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Why Martians Could Be AI

By Andrew Kim

A picture of what Alien life could possibly look like

Alien life forms are far more likely to be AI-based than little green men, claimed distinguished British astrophysicist Martin Rees, in an October 2021 essay for The Conversation. “If we were to detect extraterrestrial life, it would be far more likely to be electronic than flesh and blood – and it may not even reside on planets,” Rees wrote.

Rees, current Astronomer Royal and a former president of the Royal Society, has argued about the possibility of machine-based extraterrestrial life to the scientific community and the public alike since 2015.

In the essay, Rees claimed that his idea for machine-based life is based on the rapid advancements in computational power and robotics on Earth, which he believes to have shown that artificial intelligence will exceed human capabilities in the near future. He further noted that organic life forms such as humans are not well-suited for extended space travel or survival in extraterrestrial environments. Because of this, he argued, as organic life forms develop, they could transition into non-organic forms due to their many advantages, slowly combining with inorganic parts and evolving into cyborgs until they become fully machine-based.

While his conjecture may appear bizarre at first glance, he is hardly alone in arguing that intelligent extraterrestrial life will be discovered in the form of super-advanced AI. Avi Loeb, a theoretical physicist at Harvard who works on astrophysics and cosmology, has anticipated intelligent extraterrestrial life to assume an artificial form rather than a biological one. “AI systems could roam through interstellar space,” Loeb wrote in his 2021 Scientific American essay. Oxford futurist Anders Sandberg likewise suggested in a 2017 interview with Gizmodo about a likelihood for advanced, computer-based alien civilizations to be aestivating in zones where natural cosmological processes have been observed to be dramatically diminished.

Rees argued in a 2018 SETI Breakthrough Listen conference that scientists would be more likely to find intelligent machine-based life than intelligent biological life.

His assumption was that compared to biological life forms, machine-based life forms would require a relatively short amount of time to develop, and are incredibly resilient to the environment due to their ability to actively select their traits, which would allow them to thrive for billions of years. In contrast, Rees noted, a civilization of organic beings requires billions of years to naturally emerge and may last only at most a few millennia before transitioning into a machine-based life.

“So, if intelligence on another world emerged and involved as it has here, we’d be most unlikely to catch [intelligent life]’ in the brief interlude when it was embodied in a civilization of flesh and blood creatures,” he said in the talk, “there may be more [alien] civilizations out there than we thought, but that the majority of them would be artificial.”

Searching for machine-based life forms may be more successful if we drastically change the techniques used to search for extraterrestrial life. In a 2015 Nautilus essay, Rees theorizes that machine-based life forms’ resilience means that scientists would need to greatly expand their scope of search. Unlike biological life, which is mostly limited to the confines of its home planet, machine-based life could exist anywhere: we would have to search across the farthest corners of the universe, such as frozen tundras, lava planets, or even the empty space of the universe.

Additionally, the signals we look for would also be completely different. Current searches for extraterrestrial life revolve around biosignatures: substances that provide scientific evidence of past or present organic life. One common biosignature scientists look for is molecular oxygen in the atmosphere.

However, Rees argues in his Nautilus essay that it is unlikely that robotic life would produce biosignatures such as oxygen. Instead, machine-based life would be producing techno-signatures. Yet Rees notes that the search for techno-signature is likely to be unsuccessful, and even if it is, the signature would unlikely for the signal to be a decodable message.

“It would more likely represent a byproduct (or even a malfunction) of some super-complex machine far beyond our comprehension that could trace its lineage back to alien organic beings (which might still exist on their home planet, or might long ago have died out),” he writes, as the only potential messages we would be able to decode would be the “small subset of technology attuned to our own parochial concepts.”

It's essential to note that Rees states that his theory “is all speculative,” as he confirmed in a personal email interview. In the interview, he noted that he can’t offer an accurate description of what machine-based life may look like or be like, as there isn’t even any evidence it exists.

Nevertheless, the concept of machine-based extraterrestrial life raises fascinating possibilities. How could a super-intelligent AI develop and exist without us ever knowing? Is life much more common in the Universe than we thought? Are there other complex alien civilizations out there in the universe? Why haven’t we been able to contact any of them? If machine-based life exists, it may be able to communicate in ways beyond the abilities of organic life. It may be capable of traversing immense distances across the universe, providing new avenues for exploration and scientific discoveries.

The discovery of machine-based life would be truly revolutionary. It would show how life could exist on a completely different scale than what humans have been capable of imagining. The general consensus of the scientific community until now has been that the difficulties of discovering alien life forms mean that life is so rare in the universe, and extraterrestrial life will most likely exist in small bacteria forms that are difficult to detect. A proof of machine-based alien life would challenge this notion and truly revolutionize our understanding of how life can develop.

Regardless of whether Rees's theory proves to be accurate or not, the quest for extraterrestrial life remains an exciting and evolving field and the radical theory of machine-based life is an important part of this discussion that seeks to transform the way we understand life.

Works Cited

Dvorsky, George. “Hibernating Aliens Could Explain The Great Silence.” Gizmodo, 31 May 2017, -1795695445.

Loeb, Avi. “Microbes, Natural Intelligence and Artificial Intelligence.” Scientific American, Scientific American, 2 Oct. 2021, natural-intelligence-and-artificial-intelligence/.

Rees, Martin. Email interview. 21 January 2022.

Rees, Martin. “SETI: Why Extraterrestrial Intelligence Is More Likely to Be Artificial than Biological.” The Conversation, 18 Oct. 2021,

Rees, Martin. “Will SETI Detect Organic or Electronic Intelligence? | Martin Rees at Breakthrough Discuss 2018.” YouTube, YouTube, 29 May 2018,

Rees, Martin. “Why Alien Life Will Be Robotic.” Nautilus, 15 Oct. 2015, -alien-life-will-be-robotic-235661/.


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