Tech UPTechnologyHow rare can life be in the universe?

How rare can life be in the universe?

In Jack Williamson’s 1934 science-fiction story Born of the Sun, the Sun splits open as an immense cosmic egg from which a strange and gigantic being is born. In the movie The Blob (1958) Steve McQueen faced a shapeless, carnivorous, gelatinous-looking being that arrived from space aboard a meteorite.

Science fiction and, above all, cinema, usually show us alien life forms with a suspiciously terrestrial appearance and looking like giant insects, as in the movie Starship Troopers, loosely based on the homonymous masterpiece by the great Robert A. Heinlein.

Saving the obvious distances , can we imagine, with science in hand, to what extent life in the universe can be strange? The famous astronomer and popularizer Carl Sagan proposed throughout his career strange ideas about life in the universe: from organic molecules and microbes hidden on the surface of the Moon to that creatures the size of polar bears could inhabit Mars. But the most exotic was published in the scientific journal Astrophysical Journal Supplement in 1976 together with Edwin Salpeter -one of the great scholars of stellar evolution- before the arrival of the Pioneer 10 probe to Jupiter. Both imagined an entire ecosystem in the atmosphere joviana – which they considered to be an immense laboratory of prebiotic chemistry – similar to the one in our oceans. Taking their speculations to the limit, they imagined beings shaped like huge hot air balloons living inside the clouds – from which they would extract their food – while missile-shaped predators fed on them.

We owe one of the most fantastic exercises in scientific speculation to the unorthodox astronomer Fred Hoyle . In an intriguing fictional novel, The Black Cloud , Hoyle imagined that a gigantic interstellar cloud capable of conscious thought and movement was approaching Earth. In it, their life processes depended on the electromagnetic force (like ours) and their nervous activity propagated through the cloud in the form of radio waves. The “brain” was nothing more than molecular systems capable of growing in complexity when the cloud desired. Weak electromagnetic currents ran between these molecules so that, conceptually, their brains worked very similarly to ours. The cloud’s excursion to our Solar System responded to a very biological reason: to replenish itself with energy, which it did by absorbing large amounts of starlight. Upon approaching, the cloud finds that on the surface of the third planet there are intelligent beings capable of contacting it thanks to their radio telescopes.

Hoyle’s Black Cloud , a living organism with an age of 500 million years, as large as the orbit of Venus and with a mass on the order of Jupiter, shows us the difficulty of imagining forms of “exotic” life . We can imagine a being with these characteristics, but we know that it cannot arise from nothing; it requires a certain evolution, many previous steps. A black cloud can certainly exist, but how it came to be is an even darker mystery.

However, its existence is more than unlikely. The density of matter is so low in interstellar clouds (one atom per cubic centimeter) that the interactions between molecules, inescapable for life, occur excruciatingly slowly. The temperature also plays against it. Although there are clouds with a temperature sufficient for the appearance of life (between -50 to 80 ºC), most are too cold (-250 to -200 ºC). Furthermore, the clouds that would best meet Hoyle’s criteria, the densest ones, tend to be the coldest ones, so higher density is offset by lower atomic velocity. Regardless, Lithuanian physicist Arvydas Tamulis and his colleagues have proposed that this nebular life could take the form of a quantum computing molecular cloud that absorbs light and magnetic energy from stars and planets, processing information like a quantum computer. and would move through space using the pressure exerted by stellar radiation.

However, the life that we have seen so far is based on chemical systems where the interaction that guides them is the electromagnetic force. Is life possible in non-chemical systems? Some scientists have proposed the existence of “living beings” inside stars. Baptized with the name of “plasmobios”, they would be formed thanks to the interaction between magnetic forces and moving electric charges, which would organize themselves into increasingly complex structures. And life at the subatomic level? It would be a life based on the two nuclear forces, the strong force (responsible for the cohesion of the atomic nucleus) and the weak force (which guides certain radioactive disintegrations). In this case, the time scale we would be talking about would not be centuries or years, like the human scale, but fractions of a second. In 1992 Tobias Owen and Donald Goldsmith went a step further and speculated about hypothetical “atomic life” on the surface of these stars.

Could life exist using gravitational force? If we assume that stars play the same role as atoms in us, could star clusters be molecules and galaxies be living things? The problem is that, although galaxies are ordered systems, they are not as ordered as an amoeba. Living galaxies and galaxy clusters? Too crazy…

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