Talk about irony. At a time when many astronomers are trying hard to find evidence of alien life, a pair of astronomers at Columbia University are exploring what we might do to keep aliens from finding us.
Professor David M. Kipping and graduate student Alan Teachey say in a new paper that lasers could be used as a sort of cloaking device to conceal our planet from aliens' prying eyes.
By directing laser beams at star systems where aliens might live at just the right time, the astronomers argue, we could compensate for the slight dimming of light that occurs when the Earth crosses in front of, or transits, the sun. (Any aliens who observed a periodic diminution of starlight from our sun could infer the presence of our planet -- just as we have have used transits to detect the presence of exoplanets around other stars.)
"It's surprisingly feasible to do this, energywise," Teachey told The Huffington Post. "We could do it this year if we wanted to. We have the technology."
But why on earth would we want to do this? In fact, the idea of keeping our existence a secret might not be such a silly notion.
Some scientists have expressed concerns that if aliens knew we were here, they might want to come to Earth to plunder our planet's resources -- or worse. Renowned physicist Stephen Hawking, for one, has said that an advanced alien civilization might wipe out the human race the way a person might wipe out a colony of ants.
Such concerns have roiled the SETI (search for extraterrestrial intelligence) community in recent years. Some scientists say that, in addition to listening for radio signals from alien civilizations, we should broadcast radio signals to announce ourselves to the cosmos. Others maintain that doing so would expose humanity to needless peril.
The proposal floated by Teachey and Kipping shifts this conversation to the question of whether we should actively conceal our presence from aliens.
According to their paper, published online in Monthly Notices of the Royal Astronomical Society on Wednesday, emitting a 30-megawatt laser for 10 hours once a year would be enough to conceal our transit signal in visible light. That's comparable to the amount of energy needed to run about 70 homes over the course of a year, according to Teachey.
But not everyone is convinced the plan is workable.
Dr. Meg Urry, director of the Center for Astronomy & Astrophysics at Yale University, deemed the plan "doable but nutty."
"Because planets are ubiquitous we'd have to aim lasers at every one of thousands of them," she said in an email. "I'm sure someone could figure out the necessary time series for each star, but since the transits would only be compensated at the exact wavelength of the laser, this would fool the aliens only if their detector technology is identical to ours."
Moreover, she continued, any civilization capable of detecting us would likely be more technologically advanced than we are, "in which case our humble efforts to fool them with lasers are probably doomed."
Dr. Seth Shostak, senior astronomer at the SETI Institute in Mountain View, California, said the plan could actually backfire.
"Advanced societies will sure already have detected the periodic dimming caused by Earth's orbit around the sun," Shostak said. "If that dimming suddenly goes away thanks to our deployment of massively powerful lasers, that will call attention to our world."
Teachey acknowledged that possibility, adding that he and Kipping weren't pushing for or against the use of a laser cloak. As he told HuffPost, "We've just run the numbers, and it's up to others to decide what we ought to do."
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