Smart Luck: How the Big Bang Was Found by Accident [Slide Show]

Two astronomers recall almost mistaking light from the big bang for pigeon droppings
CMB Discovery Celebration

Scientists gathered to celebrate the 50th anniversary of the discovery of the CMB—some of the first evidence for the big bang theory—at the laboratory where it was found in 1964.
Credit: Clara Moskowitz

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When Arno Penzias and Robert Wilson made their Nobel Prize–winning big bang discovery 50 years ago, there was no “aha” moment. Instead, they were frustrated that their telescope was apparently malfunctioning, detecting a background layer of “noise” that muddied the real data they were after. It was only later, when they realized their noise was actually some of the earliest light ever created—the so-called cosmic microwave background (CMB) radiation—that the astronomers appreciated what they had done.

“At the time it was a big disappointment,” Wilson recalled at a recent 50th anniversary celebration of the discovery. “In retrospect, of course, this messy-looking record was the first evidence we had of the big bang.” Wilson, Penzias and many other scientists gathered May 20 at the site of this detection, Bell Labs in Holmdel, N.J. It was there in 1964 that the duo unwittingly found the faint light left over from just shortly after the big bang, when the universe had cooled enough from its initial extremely hot and dense state to allow photons to flow freely through space. That early light has been traveling through the cosmos ever since, and showed up as static on Bell Labs’ six-meter Horn Antenna radio telescope.

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Penzias and Wilson first considered and dismissed many possible explanations for the errant light, including, famously, the idea that it was contamination from pigeon droppings on the antenna. “Arno and I got a ladder and went up there and scrubbed off the inside of the horn,” Wilson recounted, but it made no difference: The light persisted. Eventually, they realized it closely matched predictions of the big bang theory first proposed in the 1920s, offering some of the first evidence for the idea that the universe started off very compact, and has been expanding ever since. The finding was so profound, Penzias described it in spiritual terms. “Having discovered this, it’s as close to being religious as I could be,” he said at the anniversary event.

In 1978 Penzias and Wilson were awarded the Nobel Prize in Physics for their discovery—a revelation that continues to expose new layers of the universe. This March scientists behind the BICEP2 experiment announced they had detected a polarization signature in the CMB that was likely created by gravitational waves born during the rapid expansion of the universe (a period called inflation) thought to have followed the big bang. If the finding holds up, it will mark a major advance in our understanding of the early universe that was directly enabled by Penzias and Wilson’s breakthrough 50 years ago.

That finding and the BICEP2 work highlight major changes in the way astrophysics is done that have occurred over the intervening decades. Whereas two people using a small telescope made the original discovery, the BICEP 2 collaboration involves hundreds of scientists from 11 institutions around the globe using one of the world’s most advanced instruments at the South Pole to detect a signal. Similarly, the 2012 discovery of the Higgs boson came from an international collaboration of thousands of researchers using a multibillion-dollar particle accelerator. The trend is clear: Big findings these days tend to come from big collaborations using big and expensive instruments. “It’s a difference of the scale of science,” Wilson says. “I really love the small team approach—being able to decide you want to do something and just going out and doing it.”

Back in the 1960s there were still entire swaths of the electromagnetic spectrum that astronomers had not substantially probed, and the first instruments to survey new territory could easily make groundbreaking discoveries. Now, it is harder to find such unexplored terrain. “There is not a whole chunk of the spectrum that we haven’t looked at yet,” Wilson says. “If you can look at parameters no one’s measured before, you may find something new.”

And the type of signals scientists now target tend to be so subtle they require supremely advanced telescopes and instruments, the likes of which cannot be designed or financed without a large team behind them. Furthermore, these experiments often produce such copious amounts of data that hundreds or thousands of researchers are needed to analyze the results, often with the aid of computers, clusters of computers or supercomputers.

But that does not mean there are no great mysteries left to solve or that earth-shattering discoveries like the CMB finding are relics of history. As Wilson pointed out, dark matter and dark energy—the two most dominant forms of mass and energy in the cosmos—are completely unaccounted for “We don’t really know,” he says, “what 96 percent of the universe is.”

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