Decoding the Big Bang: What’s in It for Us?

Have you heard the news? The BICEP2 team has discovered the signature of gravitational waves from the Big Bang! Whoooeee! Hot damn! So…what exactly does that mean?

First of all, BICEP2 stands for Background Imaging of Cosmic Extragalactic Polarization 2, and the researchers who’ve been mapping the sky around the South Pole with BICEP2 have found something very, very exciting.

A condensed timeline of the universe. Click to see the full, labeled version here.
Here’s how the team put it in their landmark paper: “The observed B-mode power spectrum is well-fit by a lensed-CDM + tensor theoretical model with tensor/scalar ratio r = 0:20 +0:07 -0:05, with r = 0 disfavored at 7 sigma.” Got that? Let’s face it, this is a difficult science story to comprehend, and it’s not one of those where CNN can end with, “Scientists say the breakthrough could mean an end to arthritis as we know it.” Yet, even if there is no practical benefit to humanity, this truly is an important scientific breakthrough. It tells us that the scientific narrative of where we came from is likely true. Here’s my best understanding of it, in plain words. (Bear in mind that I am only a science journalist.) Way back in 1979 graduate student Alan Guth speculated that our universe might have undergone a fantastically rapid expansion immediately after the Big Bang, doubling in size over and over and over again, before slowing to a moderate pace of growth. His “inflation” theory made sense of some problems in cosmology and has come to be widely accepted even though it remained unproven. Almost twenty years later physicist Marc Kamionkowski predicted that if inflation happened, we might be able to see its imprint on the cosmic background radiation, a sea of photons that burst through the wall of densely packed particles some 380,000 years after the Big Bang. Specifically, he predicted that gravitational waves, ripples in the fabric of space-time, would cause those photons to have “curly” polarization. And that is what the BICEP2 team has now detected. So, it now seems highly likely that we are here because inflation allowed our universe to get big enough and cool enough (in every sense of the adjective) for stars, planets, and life to form. How likely? That “7 sigma” at the end of the astrophysics-ese from the paper quoted above means that it’s incredibly unlikely that the signal the team picked up is a fluke. All the same, the team itself subjected their findings to a grueling skepticism‑and now the scientific community, even as it celebrates, continues to do the same. And this is where a deeper significance comes in. Despite the silly acronym and obscure terminology, this experiment should inspire awe in all of us. Not just about the Big Bang—though that part is pretty awesome—but about science itself. Think about the virtues this tale demonstrates. Bold Imagination: When first proposed, Guth’s theory sounded ridiculous. Why should the universe explode into being, only to put on the brakes? Yet, it now appears likely that it did. Many things in science—especially in physics—are highly counterintuitive. It takes a trained and daring imagination to steer us toward the truth. Unrelenting Empiricism: “Show me the data!” is the battle cry of scientists everywhere. However beautiful an idea, they refuse to accept it without evidence. In this case, it took another leap of informed imagination—Kamionkowski’s—to tell scientists where to look. Tenacity: These guys went to the South Pole to look for the evidence. Not the comparatively balmy McMurdo research station, but the South Pole! With chattering teeth and numb fingers, they set up their telescope and looked for B-mode polarized light in the cosmic background radiation for two years! Skepticism: After all that time, you’d think they’d jump at the chance to announce their results. But no: the team spent more than a year trying to poke holes in their own findings. They even reduced their confidence level from the above-cited 7 sigma to a little more than 5 to account for the possibility that dust interfered with their observations. Only when another team began to get similar results did they publish. Even now, other scientists, while universally praising the team, are trying to find ways to knock down their findings or propose alternative explanations. Why? It’s not that they’re meanies—it’s just how science works. What we’re seeing is the error-detection-and-correction mechanisms of science at work. Compare that with some of the wild media speculation and conspiracy theorizing that has surrounded the disappearance of Malaysian Airlines Flight 370. One self-styled expert who has a theory to propose concludes with this: “There are too many oddities in this whole story that don’t make sense if this theory isn’t the answer in my opinion.” Perhaps he’s right, but falling in love with your own idea is a well-trodden path to delusion. Scientists are human, and subject to all the petty failings of our species. Even Carl Sagan had his faults. I'm sure Neil deGrasse Tyson does, too. But the system they subscribe to is awesome. It’s what makes science the most reliable knowledge-producing system known to humanity. It’s what makes us a way for the cosmos to know itself.Tags: ,