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I just finished The Great Silence: The Science and Philosophy of Fermi’s Paradox by Milan M. Ćirković. Which I was made aware of after corresponding with the author some months ago. At the time, I was on a quest to send my Fermi’s Paradox as Proof of the Existence of God theory to people who had written about Fermi’s Paradox, and his name ended up on the list, though I forget why. He was very gracious and in addition to sending me some papers that touched on my theory for the paradox (none particularly close) he also recommended his forthcoming book. I’m grateful for the recommendation, since, despite having a Google Alert set to notify me if anyone talks about the paradox anywhere on the internet, I don’t think I ever saw an alert for this book. Thus, without the correspondence, I might have completely missed it, which would have been a great shame because it’s fantastic.
(Edit: Actually just this week as I was writing my post, but after composing the first paragraph, I finally got an alert which mentioned Ćirković’s book.)
This post will be split into two parts. In the first half I’ll review the book, and point out things I found particularly notable or interesting about Ćirković’s approach. In the second half I’ll examine the case for including my explanation as a contender using the standards Ćirković has laid out.
Review and Commentary on The Great Silence
Before I get into a discussion of the finer points of the book, I’ll start with a brief general review. In other words I’ll address the question, “Should you read this book?”
“The Great Silence” is the best thing I have ever read about the paradox, though to be fair, that’s a pretty small field. So I’ll point out, additionally, that I thought it was good enough to deserve a spot in the bookshelf on my desk. A bookshelf set aside for the 50 or so books I expect to reference again and again for a long time to come. That praise aside, this is not a book for everyone. It’s very scholarly, and sometimes goes too far in assuming background knowledge which not everyone will posses. (Including me.) But for that narrow slice of people who agree with Ćirković (as I do) that:
[Fermi’s Paradox] is…a conundrum of profound scientific, philosophical and cultural importance. By a simple analysis of observation selection effects, the correct resolution of Fermi’s paradox is certain to tell us something about the future of humanity.
(I would change “something” to “quite a bit”.) Also…
The very richness of the multidisciplinary and multicultural resources required by individual explanatory hypotheses enables us to claim that [Fermi’s Paradox] is the most complex multidisciplinary problem in contemporary science. (Emphasis original.)
If you are in this group, then “The Great Silence” is invaluable and I could not recommend it more highly.
Like Ćirković I’m going to assume a certain amount of background knowledge as we begin our discussion. If for some reason you’re only marginally familiar with Fermi’s Paradox you should go read the Wikipedia article first. And if you’re familiar with the paradox, but not familiar with my argument for why the existence of God makes a pretty good explanation, you might want to review that post as well before diving in. Those caveats aside let’s proceed.
Obviously the first thing to be done in a book like this is to define what Fermi’s Paradox is, starting with the obligatory discussion of the famous lunch where Enrico Fermi asked his question, “Where is everybody?” Once that’s out of the way, Ćirković breaks his definition up into three levels:
- ProtoFP: Exactly what Fermi said. The absence of extraterrestrials on Earth is incompatible with the rest of our assumptions.
- WeakFP: The absence of any evidence of extraterrestrials in the Solar System is incompatible with our assumptions:
- StrongFP: The absence of any evidence for extraterrestrials anywhere.
It honestly never occurred to me that someone referring to Fermi’s Paradox would be using any other definition than the strong one, but apparently it happens. Accordingly I’ll include Ćirković version of it here in full and declare that whenever I discuss the paradox I’m referring to the “Strong” version.
Strong Fermi’s Paradox(a.k.a. The Great Silence, Silentium Universi): The lack of any intentional activities or manifestations or traces of extraterrestrial civilizations in our past light cone is incompatible with the multiplicity of extraterrestrial civilizations and our conventional assumptions about their capacities.
The strength of the paradox when stated this way is perhaps most apparent when we consider how easy it is would be to detect traces of humanity if the situation were reversed and we were the extraterrestrial civilization being searched for. There are already many ways for the presence of humans to be detected by someone outside our Solar System and even more ways to detect the presence of life on Earth. All of this technology consists of things we’ve already mastered, and lack only engineering to implement them on the scale required. Meaning that it should be child’s play for a civilization even a few hundreds years more advanced than where we are currently.
Given how detectable advanced civilizations should be, Ćirković makes an interesting point, receiving an alien signal from one other civilization doesn’t necessarily resolve the strong version of the paradox. One could certainly imagine picking up a signal from someone only a few hundred years ahead of us, and still be in a situation of asking, “Where is everybody else?”
The next challenge one faces when discussing explanations for Fermi’s Paradox, is how to organize those explanations. Stephen Webb, who I’ve talked about previously, collected 75 explanations in his book, If the Universe Is Teeming with Aliens Where Is Everybody? Webb decided to organize them into these three buckets:
- They are (or were) here
- They exist, but we have yet to see or hear from them
- They don’t exist
That’s not a bad system and certainly it covers all of the possibilities, but I think Ćirković’s system is both more clever and more useful. He starts by identifying four assumptions we have made about the universe, and then grouping explanations for the paradox in buckets corresponding to which assumption would have to be incorrect for that explanation to possible.
The four assumptions are:
- Realism: The assumption that what we see is reality. Explanations which violate this assumption include things like the Simulation Hypothesis which posits that we live in The Matrix, and the “Include Aliens” flag has been set to false.
- Copernicanism: Also called the Mediocrity Principle. This is the idea that there’s nothing particularly special about humans or Earth. Explanations which violate this assumption mostly fall into the “Rare Earth” category, and include things like the theory that multicellular life is exceptionally difficult.
- Gradualism: The assumption that things will continue much as they have. That humanity will continue to expand outward, that the galaxy wasn’t markedly more dangerous in the past than it is now, etc. The popular worry that we’re going to wipe ourselves out with nukes is one example of something which violates this assumption.
- Non-exclusiveness: The assumption that there is diversity among potential extraterrestrial civilizations, that they are not likely to all behave in exactly the same manner or agree to the same things. This is closely related to the last assumption, for example maybe some civilizations will blow themselves up, but for that to be the answer we have to violate this assumption by assuming all civilizations blow themselves up.
Webb’s method works well as a logic division for all possible explanations of the paradox, but I think Ćirković’s is much better if your goal is to solve it, which takes us to the next requirement of any good book about the paradox, grading the possible solutions, which Ćirković does literally.
There are quite a few D’s and F’s (18 out of 36 total), but we’re obviously interested in the A’s. No explanation gets a straight A because that would be equivalent to declaring it The Solution, but he does give out one A- for the Gaian Window explanation. A Rare-Earth hypothesis which basically states that stable biotic feedback loops are rare, which creates several narrow bottlenecks all of which we managed to pass through, but which no else has.
Rare-Earth explanations are fairly common, indeed that’s the explanation Webb favored in his book, and to be fair there’s a lot to be said for them as potential explanations, but in general they’re the least interesting of the possibilities. In recognition of this Ćirković includes a list of his subjective favorites, these are:
- New Cosmogony (Grade: B)- I’ll discuss this in the next section.
- Astrobiological Phase Transition (Grade: B)- Something we don’t understand makes life possible only relatively recently, and may in fact periodically reset things such that life has to start over.
- Deadly Probes (Grade: B+, the next highest grade and the only B+ given)- There is a galactic ecosystem of self-replicating probes that destroy all intelligent life. I discussed this at some length in my Fermi’s Paradox and the Dark Forest post, and as always the question (which I think Ćirković doesn’t pay enough attention to) is, “What are they waiting for?”
- Transcension Hypothesis (Grade: B-)- All advanced civilizations get reduced to information flows which are hard to detect, particularly if you don’t know the protocols.
- Galactic Stomach Ache (Grade: C)- The removal of stress becomes the dominant preoccupation of civilizations, which not only absorbs all their resources, but also removes all the beneficial stress which dominated all pre-technological progress. As you can imagine I really like this explanation, so I’ll be talking about it next week, though perhaps not in the form you expect.
I agree with Ćirković that these are some of the more interesting explanations, and I’m glad he lists his favorites even if subjectivity is discouraged in science because it somewhat lets me off the hook for spending so much time on my favorite explanation, which takes us into the second half of the episode.
Supernatural Explanations for the Paradox
In one of the quotes above, Ćirković asserts that the paradox is “the most complex multidisciplinary problem in contemporary science”. But one disciple he doesn’t want to bring to the table is the discipline of theology. Specifically he says early on that he’s going to hew to “methodological naturalism” in his search for explanations. This means that he is not going to “invoke supernatural agencies and capacities in searching for an explanation for observed phenomena”. This is entirely appropriate for a book of this sort, and I have no problem with this methodology. Also it’s to his credit that Ćirković unlike so many others at least acknowledges that there might be supernatural explanations which should be in the running, absent this restriction. No the problem I have, and you knew there was one, is where do you draw the line between the supernatural and the natural?
Ćirković offers several explanations of the paradox where that line has been drawn very expansively. I’d like to look at three of his explanations, and in particular look at where he has drawn the line with each. I’ll will open each with Ćirković’s formal defining statement of the explanation:
Zoo Hypothesis: Advanced Galactic civilizations intentionally refrain from contacting newcomers for ethical reasons, reasons to do with security, or some other reasons (which would be incomprehensible to newcomers). We are located in the Galactic analogue of a zoo or a wilderness preserve—a chunk of space set aside for the low-level civilizations to evolve without interference. This no-contact policy extends to hiding traces and manifestations of their existence. We may be confident that they observe us, as we observe animals in a zoo, a lab, or a wilderness preserve, without us being aware of the fact.
This is one of the more common explanations for the paradox, frequently encountered in popular culture, for example Star Trek’s Prime Directive. According to this explanation our observation of the rest of the universe is being severely restricted. Would it be fair to say it’s unnaturally restricted? Certainly it’s unnatural to stick animals in a zoo or even a wilderness preserve. I could see an objection in jumping from unnatural to supernatural, but at the very least this explanation places limits on our ability to use methodological naturalism to get to the bottom of the paradox, because that methodology is being subverted by our “zoo-keepers”.
The New Cosmogony: Very early cosmic civilizations (…billions of years older than humanity) have advanced so much that their artefacts and their very existence are indistinguishable from ‘natural’ processes observed in the universe. Their information processing is distributed in the environment on so low a level that we perceive it as operations of the laws of physics. Their long-term plans include manipulation of these very laws in order to create new stages of cosmological evolution. Since the whole of the observable reality is, thus, partly artificial, there is no Fermi’s Paradox.
Many posts ago I talked about Carl Sagan’s novel Contact. Sagan was deeply interested in the search for extraterrestrial intelligence (SETI) and appears frequently in Ćirković’s book. “Contact” was his book about SETI, and as a bonus it also gave a fictional answer to the paradox. This answer was what you might expect with a few exceptions, most notably he introduces aliens that are so powerful they can embed a code in pi, such that once you calculate it out to a few billion digits, it turns into a binary code. You can perhaps see why this explanation which involves manipulating the laws of physics reminded me of the novel. But whether it appears in Sagan’s book or Ćirković’s the question we care about is whether this explanation might be supernatural. In my opinion, something which allows you to manipulate the laws of nature is by definition supernatural.
Simulation Hypothesis: Physical reality we observe is, in fact a simulation created by Programmers of an underlying, true reality and run on the advanced computers of that underlying reality. Due to a form of principle of indifference, we cannot ever hope to establish the simulated nature of our world, provided that the Programmers do not reveal their presence. As a parenthetical consequence, the simulation is set up in order to study a rather limited spatio-temporal volume, presumably centered on Earth—there are no simulated extraterrestrial intelligent beings, so there is no Fermi’s Paradox.
Another explanation that gets mentioned a lot, and also appears in popular culture, particularly The Matrix. I would assume here that the explanation’s supernatural character is obvious. Not only are “Programmers” gods in all but name, they have also specifically set up an unnatural reality where the laws of physics as we understand them would lead to you expect extraterrestrials, but the Programmers have chosen to leave them out of the simulation, which is hard to label as anything other than a supernatural act. Certainly it appears difficult to apply “methodological naturalism” to the question since nature is entirely what the programmers have decided it should be.
Difficult, but perhaps not impossible, and there have been various proposals over the years for ways we might be able to tell. And I assume that this is the argument most people would summon to create a dividing line between the natural and the supernatural, the dividing line of falsifiability. Which all of these explanations share, at least in theory. In the first, if at some future point we have spread out across the galaxy without encountering any zoo-keepers then that explanation would appear to be false. In the second, the task is a little more difficult, but as Ćirković points out it doesn’t provide a very good explanation for why there are no extraterrestrials technologically between us and those aliens with the power to rewrite physical laws. And I’ve already linked to some attempts to falsify the third explanation.
At this point I am perfectly comfortable declaring that there are certainly some religious explanations which are too supernatural to deserve discussion. Anyone offering up the explanation that the entire universe is only a little over 6000 years old and thus extraterrestrials wouldn’t have time to develop, should not be taken seriously. But that is not what I’m claiming. My explanation, if rendered in the same fashion as the others in the book might run as follows:
God Exists: As expected aliens do exist, and their technology is vastly superior to ours, so much so that it appears miraculous. In order to pass this technology along they need to ensure we will use it responsibly. Existence, as we recognize it, is a test of this. This test is similar to current proposals to minimize AI Risk. And similarly a full understanding of both the test and the alien’s existence would invalidate it. Accordingly they act more subtly through things like miracles and prayer. All of which is to say, that aliens exist, they do communicate with us, Therefore, there is no Fermi’s Paradox.
Stated this way I would argue that it sounds similar to all of his other proposed explanations, there’s nothing that sets it apart as being especially supernatural, particularly when compared to the other explanations I just quoted. Some people may object to the fact that I entirely leave out life after death (and in the LDS case life before birth) which is both central to the majority of religions and definitely a supernatural element, but is not the same thing possible, even likely under the Simulation Hypothesis? And yet Ćirković not only includes it, but gives it a B- grade in his assessment of how seriously it should be considered.
As far as falsifiability, I would submit that it does even better here. Most of the explanations given above are only weakly falsifiable, and in fact have a resistance to falsifiability built right into the explanation. It is not any piece of evidence, but rather a lack of evidence, that makes us think Zookeepers and Programmers might exist. On the other hand I can think of at least three straightforward ways for the God Exists explanation to be falsified:
- Under Christian eschatology (the one I am most familiar with and the one that fits best with the God Exists explanation) we read concerning Christ’s second coming, “But of that day and hour knoweth no man, no, not the angels of heaven, but my Father only.” That said, I think everyone would agree that if it’s going to happen it should happen in the next few hundred years. Let’s round that up to a thousand. I will happily say that if Christ doesn’t return by 3018 that Christians are wrong about everything, including any ways in which Christianity might explain Fermi’s Paradox.
- As I mentioned above one of the more interesting things Ćirković points out is that the mere detection of a single alien signal would not resolve the stronger versions of Fermi’s Paradox, though it would falsify some explanations. The God Exists explanation is one of those, and to falsify it we would merely need to detect one other set of intelligent aliens anywhere. Note that none of the other three examples would be falsified by this. (Though, in theory these aliens could have a religion which corresponds to the God Exists explanation of the paradox in which case their discovery would push things the other way, and make the explanation far more likely.)
- The God Exists explanation makes several predictions about how things should work. As one example, for it to be true, traditional religious morality would have to have some long term value, even in the face of steadily advancing technology. If 500 years from now all religious societies have been decisively out competed by secular societies, then it would follow that we’d have good reason to reject the God Exists explanation (as well as most of the other claims of religion.) As I discussed in a previous post, the societal benefits of religion are often overlooked. As a more recent example of that, I refer you to the study showing that religion is better than cognitive-based therapy (one of the most recommended forms of treatment) for treating the most depressed.
I’m tempted at this point to give my explanation a grade, but obviously I’m not even close to being objective enough. Perhaps Ćirković will check in and do it for me. I suspect it will be lower than I would like, because even though he calls for greater attention for even radical ideas, this explanation is still probably both too supernatural and too anti-Copernican for his tastes.
I’ve already covered the supernatural angle, so I’ll close by discussing whether the explanation is anti-Copernican. It is true that most religious cosmologies are anti-Copernican. People are quick to point out that this was literally true during the time of Galileo. But here LDS/Mormon cosmology is different. It’s profoundly Copernican. It doesn’t think there’s anything special about Earth, or humanity. In the LDS version of Genesis, God tells Moses that he has created “worlds without number” and that all of them are inhabited. I would be surprised if Ćirković found this to be a very satisfying answer, but it does technically resolve that objection. And as to Ćirković’s more practical concern that latent anti-Copernicanism is fatally undermining SETI efforts, I would argue that LDS cosmology is not contributing to that. All the Mormons I know are excited by the idea.
Many of the explanations involve aliens with godlike powers and motivations, and I for one think injecting a little god and religion into the process is therefore entirely appropriate.
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