There’s been a lot of hullabaloo about the recent revelations that the Pentagon still has/had a program investigating UFOs and the recently released footage of UFO encounters accompanying it, and furthermore, the suggestion that the aerospace contractor behind it has recovered some actual material from the UFO sites.

Personally, I don’t think it’s aliens at all. Occam’s razor would suggest otherwise. However, it’s an interesting thought experiment to think through, if the UFOs were aliens, how would that change our understanding of the universe?

Firstly, the Fermi paradox. Discovery of another alien species (especially one that’s got here, instead of in an unimaginably distant galaxy) would shift the spread of probabilities towards our universe being a fundamentally lifebearing one. We would no longer have recourse to anthropic arguments about the probability of life. We would have hard evidence that life can arise twice,in the same timeframe, and almost certainly in the same galaxy. This means that we should naively expect every galaxy to have several alien races coexisting simultaneously at all times, ourselves included.

But in many ways this renders the Fermi paradox even more acute. If we know that there are so many, why can’t we see them? Why aren’t they out there building dyson swarms and tiling the universe with paperclips? In many ways, it would thus probably be comforting. We know we likely don’t have to worry about UFAI or similar disasters in our future, since clearly they haven’t happened to the multitude of alien civilisations inhabiting our galaxy and universe. The lack of dyson swarms, however, is more puzzling. One answer is that they are there but we don’t see them as they are hidden or our instruments aren’t sensitive enough or we aren’t looking at enough of the sky. This would be a simple answer, but then the question remains, why haven’t whoever is on the dyson spheres already colonized the rest of the galaxy? Galactic colonization is pretty trivial and quick (only a few million years most likely) once your civilization has reached kardashev 2. Another possibility is that there is a hard limit on technology which renders dyson swarms impossible. The trouble is, it’s hard to see how this would work. We know dyson swarms are very impossible under known physics. They are even possible without fusion. Theoretically they are possible to construct even with current technology (!), albeit scaled to a massive extent. This means that if we know there are aliens and our galaxy is not full of dyson swarms and completely colonized then either both of our species have arisen within, say, a million years of each other and none have arisen before, or arisen in other galaxies and gone on an intergalactic colonization spree - which statistically seems unlikely. Or that there are some inherent limits in the universe as to the size and scale which civilizations can build, and very low ones at that, significantly lower than current physics would permit. Or, else there is some other reason that any alien civilization, once it reaches a high technological level, because uninterested in that kind of expansion.

The next interesting fact is that we can see the UFOs. Many reports have both visual, infrared, and radar sensing of the object. Assuming that the UFO is alien, that means that either a.) their stealth technology is so poor (or non-existent) that we can detect them. Or b.) that they want to be seen or are uninterested in hiding at any rate.

Both options are very interesting. A priori a.) seems incredibly unlikely. If they are a civilization capable of interstellar travel, it would seem absurd that they cannot hide from radar or an infrared camera. Indeed humanity at this moment possesses stealth planes that can do that. If this is the case then it would imply, perhaps, that interstellar (possibly superluminal) travel is significantly easier than we think. So easy, in fact, that a civilization could develop it before any kind of stealth technology that we possess. Perhaps even earlier than computers. Perhaps our civilization has, for whatever reason, taken a technologically and scientifically deviant course and somehow missed easy superluminal travel while developing many other technologies to compensate. This is consistent with the observation that many UFOs often make seemingly “impossible” maneuvers, and none have been reported with reaction like rocket engines. If there exists any kind of reactionless drive ,then interstellar travel would be significantly easier than we project today, even without FTL travel. Reactionless drives would also explain another puzzling question. If there are aliens here, why did we not see them arrive? Interstellar flight burns a huge amount of energy. We should be able to see any fusion or antimatter or whatever interstellar craft beginning its decelleratory burn into our solar system. At least recently. Granted they may have decellerated and set up camp in the Oort cloud many centuries ago, but if then they need to travel into the inner system, and we should be able to detect any fusion craft, even small interplanetary ones, operating in our immediate vicinity. If they have some kind of inertialess, reactionless drive, then this detection possibility becomes significantly more difficult. Even so, if the hypothetical aliens did not have stealth technology when they arrived, it still does not explain why they haven’t managed to copy it off of us in the first place.

Option b.): that the aliens are uninterested in hiding, or actively want to be seen also doesn’t make much sense. Imputing motives to alien intelligence is hard, but it is difficult to discern a consistent motive from what evidence we have. If they are uninterested in hiding, then why are they not much more obvious? They are a species capable of traveling between the stars, who have been observing us at least since the 1940s (when the first serious reports started arriving) and possibly significantly before. They undoubtedly have managed to analyze our languages and communication systems. If they wanted to they could easily park their ship next to earth, and announce their presence. Since they have not done that yet, then that implies that they are not ready or wanting to reveal themselves to us yet. Yet, if that is the case, why send ships down to Earth, for whatever purpose (likely study) which can be detected with our native technology. This seems like an incredibly oversight which no reasonable alien civilization will make. So we are left with a paradox. It is possible that for whatever reason the aliens enjoy messing with us, as in the buzzers in Hitchhikers Guide to the Galaxy. But, given the likely expense and difficulty of interstelllar travel, this seems like an incredibly strange and wasteful use of resources.

Thus, if the UFOs are aliens, a lot of what we currently think about the universe would be upended. The Fermi paradox would, in fact, become more pressing, since we know there are aliens out there, the question then becomes, why haven’t they colonized the universe yet. Their existence would seem to imply some hard and low limits on the capabilities of civilizations (including making dyson spheres impossible!, and likely full AI too!). It would imply that interstellar travel is likely easier than we would expect and has a greater reward than staying at home to build up an individual solar system, and, in general it tilts the balance of probability more towards a standard science fiction universe of many alien species, each of a high technological level but nowhere approaching a realistic Kardashev 2,without vast UFAI takeovers and with easyish communication and travel between them. In many ways, this is nicer and much less bleak than the standard futurist vision of an empty universe in which we are either alone or about to be eaten by an alien expanding paperclipper, and whose future will likely be dominated by AI singletons of an unimaginable scale. On the other hand, such a universe implies strict limits on  technology including technologies which we suspect are possible under current physics, and that is somewhat depressing. Or, more likely, that the actual strategic equilibrium of the universe is significantly stranger than we can imagine now.