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Two scientists propose using lasers to cloak Earth … from aliens

A Cloaking Device for Planets
Over the last several years, humankind’s fascination with finding extraterrestrial life has no doubt reached a rolling boil. From China’s massive resident-displacing radio telescope to Yuri Milner and Stephen Hawking’s $100 million Breakthrough Initiatives program, it’s been an all-out sprint to find even a shred of evidence pointing towards the existence of aliens. While initiatives such as these indicate a general interest in finding E.T., two scientists from Columbia University’s Cool Worlds Lab have proposed an idea to actually hide Earth from the view of potential outside visitors by manufacturing a laser-assisted cloak. Sounds like someone’s thinking the events in Independence Day could come to pass.

Jokes aside, Alex Teachey and David Kipping’s cloak plan is not only one of the few real news stories published on April Fools’ Day but comes backed with a healthy dose of calculated science to support the theory. In a nearly six-minute video posted to Cool Labs’ YouTube channel, Teachey details exactly how a planetary cloaking device might work and explains that “we humans could build a cloaking device for the Earth, right now.”

Alex Teachey (pictured) and David Kipping say using lasers could cloak Earth from aliens
Alex Teachey (pictured) and David Kipping say using lasers could cloak Earth from aliens Cool Worlds

Teachey applauds the Kepler space telescope’s success in finding planets by way of the transit method, a method which works by observing small disturbances (or dips) in the light emitted from a star. This method allows astronomers to conclude that each time star’s brightness dips, it’s likely the result of an orbiting planet passing in front of that star. Conversely, if the brightness remains unchanged or experiences no dip, then one would reasonably conclude that no planet is in front of that star. Teachey and Kipping’s plan would essentially make it so Earth wouldn’t produce a dip in star brightness even if it was directly in front of said star.

“Well, if you wanted to cloak a planet, if you wanted to make it look like the planet is not there at all, you’ve got to get rid of that dip [or] you’ve got to fill in that missing starlight,” Teachey explains in the video. “We’ve calculated that you could totally do this, absolutely feasible, to fill in that missing starlight using lasers.”

Teachey acknowledges a laser’s inherently narrow emitted beam but points out that if a laser beam were to travel several light years, the beam would dramatically widen. In fact, the beam would widen so much over a long distance that it would appear to be millions of kilometers wide if viewed from another solar system. What this means then, is that any planet in the line of that beam would not (likely) have the ability to notice a dip in a star’s brightness, thus effectively cloaking planet Earth.

“Any planet falling within that beam would not observe the dip in the starlight, they would not see our transit at all,” Teachey continues. “They would deduce that there is no planet there at all. And you can do this totally, feasibly, with modest power requirements.”

Alex Teachey says the ISS solar array gathers enough annual energy to power an Earth-cloaking laser
Alex Teachey says the ISS solar array gathers enough annual energy to power an Earth-cloaking laser Cool Worlds

Specifically, Teachey’s calculations show a requirement of anywhere from 30 to 230 megawatts of power for the laser to achieve peak intensity. To hammer home just how reasonable this is, he mentions that the International Space Station’s solar array absorbs enough energy to produce this much power in just one year. Furthermore, Teachey says this same laser method can also be used to completely mask the appearance of an atmosphere on Earth which would, in theory, further prove to onlookers that the planet is either non-existent or uninhabited.

Teachey closes by offering up reasons why humanity would want to cloak Earth, bringing up the fact that a number of scientists (including Stephen Hawking) have expressed how dangerous it might actually be to come in contact with an alien race. Citing times in which a more technologically advanced civilization conquered a less advanced group, Teachey says it may be wiser to hide than to experience another “terrible moment in the history of humanity.”

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