It was the low, hissing sound of static, like what you might hear if you tuned your radio between stations. The year was 1963, and all Robert Wilson and Arno Penzias, a pair of radio astronomers at Bell Laboratories, wanted to measure the minimum brightness of the sky. But this low, hissing static was getting in the way.
The static signalled the existence of extra radiation. But for the life of them, Wilson and Penzias couldn’t figure out where on Earth this radiation was coming from.
According to Smithsonian, the pair had ruled out radio noise from nearby cities, after-effects of nuclear detonations, and signals from the Van Allen belts, the huddles of charged particles loitering around by Earth’s magnetic field.
“I had a lot of experience fixing practical problems in radio telescopes,” Robert Wilson told Smithsonian. “We looked for anything in the instrument or in the environment that might be causing the excess antenna noise. Among things, we searched for radiation from the walls of the antenna, especially the throat, which is the small end of the horn. We constructed a whole new throat section and then tested the instrument with it.”
And then they noticed them. A pair of pigeons living inside their radio antenna, recklessly splattering the expensive instrument with their gooey bird droppings. Wilson and Penzias wondered if these feathered squatters might somehow be causing that annoying static.
So the scientists went out and got a Havahart trap and jailed the unsuspecting pigeons inside so they could send them far, far away.
“We took the pigeons, put them in a box, and mailed them as far away as we could in the company mail to a guy who fancied pigeons,” Wilson said in an Aeon video. “He looked at them and said these are junk pigeons and let them go and before long they were right back.”
But in the meantime, Wilson and Penzias had ruled out the pigeons as a source for the strange signal. Even with the pigeons gone, the static was still there.
The afterglow of the big bang
This clued them in that the noise wasn’t coming from Earth at all, or even from inside the galaxy. “We were really running out of ideas when we heard about the idea of radiation left over from the big bang,” Wilson said in the Aeon video.
Around that time Robert Dicke, a physicist at Princeton, was piecing together a theory that stated that if the universe was truly created in the big bang, “the residue of the explosion would now be a low level background radiation spread evenly throughout the universe,” Futurism writes.
Dicke was talking about something called the cosmic microwave background, which is the faint afterglow of the big bang, a whisper from the formation of the universe, an echo of the universe’s first baby cries.
Back in the days of analogue television and radio, you could see this afterglow in a small fraction of the snowy static between channels and hear it in the hisses that filled the spaces between radio programs.
And it was this cosmic microwave background radiation that was clouding their experiment. It was the very first confirmation of the big bang.
In 1978, Wilson and Penzias received the Nobel Prize in physics for their accidental discovery of cosmic microwave background radiation.
“We started out seeking a halo around the Milky Way and we found something else,” Wilson told Smithsonian. “When an experiment goes wrong, it’s usually the best thing. The thing we did see was much more important than what we were looking for. This was really the start of modern cosmology.”
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