Are we alone in the universe? Indeed, it could not be a question that has captured the human imagination more than this one, perhaps as long as human beings have walked on this earth. While scenes of little green men or even monstrous predator aliens characterize popular movies, experts say truth may actually turn out way more eclectic and exciting. The possibilities of extraterrestrial life are endless and as varied as the cosmos itself.
But scientists conjecture that most likely, the form would be very much decided by conditions on their home planet or moon. On a planet with an atmosphere packed thick with gases, aliens might develop flying forms to cruise through the skies, says Ali. And on a high-gravity planet, they might evolve stouter and elephant like.
But what if the aliens evolved underground? “If the radiation level is too high on the planet, it would force life forms to live under the ground insulated by soil,” says Valentina Erastova, a Chancellor’s Fellow of Chemistry at the University of Edinburgh. Now, such subterranean creatures could resemble fungi—like the vast network of roots called mycorrhiza that populate Earth’s underground.
A 2019 study in Monthly Notices of the Royal Astronomical Society claimed that aliens could also glow in different colors to protect their bodies from extreme ultraviolet radiation. Fast forward, these glowing aliens could use proteins or pigments that absorb the energy from UV light and then add it in at a safer wavelength on the visible spectrum.
Yet the most common form of life we might encounter is likely to be much simpler, “It is far more likely that life would be single cellular,” says Sarah Rugheimer, associate professor of astronomy and astrophysics at York University in Toronto. After all, for most of Earth’s history, life was predominantly microbial and even now our biosphere is largely composed of microbes.
What if, however, we go outside these recognizable life forms? “Life as we don’t know it” is what Sarah Stewart Johnson tries to define. She got interested in alien life following a visit she made to the volcano Mauna Kea in Hawaii, Neckar, when she saw a small fern growing inside dried-up lava. It totally gave her the impetus to believe that life could succeed in tough environments. “Even places that seem familiar—like Mars, a place that we think we know intimately—are able to completely throw us for a loop,” says Scott.
A NASA-funded project, led by Johnson, called the Laboratory for Agnostic Biosignatures, or LAB, has begun the search for far more fundamental markers of biology. Instead of looking for such specific biosignatures, LAB looks for evidence of complexity and disequilibrium—for example, way more molecules than expected of some type that would seem biological processes at work. It’s a way of looking for life-forms that may not have the same biochemical ground rules as Earth life.
Other places sportive of life in our solar system would be Jupiter’s moon Europa, Saturn’s moon Enceladus, or even Titan. In this case, Europan life could also exist in its subsurface ocean and take the form of shrimp or squid since NASA has been studying extreme shrimp ecosystems in the Caribbean, looking to get some idea of what life is like on such an icy moon.
Looking further afield, in distant galaxies, the possibilities are even more mind-bending. According to Manchester University’s Professor Michael Garrett, life forms on a massive planet with strong gravity might be squat and muscular while those on a less massive planet might be spindly and tall. Life on a planet orbiting a red giant star might have large sensitive eyes to detect the dim light abdominally.
Other experts, however, hold the belief that life elsewhere in space could take recognizable forms due to convergent evolution. The latter is normally referred to as the phenomenon where similar environmental pressures under which organisms live could lead to the development of similar characteristics, such as limbs, heads, and sensory organs.
Other scientists believe any aliens would not have to look anything like a human. Experts, such as satellite expert Dr. Maggie Aderin-Pocock, have based their theories on what the aliens could look like on Titan, similar to large jellyfish with appendages shaped in an onion form worn top to toe. These could well be based on silicon rather than carbon, living on light through their skin and chemicals consumed through their mouths.
Now, speculatively, a few scientists have gone so far as to suggest that high-order extraterrestrial intelligences perhaps bioengineered their own bodies or are fully mechanical. Not unlike what the human species is now starting to do with their bodies, with contact lenses, pacemakers, artificial joints, which extraterrestrial beings may have simply taken to their logical conclusion. Thus, the highest order of aliens would be more robot in nature, with brains which could be uploaded, so mechanical bodies, like Commander Data from Star Trek, as one scientist put it.
Whether we ever find alien life or not, one thing’s for sure: vast must be the range of possibilities. Glowing, fungal creatures; mechanical beings the possibilities this universe can offer to take in realization of life are simply endless. And in search of the answers, we keep growing our perception of the incredible plasticity of life and the boundlessness of the cosmos.
