Gamma Ray Bursts, Mass Extinctions and the Fermi Paradox

Interestingly, in a study published on arXiv.org, we find the potential that gamma ray bursts (massive explosions with the majority of the energy directed out of the magnetic poles that occur when stars go hypernova or two neutron stars collide or even coming from black holes) could explain away the Fermi Paradox (the question that given the ubiquity of planets, the age of the universe and some other factors, why haven’t we been visited by aliens yet).

When the universe was younger (the article states from the beginning of the universe to about 5 billion years ago) the galaxies were smaller and much more tightly packed with stars, which meant the chances of a planet being hit by a gamma ray burst was really quite high (95% chance within a billion years). The gamma ray bursts would sterilise the planets, meaning that no life could have evolved before 5 billion years ago.

This means that, if the research is correct, life on earth would have evolved -roughly- around the time that the galaxies spread out enough to allow planets not to be hit by gamma ray bursts very commonly. Meaning we could be amongst the first generations of life in the universe.

One of the counter-points to the Fermi Paradox conclusions was by lead study author Tsvi Piran, who said “we address life as we know it on Earth. One can imagine very different forms of life that are resilient to the relevant radiation.”

But I would suggest that life wouldn’t necessarily evolve in the direction of being able to withstand such strong radiation, as the gamma ray bursts, while being much more common earlier, were still a billion or so years apart. It would take a planet that was very regularly bathed in intense radiation to evolve life that could withstand a gamma ray burst (or an extremely lucky random mutation). And we’re not very sure that any life -can- survive in areas with very large amounts of radiation.

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