When Lucianne Walkowicz was a child growing up in Los Angeles, she loved to conduct “experiments” at home using materials she found close at hand, in her family’s kitchen and elsewhere. “I would hide a loaf of bread under the couch,” she says, “to see if it got all moldy. I kept things in the refrigerator for months at a time to see what would happen. I had a sign on the fridge that said, ‘If you don’t know what it is, don’t eat it!’ Once,” she admits, “I even ruined my mother’s pearl necklace!”
Nowadays, as Henry Norris Russell Fellow and Associate Research Scholar in the Department of Astrophysical Sciences at Princeton University (and soon to be an Astronomer at Chicago’s Adler Planetarium), Walkowicz studies objects far more distant than a loaf of bread under the couch. She is an astrophysicist who looks for planets that just might be home to intelligent life. How does she manage that? She studies stars. “You can learn a lot about planets by observing stars,” she says.
“I work with the Kepler Mission,” she explains, referring to an ongoing NASA project to observe very closely one part of the Milky Way galaxy to gather as much information as possible about those 160,000 stars. The Kepler telescope, in orbit above the Earth, “measures light and looks for planetary transits,” those scientifically valuable instances when a planet, from our point of view, passes in front of a star. By observing the light emitted by a distant star, astronomers can tell when the star seems to give off more or less light than expected. Such anomalies can suggest that a star’s light output is being obscured or intensified by the presence of an unseen planet and the radiation it generates.
And what have Walkowicz and other astrophysicists found? “The Kepler Mission has found that almost every star has at least one planet.”
OK, so now for the big question: Are they out there? Walkowicz, ever the scientist, is careful not to overstate the case. “The formal answer is that we don’t know,” she says. “The intuitive answer,” she adds, “is that they’re almost assuredly out there.” At which point any interviewer must ask, What about the Fermi Paradox—the contrast between the seemingly high probability of extraterrestrial life and the fact that no one on Earth has yet (as far as we know) seen any ET’s up close and for real. Or, as the great physicist Enrico Fermi is said to have asked, “Where are they?”
To which Walkowicz responds, referring to some of the commonly cited resolutions to the famous conundrum, “Space is big: it’s hard to move at the necessary speed. Or, civilizations self-destruct faster than the time it takes to learn to travel. Or, we can only discover life that’s similar to some life on Earth, because that’s what we will be able to recognize.”
But if Walkowicz is discouraged by the difficulty of resolving the Fermi Paradox, she certainly doesn’t show it. On top of her work with Kepler, she has her own project with SETI, the Search for Extraterrestrial Intelligence, that looks for signals in the existing data. “It looks for signals in the data,” she explains. “We get lots of light and radio waves that are natural, and we look for artificial signals.” That effort requires letting go of pre-existing notions, she explains. “What if we have already detected intelligent life but haven’t noticed it in the data? Most efforts presuppose the nature of an artificial signal. People look for things that they know already exist. That’s how you get funding.”
To counteract the limitations of the usual model for processing data, Walkowicz is taking some of the potential for human error or misperception out of the equation. “I’ve started to use machine learning to look for patterns in the existing data. It’s now used to study consumer behavior. These are powerful techniques for analyzing data, and we use them to look for clustering, for data that are self-similar, for outliers. For instance, we look for stellar variability that doesn’t look like any other stellar variability in the data. Are there any light curves that look unlike any other light curves?” In this way, she hopes to find reason to believe that other intelligent beings are indeed out there.
Walkowicz knows that skeptics—and scientists—are not easily convinced. “It’s hard to get a smoking gun,” she says. “You find the anomalies and then ask what natural models would explain these findings. You look for the simplest explanation and then test it, working your way backward through the increasingly complex explanations. Fishing expeditions are hard because you don’t always catch fish.”