on Crawford Hill in Holmdel NJ – In 1964 while using the Horn Antenna, Penzias and Wilson stumbled on the microwave background radiation that permeates the universe. By the middle of the 20th century,
cosmologists had developed two different theories to explain the creation of the universe. Some supported the
steady-state theory, which states that the universe has always existed and will continue to survive without noticeable change. Others believed in the
Big Bang theory, which states that the universe was created in a massive explosion-like event billions of years ago (
later determined to be approximately 13.8 billion years). In 1941, Andrew McKellar used W. S. Adams' spectroscopic observations of
CN absorption lines in the spectrum of a B type star to measure a blackbody background temperature of 2.3 K. McKellar referred to his detection as a "'rotational' temperature of interstellar molecules", without reference to a cosmological interpretation, stating that the temperature "will have its own, perhaps limited, significance". To measure these faint radio waves, they had to eliminate all recognizable
interference from their receiver. They removed the effects of
radar and
radio broadcasting, and suppressed interference from the heat in the receiver itself by cooling it with liquid
helium to , only 4 K above
absolute zero. When Penzias and Wilson reduced their data, they found a low, steady, mysterious
noise that persisted in their receiver. This residual noise was 100 times more intense than they had expected, was evenly spread over the sky, and was present day and night. They were certain that the radiation they detected on a wavelength of did not come from the
Earth, the
Sun, or
our galaxy. After thoroughly checking their equipment, removing some
pigeons nesting in the antenna and cleaning out the accumulated
droppings, the noise remained. Both concluded that this noise was coming from outside our own galaxy—although they were not aware of any
radio source that would account for it. At that same time,
Robert H. Dicke,
Jim Peebles, and
David Wilkinson,
astrophysicists at
Princeton University just away, were preparing to search for
microwave radiation in this region of the spectrum. Dicke and his colleagues reasoned that the Big Bang must have scattered not only the matter that condensed into galaxies, but also must have released a tremendous blast of radiation. With the proper instrumentation, this radiation should be detectable, albeit as microwaves, due to a massive
redshift. When his friend
Bernard F. Burke, a professor of physics at
MIT, told Penzias about a preprint paper he had seen by Jim Peebles on the possibility of finding radiation left over from an explosion that filled the universe at the beginning of its existence, Penzias and Wilson began to realize the significance of what they believed was a new discovery. The characteristics of the radiation detected by Penzias and Wilson fit exactly the radiation predicted by Robert H. Dicke and his colleagues at Princeton University. Penzias called Dicke at Princeton, who immediately sent him a copy of the still-unpublished Peebles paper. Penzias read the paper and called Dicke again and invited him to Bell Labs to look at the horn antenna and listen to the background noise. Dicke, Peebles, Wilkinson and P. G. Roll interpreted this radiation as a signature of the Big Bang. To avoid potential conflict, they decided to publish their results jointly. Two notes were rushed to the
Astrophysical Journal Letters. In the first, Dicke and his associates outlined the importance of cosmic background radiation as substantiation of the Big Bang Theory. In a second note, jointly signed by Penzias and Wilson titled, "A Measurement of Excess Antenna Temperature at 4080 Megacycles per Second," they reported the existence of a 3.5 K residual background noise, remaining after accounting for a sky absorption component of 2.3 K and a 0.9 K instrumental component, and attributed a "possible explanation" as that given by Dicke in his companion letter. In 1978, Penzias and Wilson were awarded the
Nobel Prize for Physics for their joint detection. They shared the prize with
Pyotr Kapitsa, who won it for unrelated work. In 2019, Jim Peebles was also awarded the Nobel Prize for Physics, “for theoretical discoveries in physical cosmology”. == Bibliography ==