Powerful lasers could be used by astronomers to prevent aliens from discovering Earth according to two astronomers at Columbia University in New York.
Several prominent scientists, including Stephen Hawking, have cautioned in the past against humanity broadcasting its presence to intelligent life on other planets.
It is thought that other civilisations could find Earth-like planets using the same techniques that we do, searching for the dip in light when a planet moves directly in front of the star it orbits.
This process constitutes the main way that the Kepler mission and similar projects search for planets around other stars; it has confirmed more than 1,000 planets using this technique, with many of these worlds similar in size to the Earth.
Astronomers David Kipping and Alex Teachey have speculated that aliens could use the same 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.
Their solution involves emitting a continuous 30 MW laser for about 10 hours once a year that would eliminate the light blip that could be used to find Earth.
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