From my knowledge of the world that I see around me, I think that it is much more likely that the reports of flying saucers are the results of the known irrational characteristics of terrestrial intelligence than of the unknown rational efforts of extra-terrestrial intelligence.
~Richard P. Feynman, The Character of Physical Law
On June 25th, the Office of the US Director of National Intelligence created a national stir by releasing a long awaited, if short, nine-page unclassified report entitled, “Preliminary Assessment: Unidentified Aerial Phenomena.” It was created under the direction of the Intelligence Authorization act of 2021 to assess the threat posed by unidentified areal phenomena, and the results of the Department of Defense Unidentified Aerial Phenomena Task Force (UAPTF) effort to understand this threat. Put in more popular parlance, it was an official government report about UFOs.
The report came almost 74 years to the day after a pilot flying near Mt. Rainier sighted a string of nine “shiny unidentified flying objects,” which the press reported as flying saucers, launching the modern UFO era. The report publicly enumerated the existence of 144 UAP’s reported by US government sources since 2004. Of these, one was subsequently definitively determined to be a large, deflating balloon. The other 143 reported sightings remain unidentified, a fact that has stirred a great deal of popular interest.
UFOs, like beauty, remain in the eye of the beholder. UFO enthusiasts heralded the report as the first official evidence of possible extraterrestrial intelligence, while media from around the world focused on the large number of official sightings that remain unexplained and speculated on everything from unknown Chinese or Russian technology to, of course, aliens.
For those less committed to dreams of little green men, the report instead made it clear that “unidentified” simply means there is not sufficient data, based on the reporting, to identify the source of the sighting. Mick West, a writer who has spent years debunking UFO myths, stressed the central conclusions of the report, which indicated that limited data and inconsistent reporting are prime reasons these objects remain unidentified—not because of their intrinsic strangeness—and that “UAPs probably lack a single explanation.” As West put it, “The report suggests the majority of cases, if solved, would turn out to be a variety of things like airborne cluster or natural atmospheric phenomenon.”
Of course, no such qualification is likely to ever convince true believers that UAPs are neither evidence of advanced extraterrestrial intelligence, nor of super-secret advanced technologies possessed by our terrestrial military adversaries. In the interaction that led Feynman to his famous quote about flying sources, he claimed an antagonist interrogated him by saying “Is it impossible that there are flying saucers? Can you prove that it’s impossible?” Feynman replied that the business of science isn’t in such discussions. Rather, “It is scientific only to say what is more likely and what is less likely, and not be proving all the time the possible and impossible.”
So it is fair to say, in these terms, that the presumption that UAPs represent alien spacecraft is very unlikely. In fact, I would argue that it is so unlikely that essentially any other explanation one can come up with, no matter how exotic, is bound to be more likely.
How can I say this, without having knowledge about possible super-advanced alien technologies? The reasons are numerous, and I have written about this in various books, but there are essentially five major arguments:
- The Laws of Physics: Travel from another star in any reasonable time requires near-light speed travel. A ship propelled by onboard conventional rocket fuel would require more fuel than there is mass in the visible universe to accelerate to near light speed and slow down at the end of the voyage, so clearly some more advanced fuel would be required. But even using nuclear fusion one would use more than 2,000 times the mass of the ship in fuel for each acceleration and deceleration to and from near-light speed. Basic physics constraints imply that any on-board propulsion technology that could power a conventional ship-sized spacecraft to travel from one solar system to another at near light speed and decelerate it within our solar system would require using energy that is comparable to the entire amount of power used by all of humanity at the current time. Hard to imagine any civilization devoting such extensive resources to visit us only to hang around secretly spying on aircraft carriers, or abducting humans to perform kinky experiments.
- It only hurts when you stop: Some reports claim UAPs travel extremely fast and stop or turn instantly. No matter what the propulsion system, g-forces experienced in such a maneuver would be enough to crush steel, not to mention the unfortunate aliens inside. That is, unless one had “inertial dampers” like they have in Star Trek, which, alas, are science fiction technobabble.
- The Lunar Module was ugly for a reason: Moving in space and traveling in our atmosphere are two different things. There is no reason to have fancy aerodynamics in space because there isn’t any atmosphere to have dynamics in. Whatever craft you travel in through the galaxy will not be the same type of craft you would want to design to perform aerial acrobatics in on Earth.
- Why here?: Most Stars in the galaxy are older than our sun so it is reasonable to suspect that an advanced civilization, if such civilizations survive periods like the one we are now living in, would have been able to observe the Earth since its formation. But over the past 4.5 billion years, we have only been sending out signals of technological intelligence for a century or so, meaning that observing Earth at any random time since it formed, one would only have a one in 50 million chance of detecting life here. Moreover, since our radio and TV signals have only been traveling at light speed for 100 years, any civilization that detected such signals would have to be: (a) close by, and (b) ready to immediately launch a massive, complex, and expensive light speed mission to Earth in order to have made it here by now. And that is if they were lucky enough to detect our signals in the first place. There are an infinite number of frequencies to search, and as anyone who has cable TV knows, where there are only perhaps 400 channels to scan, one generally has a hard time finding what one is looking for before the program one is seeking is over.
- Why travel in the first place: In this pandemic era, many of us have learned that it is a lot easier to have a ZOOM meeting than to try to embark on air travel across international lines. This is particularly true for space travel. It is far, far easier to both search for extraterrestrial intelligences by listening for signals, or to attempt to communicate with other galactic species by cleverly sending signals, than it is to try and bridge the gap with spacecraft. If we are ever to learn about intelligent aliens, it won’t be by meeting them in the air, but by listening or watching the heavens. Even that is a longshot, but at least is possible. That truth goes for aliens as well as for us.
Given a universe full of 100 billion galaxies, each containing perhaps 100 billion stars, and given that most stars have solar systems around them, and given that life on Earth evolved about as soon as the laws of physics and chemistry allowed, with just water, sunlight, and organic materials—all of which exist in abundance throughout the galaxy—I expect that life exists in profusion throughout the galaxy. Intelligent life is probably far rarer—it took over four billion years for hominids to evolve on our planet, and there is no reason to suspect that we are atypical.
But, as Douglas Adams put it in The Hitchhikers Guide to the Galaxy: “Space is big. Really big. You just won’t believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space…” As much as we might want definitive evidence that we are not alone—namely proof that other intelligent technological species exist—the likelihood of obtaining such evidence probably slim. The probability of being actually visited by other intelligent lifeforms is even more remote, essentially zero. Not impossible, as Feynman would admit, but sufficiently unlikely that we can usefully worry about other things instead.
Lawrence M. Krauss, a theoretical physicist and cosmologist, is the president of the Origins Project Foundation, and the author of the bestselling book The Physics of Star Trek. His most recent book is The Physics of Climate Change.