Are Fast Radio Bursts a sign of aliens?

In a recently published paper in The Astrophysical Journal Letters, Manasvi Lingam and Abraham Loeb, from the Harvard Center for Astrophysics, propose a rather intriguing explanation for the phenomena known as Fast Radio Bursts (FRBs). FRBs are very powerful and very short bursts of radio waves, originating, as far as is known, galaxies other than our own. FRBs last for only a few milliseconds, but, during that interval, they shine with the power of millions of suns.

The origin of FRBs remains a mystery. Although they were first detected in 2007, in archived data taken in 2001, and a number of FRBs was observed since then, no clear explanation of the phenomenon was yet found. They could be emitted by supermassive neutron stars, or they could be the result of massive stellar flares, millions of times larger than anything observed in our Sun. All of these explanations, however, remain speculative, as they fail to fully account for the data and to explain the exact mechanisms that generate this massive bursts of energy.

The rather puzzling, and possibly far-fetched, explanation proposed by Lingam and Loeb, is that these short-lived, intense, pulses of radio waves can be artificial radio beams, used by advanced civilizations to power light sail starships.

Light sail starships have been discussed as one technology that could possibly be used to send missions to other stars. A light sail, attached to a starship, deploys into space, and is accelerated using energy in the sending planet by powerful light source, like a laser. Existing proposals are based on the idea of using very small starships, possibly weighting only a few grams, which could be accelerated by pointing a powerful laser at them. Such a starship could be accelerated to a significant fraction of the speed of light in only a few days, using a sufficiently powerful laser, and could reach the nearest stars in only a few decades.

In their article, Lingam and Loeb discuss the rather intriguing idea that FRBs can be the flashes caused by such a technology, used by other civilizations to power their light sail spaceships. By analyzing the characteristics of the bursts, they conclude that these civilizations would have to use massive amounts of energy to produce these pulses, used to power starships with many thousands of tons. The characteristics of the bursts are, according to computations performed by the authors, compatible with an origin in a planet with a size approximately the size of the Earth.

The authors use the available data, to compute an expected number of FRB-enabled civilizations in the galaxy, under the assumption that such a technology is widespread throughout the universe. The reach the conclusion that a few thousands of this type of civilizations in our galaxy would account for the expected frequency of observed FRBs. Needless to say, a vast number of assumptions is used here to reach such a conclusion, which is, they point out, consistent with the values one reaches by using Drake’s equation with optimistic parameters.

The paper has been analyzed by many secondary sources, including The Economist and The Washington Post.

 

Image source: ESO. Available at Wikimedia Commons.

Is there life out there?

As reported in an article in the journal Nature, Proxima Centauri (pictured), the star nearest to our sun, has an Earth sized planet, orbiting the “Goldilocks” zone (not too hot, not too cold).

The recently discovered planet orbits the mother star in 11 days, an orbit much smaller and much closer to its sun than the orbit of the Earth. However, since Proxima Centauri is a red dwarf, it is much cooler than our sun, which makes this orbit to be just the right size. The planet, named Proxima Centauri b, weights between 1.3 and 3 times the Earth, which makes it likely that it may be a rocky planet. The distance to the star makes it possible that it may exhibit liquid water.

proxima

This combination of factors makes it the planet most likely to help us obtain additional information about the possible existence of life outside of Earth. Earth based instruments, such as the European Southern Observatory, ESO, an array of telescopes in the Atacama desert, in Chile, will be able to obtain additional information.

ESO was involved in the discovery of Proxima Centauri b, and likely to play an important role in the discovery of further information about this planet that, in astronomical terms, lies tantalising close to Earth, at “only” 4.2 light-years. Sending a spacecraft out to that planet may also be a possibility, albeit a very challenging one.

The challenges involved in obtaining further information about this planet are significant, but not unsurmountable, as the Economist reports. In a few years, we may have some better answers to Fermi’s famous question, “Where are they?”, referring to the possibility of extra-terrestrial life.

 

The aliens are silent because they are dead

In a paper recently published in the journal Astrobiology, Aditya Chopra and Charles Lineweaver, from the Australian National University, argue that the reason we have not met intelligent aliens is because, in general, life does not evolve fast enough to become a regulating force on planet ecologies.

Heavens_Above_Her

If this explanation holds true or if it is, at least, one of the possible explanations, then many planets may have developed life, but in few or none of them has life lasted long enough to be able to regulate greenhouse gases and albedo, thus maintaining surface temperatures compatible with life. If this is true, then extinction is the default destiny for the majority of life that has ever emerged on planets in the galaxy and the universe. Furthermore, only planets where life develops rapidly enough to become a regulating force in the planet ecology remain habitable and may, eventually, develop intelligent life.

(Photo by By Ian Norman, via Wikimedia Commons).