THE NEED FOR A PARADIGM SHIFT IN OPTICAL ASTRONOMY: A SOLUTION GIVEN BY LIQUID MIRRORS AND EXAMPLES OF THEIR APPLICATIONS TO COSMOLOGY

I argue that there is a crisis in optical Astronomy due to a paucity of telescopes and thus the need for a paradigm shift in telescope technology. Large increases in collecting areas and observing time/astronomer are only possible if we forgo the fully steerable multipurpose telescope with a glass primary mirror that has dominated astronomical research. Only by adopting entirely novel technologies that allow one to build large and inexpensive telescopes can we achieve truly large improvements. This may come at the expense of versatility and may entail changes in the observing strategies astronomers are now accustomed to. I build my case around a new technology, liquid mirrors, that although in its infancy has achieved credibility. I argue that forthcoming technological improvements will make Liquid Mirror Telescopes (LMTs) nearly as versatile as conventional telescopes. I address the issue of the fields accessible to LMTs equipped with novel optical correctors. Optical design work and exploratory laboratory work indicate that a single LMT should be able to access, with excellent images, subregions anywhere inside fields as large as 45 degrees. As a practical example of what an LMT can do with the present technology, I examine the expected performance of a 5-m liquid mirror telescope, presently under construction, dedicated to a cosmological survey. It is rather impressive, due to the fact that the instrument works full-time on a four-year survey: Spectrophotometry reaches B=24 with a signal to noise ratio of 10 within a 200\AA bandpass for all objects within 300 square degrees and wide-band photometry reaches about B=27. I give three examples of cosmological projects that can be done with the data.