In this brief survey, three topics will be described:

All kinds of primeval perturbations of the Universe should result in fluctuations of the microwave background radio emission. Here we report our latest upper limits to these fluctuations on scales 5′ to 3°. Using the new 600-m Soviet Radio Telescope we obtained a mean temperature profile of the region from 08h to 15h in R.A., centred at the declination of the Coma Cluster. 20 good records of this region were used in the final reduction of the data. After “normalization” of these data by filtering out low-frequency atmospheric noise and “bursts” which exceed the 4σ level we calculated an upper limit to the fluctuations of the microwave background radiation.

Up to Symposium Session IV, the observed properties of the large scale structure of the Universe have been discussed in terms of studies based on the spatial distribution of galaxies with redshift less than one; studies which indicate clustering on characteristic scales up to ~20 Mpc or equivalently ~1015M⊙. Such a survey is rather local in scope compared to what in principle could be inferred from the measurement of temperature fluctuations in the relict radiation surviving from Z ≃ 1000 as the fossil imprint of “primordial” density fluctuations on scales up to the horizon at the epoch of decoupling, M ≃ 1019M⊙. However, the investigation of structure over a still-larger sample volume and scales greater than 1015M⊙ is not a possibility which I wish to stress in this paper. Rather, given our present state of ignorance about the formation of structure, perhaps a more fruitful first approach would be to examine small angular scales in the relict radiation for insight into the evolution of density perturbations by a careful comparison between the observationally inferred “initial” spectrum of mass inhomogeneities present back at the epoch of decoupling, and the mass spectrum of clustering which characterizes the present Universe.

The fact that x-ray astronomy could yield cosmological information was apparent in the earliest rocket flights carried out in 1962 and 1963 (Giacconi et al, 1962, Bowyer et al, 1963). These flights established that diffuse radiation was present around the sky; indeed one of the first theoretical papers commenting on the x-ray results was by Fred Hoyle (1963) showing that the observed background flux was below that predicted for the hot, steady-state universe. A few years later, the first discrete source was credibly identified with an external galaxy (Byram, et al. 1966).

The number-magnitude relation for galaxies is an insensitive test for discriminating between cosmological models. Nevertheless, counts of faint galaxies enable us to investigate possible evolutionary effects, which may be caused by time dependence of the luminosity and/or number density of galaxies.

The clearest evidence that galaxies evolve comes from the Milky Way: here we see stars with ages and lifetimes differing by 4 orders of magnitude, and with chemical compositions indicating a hundred-fold enrichment in metals between the times of formation of the halo and most disc stars. the general resolution of Olbers' Paradox also gives evidence for cosmological change: the sky is dark because galaxies turned on a finite time ago (Harrison, 1974). Here I discuss some of the further evidence for galactic evolution that is emerging from observations probing billions of years in lookback time.

The theory of the dynamics of star clusters (cf. Spitzer 1975 for a review) is by now so well developed that we have, or think we have, a moderately accurate picture of the physical processes acting in and the overall evolution of spherical systems. in contrast, flattened and/or rotating systems are apparently subject to a variety of ill-understood instabilities which ultimately are a manifestation of the second law of thermodynamics; at given total energy, a system will tend to increase the fraction of its kinetic energy in disordered rather than ordered form. But spherical systems (globular clusters, elliptical galaxies, Morgan cD clusters of galaxies) are relatively smooth and featureless; they show little substructure indicating, presumably, that they are quite stable to perturbations of their fundamental normal modes, and they are normally modeled as rather “hot”, pressure supported systems.

Unfortunately, there is as yet no direct observation of a forming galaxy, nor of a manifestly “young” galaxy. It is not even clear what such galaxies might look like. There are, however, some lines of attack that will yield indirect information about the environment in which galaxies formed. There is no lack of theories of galaxy formation, many of which provide quite different scenarios for the birth-process. the hope is that theories of galaxy formation may indicate what young galaxies ought to look like and thus guide us in our search for such objects.

The absorption line spectra of some QSOs are similar to the absorption line spectra imposed by the interstellar medium in our own galaxy on the spectra of hot stars (see Figure 1). the spectra of other QSOs show P Cygni profiles similar to those of hot stars with mass outflow (see Figure 2). the absorption lines in both of these types of spectra are due to the resonant transitions of hydrogen and of the more abundant elements.

Investigations of small scale angular fluctuations and the spectrum of the microwave background radiation is one of the main methods of studying the large scale structure of the Universe. Figure 1 shows the principal stages of the evolution of the Universe. Today we can directly observe galaxies, clusters of galaxies and quasars in the redshift range z ≤ 3.5 by optical, radio and X-ray astronomy. These observations show that significant density perturbations δρ/ρ > 1 are present on mass scales M < 1016 M⊙. the Universe is essentially uniform δρ/ρ < 1 on large scales M ≫ 1016 M⊙.

The aim of this communication is to investigate what constraints to the cosmological parameter Ω = 2qO can be obtained if one assumes that primaeval whirl motions or adiabatic density perturbations with an appropriate initial spectrum were responsible for the formation of large scale structure in the Universe. These constraints are readily obtained from the two conditions: (i) an upper limit to small scale temperature fluctuations of the microwave background radiation, and (ii) the requirement that the primaeval perturbations should be large enough in order to produce observed structures.

In summary, this brief communication outlined first the recent measurement of large-scale anisotropy of the relic radiation by the Berkeley group of Smoot, Gorenstein and Muller (1977). the customary peculiar velocity interpretation of the dipole term gives v = 390 ± 60 km/sec in the direction of α = 11h.0 ± 0h.5 and δ = 6° ± 10°. These values differ from the preliminary results of Corey and Wilkinson (1976) by less than twice their reported errors.

The God-father of psychoanalysis Professor Sigmund Freud taught us that the behaviour of adults depends on their early childhood experiences. in the same spirit, the problem of cosmological analysis is to derive the observed present day situation and structure of the Universe from certain plausible assumptions about its early behaviour. Perhaps the most important single statement about the large scale structure is that there is no structure at all on the largest scale − 1000 Mpc and more. On this scale the Universe is rather uniform, structureless and isotropically expanding - just according to the simplified pictures of Einstein-Friedmann……. Humason, Hubble…. Robertson, Walker. On the other hand there is a lot of structure on the scale of 100 or 50 Mpc and less. There are clusters and superclusters of galaxies.

We give a short review of the general picture and main features of the formation of galaxies and clusters of galaxies on the basis of the adiabatic theory. Detailed discussions of these questions are published in references 1–6. Some related problems of the formation and development of large scale structure in the Universe according to the same theory are considered in Zeldovich's report.

There are at least two reasons for examining different theories of galaxy formation:

A highly excited state of the cosmic medium might develop in the isotropic Big Bang starting with weak irrotational perturbations that were likely to be of entropy type. Supersonic matter currents are an indispensable feature of this state. Initial irrotational gas motions become vortical when they become supersonic. One can expect that this may provide a clue in galactic cosmogony (1970, Nature, 226, 440).

The statistical nature of the galaxy distribution is in a sense remarkably simple. the two-point correlation function ξ(r), which measures the count of galaxies at separation r in excess of that expected for a random distribution, varies as ξ∝;r−1.8 for ξ>1(r ≲15 Mpc). At larger separations ξ apparently decreases more rapidly. the power law behavior is observed in different galaxy catalogs of varying depth and positions in the sky. What is the explanation of this universal behavior of ξ(r), and what do correlation functions tell us about the initial conditions at the recombination epoch and/or the value of Ω?

The X-ray telescope for HEAO-B, due for launch next year, will extend our observing power in X-ray astronomy by a very large factor. For example, its sensitivity to point sources will be 103 greater than the limit of existing X-ray sky surveys. Even more intriguing will be its capability to image the all-sky X-ray background radiation on an arc minute or sub arc minute scale. the origin of this background is still a mystery. the simplest hypothesis, that it is the integral of radiation from the more distant members of the classes of discrete X-ray sources such as clusters of galaxies, Seyferts, QSO's and other active galaxies, can only explain part of the background.

After recombination in the early Universe, gas will pass through a neutral phase on its way to condensation into galaxies and stars. Radio emission in the reshifted 21 cm line of neutral hydrogen can be used to detect condensations in the early Universe. Sunyaev and Zeldovich (1972, 1975) have suggested that primordial protoclusters may be predominantly neutral at z = 3 to 10 and may have neutral hydrogen masses ~ 1014 M⊙. Two observational approaches have been made to the search for this emission.

The cosmological turbulence theory and the theory of adiabatic fluctuations predict different orientations of galaxies in clusters and superclusters. the first theory favours the alignment of the planes of galaxies with the supergalactic plane, whereas the planes of spiral galaxies formed according to the second theory are perpendicular to the plane of a supergalaxy.