A breakthrough with a bang: Bell Labs discovery changed our view of the universe By Aron Heller | Nokia, Monday, 20 May 2024

For much of the 20th century, there was a passionate debate among astronomers about the origins of our universe. Astronomers had already established that the universe was constantly expanding. But the question remained: Why?

The experts were divided. There were those who believed in the Big Bang theory of a hot early universe that was created in a massive explosion-like event that created everything, resulting in a dynamic and evolving universe. Then there were those who swore by the alternative steady-state theory that posited the universe had always existed and would persist in a static, timeless expanse growing into infinite space.

Exactly 60 years ago, Bell Labs researchers Arno Penzias and Robert Wilson put an emphatic end to that dispute when they used a leftover research tool to discover cosmic microwave background radiation from a hilltop in a bucolic New Jersey township on May 20, 1964.

The mysterious, low steady hissing they observed with a 20-foot horn antenna was in fact cosmic radiation that had survived from the earliest days of the universe. In other words, Penzias and Wilson had figured out our origins. It was the experimental proof of the Big Bang, the vast explosion that created the universe some 13.8 billion years earlier.

Penzias and Wilson would go on to win the 1978 Nobel Prize for Physics for their discovery and it would go down as one of the signature achievements in Bell Labs’ 100-year history.

Unlike other Bell Labs milestones like the inventions of the transistor, the laser and the solar cell that changed how we live, the discovery of cosmic background radiation helped answer the question of why we live.

“It turned the study of the universe as a whole from philosophical speculation into science,” explained Gregory Wright, a Bell Labs radio astronomer. “It was the first tangible evidence that made it possible to understand how the universe had evolved from a specific model.”

An accidental breakthrough

Penzias and Wilson’s discovery forever changed our understanding of the cosmos. But they began their historic quest with far more modest ambitions.

Working with sensitive radio equipment at the Bell Labs Crawford Hill Laboratory outside Holmdel, New Jersey, Penzias and Wilson initially sought to use the antenna only temporarily as a radio telescope. They hoped to measure radio noise and figure out the limits on communications when pointing a very good antenna upward.

The Holmdel Horn Antenna was originally designed for early experiments in satellite communication. It was used to detect radio waves that were bounced off Project Echo balloon satellites and later Telstar, the first orbiting communications satellite to transmit TV signals. These radio waves were so weak, that to detect them it was necessary to eliminate all possible interference.

But when they began their experiments, Penzias and Wilson came across a uniform hiss that seemed to be coming from all parts of the sky and had no obvious explanation. At first, they suspected it was background noise coming from New York City or radiation from a nuclear explosion.

At some point they even wondered if it was the result of pigeon droppings inside the 20-foot horn antenna they were using. They set up pigeon traps and even scrubbed away the “sticky deposits” these pigeons left behind for fear they were altering their measurements. When the pigeons kept returning, Wilson said a technician brought in his shot gun.

“In the interest of science, the pigeons were dispatched,” Wilson said with a chuckle.

Still, the noise persisted. Was there something wrong with the antenna?

“It was worrisome for a long time,” Wilson explained. “Something was going on that we didn’t understand. We both believed in physics, and we both knew that it had to come from somewhere. There had to be some explanation for what we were seeing. We thought of it as a problem and after we ticked off all these things we were running out of excuses.”

Only after almost a year of testing did the duo finally come to recognize the source of the mysterious radio signal for what it really was: remnants of the Big Bang.

Proof of The Big Bang

The Big Bang theory was first postulated by Belgian physicist George Lemaitre in 1927. Two years later, famed astronomer Edwin Hubble showed that galaxies were moving away from one another at remarkable speeds. It implied that space between galaxies was constantly expanding. A few physicists led by George Gamow advocated the theory, arguing that this expansion meant that the universe must have been much more compact in the past. If you stretched that concept to the limit, that would mean the universe had been infinitely dense at some point far back in time.

Gamow and his colleagues argued that the laws of physics would indicate that the densest, infinitely hot point marked the moment of creation — a cataclysmic event astronomers called the Big Bang. That explosion led to a universe that perpetually expanded and cooled, allowing particles to combine and eventually form into atoms. Those atoms would fall into giant gas clouds of hydrogen and helium that later collapsed under their own weight to make young galaxies.

But scientific proof of this theory would remain elusive until Penzias and Wilson’s actual measurement of that tiny bit of warmth remaining from the earliest observable event in the history of the universe. They gauged a temperature of just 2.7 degrees above absolute zero that filled every corner of space. It was a temperature consistent with the measured production of elements in the Big Bang.

Just as Penzias and Wilson were making their explosive discovery, a group of researchers and astrophysicists at nearby Princeton University were looking for a way to detect residual radiation they believed would have resulted from the Big Bang. The radiation detected by Penzias and Wilson was a perfect match for what the Princeton researchers had predicted.

“Everything started out as protons and neutrons. The light elements (mostly helium and lithium) were cooked in the early universe, and this set the stage for making the heavier elements in the stars that made up the planets, our bodies and everything else,” said Wright, who worked at the Crawford Hill site for years. “This discovery turned cosmology from things that you just kind of thought about and wrote theoretical papers about into things that you could measure.”

A Bell Labs pattern

This “accidental” discovery reflected Bell Labs culture – researchers worked on problems with a real human need, such as satellite communications, but also followed their curiosity, opening the door for new discoveries and new research directions.

It followed a familiar pattern.

In 1947, Bell Labs physicists were aiming to improve telephone calls by developing a smaller electrical device that consumed less power than vacuum tubes. The result was the transistor, which revolutionized electronics. A year later, Claude Shannon ushered in the digital era with information theory. Shannon also initially sought to merely improve telecommunication channels. He ended up establishing the foundation for computing, digital media, compression, cryptography and the internet.

It was the type of Bell Labs mentality reflected by the quote featured beneath the bust of Bell Labs’ namesake Alexander Graham Bell at the entrance to company headquarters in Murray Hill, New Jersey.

“Leave the beaten track occasionally and dive into the woods. You will be certain to find something you have never seen before.”

And in the case of Penzias and Wilson leaving the beaten track led to the discovery of “cosmic processes that took place a very long time ago, at the time of the creation of the universe,” as described by the Nobel Prize awarding committee.

It also marked a milestone in Bell Labs history in space. Bell Labs was later responsible for system analysis and evaluation for Project Mercury, the first U.S. program to put a man in space. Bell Labs also offered technical advice to the Gemini and Apollo programs, which eventually landed the first man on the Moon. And today, we are preparing the mission to establish the first mobile network on the Moon.

Penzias and Wilson continued to collaborate even after their seminal 1964 discovery. Among their other breakthroughs was the 1970 discovery of carbon monoxide in interstellar clouds where stars were forming. For that they used a millimeter-wave receiver developed at Bell Labs for communications.

As for the site of their historic discovery, the Holmdel Horn Antenna became a National Historic Landmark after Wilson long advocated for its preservation. Just a month ago it was celebrated as the centerpiece of the newly dedicated and aptly named Dr. Robert Wilson Park.

“From this simple beginning, cosmic microwave background has grown to be our best source of information about the early universe,” Wilson told the crowd at the Apr. 20 ceremony. “It has been a wonderful ride.”