The topic that I have to introduce today is concerned with the question as to whether or not we can obtain any cosmological information from radio astronomy. Alternatively, we may ask “Where does radio astronomy have an impact on cosmology?” There are several areas that must be discussed. They are:

1. 1) The discovery and interpretation of the microwave background radiation.

2. 2) The identification of powerful radio sources and the discovery that many of them have large redshifts. If we can prove that the large redshifts mean that the objects are at great distances, then we can use these radio sources as follows:

   1. (a) We can attempt to obtain a Hubble relation for the optical objects which are identified with radio galaxies;

   2. (b) We can look for a relation between the angular diameters of the radio sources and the redshifts of the optically identified objects and we can also look at relations between the angular diameter and the radio flux;

   3. (c) We can construct log N - log S curves and we can carry out luminosity volume tests.