Holmdel Horn Antenna: Where The Big Bang Was Discovered

Physicists and astronomers believe that the universe began with the Big Bang—a cataclysmic event that occurred roughly 13 billion years ago which gave birth to the universe. The Big Bang theory suggests that the entire universe was concentrated in an incredibly hot and dense state, called the singularity, which began to rapidly expand resulting in the formation of matter, including subatomic particles and atoms. These atoms then clumped together to form galaxies, stars, and other structures in the universe.

For a long time scientists wondered that an event as powerful as the Big Bang ought to leave some evidence, a “relic” radiation in the form of a cosmic background noise that permeates all of the universe. The cosmic microwave background (CMB) was first predicted in 1948 by American cosmologists Ralph Alpher and Robert Herman. The mainstream astronomical community, however, was not intrigued at the time by cosmology. The Big Bang theory itself was largely debated. The alternative being the Steady State theory which posits that the universe has existed for eternity and is roughly the same at any point in time.

Holmdel Horn Antenna.

The first published recognition of the CMB radiation as a detectable phenomenon appeared in a brief paper by Soviet astrophysicists A. G. Doroshkevich and Igor Novikov, in the spring of 1964. The same year, Robert H. Dicke, and his colleagues at Princeton University, Jim Peebles, and David Wilkinson, astrophysicists began preparing to search for this microwave radiation. 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. Given the appropriate instruments, they believed this radiation could be detected, albeit in the form of microwaves, owing to significant redshift.

Just 60 km away at Crawford Hill, in Holmdel Township, New Jersey, Arno Penzias and Robert Wilson were experimenting with a supersensitive horn antenna to map radio signals from the Milky Way. The Holmdel Horn Antenna was originally built as part of Project Echo to detect radio waves bounced off large balloon satellites. Project Echo was a NASA initiative, where large inflated mylar spheres up to 100 feet across were orbited some 1,000 miles above Earth passively reflecting radio signal directed towards its large shiny surface. NASA made these simple passive reflectors for intercontinental telephone, radio, and television transmission.

The Horn antenna at Holmdeal was constructed to communicate with these Echo satellites. This antenna is 50 feet long with an opening 20 feet square, that tapers to an 8 inch outlet, through which the radio waves were funneled into a receiver.

Photo credit: Jeff Keyzer/Flickr

Shortly after Project Echo, the Telstar satellite was launched, rendering the Echo system obsolete with its integrated transponders. This advancement freed the antenna from its prior commercial constraints, making it available for research purposes. Seizing the opportunity, Penzias and Wilson decided to utilize it for the analysis of radio signals originating from the interstellar spaces. However, as they began their observations, they encountered a mysterious background noise in the microwave spectrum, seemingly emanating from all directions of the sky. They thoroughly examined their equipment and even cleaned the antenna of pigeon droppings to eliminate potential sources of interference, yet the noise persisted. They both concluded that the noise originated beyond our own galaxy, although they remained unaware of any known radio sources that could explain it.

When a friend and professor of physics at MIT, told Penzias about a paper he had seen by Jim Peebles on the possibility of finding radiation left over from the Big Bang that filled the universe at the beginning of its existence, Penzias and Wilson began to realize the significance of what they had discovered. Penzias got in touch with Dicke, and invited him to Bell Labs to look at the horn antenna and listen to the background noise. Dicke concluded that the characteristics of the radiation detected by Penzias and Wilson fit exactly the radiation predicted by him and his colleagues at Princeton University.

Arno Penzias, right, checking the inside of the horn antenna with Dr. Wilson (on ladder). Photo credit: Nokia Bell Labs

A pair of short papers appeared in Astrophysical Journal Letters in July 1965 announcing the findings, first Dicke’s theoretical treatment and then Penzias and Wilson’s observational findings, each paper acknowledging the other. In 1978, Penzias and Wilson were awarded the Nobel Prize for Physics, and the Holmdel antenna was designated as a National Historic Landmark.

The Holmdel Horn Antenna is now defunct and lies within a 43-acre site formerly owned by Bell Labs, among a few derelict structures built for communications research. In 2021, the site was sold to a local builder, who expressed desire to build high-end residences in the property. It’s believed that the antenna might get relocated to another place. In response, the town has agreed to buy part of the property where the antenna stands, leaving the rest for the owners to develop. The town wants to make this 35-acre chunk of the hill into a park, with the historic antenna and a visitor center.

Dr. Wilson and Dr. Penzias in 1978