Alternate Life Forms: The Shadow World of our Biosphere

Nasa released information regarding alternate life forms which eerily coexist with us on planet earth.

As the new scientist describes it:

We could be witnessing the first signs of a “shadow biosphere” – a parallel form of life on Earth with a different biochemistry to all others. Bacteria that grow without phosphorous, one of the six chemical elements thought to be essential for life, have been isolated from California’s Mono Lake. Instead of phosphorous, the bacteria substitute the deadly poison arsenic.

But this is nothing new…

Arsenic, which is chemically similar to phosphorus, while poisonous for most Earth life, is incorporated into the biochemistry of some organisms. Some marine algae incorporate arsenic into complex organic molecules such as arsenosugars and arsenobetaines. Fungi and bacteria can produce volatile methylated arsenic compounds. Arsenate reduction and arsenite oxidation have been observed in microbes (Chrysiogenes arsenatis). Additionally, some prokaryotes can use arsenate as a terminal electron acceptor during anaerobic growth and some can utilize arsenite as an electron donor to generate energy. It has been speculated that the earliest life on Earth may have used arsenic in place of phosphorus in the backbone of its DNA.

The idea of  hypothetical types of biochemistry and the different types of speculative biochemistries of alien life forms that differ radically from those known on Earth intrigues both scientists and SF writers. Theories about extraterrestrial life based on these “alternative” biochemistries are common in science fiction. Perhaps the most extreme example in science fiction is James White’s Sector General: a series of novels and short stories about multienvironment hospital for the strangest life-forms imaginable, some of them breathing methane, chlorine, water and sometimes also oxygen. Some of the species metabolise directly hard radiation and their environment doesn’t differ much from the atmosphere of a star, while others live in near absolute zero temperatures. All life forms are classified according to their metabolism, internal and external features, and more extreme abilities (telepathy, empathy, hive mind, etc.) with four letter codes. Humans from Earth share the DBDG specification with small furry beings called Nidians.

Fred Hoyle’s classic novel The Black Cloud features a life form consisting of a vast cloud of interstellar dust, the individual particles of which interact via electromagnetic signalling analogous to how the individual cells of multicellular terrestrial life interact. Outside of science-fiction, life in interstellar dust has been proposed as part of the panspermia hypothesis. The low temperatures and densities of interstellar clouds would seem to imply that life processes would operate much more slowly there than on Earth. Inorganic dust-based life has been speculated upon based on recent computer simulations.

Similarly, Arthur C. Clarke’s “Crusade” revolves around a planetwide life-form based on silicon and superfluid helium located in deep intergalactic space, processing its thoughts slowly by human standards, that sends probes to look for similar life in nearby galaxies. It concludes that it needs to make planets more habitable for similar life-forms, and sends out other probes to foment supernovae to do so. Clarke implies that this is what accounts for most supernovae having occurred in the same region of space and warns that the effort will eventually reach Earth.

Robert L. Forward’s Camelot 30K describes an ecosystem on the surface of Kuiper belt objects that is based on a fluorocarbon chemistry with OF2 as the principal solvent instead of H2O. The organisms in this ecology keep warm by secreting a pellet of uranium-235 inside themselves and then moderating its nuclear fission using a boron-rich carapace around it. Kuiper belt objects are known to be rich in organic compounds such as tholins, so some form of life existing on their surfaces is not entirely implausible–though perhaps not going so far as to develop natural internal nuclear reactors, as have Forward’s. Fluorine is also of low cosmic abundance, so its use in this manner is unlikely.

In Forward’s Rocheworld series, an Earth-like biochemistry is proposed that uses a mixture of water and ammonia as its solvent. In Dragon’s Egg and Starquake, Forward proposes life on the surface of a neutron star utilizing “nuclear chemistry” in the degenerate matter crust. Since such life utilised strong nuclear forces instead of electromagnetic interactions, it was posited that life might function millions of times faster than typical on Earth.

Gregory Benford and David Brin’s Heart of the Comet features a comet with a conventional carbon-and-water-based ecosystem that becomes active near the perihelion when the Sun warms it. Brin’s own novel Sundiver is an example of science fiction proposing a form of life existing within the plasma atmosphere of a star using complex self-sustaining magnetic fields. Similar sorts of plasmoid life have sometimes been proposed to exist in other places, such as planetary ionospheres or the interstellar medium, but usually only by fringe theorists. Gregory Benford had a form of plasma-based life exist in the accretion disk of a primordial black hole in his novel Eater.

The suggestion that life could even occur within the plasma of a star has been picked up by other science fiction writers, as in David Brin’s Uplift Saga. The idea is that places where reactions occur–even an incredible environment as a star–presents a possible medium for some chain of events that could produce a system able to replicate.

The Outsiders in Larry Niven’s Known Space universe are cryogenic creatures based on liquid helium. They derive thermoelectric energy from a temperature gradient by basking half their body in sunlight, keeping the other half in shadow and exposed to interstellar vacuum.

Stephen Baxter has imagined perhaps some of the most unusual exotic life-forms in his Xeelee series of novels and stories, including supersymmetric photino-based life that congregate in the gravity wells of stars, entities composed of quantum wave functions, and the Qax, who thrive in any form of convection cells, from swamp gas to the atmospheres of gas giants. In his book Manifold: Space, he also proposes natural robots, life forms made of iron, called the Gaijin, evolving from creatures in oceans of Iron carbonyl.

In his novel Diaspora, Greg Egan posits entire virtual universes implemented on Turing Machines encoded by Wang Tiles in gargantuan polysaccharide ‘carpets.’ The sentient ocean that covers much of the surface of Solaris in Stanislaw Lem’s eponymous novel also seems, from much of the fictional research quoted and discussed in the book, to be based on some element other than carbon. In the same novel Egan describes lifeforms in the 6-D ‘macrosphere’ which use a collapsed atom chemistry with energetic processes of the same order as nuclear reactions, due to the peculiarities of higher dimensional physics.

In her novel Brain Plague, Joan Slonczewski describes a species of intelligent microrganisms with arsenic based chemistries that live symbiotically with human hosts.

Sergeant Schlock is one of the lead characters in the webcomic Schlock Mercenary. His species, Carbosilicate Amorphs, evolved from self-repairing distributed data storage devices, and as such, redundantly distribute their ‘brain’ throughout their body. They are highly resistant to Hard Vacuum, explosive decompression, projectile weapons, chemical-based explosives, and dismemberment. Their only specialty organ is their eyes, which they harvest as fruit from the Ghanj-Rho eye-tree on their home planet. While the Amorphs have the ability to move fast, quietly, and sprout appendages at will, they excel at ‘closer-than-melee-range combat, primarily “meme-toxins” against other Amorphs.

A more farcical example comes from the Hitchhiker’s Guide to the Galaxy, where the Hooloovoo are a hyperintelligent shade of the colour blue.

Alien warriors recruited by the god Klael in David Eddings’ “Tamuli” trilogy are noted by their human opponents to breathe marsh-gas (methane). Within Eddings’ universe, this limits their capacity for exertion in an oxygen atmosphere, and also determines the tactics used to fight them and eventually to destroy them in their encampments.

The eponymous organism in Michael Crichton’s The Andromeda Strain is described as reproducing via the direct conversion of energy into matter.

Let the games begin…

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