Lasers could hide Earth from deadly aliens, 2 astronomers say

Finding life on another planet is like the Holy Grail of space exploration. But if you've kept tabs on recent Hollywood movies, there's also a belief that aliens may want to kill us all.

To prevent the potential annihilation of the human race, two astronomers from Columbia University are proposing that Earth use lasers to hide itself from potential alien foes.
Professor David Kipping and graduate student Alex Teachey published a paper in the journal Monthly Notices of the Royal Astronomical Society on Thursday on how our Earth can cloak itself from other intelligent life that may want to exploit our planet for its natural resources.
Here on Earth, scientists are looking for Earth-like planets by searching for light dips that suggest a planet is orbiting around a star. In fact, NASA's Kepler mission looks for these events, also known as transits, to find planets. So far, the spacecraft has discovered more than 1,000 planets, with a dozen of those in habitable zones of the stars they orbit.
Realistically, if our scientists are searching for alien civilizations by looking for light dips, there's a chance aliens are using similar methods to find us, Kipping said.
Also, recent news of the dimming light of Tabby's Star, which had some thinking the space anomaly was an alien megastructure, inspired Kipping to propose a way to hide Earth from advanced alien civilizations.
"About 10 years ago, it was proposed that aliens might choose to signal their presence to us not through radio waves, but by building megastructures, which would transit their star and create very weird and artificial-looking transits," he told CNN. When a planet transits in front of its star, it produces a predictable shape in the decrease of star light. An artificial transit is anything that deviates from that and cannot be explained.
But building a megastructure to hide our planet seemed beyond human capability. So Kipping and his colleague Teachey proposed another idea: Why not use lasers?
Lasers similar to those used on the Very Large Telescope in Chile could help cloak our planet, two astronomers say.
"We realized that because lasers are narrow directed beams, it was quite feasible to produce artificial transits," Kipping said. "We then took this a step further and had the idea that one could use such a laser system to completely cloak the Earth's transit," he explained.
And it would have a low energy impact, he explained. The laser system Kipping is proposing used the same amount of energy as 70 American homes in a year.
"We can already build these types of lasers. So we could build this device today," he said.
Seth Shostak, director of the Center for SETI Research, a group that is searching for intelligent extraterrestrial life, is a bit skeptical about the effectiveness of a laser-cloaking device.
"To do this over all the wavelengths of visible light would require a lot of energy," he said. "And you know what? If they've already found Earth, and then suddenly see it 'disappear,' that's a signal that we're here."
This idea of unfriendly aliens is not new. Scientists such as Stephen Hawking have warned against humans broadcasting our existence out into space.
However, Shostak isn't worried about deadly aliens taking over Earth anytime soon.
"We've been broadcasting our presence into space since World War II with TV, FM radio and radar. These signals could be picked up by advanced aliens. Even hostile ones. But there's no point in worrying about it. We've already told the cosmos we're here," Shostak said.
Although the conversations on hiding Earth are preliminary, it's possible that lasers will become more important in space technology, such as propelling spacecrafts, Kipping said.