Most of the time when we talk about silly scientific papers related to alien life, we’re talking about crazy ideas for how to find aliens. But a new study in the Monthly Notices of the Royal Astronomical Society proposes a way of hiding from aliens. Humans are so fickle.
A lot of our search for Earth-like planets (and, by extension, for life as we know it) hinges on transiting planets. These are planets that pass in front of their host star in such a way that the transit is visible from our perspective. The movement of the planet in front of the host star makes the light from that star dim or flicker, and we can use that to determine all sorts of things about distant worlds — including how suitable they may be for life.
Some scientists have suggested that we should hope that Earth is a transiting planet from the perspective of some other world that hosts intelligent life. In other words, our best shot at finding aliens might be hoping that they’re using exactly the same methods of planetary detection that we are, and that they can see the passage of Earth in front of the sun with their telescopes. If we made a lot of noise in the direction of those theoretical planets, we might get their attention faster.
Or we could point lasers at them instead.
Professor David Kipping and graduate student Alex Teachey, both of Columbia University, decided to see how much laser light it would take to mask the dimming caused by our planet’s transit. According to their math, it would take about 10 continuous hours of shining a 30 MW laser once a year to eliminate the transit signal in visible light. Actually replicating every wavelength of light emitted by the sun would take about 250 MW of power.
“Alternatively, we could cloak only the atmospheric signatures associated with biological activity, such as oxygen, which is achievable with a peak laser power of just 160 kW per transit. To another civilization, this should make the Earth appear as if life never took hold on our world,” Teachey said in a statement.