The Largest Things in the Universe

In the early 1960s improved observations of distant radio sources revealed that the radio emission was often coming from two regions in space located on opposite sides of a faint, visible galaxy. The double radio source might be a minute of arc or so in extent with a much smaller (in angular size) galaxy located between the radio "blobs." Double radio sources were duly found to be common, but because of the poor resolution of those early radio telescopes little more could be said than that the radio source was a double. I recall endless discussions over lunch at Jodrell Bank in which we wondered why radio sources might be double. It soon became fashionable to invoke explosive events inside galaxies, which for some unknown reason ejected material in two directions. The central galaxy, if one could be seen at all, was often observed to have very active nucleus, inferred from the Doppler shifts of their light emission that implied chaotic motion.

An alternative explanation to account for the chaos in those distant radio sources was that galaxies were in collision, with each being torn asunder by their interaction.

Whichever idea one favored, it became apparent that in these radio galaxies immense amounts of radio, light, and even X-ray energy were being generated by dramatic events in the nucleus of what was usually the most massive member of a dense cluster of galaxies.

As a teenager I used to listen to the BBC on shortwave radio and one evening heard a talk about radio astronomy by Bernard Lovell, the Director at Jodrell Bank in England. I had never heard of radio astronomy, Jodrell Bank, or Lovell. During his talk he played a tape recording of what he claimed was the sound of colliding galaxies. 1 listened to the hiss of receiver noise, which gradually grew stronger and then weaker as the radio source Cyg A passed through the beam of the Jodrell Bank telescope. This stirred my imagination and about 8 years later I began working at Jodrell Bank as a graduate student.

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