Scientists: We can hide Earth from belligerent aliens by blinding them with lasers
It might sound fun, but, frankly, it's probably safest to avoid it altogether - at least until we're good and ready.
That's the thinking behind a new proposal in the Monthly Notices of the Royal Astronomical Society.
The researchers suggest that we could point lasers at nearby stars to hide our planet from alien life who may not intend to come in peace.
It's a little counter-intuitive, since lasers are so bright, and shining one in an alien's eyes (or eye?) initially sounds like a good way to provoke them. But it makes sense once you consider how aliens might detect our existence.
When Earth orbits the sun, it dims the light radiating off the star a tiny bit. If aliens are looking for us, they might detect this brief moment of dimming, called a transit. Watching for this transit across distant stars is how we've found thousands of exoplanets and how some scientists think we could locate alien life ourselves.
If aliens are using the transit to find us, we might be able to counteract the change in light by emitting a fake signal: laser light.
To make this work, you'd need to run a laser for about 10 hours a year, pointed at star systems where aliens are most likely to exist, and feed it 30 megawatts of power (akin to a nuclear submarine's energy output).
Astronomer Alex Teachey, who proposed the idea with his graduate adviser David Kipping, told Scientific American that the energy requirements wouldn't be extraordinary.
He estimated that we could collect the power from a relatively small area of solar panels gathering energy all year, according to an episode of the magazine's podcast, "60-second Science."
A beam with enough power could make it appear Earth isn't there, or perhaps hide our atmospheric signatures, making Earth look like a dead planet.
But Seth Shostak, director of the Center for Search for Extra-Terrestrial Intelligence (SETI) Research, told CNN that he was skeptical about how effective Teachey's concept would be.
"If they've already found Earth, and then suddenly see it 'disappear,' that's a signal that we're here," he said.
Contact with unknown civilizations with technology more advanced than ours' might be dangerous, at least if you believe the famed physicist Stephen Hawking. He told the Discovery Channel in 2010: "If aliens visit us, the outcome would be as much as when Columbus landed in America, which didn't turn out for the Native Americans." (Other researchers are skeptical aliens would do us harm, let alone visit us or even care we exist.)
Using our own planetary transit could also allow us to signal our presence, if we decide that's something we want to do. But this if aliens are using other methods to find inhabited worlds like ours - or we point the beam in the wrong direction - the lasers won't do us any good.