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fliptop [soylentnews.org] writes:

Two astronomers at Columbia University have suggested earthlings could use lasers to conceal the presence of Earth from intelligent life on other planets [homelandsecuritynewswire.com]:

RAS [Royal Astronomical Socitety] notes [ras.org.uk] that several prominent scientists, including Stephen Hawking, have cautioned against humanity broadcasting our presence to intelligent life on other planets. Other civilizations might try to find Earth-like planets using the same techniques we do, including looking for the dip in light when a planet moves directly in front of the star it orbits.

These events — transits — are the main way that the Kepler mission and similar projects search for planets around other stars. So far Kepler alone has confirmed more than 1,000 planets using this technique, with tens of these worlds similar in size to the Earth. [Professor David] Kipping and [graduate student Alex] Teachey speculate that alien scientists may use this approach to locate our planet, which will be clearly in the “habitable zone” of the Sun, where the temperature is right for liquid water, and so be a promising place for life.

Hawking and others are concerned that extraterrestrials might wish to take advantage of the Earth’s resources, and that their visit, rather than being benign, could be as devastating as when Europeans first travelled to the Americas.

[...] According to the authors, emitting a continuous 30 MW laser for about ten hours, once a year, would be enough to eliminate the transit signal, at least in visible light. The energy needed is comparable to that collected by the International Space Station in a year. A chromatic cloak, effective at all wavelengths, is more challenging, and would need a large array of tuneable lasers with a total power of 250 MW.

Previously:
Narrow SETI Targets by Looking at Places Where Earth Transits can be Seen [soylentnews.org]
Kepler Extended Mission Finds More Exoplanets [soylentnews.org]
NASA’s Kepler Mission Discovers Earth-Like Planet In Sun-Like Star's Habitable Zone [soylentnews.org]

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