The Space Reviewin association with SpaceNews

galaxy illustration
Artist’s depiction of the Milky Way Galaxy. The relatively short time it would take to colonize the galaxy forms the basis of the Fermi paradox. (credit: NASA)

The other side of the Fermi paradox

The Fermi paradox—the estimation that extraterrestrial civilizations are common and would naturally expand into space, contradicting the lack of evidence that they exist anywhere—is the subject of fascinating speculation and guesswork. Every possible fate of extraterrestrial intelligence is proposed and explored. These thought experiments are not only interesting in their own right, but may help evaluate the state of a more terrestrial civilization. What will happen to humankind in the future? By examining the possible futures of extraterrestrial civilizations, we are simultaneously examining the possible futures of our own civilization. Put in another way, if an alien civilization somewhere had their own version of the Fermi paradox, they would be speculating on our future in the same way that we speculate on theirs.

Stephen Webb’s book on the Fermi paradox, If the Universe Is Teeming with Aliens… Where Is Everybody? Fifty Solutions to the Fermi Paradox and the Problem of Extraterrestrial Life, puts its fifty solutions into three broad categories: “They Are Here”, extraterrestrials are in our vicinity, but hidden somehow; “They Exist But Have Not Yet Communicated”, they exist on a faraway world and have not reached us yet; and “They Do Not Exist”, they have never existed in the first place, or they have existed but have since gone extinct. Each of these categories has an equivalent for future human civilization: “We Will Exist Everywhere”, we will spread out from Earth and colonize space; “We Will Exist On Earth Only”, we will remain on Earth and fail to colonize space; “We Will Not Exist”, we will go extinct.

By examining the possible futures of extraterrestrial civilizations, we are simultaneously examining the possible futures of our own civilization.

Not every solution to the Fermi paradox is applicable to human civilization. All those which state that extraterrestrial intelligence does not exist in the first place are irrelevant (unless you argue that there is no intelligent life on Earth!). But many others are relevant and interesting predictions of the future of humankind.

“Solution 10: They Have Not Had Time to Reach Us” becomes “We Have Not Had Time to Reach Them”, which is appropriate for human civilization today, considering the short time that humans have existed, and the even shorter time that humans have had spaceflight. “Solution 14: They Stay at Home…” becomes “We Stay at Home”, arguing that we will stay on Earth due to apathy, technology, economics or politics (e.g. Proxmire effect or Park hypothesis. “Solution 15: …and Surf the Net” deals with the creation of virtual reality worlds so impressive that real world challenges, such as space colonization, pale in comparison. Games and virtual worlds such as World of Warcraft and Second Life have already gained a reputation for being addictive and all-consuming. Future generations of these immersive fantasy worlds will compel more people to neglect the real world.

While staying on Earth is a mediocre future for humankind, of course the worst possible future is extinction. Webb discusses gamma ray bursts and asteroid collisions as natural extinction events. A technological civilization is itself a risk, with its nuclear and biological weapons. In addition, Webb describes the exotic possibility of powerful, autonomous alien weapons (Solution 22: Berserkers) that either deliberately or inadvertently destroy all civilizations that they find.

There is a significant connection between the categories of “We Will Exist On Earth Only” and “We Will Not Exist”. Webb explained the strong motive for all civilizations—both extraterrestrial and human—to pursue colonization: “…in any case it seems a wise idea for a species to expand into space to guard against the possibility of planetary disaster”. Remaining on a single planet increases the risk of extinction, as Stephen Hawking and many others have stated.

The Fermi paradox is based on the premise that it is natural, logical and right for extraterrestrial civilizations to colonize space. The other side of the Fermi paradox is that it is natural, logical, and right for human civilization to colonize space. Anti-human-spaceflight advocates tend to hold the contradictory idea that colonization is alright for extraterrestrials, but wrong and immoral for us. However, colonizing and populating space is advantageous for every civilization; whether it happens to be extraterrestrial or terrestrial is beside the point.

If extraterrestrial civilizations do not exist, it is even more important for humans to survive and colonize space.

Webb’s 50th solution is the one that he believes is the most likely. Unfortunately for extraterrestrial enthusiasts, the solution is depressingly pessimistic: “…the only resolution of the Fermi paradox that makes sense to me—is that we are alone.” Webb’s preferred solution is highly controversial, but it satisfies Ockham’s razor; out of all the Fermi paradox explanations, it is the simplest one. On the other hand, the solution is only as good as the evidence it is based on. New evidence could lead to a different solution to the paradox.

If extraterrestrial civilizations do not exist, it is even more important for humans to survive and colonize space. If we do not do it, then no one else will. If extraterrestrial civilizations exist, the task will be shared. In any case, the ultimate goal for all civilizations is to spread life throughout the galaxy, to transform a largely dead galaxy into a living one.