According to a scientist duo at New York-based Columbia University, one way Earth could avoid detection by extraterrestrials is laser cloaking. Published in the Monthly Notices of the Royal Astronomical Society, the proposal, by professor David Kipping and his student Alex Teachey, talks about using lasers to conceal our planet from the watchful, prying eyes of aliens.
If aliens do indeed exist, chances are that they’re on the lookout for Earth-like habitable planets. In case that’s true, advanced extraterrestrial civilizations might already be using the same techniques that we human beings rely on to discover new planets: spotting a dip in light when a celestial body comes directly opposite to the star it orbits.
Known as transits, such events are one of the major ways NASA’s Kepler and similar discovery missions look for planets orbiting other stars in the Milky Way. Launched back in 2009, the space observatory has so far located over 1,000 explanets belonging to as many as 440 stellar systems. At this very moment, Kipping and his team believe, some alien civilizations might be looking for Earth. This interest in our planet could be because it lies in the habitable zone of the Sun, where the temperature is just right for the presence of liquid water, and subsequently, of life.
Scientists like Stephen Hawking have long warned us about the implications of broadcasting our presence to beings of other planets. According to him, extraterrestrials might be interested in exploiting our planet’s resources. Thus, instead of being friendly, their visit could likely spell disaster for human beings. In their new proposal, the duo suggests the use of powerful lasers to mask Earth’s transits.
When pointed at stars that might be inhabited by alien life, the laser beams could compensate for the dip in light during transits. To eliminate the so-called transit signal, especially in terms of visible light, Earth will have to emanate a 30 MW laser for around 10 hours, once every year. This is equivalent to the amount of energy harvested by the International Space Station in an entire year.
To prevent alien detections of all kind, the team has proposed the use of a chromatic cloak that remains hidden at all wavelengths. Such a massive cloak, however, will require a large number of lasers, consuming a total power of nearly 250 MW. Speaking about the concept, Teachey, a graduate student at Columbia University, said:
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.
Laser cloaking, the astronomers believe, could help alter the way Sun’s light drops during a transit. In addition to masking our presence, it could also serve as a means of communication, allowing us to transmit targeted information along the laser beams. Kipping added:
There is an ongoing debate as to whether we should advertise ourselves or hide from advanced civilizations potentially living on planets elsewhere in the Galaxy. Our work offers humanity a choice, at least for transit events, and we should think about what we want to do.
Since human beings are already capable of altering transit signals, it is possible that extraterrestrials also possess such an ability. Consequently, the researchers believe that the Search for Extraterrestrial Intelligence (SETI), which is currently tasked with detecting alien radio signals, could be used to spot artificial transits.
Source: Royal Astronomical Society