Occasionally, the most astounding scientific discoveries are the least anticipated and come more by chance than by design. Consider Bell Labs researchers Arno Penzias and Robert Wilson, who set out to map radio signals from the Milky Way and became the first to quantify cosmic background radiation (CMB).
Their monumental finding made it possible to collect information on cosmic events that occurred approximately 14 billion years ago, forever altering the discipline of cosmology and transforming it from a specialty of a handful of astronomers to a “respectable” branch of physics practically overnight.
In the 1950s, there were essentially two geneses of the universe theories. One was the Steady State Theory, which posited that the universe was homogeneous in space and time and would continue to be so forever.
The more controversial idea aimed to include Edwin Hubble’s 1929 discovery that galaxies migrate apart at extraordinary speeds.
A group of physicists led by George Gamow believed that the distance between galaxies must have been smaller in the distant past, implying that the universe was once infinitely packed.
Everything in the cosmos erupted from this extremely dense and hot condition in a cataclysmic explosion known as the “Big Bang.”
Bell Labs constructed a 20-foot-tall horn-shaped antenna near Holmdel, New Jersey, in 1960 as part of an early satellite transmission system called Echo.
However, the launch of the Teslar satellite a few years later rendered the Echo system outdated for its intended commercial use. Penzias and Wilson utilized the antenna as a radio telescope to amplify and measure radio emissions from intergalactic space.
To accomplish this, they had to erase all discernible interference from their receiver, including reducing the effects of radar and radio broadcasts and suppressing interference from the receiver’s core by cooling it with liquid helium.
Robert Wilson Arno Penzias
However, when Penzias and Wilson reduced their data, they discovered a radio-like background “noise” that interfered with their findings. The noise was a homogeneous signal in the microwave band (7.35 centimeters in wavelength) that seemed to emanate from all directions.
Penzias and Wilson ruled out every potential source of the extra radiation by conducting exhaustive tests. They pointed the antenna at New York City and determined that the interference was not caused by urbanization. Nor was it radiation from our galaxy or radio sources beyond our solar system.
They concluded that the issue might have been caused by the droppings of pigeons roosting in the horn-shaped antenna, devised a pigeon trap to remove the birds, and spent hours cleaning pigeon poo from the device.
During his early days at Bell Labs, Ivan Kaminow, a coworker of Penzias, jokingly remarked that Penzias and Wilson “looked for dung but discovered gold, which is exactly the opposite of most of us experience.” However, the background radiation persisted.
Therefore, Penzias and Wilson sought out theoretical explanations. Robert Dicke, a physicist at Princeton University, hypothesized around the same time that if the Big Bang theory created the world, low-level background radiation with a temperature of approximately 3 degrees Kelvin would exist throughout the universe.
Dicke had searched for evidence to support his theory before Penzias and Wilson contacted his lab. He traveled to Bell Labs and established that the unexplained radio signal was, in fact, cosmic background radiation — evidence of the Big Bang. Dicke shared his theoretical work with Bell Labs even as he revealed to his Princeton colleagues, “We’ve been scooped.”
Both groups simultaneously published their findings in Astrophysical Journal Letters. In 1978, Penzias and Wilson were awarded the Nobel Prize in Physics for their accidental discovery of the CMB.
NASA launched the Cosmic Microwave Background Explorer (COBE) satellite more than three decades later to explore the CMB in great detail, providing the first map examining the minute anomalies, or “ripples,” in the microwave background.
In 1990, the Holmdel radio antenna was declared a National Historic Landmark. Even the humble pigeon trap has been preserved for posterity.
It is presently on permanent display in Washington, D.C., as part of the “Exploring the Universe” exhibit at the Smithsonian Institution’s National Air & Space Museum, which opened in September 2001.
And Penzias and Wilson went down in scientific history for a significant discovery that opened a window into the early universe, allowing astronomers and physicists to view the conditions that gave rise to the splendor of the current universe.
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