SETI: Why extraterrestrial intelligence is more likely to be artificial than biological

This article was first published by The Conversation.'s Expert voices: Op-Ed and Insights was contributed by the publication.
Martin Rees Emeritus Professor of Cosmology & Astrophysics, University of Cambridge

Is there intelligent life in other parts of the universe? This question has been debated for many centuries, if it not millennia. It is only recently, however, that we have had any chance to find out. Initiatives such as SETI (Search for Extraterrestrial Intelligence), which uses radio telescopes to actively listen for messages from alien civilizations, are a recent example.

If these searches are successful, what should we expect to find? My suspicion is that these searches are unlikely to find little green men, something I speculated at Breakthrough Listen (a SETI Project) conference.

Imagine that life started on other planets and that evolution followed a Darwinian pattern. This is unlikely. It is highly unlikely that technology and intelligence would progress at the same rate as it does on Earth. If the planet was significantly behind, it would be clear that there is no evidence of extraterrestrial existence to our radio telescopes. Life could have started around a star that is more than a billion years old, but it was not the Sun.

Related: 9 scientific reasons why humans haven’t discovered aliens yet

Human technological civilization dates back only millennia at most. It may only be a few more centuries before organic materials like carbon are replaced or transcended with inorganic intelligence such as AI. AI may soon be able use far more data than it currently does, as computer processing power is increasing exponentially. It would seem that AI could become exponentially more intelligent, surpassing human intelligence.

One way to start is to improve our intelligence through genetic modification, which can be combined with technology to create cyborgs that have both organic and inorganic parts. This could lead to fully artificial intelligence.

AI may even be able to evolve, creating better and better versions of itself on a faster-than-Darwinian timescale for billions of years. The human-level intelligence of an organic human would then only be a temporary occurrence in human history before machines takeover. If alien intelligence had evolved in a similar way, it would be very unlikely that we could catch it in its biological form. Extraterrestrial life would likely be electronic if it were discovered. It may even not exist on planets.

Therefore, we must reinterpret Drake's equation. It was created in 1960 to determine the potential number of civilizations within the Milky Way. This equation is made up of several assumptions. It includes the number of planets, as well as the time a civilization can release signals into space. The estimated range for this equation is between 1,000 and 100,000,000 years.

However, the life span of an organic civilization could be only millennia. While its electronic diaspora can last for billions of year, it may not live beyond that. This means that there could be many more civilizations than we think, but most of them would be artificial.

It is possible that we may want to reconsider the concept of alien civilisations. A civilisation is a group of people. Extraterrestrials, on the other hand, might have a single integrated intelligence.

Encoding messages

It is unlikely that SETI would record decodable messages if it succeeded. It may instead detect a byproduct or malfunction of a super-complex machine that is beyond our understanding.

SETI is primarily concerned with the radio portion of the electromagnetic spectrum. We don't know what is out there so we need to explore all wavebands. We should not only listen for radio transmissions, but also look out for other evidence of natural phenomena or activity. These could be artificial structures that surround stars to absorb their energy (Dysonspheres), or artificially made molecules such as chlorofluorocarbons, which are nontoxic, nonflammable chemicals that contain carbon, chlorine and fluorine in the planet atmospheres. These chemicals are greenhouse gases that cannot be produced by natural processes. They could indicate terraforming (changing a world to make it more habitable), or industrial pollution.

Dyson spheres could be built by advanced extraterrestrials. (Image credit: Eduard Muzhevskyi/Shutterstock)

It would be worthwhile to look for alien traces in our solar system, I'd argue. Although we can rule out human-like species visiting, there are still other possibilities. A civilization from another planet that has mastered nanotechnology could have transferred its intelligence, for example, to tiny machines. With a swarm of microscopic probes, it could invade other worlds or asteroid belts.

Even if we received a radio message that could be decoded, how would we know the intentions of the super-intelligent sender? There are many bizarre motives, including religious, financial and ideological that have fueled human endeavors in the past. We don't have any idea what they might be. They might be inquisitive and peaceful. They may be less intrusive and realize that it is easier to think about low temperatures, far from any star, or hibernating for billions upon billions of years, until it gets cooler. They could also be expansionists, which seems to be the expectation of many who have thought about the future course of civilisations.

The future of intelligence

Intelligent species might become unfathomably intelligent as the universe evolves. Take a look at our future. Stark births and deaths will eventually happen slowly in our galaxy, until the Milky Way collides with the Andromeda in approximately a billion years. After that, the debris from our galaxy, Andromeda, and its smaller companions in our local group, galaxies, will clump together to form one amorphous galaxy. Meanwhile, distant galaxies will move away and eventually disappear.

Our remnant will last for longer than expected, possibly allowing for the emergence of a civilization that could possess huge amounts of energy and even harness the entire mass of a galaxies.

This could be the end of the long-term trend towards living systems becoming more complex. All the atoms once found in stars and gases could now be transformed into a gigantic organism on a galactic scale. Starlitue fiction writers envision stellar-scale engineering that creates black holes and wormholes, which connect different points in spacetime. This could provide shortcuts for space travellers. These ideas are beyond what we have technologically possible, but they do not violate basic physical laws.

Are we artificial?

Human intelligences could also be capable of building computers with huge processing power. Some complex phenomena, such as climate change, can already be modeled by humans. However, intelligent civilisations may be able simulate living things with actual consciousnesses and entire worlds.

Are we only characters in an alien computer-game? (Image credit: Mertsaloff/Shutterstock)

How can we be sure that we are not living in a simulation made by technologically superior aliens, and how do we find out? Perhaps we are just entertainment for the supreme being running this model. If life can create technologically advanced civilizations capable of making computer programs, then there might be more simulation universes out there than there are real ones. It is possible that we could be in one.

Although it may sound crazy, this conjecture is based on current knowledge of physics as well as cosmology. However, we should be open-minded to the possibility of not understanding everything. Maybe the laws and constants that we observe and measure are not universal and may differ from one another. This would open up even more amazing possibilities.

Physical reality may contain complexities that our intellect and senses cannot grasp. One electronic brain may have a completely different view of reality. We cannot predict their motivations. We cannot determine if the current radio silence SETI is experiencing indicates an absence of advanced alien civilisations or a preference.

*This article was partly inspired by a speech that the author gave at the 2018 Breakthrough Listen conference.

This article was republished by The Conversation under Creative Commons. You can read the original article.

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