Quasar transmits from the early days of the universe

In the 1950s, astronomers discovered radio sources to which point-like, i.e. star-like objects could be assigned in the visible light range. Until then, whole galaxies had been identified as radio sources. The findings were called “quasi-stellar objects”, or quasars for short. Later, however, researchers realized that quasars are embedded in galaxies after all, and in fact constitute their active nuclei radiating in many wavelength ranges. That they had been seen only as point sources was simply...