When a team of scientists gathered last Monday to announce they had detected primordial ripples in space-time that emanated from the Big Bang, what got lost in the news was the process. How did this team, led by four scientists scattered across the United States and using a small telescope at the South Pole, arrive at this stunning conclusion?
It isn’t like the universe just lays down its hand and shows its cards because the right kind of telescope has been built; a delicate measurement like this one requires persistence, skepticism, and months of work to make sure it is not an artifact.
The South Pole telescope, called BICEP2, took measurements of the polarization of the cosmic microwave background — light from several hundred thousand years after the Big Bang. It collected data from 2010 to 2012. Then, researchers spent a long time analyzing the measurements.
At the press conference, I asked the panel when and how they each grasped that they might actually be detecting the signal they were seeking. Here’s what “Aha!” really sounds like:
Clem Pryke, associate professor at the University of Minnesota: “It’s mind-boggling to go looking for something like this and actually find it. . . . The world of experimental physics is littered with guys who spent decades searching for something. It’s just been a really incredible experience to actually find what we’re looking for. Of course, we write grant proposals and make it look like we’re going to find it. It’s one thing to say that and another thing to really believe it in your heart.”
Jamie Bock, professor of physics at CalTech: “I distinctly remember our collaboration in the last year, where the first half of the meeting, we had been thinking, ‘We’ve got to get a paper out and let’s just try to set an upper limit.’ And the data wouldn’t cooperate. And then the second day, I think someone showed a cross-spectrum and then it just dawned on everyone: Well, maybe this really is real. And then we had this one-year odyssey of doing all the testing.”
Chao-Lin Kuo, assistant professor of physics at Stanford University: “There is variation among the four of us and everybody in the collaboration, as well. Me, personally, I started to think maybe this is real about six months ago, 50-50 and that became 90 and 95, and so on.”
John Kovac, associate professor of astronomy at Harvard-Smithsonian Center for Astrophysics: “That’s part of the process and part of the strength of having so many of us scrutinize this with different kinds of skepticism. . . . The story that we’re testing with this data set sounds so fantastical! We know it’s good physics, but the extrapolation from the physics that we understand, combined with these models that have been built by theorists, to testable predictions, come from such an exotic regime — the beginning of our universe.”
“We needed a lot of convincing the signal was real. The emotional process for us was helped by setting a series of concrete tests and milestones passed through the end of last year. And by the end of December, it was passing each of these tests.”