Annu. Rev. Astron. Astrophys. 1988. 26: 631-86 Copyright © 1988 by Annual Reviews. All rights reserved

10. LOOK TO THE FUTURE

New observational data expected over the next 5 to 10 years will clarify the nature and properties of the large-scale structure. Some of these observations are listed below:

1. Extensive redshift surveys of galaxies over large areas of the sky. These surveys will reveal the shape, type, and extent of structures and void; in the galaxy distribution.

2. Automated deep surveys of clusters of galaxies, including complete samples of X-ray clusters. These surveys will be used to trace the largest scale structures, as discussed in this article.

3. Extensive mapping of the velocity field around us, to larger scales, using various distance indicators.

4. Large samples of high-redshift galaxies, quasars, and quasars absorption lines. These will be available and used as tracers of structure at high redshifts, and the information obtained will help unravel the evolution of structure with time.

5. Very precise measurements of the fluctuations in the microwave background radiation, T / T. These should either detect some anisotropy on large scales or provide a theory-challenging strong limit of isotropy.

The expected observational advances will be of fundamental importance for our understanding of the formation of galaxies and structure in the Universe. Which of the current models will survive, or which new models will be initiated as a result of the new observations, cannot be predicted with assurance at this time.

ACKNOWLEDGMENTS

I am grateful to A. Dekel, J.P. Ostriker, P.J.E. Peebles, H.J. Rood, D. Schramm, and A. Szalay for helpful discussions on the topic of this paper. I also express special gratitude to Ray Soneira for the many stimulating and pleasant discussions we had during our collaboration.