Cosmic Black-Body Radiation--A Measurement of Excess Antenna Temperature at 4080 Mc/s

with Steven Claydon

With all the information hidden within it, the cosmic microwave background radiation, or CMB, was the astronomical equivalent of the human genome. Just as the genome bears all of the data required to manufacture and operate a human being, the microwave background encodes all of the information - all the initial conditions and physical laws - for making and operating a universe.*

Udolpho presents an exhibition in celebration of the 50th anniversary of one of the greatest discoveries in the history of science. In 1965, two astrophysicists, Arno Penzias and Robert Wilson, detected the first physical evidence of the birth of the Universe - the echo of the Big Bang. The discovery of this cosmic microwave background (CMB) won Penzias and Wilson the Nobel Prize in Physics in 1978.

In the early 1960s the astrophysicist Robert Dicke, together with the theoretical physicist Jim Peebles at the Physics Department of Princeton University, made the prediction that remnant radiation left from a hot Big Bang could be measured as a faint source in the microwave region of the electromagnetic spectrum. While building their instruments in search of this source, twenty miles away at the Bell Labs research facility, birthplace of modern radio astronomy, the two observational astronomers Arno Penzias and Robert Wilson unwittingly measured just this radiation while calibrating their horn antenna for measurements of galactic radio emissions. After a year of investigating all possible sources of this 3 degree excess temperature coming from every corner of the sky, Penzias by chance heard about the research taking place at Princeton, and after a now-famous telephone conversation with Robert Dicke finally learnt of the true source of the mysterious excess noise in his radiometer: the afterglow of the Big Bang.

Although this meant that Dicke had been scooped, his and Peebles’ explanation for the excess radio noise led to the publication of two landmark companion papers published in the Astrophysical Journal in 1965. Dicke and Peebles’ Cosmic Blackbody Radiation and Penzias and Wilson’s A Measurement of Excess Antenna Temperature at 4080 Mc/s were a scientific sensation and heralded the golden age of cosmology we live in today. The publication of these two papers definitively proved that the universe began with a Big Bang and the main rival - the Steady State theory championed by Fred Hoyle - was finally discredited. Decades of intense research and ever-more detailed measurements of the CMB followed, culminating in the Planck Satellite All-Sky-Map of 2013: the most precise picture of the infant cosmos ever made. Planck’s measurement of the CMB has further refined what is called the Standard Model of Cosmology - with its information about the age, mass, and density of the universe - to an astonishing degree of precision. The theory of an inflationary episode in the early universe, born as pure speculation in the early 1980s, was eventually also proved by CMB data. What has become the corner-stone of modern cosmology was made possible by Wilsons and Penzias’ discovery fifty years ago.

The exhibition Cosmic Black Body Radiation - A Measurement of Excess Antenna Temperature at 4080 Mc/s assembles for the first time the original scientific papers relating to this discovery from the personal archive of their authors - the Einstein Professor of Science at Princeton, Professor P. J. E. Peebles, widely regarded as the father of modern cosmology, and Dr Robert Woodrow Wilson, Nobel Prize winner and Senior Scientist at the Harvard Smithsonian Centre for Astrophysics. To illustrate the advancement made possible by the discovery of the Cosmic Microwave Background in 1965, the Planck CMB All Sky Map of 2013 is displayed alongside a specially commissioned poster edition by the artist Steven Claydon, depicting the focal plane of the Planck satellite. The exhibition is accompanied by an essay on the history of the discovery of the CMB by the physicist and author Dr Amedeo Balbi, currently at the Physics Department, University of Rome Tor Vergata and member of the Planck Collaboration from 2009 to 2012.

* Michael D. Lemonick - Echo of the Big Bang, p.11.