Great surprises science don’t just happen–they’re engineered.
When researchers announced earlier this week that they might have made what is essentially the scientific breakthrough of the year–echoes from the earliest fraction of a second after the Big Bang known as primordial B-mode polarizations–it seemed to come out of left field. Similarly large announcements, like the discovery of the Higgs boson, generally have followed months of speculation, rumors, and even leaks.
It’s standard practice for researchers to keep tight-lipped about their results. No one wants to cavalierly mention half-finished data to a colleague and give them the wrong impression or worse, tip off a rival project. Yet scientists are human, and humans love to gossip. In this world of science blogs and Twitter, the BICEP2 collaboration maintaining secrecy so well is almost unheard of.
The researchers didn’t use some sort of unhackable connection and they didn’t pass notes written in indecipherable code. They had to rely on each other to keep quiet until they could casually drop a major discovery on the world. Here’s how they did it.
The search for primordial B-mode polarizations started in 2001 over a game of tennis. Physicist Jamie Bock, then a researcher at JPL (now at Caltech) had a regular match going with an astrophysics postdoc named Brian Keating (now at the University of California, San Diego).
“Brian would bug me about a degree scale polarization experiment,” said Bock. “And after every match I’d go ‘Uh huh, OK, sure.’ But after a while he started to convince me this was worth doing.”
“That’s when we were all like, ‘Wow, crap, maybe it is real.’”
At JPL, Bock had been working on specialized detectors (still under development at the time) that, if placed in a small telescope at the South Pole, could potentially detect the primordial B-modes. He approached the late Caltech physicist Andrew Lange with a proposal to search for this signal. Well known in the field, Lange helped Bock assemble the team of scientists, post docs, and grad students to achieve their goal.
“With his help, the whole project just took off,” said Bock, who became one of BICEP’s four principal investigators.
The theory of inflation, which posits that the universe went through a massive expansion very early in its history, is about 30 years old. Scientists have long known the event, if it had happened, would have left its mark on the cosmos in the form of characteristic twists in light arriving from 380,000 years after the Big Bang known as the cosmic microwave background (CMB). But the hunt for primordial B-modes was known for at least two decades in the field as a “high risk, high reward” experiment.
To detect the signature of inflation, a telescope would need to discriminate minute changes in temperature on the order of 10 millionths of a degree. Some versions of inflation also might have produced a signal that was virtually imperceptible. But if they could be found, these primordial B-modes would open up a whole new world of physics. Besides providing proof for inflation, the signal would allow scientists to probe unheard of energy levels in the early universe and provide Einstein with another notch in his science belt by proving gravitational waves were real.
“People said, ‘Collect B-modes, collect your Nobel Prize,’” said astronomer Christopher Sheehy, a graduate student at the University of Chicago who joined the team in 2006 under cosmologist Clement Pryke, now at the University of Minnesota. (Full disclosure: Sheehy, as well as another grad student mentioned in this piece later, Jamie Tolan, were undergraduate classmates of mine at the University of California, Berkeley.)
The first BICEP project ran from 2006 to 2008 at the South Pole. Though it did not include the specialized detector Bock had been developing at JPL, it was the first step in collecting data and understanding what the team was searching for. A successor experiment incorporating new the new detector technology, BICEP2, started in 2010 and gathered data until 2012.
“We saw hints in these early stages,” said cosmologist John Kovac of Harvard, another principal investigator on BICEP. “But I would say the process for us was of a slow emergence of this signal from the noise.”
Some bloggers were speculating before the team’s announcement that they’d have to be 007-level spies to keep the results under their hat.
Everyone on the team started with a large dose of skepticism about what they were seeing. They didn’t want to get overly excited and unintentionally skew their results. Moreover, they still were not sure at this point that the primordial B-modes could be seen at all.
“We were trying to stay kind of logical and impartial, trying to look at what the data’s telling us,” said Jamie Tolan, a physics graduate student at Stanford University who joined the team under the final principal investigator, physicist Chao-Lin Kuo, in 2007.
If worst came to worst, and signal turned out to be nothing, the BICEP team figured it would at least set tighter limits on what other collaborations should one day see. But as more data came in “we realized there was something there,” said Bock.
The team worked hard to ensure this wasn’t some other signal they were detecting erroneously. The telescope and instruments, for instance, can be a source of noise that might happen to mimic the primordial B-mode polarizations.