Hamed, "The Future of Fundamental Physics", Daedalus, Vol. 141, Issue 3, Summer 2012, Science in the 21st Century, American Academy of Arts and Sciences, 2012.
- N. Arkani-Hamed, F. Chachazo, Cheung and J. Kaplan, "A
Duality for the S Matrix", July 2009. hep-th/0907.5418.
- N. Arkani-Hamed, F.Cachazo, Cheung and J. Kaplan, "The S
Matrix in Twistor Space", March 2009.
- N. Arkani-Hamed, D. Finkbiner, T. Slatyer and N. Weiner,
``A Theory of Dark Matter", Phys.
Rev. D79:015014, 2009.
- N. Arkani-Hamed and S. Dimopoulos, ``Supersymmetric
Unification Without Low Energy Supersymmetry and Signatures for
Fine-Tuning at the LHC", JHEP:0506:073,
- N. Arkani-Hamed, A. G. Cohen, and H. Georgi, ``Electroweak
Symmetry Breaking from Dimensional Deconstruction", Phys. Lett. B 513, 232
- N. Arkani-Hamed, S. Dimopoulos, and G. Dvali,
``Phenomenology, Astrophysics and Cosmology of Theories with
Sub-Millimeter Dimensions and TeV Scale Quantum Gravity,"
Phys. Rev D
59, 086004 (1999).
- N. Arkani-Hamed, S. Dimopoulos, and G. Dvali,``The
Hierarchy Problem and New Dimensions at a Millimeter," Phys.
Lett. B 429, 263 (1998).
Institute for Advanced Study
School of Natural Sciences
Princeton, NJ 08540
E-mail: arkani at ias.edu
E-mail: mat at ias.edu
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