By Jack Singal
Recent declassified images and videos of seemingly strange shapes darting across the sky may have caused a media storm, but the real story that needs to be told is that we finally know something about the likelihood of intelligent life in the Universe.
Ancient questions and modern imaginations
People have wondered whether or not there are other beings and minds beyond the Earth at least since the ancient Greek philosopher Epicurus in the third century BC. It was an active topic of theological debate through the Renaissance, and eventually imagining aliens, their worlds, and their possible visits to us became a major part of popular culture in the 20th century. Cultural takes on alien life and UFOs have ranged from the more thoughtful and philosophical to the absurdity of gray beings conspiring with international government officials.
Starting in the summer of 2021, such speculations received a major boost with the release of newly declassified footage from the Pentagon showing purportedly unidentified objects improbably moving through the sky. These grainy images received widespread coverage in news and social media. It is ironic that these often blurry and confusing images are coming out just when we’ve actually discovered more than we used to know about the likelihood of alien life.
New data for an old question
The scientific assessment of the probability of intelligent life being out there involves factors from both astronomy and biology. From astronomy, we need to know the prevalence of planets that are capable of supporting intelligent life, and from biology we need to know how likely it is for life to appear and then evolve to intelligent forms. Until very recently, we could only speculate on the astronomical question—the total number of known planets outside of our solar system was zero from the dawn of astronomy until 29 years ago. Even 15 years ago, it was barely more than 100. Today, we have confirmed more than 5000 extrasolar planets and that number is rapidly increasing. We are in the midst of a scientific revolution in our understanding of “exoplanets,” or planets outside the solar system.
There are several ways to detect planets around other stars, but the way that might seem most intuitive—seeing them directly through a telescope—is the least common. Much more important is the detection of planets via the transit method, where a planet passes in front of its star from our viewpoint, blocking a tiny fraction of the star’s light that would otherwise make its way to us. Seeing the star’s light briefly and periodically dim from our perspective allows astronomers to infer the planet’s orbital distance, size, and other characteristics.
Right: Data from NASA’s Kepler satellite telescope showing a planetary transit event for a distant star, where the star’s measured light flux decreases by less than 1% as the planet passes in front of the star from our perspective. (Credit: NASA.)
We have learned in the past decade that planets are ubiquitous in our Galaxy, and come in all combinations of sizes and distances from their stars. We now know that it is not rare for planets to have the characteristics that would allow them to support intelligent life: moderate temperatures to allow the chemistry of life, as well as hard surfaces with elements to allow the building of complex molecules and the construction of tools and structures.
(Image credit: PHL @ Arecibo.)
Now that we know that planets capable of supporting intelligent life are quite common, the unknown factors determining how widespread or rare intelligent life is in the Galaxy are those that biologists, not astronomers, can answer. However, considering that there are seemingly potentially billions of worlds suitable for intelligent life in our Galaxy, that life on Earth emerged relatively quickly after its formation, and that brains evolved independently at least three times throughout life’s history on Earth, it is reasonable to conclude, in this author’s opinion, that it is more likely than not that at least some other form of intelligent life is out there, somewhere.
[Check out this interactive data visualization from Information is Beautiful to explore some of the equations astronomers use to estimate the number of planets with intelligent life in our Galaxy and Universe.]
UFOs: Open-minded skepticism
If we accept the premise that there is likely to be other intelligent life out there in the Galaxy and beyond, can we expect to meet them? Are the vast distances between the stars too daunting, or have civilizations had millions of years to advance and conquer those distances? Have they visited us?
These questions are still in the realm of pure speculation, but we need to evaluate claims of UFO phenomena with an appropriate amount of skepticism. First of all, we should assume that any image or video posted to social media or featured on a news platform that depends on viewer ratings or clicks for revenue (which is all of them) has been deceptively edited. Such edits can include cropping to remove context which could indicate the sizes and distances involved, and speeding up or slowing down videos to make motions look more bizarre.
Next, we should consider whether it may actually be mundane objects, such as kites, drones, or airplanes, that we are seeing. These are often difficult to rule out because of poor image and video quality, as well as the potential edits mentioned. For example, a widely circulated video seemed to show a triangular object with flashing lights moving rapidly. However, a careful analysis showed that the apparent triangular shape could arise due to the shape of the camera’s aperture with an out-of-focus object (and indeed upon close examination in sections of the video other objects temporarily appeared to have a triangular shape), while the rate with which the object moved across the screen, given the size of field of view, was calculated to be consistent with an airplane flying at a standard speed and altitude.
Lastly, even if we are convinced that we are seeing a truly mysterious phenomenon, we must remember that our atmosphere is an amazing place. We know it can produce tornadoes that can pick up and throw a car, multiple images of the Sun that ring the sky, triple rainbows, and many other phenomena that are at least as interesting and seemingly improbable as an object flying through the air.
Observations planned for the coming decades have the potential to possibly discover the chemical signatures of life or industrial civilization on a distant exoplanet, and we might detect a radio or laser signal of intelligent origin at any point. These would be infinitely more important than any amateur video of the sky, and even in their absence we can continue to marvel at what we have learned from the exoplanet revolution of the past decade.
These ideas were discussed in detail in a recent KIPAC public lecture.
(The author, a former KIPAC member, is now an associate professor of physics at the University of Richmond and was a visiting scholar at KIPAC for the 2021-2022 year.)
