P. de Bernardis, S. Masi , G. Moreno Dipartimento di Fisica, Universita' "La Sapienza" 00184 Roma Italy ABSTRACT. Anisotropy measurement techniques and results are reviewed, with special attention given to experimental problems. The cosmological relevance of the dipole anisotropy, the only anisotropy truly detected in the Cosmic Background Radiation, is discussed. 1. INTRODUCTION Anisotropy of the Cosmic Background Radiation at 2.7 K (CBR hereafter) is a cosmological topic with a wide range of applications. In order to define anisotropy let us consider fig. 1 a, where the celestial sphere is shown with two beams A and B, with beamwidth 0 and angular separation e. We define the anisotropy of CBR at angular scale e in terms of the difference i'2,1 between the CBR flux I(ex,u) measured in the two beams. At small angular scales (e ) a "stochastic" approach is preferred, and the anisotropy is defined as .cJ I = GBP (1) I e where the brackets indicate averages over the whole celestial sphere. At large angular scales e>l a deterministic approach is preferred, and the CBR flux I(ex, S) is expressed as a sum of spherical harmonics (2) I (ex, S) = I ~ aIm Y (ex, S) lm I,m The alm coefficients give the dipole, quadrupole and higher order components of the anisotropy. 257 P. Galeotti and D. N. Schramm (eds.), Gauge Theory and the Early Universe, 257-282.

Supernovae are among the most exciting things occurring in the universe. Much recent research has concentrated on phenomena related to supernovae. For example, the origin of the cosmic rays and the origin of the bulk of the heavy elements seem to be closely associated with the phenomenon of supernovae. With the discovery of the pulsar in the Crab, it seemed clear that supernovae were also intimately as sociated with the formation of neutron stars and perhaps even black holes. The purpose of the conference, of which this volume contains the proceedings, was to bring together the leaders of supernova re search, each of whom has concentrated on different aspects of the problem, to try to form a coherent picture both observationally and theoretically of our current understanding of supernovae. In so doing, key invited talks were presented on the light curves of super novae, both observationally and theoretically; on the possible uses of supernovae, for example in determination of the Hubble Constant; on the formation and evolution of supernova remnants, again both ob servationally and theoretically. The possibility that supernovae might explain quasars was also presented. A review of the current status of statistics of supernovae was presented, giving the rate at which they go off and the implications with regard to what mass stars are the progenitors for supernovae. Again, this was presented both from the observational point of view and from the theoretical stellar evolution point of view."

The second Erice course in the school of Particle-Astrophysics was held in May, 1988. The topic choosen was Dark Matter. This is one of the most exciting top ics at the interface of particle physics and astrophysics. It is developing rapidly now due to a coming together not only of the theoretical concepts from the early universe with the theoretical concepts of galaxy formation, but also the coming to gether of the theorists, experimentalists and observers. It is with Dark Matter, the combined interrelated topics of galaxy formation and the generation of large scale structure that we see a confrontation of the exotic ideas from the early universe, such as phase transitions and unification, coming face to face with the realities of traditional observational cosmology. These realities have recently been heightened by the tremendous number of new observations, demonstrating that large scale structure of the universe is far more complex than anybody had suspected. In particular, we now see large scale foam, apparent large scale velocity fields, indicating devations from the Hubble flow, large scales of the order 100 Mpc, and galaxy formation occurring at high red shifts much greater than unity. We also see an apparent correlation of clusters of galaxies that may even exceed the c- relation of galaxies despite their being on much larger scales with lower average densities."

This volwne is the proceedings of the third school in particle astrophysics that Schramm and Galeotti have organized at Erice. The focus of thirs third school was the Generation of Cosmological Large-Scale Structure. It was held in November of 1996. The fIrst school in the series was on "Gauge Theory and the Early Universe" in May 1986, the second was on "Dark Matter in the Universe" in May 1988. All three schools have been successful under the auspices of the NATO Advanced Study Institute. This volume is thus the third in the series of the proceedings of these schools. The choice of the topic for this third school was natural, since the problem of generating a large-scale structure has become the most pressing problem in cosmology today. In particular, it is this generation of structure that is the interface between astronomical observations and particle models for the early universe. To date, all models for generating structures inevitably require new fundamental physics beyond the standard, SU x SU X U , model of high energy physics. The 3 2 I seeds for generating structures usually invoke unifIcation physics, and the matter needed to clump and form them seems to require particle properties that have not been seen in laboratories to date.

The second Erice course in the school of Particle-Astrophysics was held in May, 1988. The topic choosen was Dark Matter. This is one of the most exciting top ics at the interface of particle physics and astrophysics. It is developing rapidly now due to a coming together not only of the theoretical concepts from the early universe with the theoretical concepts of galaxy formation, but also the coming to gether of the theorists, experimentalists and observers. It is with Dark Matter, the combined interrelated topics of galaxy formation and the generation of large scale structure that we see a confrontation of the exotic ideas from the early universe, such as phase transitions and unification, coming face to face with the realities of traditional observational cosmology. These realities have recently been heightened by the tremendous number of new observations, demonstrating that large scale structure of the universe is far more complex than anybody had suspected. In particular, we now see large scale foam, apparent large scale velocity fields, indicating devations from the Hubble flow, large scales of the order 100 Mpc, and galaxy formation occurring at high red shifts much greater than unity. We also see an apparent correlation of clusters of galaxies that may even exceed the c- relation of galaxies despite their being on much larger scales with lower average densities."

Supernovae are among the most exciting things occurring in the universe. Much recent research has concentrated on phenomena related to supernovae. For example, the origin of the cosmic rays and the origin of the bulk of the heavy elements seem to be closely associated with the phenomenon of supernovae. With the discovery of the pulsar in the Crab, it seemed clear that supernovae were also intimately as sociated with the formation of neutron stars and perhaps even black holes. The purpose of the conference, of which this volume contains the proceedings, was to bring together the leaders of supernova re search, each of whom has concentrated on different aspects of the problem, to try to form a coherent picture both observationally and theoretically of our current understanding of supernovae. In so doing, key invited talks were presented on the light curves of super novae, both observationally and theoretically; on the possible uses of supernovae, for example in determination of the Hubble Constant; on the formation and evolution of supernova remnants, again both ob servationally and theoretically. The possibility that supernovae might explain quasars was also presented. A review of the current status of statistics of supernovae was presented, giving the rate at which they go off and the implications with regard to what mass stars are the progenitors for supernovae. Again, this was presented both from the observational point of view and from the theoretical stellar evolution point of view."

This volwne is the proceedings of the third school in particle astrophysics that Schramm and Galeotti have organized at Erice. The focus of thirs third school was the Generation of Cosmological Large-Scale Structure. It was held in November of 1996. The fIrst school in the series was on "Gauge Theory and the Early Universe" in May 1986, the second was on "Dark Matter in the Universe" in May 1988. All three schools have been successful under the auspices of the NATO Advanced Study Institute. This volume is thus the third in the series of the proceedings of these schools. The choice of the topic for this third school was natural, since the problem of generating a large-scale structure has become the most pressing problem in cosmology today. In particular, it is this generation of structure that is the interface between astronomical observations and particle models for the early universe. To date, all models for generating structures inevitably require new fundamental physics beyond the standard, SU x SU X U , model of high energy physics. The 3 2 I seeds for generating structures usually invoke unifIcation physics, and the matter needed to clump and form them seems to require particle properties that have not been seen in laboratories to date.