08 March 2014

A flirtation with astronomy

A strikingly strange object
It's a bird - it's a plane - no, it's an early microwave antenna! It was used by Arno Penzias and Robert Wilson at the Bell Laboratories in New Jersey in the age of the first satellites, eg Telstar, to pick up communication signals - and could also be used to detect astronomical signals.

The horn shape suppresses radiation from directions other than that in which the horn is pointing, and is meant to particularly block signals from the ground, a strong source of microwave radiation.

The antenna was picking up extra radiation as ‘noise’ and this remained constant wherever the horn pointed in the sky. Penzias and Wilson spent a year carefully ruling out possible causes, including the removal of some pigeons roosting in the antenna, and through conversations with a group of researchers in Princeton, led by Robert Dicke,  they realised they had serendipitously discovered the cosmic microwave background radiation. 

The work was done in 1964 and for this, Penzias and Wilson were awarded the Nobel Prize in physics in 1978.

But what did this cosmic microwave background radiation mean? It was strong evidence for the Big Bang, as Professor Carolin Crawford spelt out in her lecture, "Echoes of the Big Bang", which you can read here; the image comes from one of the accompanying powerpoint slides.

Her next lecture in the Gresham Professor of Astronomy series, "How the Earth Moves," is at the Museum of London on Wednesday 2nd April. These are really popular lectures - I arrived early at the Big Bang talk, and the theatre was already almost full.

No comments: