Recently science and science fiction writer Matt Williams has been writing a series at Universe Today on why the extraterrestrial intelligences that many believe must exist in our universe never show up.
Last week, we looked at the hypothesis that planets that can host life are rare so there are not many aliens out there to find. This week we look at a more ominous hypothesis.
In “Beyond “Fermi’s Paradox” III: What is the Great Filter?” (July 23, 2020), Williams asks us to consider: “there is something in the Universe that prevents life from reaching the point where we would be able to hear from it.” What could that “something” be?
Humanity seems to have a bright future, i.e., a non-trivial chance of expanding to fill the universe with lasting life. But the fact that space near us seems dead now tells us that any given piece of dead matter faces an astronomically low chance of begating such a future. There thus exists a great filter between death and expanding lasting life, and humanity faces the ominous question: how far along this filter are we?
… The easier it was for life to evolve to our stage, the bleaker our future chances probably are.Robin Hanson, “The Great Filter—Are We Almost Past It?” at George Mason University (August 1996/September 15, 1998)
It’s a simple argument: If it was easy for life in the u niverse to evolve from mud to advanced space exploration, we should indeed be seeing lots of aliens, Star Trek–style. So, if we don’t, perhaps a catastrophe lies between where we are now and where they would need to be to reach us.
As Hanson puts it,
Even if life only evolves once per galaxy, that still leaves the problem of explaining the rest of the filter: why we haven’t seen an explosion arriving here from any other galaxies in our past universe? And if we can’t find the Great Filter in our past, we’ll have to fear it in our future.Robin Hanson, “The Great Filter—Are We Almost Past It?” at George Mason University (August 1996/September 15, 1998)
But how do Hanson and others classify advances in technological civilization beyond where we are now? They use the Kardashev scale, which originated in a 1964 essay by Russian astrophysicist Nikolai Kardashev (1932–2019).
Kardashev’s scheme of advancement used only three tiers, defined in terms of energy consumption (which enables power). But the concept has since grown to at least seven tiers. That’s counting from 0 (where we are now, living only on and from Earth) through to VII (“Traveler of all universes, multiverses, megaverses”). So the total is 8 in all. Cosmologist John D. Barrow (1952–2020) also developed additional internal categories to cover different types of technological development.
Here’s an image of the energy consumption on the original Kardashev scale, from now to Star Trek (courtesy INdif, Energy consumption I – III Indif CC BY-SA 3.0):
At Futurism, where six categories of civilization are described, we are told that we may go from a Type 0 civilization to a Type I civilization in the next century:
A Type I designation is a given to species who have been able to harness all the energy that is available from a neighboring star, gathering and storing it to meet the energy demands of a growing population. This means that we would need to boost our current energy production over 100,000 times to reach this status. However, being able to harness all Earth’s energy would also mean that we could have control over all natural forces. Human beings could control volcanoes, the weather, and even earthquakes! (At least, that is the idea.) These kinds of feats are hard to believe, but compared to the advances that may still be to come, these are just basic and primitive levels of control (it’s absolutely nothing compared to the capabilities of societies with higher rankings).Jolene Creighton, “The Kardashev Scale – Type I, II, III, IV & V Civilization” at Futurism (July 19, 2014)
But the obvious question, which Williams raised in his series, is: If they aliens are so powerful, where are They?
Some hint of what could go wrong might be gleaned from a couple of snippets from Jolene Creighton’s discussion at Futurism:
But now, onto Type III, where a species then becomes galactic traversers with knowledge of everything having to do with energy, resulting in them becoming a master race. In terms of humans, hundreds of thousands of years of evolution – both biological and mechanical – may result in the inhabitants of this type III civilization being incredibly different from the human race as we know it. These may be cyborgs (or cybernetic organism, beings both biological and robotic), with the descendants of regular humans being a sub-species among the now-highly advanced society. These wholly biological humans would likely be seen as being disabled, inferior, or unevolved by their cybernetic counterparts.Jolene Creighton, “The Kardashev Scale – Type I, II, III, IV & V Civilization” at Futurism (July 19, 2014) [emphasis added]
But then we read,
Type V. Yes, Type V might just be the next possible advancement to such a civilization. Here beings would be like gods, having the knowledge to manipulate the universe as they please. Now, as I said, humans are a very, very long way from ever reaching anything like this. But it’s not to say that it cannot be achieved as long as we take care of Earth and each other. To do so, the first step is to preserve our tiny home, extinguish war, and continue to support scientific advances and discoveries.Jolene Creighton, “The Kardashev Scale – Type I, II, III, IV & V Civilization” at Futurism (July 19, 2014) [emphasis added]
The universe(s) Creighton is describing don’t sound like very nice places. It’s not hard to see why some of the “inferiors” of Type III civilizations might come up with a scheme, for their own protection, to prevent their betters from reaching Type V, where the betters morph into gods …
Hanson himself was more pragmatic. He envisioned a nine-stage filter through which a space-worthy civilization must pass, in which case the space failures probably got filtered out long before any Stage III conflict. Williams lists Hanson’s nine stages:
● Habitable star system (organics and habitable planets)
● Reproductive molecules (e.g. RNA)
● Prokaryotic single-cell life
● Eukaryotic single-cell life
● Sexual reproduction
● Multi-cell life
● Animals capable of using tools
● Industrial civilization
● Wide-scale colonizationMatt Williams, “Beyond “Fermi’s Paradox” III: What is the Great Filter?” at Universe Today
In Hanson’s scheme, we are living between Stages 8 (Industrial civilization) and 9 (Wide-scale colonization).
We can now state the problem more precisely. If it was very difficult to get from goo to zoo to you, not many space aliens have made it—thus they don’t exist, so we don’t hear from them. Alternatively, it was easy for them to get here, between 8 and 9, and it was here that something catastrophic happened … Which means that we might not get past this point ourselves either.
Of course, it’s possible that a catastrophe would not wipe out high-tech aliens but rather send them back to a sort of Stone Age. They’d still be out there but we’d need to find them. They’d be in no position to be looking for us. The sense of it is perhaps best given by a saying often attributed to, Albert Einstein is “I do not know with what weapons World War III will be fought, but World War IV will be fought with sticks and stones.” That sure takes the shine out of the “Boldly go” from Star Trek.
On the other hand, from a literary point of view, such a tragic perspective enables science fiction to aim at the highest form of literary art: tragedy. In tragedy, characters behave nobly amid looming disaster. Realistically, much science fiction is stuck at a lower level: the morality play (where we are told implicitly how we ought to live by the virtuous examples of the “good” characters).
Literary virtue signaling isn’t wrong in principle except for this: By its very nature, virtue signaling cannot be among the highest art forms. In this world, virtue is not reliably rewarded. And the greatest art must be truest to nature.
In any event, theoretical physicist and futurist Michio Kaku thinks that the next hundred years will tell whether we are divine, dimmed, or doomed:
He’s not rushing it:
Hey, it’s only fiction (?).
You may also enjoy these accounts of why we do not see the aliens:
1.Are the Aliens We Never Find Obeying Star Trek’s Prime Directive? The Directive is, don’t interfere in the evolution of alien societies, even if you have good intentions. Assuming the aliens exist, perhaps it’s just as well, on the whole, if they do want to leave us alone. They could want to “fix” us instead…
2.How can we be sure we are not just an ET’s simulation? A number of books and films are based on the idea. Should we believe it? We make a faith-based decision that logic and evidence together are reasonable guides to what is true. Logical possibility alone does not make an idea true.
3.Did the smart machines destroy the aliens who invented them? That’s the Berserker hypothesis. A smart deadly weapon could well decide to do without its inventor and, lacking moral guidance, destroy everything in sight. Extinction of a highly advanced civilization by its own lethal technology may be more likely than extinction by natural disaster. They could control nature.
4.Researchers: The aliens exist but they are sleeping… And we wake them at our peril. The Aestivation hypothesis is that immensely powerful aliens are waiting in a digitized form for the universe to cool down from the heat their computers emit.
5.Maybe there are just very few aliens out there… The Rare Earth hypothesis offers science-based reasons that life in the universe is rare. Even if life is rare in the universe, Earth may be uniquely suited to space exploration, as the Privileged Planet hypothesis suggests.