Arno Penzias and his co-Nobel Laureate Robert Wilson came to Lindau for the first time 1982. In principle, they could have attended the previous physics meeting, in 1979, the year after their prize year. If so, there would have been no less than three talks on radio astronomy at that meeting. This shows that some 270 years after Galileo Galilei constructed his optical telescope in 1609, observations in the radio wave part of the spectrum of electromagnetic radiation has become an important way to study the physics going on in the Universe. At the Lindau meeting, Penzias and Wilson reported on different aspects of a joint project using Bell Laboratory’s excellent equipment. Wilson’s talk was scheduled first, which made Arno Penzias refer to it a couple of times for more general information. In the project radio observations were made of the abundance of the molecule carbon monoxide, CO, in the interstellar medium. With the precision obtained they could actually not only measure the normal molecule CO, but also molecules made up of different isotopes of C and O. While Wilson used their observations to learn about molecular clouds, the scientific subject of Penzias was how this information on the abundance of isotopes of the elements C and O can be used to infer what goes on in space. He first gives a short review of the production of the elements from the Big Bang to recent times. Since only the lightest elements were produced originally, the heavier ones, such as C and O, were produced in stars and blown out into space after supernova explosions. The most interesting result that Penzias describes is probably that the variation of the isotopes in our solar system is not the same as in interstellar space. This seems to imply that there were some special nuclear processes going on when our planetary system was formed. It can also be noted that Penzias both starts and ends his talk in German, at the end thanking Count Lennart Bernadotte for a very nice meeting!