Reinventing Discovery - Michael Nielsen [72]
The back-and-forth discussion of ideas at this stage was astonishing. I’d like to give a blow-by-blow account, but it would take far too long even to summarize here—this isn’t a book about how to discover and understand a new type of galaxy! But what was especially remarkable about the discussion was its style. It’s the kind of discussion any scientist recognizes. Scientific discoveries often begin with a bit of a mystery, vague suspicions, and some half-baked ideas—just like the initial vague suspicion that the green peas might be a new type of galaxy. That initial suspicion is gradually refined. New ideas are introduced, tested, improved, and sometimes discarded. Participants become obsessed, as their suspicions slowly turn into hard, detailed fact. This is the process of research, familiar to any research scientist, and it’s exactly what you see in the Galaxy Zoo discussion of the green peas. It’s eerily reminiscent of the discussions in the Polymath Project. The Zooites may be amateurs—they know far less about astronomy than many of the polymaths do about mathematics, and there is more levity in the Galaxy Zoo discussion—but underneath these differences, there is the same fertile sense of ideas growing and being refined, of a conviction that there is something here to be known, and a determination to get to the bottom of it. The Zooites don’t have the credentials of some of the polymaths. But they are scientists.
As the Zooites gradually developed more precise criteria characterizing the green pea galaxies, they also became more sophisticated in how they found candidate images. No longer were they just sifting through Galaxy Zoo images by hand. Instead, they went to the original SDSS data, and developed sophisticated database queries that automatically searched the entire SDSS data set for galaxies that fit their criteria. Those candidates were then closely scrutinized by volunteers, and a list of 200 or so drawn up that seemed likely to be the new type of pea galaxy.
The professionals watched all this discussion wit interest, and in early July of 2008 Schawinski, now a postdoctoral scientist at Yale University, and a Yale student named Carolin Cardamone decided to ramp up their involvement. In collaboration with the Zooites, Cardamone and Schawinski began detailed spectral analyses of the peas using sophisticated computer software. Over the next nine months they completed the work begun by the Zooites. The picture of the peas that emerged showed that they were, indeed, a new type of galaxy. They were ultra-compact, less than 10 percent the mass of our Milky Way galaxy, and forming stars very quickly—whereas the Milky Way produces just one or two new stars every year, the peas produce more like 40 new stars per year, despite being far smaller. And the galaxies were extremely bright for their size.
The green peas and the voorwerp are just two of the many discoveries made by Galaxy Zoo. Another Galaxy Zoo project was to search out images of merging galaxies (see the image on the next page). Mergers are life-changing events for galaxies, and so understanding mergers is of great interest to astronomers and astrophysicists. Our own Milky Way is currently merging with several small dwarf galaxies, and has been predicted to one day merge with the giant Andromeda galaxy, currently two million light-years away. Unfortunately, despite their importance, merging galaxies aren’t so easy to find, and as a result most studies of mergers use samples containing only a few dozen merging galaxies. The Galaxy Zoo merger project quickly found 3,000 merging galaxies, a treasure chest of mergers for future studies. Other objects the Zooites have gone hunting for include gravitational lenses (objects whose gravity actually warps and focuses the light from objects that are farther away), and paired galaxies (galaxies that appear to be on top of one another, but where one galaxy