- Astrophysics california Institute of Technology and Astronomer, Mount Wilson and Palomar Observatories, USA
After it had been established that most of the so-called nebulae are extragalactic stellar systems, it was natural that the early investigators concentrated their efforts on the problems of the absolute dimensions and of the physical characteristics of these systems (5), (51). It was most unfortunate, however, that many of these efforts were and still are based on autistic thinking and can therefore not lead to any trustworthy results without the additional support of scientifically sounder methods of observation and of analysis. Instead of determining distances by comparing them with some standard lengths, assumptions were made about the nature of certain classes of variable stars and about the absolute magnitudes of the brightest stars in various stellar systems. The mistakes resulting from poor discrimination between different types of stars as well as between single stars, multiple stars and emission nebulosities are well known. As a matter of fact, even if all of the issues concerning the characters of special types of stars located in vastly different regions of space could be resolved, there still would remain the thorny problem of the general and patchy intergalactic absorption and the interstellar absorption both in our own galaxy and the distant galaxies investigated.