|Aldering Greg||Type Ia Supernove & The Accelerating Universe||Work by two independent
research teams - the Supernova Cosmology Project and the High-Z Team - has shown evidence
using Type Ia supernova at <z> ~ 0.5 that the expansion of the universe is
Observations of the CMB and cluster abundances confirm these findings, while new tests have strengthen the case for Type Ia supernovae as reliable distance indicators.
In addition to reviewing these findings, this talk will discuss programs which are now being developed to obtain much tighter cosmological contraints using Type Ia supernovae, and which should also lead to a much better understanding of their behavior.
||Superstring Phenomenology and Large extra Dimensions||The recent understanding of
string theory opens the possibility that the string scale can be as low as a few TeV. The
apparent weakness of gravitational interactions can then be accounted by the existence of
large internal dimensions, in the submillimeter region.
Furthermore, our world must be confined to live on a brane transverse to these large dimensions, with which it interacts only gravitationally. This scenario gives a new theoretical framework for solving the gauge hierarchy problem and the unification of all interactions. It has dramatic implications for observations at future particle colliders, such as production of Kaluza-Klein states and graviton emission in the bulk of extra dimensions. It also predicts a radical change of gravitational forces in the submillimeter range, which can be measured in non-accelerator gravity experiments.
||Neutrino Astrophysics||Beautiful observations
carried out in deep underground laboratories in the United States, Japan, Russia, Italy
(LGNS), and Canada with elusive particles called neutrinos (theory provided by Enrico
Fermi) have recently confirmed in a direct way the basic ideas of how the sun shines.
Scientists use neutrinos, which interact very weakly with matter, to reveal details of the
inner workings of the sun in much the same way as X-rays reveal the inner workings of our
bodies. The results of these pioneering experiments provide evidence of new physics beyond
what is in the textbooks (as anticipated by Bruno Pontecorvo).
New experiments are underway in the ice under Antarctica and deep under the Mediterranean Ocean. These experiments are designed to detect higher energy neutrinos from some of the most distant and energetic astronomical sources in the universe. The under-ice and under-water experiments have the potential to test special and general relativity to unprecedented accuracy and to provide an understanding of the origin of the highest energy cosmic rays. They may also reveal new types of astronomical sources that cannot be observed with ordinary light (photons).
||The New Generation of Interferometric Gravitational Wave Detectors||The effort to develop suspended mass interferometers for gravitational wave detection has lead to an ambitious new set of long baseline interferometers that will soon become operational. The goals and status of the various projects and planned early physics programs will be presented. The anticipated sensitivities of these instruments will be compared with expected source rates, as well as the prospects for using the combined data from the worldwide network of interferometers for the most sensitive searches.|
|Choquet Bruhat Yvonne
Local and Global Results on Solutions of the IVP for E.E's
|A quick survey of known results and an exposition of the new global results for spacetimes with U(1) symmetry groups.|
|The Global Initial Value Problem in General Relativity||The lecture shall, in
part, discuss the progress that has so far been accomplished in the investigation of the
global initial value problem in general relativity and, in addition, address the
fundamental open problems that remain to be solved.
In particular the development of the theory of gravitational radiation shall be discussed. Also, the problem of the formation and structure of spacetime singularities shall be discussed in relation to the fundamental issue of predictability. Here, the lecture shall touch on what can be learned from the study of analogous problems in fluid mechanics.
||Resonant Dectectors of Gravitational Waves||Five resonant-mass gw
detectors are in operation in Australia, Italy and USA. The strongest potential sources of
gw burst in our Galaxy and in the Local Group are today monitored by such instruments.
With the formation of the International Gravitational Event Collaboration, the activity of
these bar detectors passed a phase transition: from the occasional exchange of data
between two groups to the systematic exchange of data among all the groups.
To fully exploit the potentiality of these detectors, R&D programs devoted to the development of transducer-amplifier chains are in progress.
Advanced bars and future spherical detectors can join with confidence the world wide gw observatory in formation at the beginning of the new millennium with the first generation large interferometric detectors.
||The distance scale of GRBs and the role of BeppoSAX||A new picture of the
GammaRay Burst Universe follows the revolution started in 1997 with the discovery of the
afterglow by BeppoSAX satellite.
By chaining the capability of different instruments aboard the satellite a team of experimenters, duty scientists and operation engineers succeeded in pointing the burst location 8 hours after the burst and in detecting for the first time a faint fading source associated to the burst.
This unexpected discovery was followed by observations, in the locations distributed by the BeppoSAX Team, with the largest instruments in all wavelengths, resulting in the detection of the transient source in the optical and radio band and arriving to determine the distance, the angular size an thence the energy of the phenomenon.
||Fundamental Strings and Schwarzschild Black Holes||One studies the effect of increasing self-gravity (i.e. of increasing the string coupling, g ) on the energy and size of very massive, uncharged (fundamental ) string states. Is is found that the size of a typical self-gravitating string state of mass M shrinks when g increases, and becomes comparable to its Schwarzschild radius when g^2 M ~ M_string. Such a compact string state has (in order of magnitude) the correct number of states to match the Bekenstein-Hawking entropy of a black hole. This result clarifies previous work by Susskind, and by Horowitz and Polchinski, on the correspondence between self-gravitating string states and Schwarzschild black holes. It suggests that the energy levels of (non-extreme) quantum black holes have a small degeneracy, and are densely distributed.|
LISA and future GW Interferometers
|De Bernardis Paolo
||Maps of the primeval Universe||Cosmic Microwave Background Anisotropy experiments have recently resolved sub-horizon structures on the last scattering surface at z=1000. I review the technical advances which made this possible, the current results and their cosmological significance, with special attention to the determination of the total mass-energy density in the Universe.|
|Djorgovski S. George
||Gamma-Ray Bursts, Their Afterglows and Host Galaxies||Panchromatic observations of cosmic gamma-ray bursts (GRBs) and their afterglows demonstrated their cosmological origin and relativistic motions in them. The implied isotropic energy releases are up to 10**54 erg in gamma-rays alone (i.e., not including neutrinos, gravitational waves, or high-energy cosmic rays). However, there is now a good evidence that at least some bursts are relativistically beamed. The GRB afterglows represent highly relativistic explosions, and their behavior is described well by simple relativistic shock models. There is also some evidence that at least some GRBs are associated with supernovae. GRBs occur within the stellar extent of their host galaxies, which appear typical for their redshifts. GRBs may be usable as probes of the cosmic star formation history and the intergalactic medium at high redshifts.|
||The Structure of the Universe on 100 Mpc Scales||Observational evidence
for the presence of a scale 100 - 130 h^-1 Mpc is reviewed. Quantitatively the scale is
manifested by a peak (bump) in the power spectrum of the distribution of galaxies and
galaxies, by the presence of secondary peak(s) of the correlation function, and by the distribution of nearest neighbors of superclusters. The scale corresponds to the mean separation of rich superclusters across voids. Theoretically the scale can be explained by certain processes during the inflation which modify the scale-free primordial power spectrum. Models with modified inflation are compared with observations.
||Gravity Probe-B Status|
|Ferrara Sergio||Supergravity:achievements and perspectives||A status report of Supergravity,the supersymmetric extension of General Relativity,is presented.In its twentyfifth year from its discovery, the main focus will be on its recent applications,uncovering various dualities of string and M-theory,black hole physics and the dynamics of extended objects(p-branes)with their relation to gauge quantum field theories.|
|Horowitz Gary||Quantum Gravity at the Turn of the Millennium||I will review the current state of research in quantum gravity. Over the past fifteen years, two approaches have emerged as the most promising paths to a quantum theory of gravity: string theory and quantum geometry. I will discuss the main achievements and open problems of each of these approaches and compare their strengths and weaknesses.|
|Green Michael||The Pointless Physics of String Theory||String theory avoids the
well-knwn problems associated with point-like singularities in electromagnetism and
This talk will present an introductory overview of recent developments, with special emphasis on the role of extended solitons on the non-perturbative structure of the theory.
||Chaotic phenomena in astrophysics and cosmology||The concepts of chaos and unpredictability had radical influence on various areas of physical science during the recent decades.We know that even classical Newtonian systems exhibit chaos and can be unpredictable in a way that is as profound as Godel-Chaitin incompletness theorems. We will review the consequences of this fact concerning certain key astrophysical and cosmological problems. Among the issues to be discussed will be the galactic dynamics, dependence of CMB properties on cosmological parameters, the instability in Wheeler-DeWitt superspace. Computational and observational aspects of those 'chaotic' phenomena, particularly involving such powerful descriptors as the Kolmogorov complexity - algorithmic information and random sequences, will be discussed.|
|Kajita Takaaki||Super-Kamiokande||Recent results from the Super-Kamiokande experiment on solar, atmospheric and accelerator neutrinos|
||On the Analysis of PDE's and General Relativity||The goal of the talk is to analyze the role played by
the modern theory of Partial Differential Equations in General Relativity. I plan to
illustrate some of the great success stories of this relationship suh as Positivity of
Mass and refinements of it, the stability of the Minkowski space and the proof of cosmic
censorship for a nontrivial spherically symmetric model.
I also plan to discuss what form this relationship may take in the future and outline a program of activity, within Mathematics, with highest potential for future progress.
||Geodesic Precession in Binary Neutron Stars||In this talk I review the evidence for geodesic precession observed in binary neutron stars. New observations and results are presented, focusing in particular on the binary pulsar B1913+16. These new results are used to investigate and model the binary system and to make predictions about its future. Besides reviewing the observational evidence for geodesic precession in binary neutron stars, the prospects for quantitative tests of theories are discussed. In order to highlight the observational strategies, an overview of the principles of radio pulsar observations is also given.|
|Narayan Ramesh||Black Hole and Neutron Star X-ray Binaries at Low Mass Accretion Rates||At low mass accretion rates, black hole and neutron star X-ray binaries have unusual properties. Notably, black hole systems are as much as 100 times fainter than equivalent neutron star systems. It is possible that the difference arises because black holes have event horizons while neutron stars have surfaces. If true, this might be a powerful technique to confirm the reality of the event horizon. The talk will review the observational data on low-luminosity X-ray binaries and the relevant theoretical ideas.|
||Cosmic Concordance||Has a viable new model emerged that is consistent with all cosmic observations: CBR fluctuations, large-scale structure, supernova observations, Lyman-alpha clouds and galaxy formation? It appears that this is the case and, most startlingly, the evidence strongly indicates that this best model requires large amounts of dark energy, some form of the repulsive force introduced by Einstein as a cosmological constant. Although the true model is almost certainly unknown, its properties must be close to the cosmologically flat Lambda CDM model with Omega_m approximately 1/3, Omega_Lambda approximately 2/3, h approximately 2/3, Omega_b approximately 1/25 and spectral index n approximately 1. The "cosmic triangle" provides a helpful tool to visualize the current state and evolutionary path of the universe in dimensionless parameter space.|
||The Hot Big Bang: Physics and Cosmology||The discovery of the
cosmic microwave background 36 years ago established the Hot Big Bang model, and
demonstrated convincingly that early epochs in the history of the Universe were very
different from the present.
Studies of the cosmic microwave background (CMB) have also turned cosmology into a real physical science: CMB measurements can be used to shed light on areas of fundamental physics (the half-life of the neutron; the number of neutrino families; the energy density of the vacuum) as well as to refine our understanding of the evolution of the Universe. I will review the transition to physical cosmology over the past 3-4 decades, with special emphasis on the physics underlying anisotropies in the angular distribution of the CMB.These promise to refine our understanding of fundamental physics as well as to provide quite precise values of key cosmological parameters. CMB observations already available, for instance, suggest that the Universe has a flat spatial geometry, in keeping with predictions of the inflationary variant of Hot Big Bang cosmology. Improved observations will help refine values for the rate of expansion of the Universe and set limits on the vacuum energy.
||Gravitational Collapse of the Wavefunction: an
Experimentally Testable Proposal
||There are powerful (though disputed) reasons to expect that the enigmatic phenomenon of wavefunction collapse is a real physical process that arises as a consequence of a tension between the principles of quantum mechanics and those of general relativity. Accordingly, it is proposed that the quantum superposition of two stationary quantum states is unstable if there is a significant mass displacement between these individual states; moreover, the superposition should decay into one or the other of these stationary states in a time-scale of the order of hbar /EG, where EG is the gravitational self-energy of the difference between the two mass distributions involved. This proposed effect is experimentally testable in technically difficult but feasible experiments. Some of these experiments will be described, as well as the underlying theory.|
||Black Holes and Gamma Bursts||The idea that the vacuum polarisation process occurring during gravitational collapse to a Black Hole endowed with electromagnetic structure (EMBH) could be the origin of gamma ray bursts (GRBs) is further developed. EMBH in the range 3.2 - 10^6 solar Masses are considered. The formation of such an EMBH, the extraction of its mass-energy by reversible transformations and the expansion of the pair-electromagnetic pulse (PEM pulse) are all examined within general relativity. The PEM pulse is shown to accelerate particles to speeds with Lorentz gamma factors way beyond any existing experiment on Earth. Details of the expected burst structures and other observable properties are examined|
|Schwarz John||Recent Developments in Superstring Theory||This talk will begin with a brief introduction to superstring dualities, M theory, and p-branes. This will then be followed by some more recent results in the theory of D-branes. These results concern noncommutative gauge theory on D-branes containing magnetic fields and tachyon condensation on unstable D-brane world-volumes.|
||Strong Field Gravity Measurements
Oscillations from Low Mass X-ray Binaries
|The relativistic precession model for quasi periodic oscillations, QPOs, in low mass X-ray binaries is reviewed. The behaviour of three simultaneous types of QPOs is well matched in terms of the fundamental frequencies for geodesic motion in the gravitational field of the accreting compact object, for reasonable star masses and spin. The model ascribes the higher frequency kHz QPOs, the lower frequency kHz QPOs and the horizontal branch oscillations to the Keplerian, periastron precession and nodal precession frequencies of matter inhomogeneities orbiting close to the inner edge of the accretion disk. The remarkable correlation between the centroid frequency of QPOs in both neutron star and black hole candidate low mass X-ray binaries is very well fit by the model. Some testable predictions are described. QPOs from low mass X-ray binaries might provide an unprecedented laboratory to test general relativity in the strong field regime.|
|Sunyaev Rashid||Accretion onto black holes and neutron stars in low mass X-Ray binaries - theory versus observations.|
||Spectral and timing signatures of the converging inflow into Black Hole: Observational evidence of a black hole existence.||Do black holes interact with an accretion flow in such a way so a distinct observational signature entirely different from those associated with any other compact object exists? In other words can the existence of a black hole be solely inferred from the radiation observed at infinity. An accreting black hole is, by definition, characterized by the drain. Namely, the matter falls into a black hole much in the same way as water disappears down a drain - matter going in and nothing comes out. The accretion proceeds almost in a free-fall manner close to the black hole horizon where the strong gravitational field dominates the pressure forces. In my talk I present calculations of the specific features of X-ray spectra formed as a result of upscattering of the soft photons in the converging inflow into the Black Hole. I will clearly demonstrate that these spectra emerging from the converging inflow are a inevitable stamp of the black hole.|
|Tsubono Kimio||Status of TAMA||In September 1999, we performed the first observation run of the TAMA300 laser interferometric gravitational wave detector with almost final setup except for the power recycling. We could operate the detector continuously over seven hours. We have already accumulated several days data and analyzed it to find possible signals. Preliminary result of the data analysis will be reported.|
|White Nicholas||Cosmic Journeys: To the edge of Gravity, Space and Time||The nature of gravity and its
relationship to the other forces is one of the major challenges facing us as we begin the
new century. In order to make progress we must challenge the current theories by observing
the effects of gravity under the most extreme conditions possible. Black holes represent
one extreme, where the laws of physics as we understand them break down. The Universe as
whole is another extreme, where its evolution and fate is dominated by the gravitational
influence of dark matter and the nature of the Cosmological constant. In the extreme
conditions in the early universe it is thought that gravity may somehow be unified with
the other forces. I will outline NASA's "Cosmic Journeys" program designed to
observe the extremes of gravity throughout the universe.
This program will probe the nature of black holes, ultimately obtaining a direct image of the event horizon. It will investigate the large scale structure of the Universe to constrain the location and nature of dark matter and the nature of the cosmological constant. Finally it will search for the highest energy processes, that might approach those found in the early universe.
|Yau Shing-Tung||Einstein and Geometry||Among the topics to be
discussed are: basic nonlinear phenomena governed by the Einstein equations with special
attention to the issue of the creation of singularities and
their structures; questions related to the Penrose conjecture on cosmic censorship; the global structure of space-time due to the evolution of Einstein equation, the relation of global conserved quantities related to singularity;. whether a nonsingular initial data can give rise to nonsingular space-time, in particular, several asymptotically flat nonsingular static space time and their stability; some numerical calculations on gravitational waves