UFOs and Aliens: As a Scientist, I Believe in Both, But Here’s Where I Draw the Line

Reports of strange lights in the sky. What appear to be craft flying through the air following impossible trajectories. Radar and camera signatures of mysterious origins. Whatever you want to call them—Unidentified Flying Objects (UFOs) or Unidentified Anomalous Phenomena (UAPs)—they are certainly weird. I get it; many of the questions we have about these bizarre occurrences do not have a satisfying answer.

But this is exactly why, as a scientist, I won’t say they’re aliens.

🛸 Did You Know? UAP originally stood for “Unidentified Aerial Phenomena.” However, to be consistent with the National Defense Authorization Act (NDAA), NASA switched to calling UAPs “Unidentified Anomalous Phenomena” in 2022.

While reports of alien ships have been a part of our culture since we began training the first astronauts at the dawn of the space age, there’s been a resurgence in UAP curiosity over the past two years, with congressional hearings, NASA-led working groups, public databases, and more, all devoted to answering the timeless question: what’s that in the sky? And the supposed evidence is compounding, too, with recordings from military and civilian pilots and crew. They have released footage of (what appear to be) flying machines crisscrossing their field of view, or screens showing radar, infrared, or other remote imaging of objects exhibiting downright strange behavior.

Many of these sightings end up having mundane, technical explanations, like wayward drones, miscalibrated sensors, or incomplete information, all of which create the illusion of something unusual.

Admittedly, some sightings defy explanation. These are situations in which no team of experts has been able to identify a cause behind a strange UAP report. That’s why the Office of the Director of National Intelligence designated a UAP Task Force to try to explain 143 mysterious sightings from a 2021 report. For example, in one 2015 case, Navy pilots observed objects moving fast with great agility, in some cases appearing to plunge underwater. To date, there has been no commonly agreed upon explanation for those sightings.

And without additional information, scientists have to stop and say three simple words: “I don’t know.”

But that phrase doesn’t mean we live in a sea of ignorance. We can say that we don’t know the true origins of the most mysteries of UAPs, and we can also say that they are likely not aliens.

After all, mysteries abound not just in Earth’s atmosphere, but throughout the cosmos. We don’t understand what powers Jupiter’s giant storms. We don’t understand why the sun’s corona is so hot. We don’t understand how the first stars appeared in the universe … and so on. Ongoing mysteries are the reason that scientists get out of bed in the morning. Because we suppose that aliens are intelligent and technologically sophisticated, we could potentially turn to them to explain everything: aliens are powering Jupiter’s giant storms, and heating up the sun’s corona, and creating the first stars.

To Prove the Existence of Aliens, You Need a Body of Evidence

Finding the answers to any of these mysteries requires incredibly high standards of evidence. You can posit any theory you want, with as much beauty and sophistication and force of argument as you can cram into it—but if it goes against the evidence, it’s tossed in the trash.

For example, the history of science is littered with ideas that sounded good, but ultimately did not live up to the evidence. We used to think that a mother’s stress levels caused birth defects, that the sun orbited around Earth, and that an invisible kind of fluid was responsible for causing heat. With more evidence, we now understand genetics, gravity, and thermodynamics, and so we left those old ideas behind.

When it comes to UAPs, if you want to claim that aliens are visiting Earth and this is what we’re seeing, by all means, go ahead. It’s a hypothesis, and a testable one at that: if we were to ever get our hands on one of these supposed spacecraft, crack open the door, and say hello to whomever is inside, then the hypothesis would be validated.

But we haven’t yet done that. So we can’t say for certain that UAPs, even some of them, are due to alien activity. It’s in the name, after all: unidentified anomalous phenomena remain unidentified. As soon as you claim that an unexplained incident is due to alien activity, then you’re claiming to have an identification for the aliens that caused the incident.

Since evidence is the ultimate judge, you need a substantial amount of positive evidence working in your favor. You also need a cohesive base of support for your hypothesis. In other words, you can’t drop a bomb like “it’s aliens” and walk away; you have to back it up and provide additional sources of evidence. For example, I can say with an extreme amount of confidence that our universe is 13.77 billion years old. I didn’t just pull that number out of a hat, or make an educated guess. That number comes from over a century of studying the universe: combining data and more than one line of evidence from the expansion rate of the universe, observing the leftover light from the Big Bang, taking insights from nuclear theory, and more. Every simple statement in science is backed up by mountains of evidence.

These are not impossible questions to navigate, but to date, there have not been any successful answers, and so the alien hypothesis remains a relatively weak one.

Why You Shouldn’t Jump to Conclusions

On the other hand, as long as UAPs remain unidentified, it’s impossible to rule out an alien hypothesis entirely. However, without further evidence, we can point to potential explanations that make a much stronger case and more readily coexist with our wider body of knowledge—even if we can’t yet prove them. For example, we know that sensors occasionally malfunction and give false readings, or that computer analysis algorithms can misinterpret data. Therefore, what appears to be an alien ship may in fact be a weather balloon instead. It does not take great leaps in logic or vast knowledge to make such a statement, and so it’s a much stronger hypothesis, simply because it’s a more likely, albeit mundane, explanation.

Lastly, intelligent aliens make for a poor scientific hypothesis because the idea of intelligent aliens could explain virtually any mysterious phenomenon. When scientists come across a new situation and want to explain it, they can’t just make up supernatural stories. They are forced to explain the situation in terms of rules of the natural world: forces, energies, particles, and so on.

Because aliens could explain everything, they end up explaining nothing. Aliens on Earth are not a useful scientific hypothesis, because it doesn’t help us dig deeper into the workings of nature. Instead, aliens bring up more questions than they answer, making our scientific lives more complicated, which is the opposite of what we try to do in science.

The Bottom Line

Speaking personally, I think there are aliens out there in the universe. There are likely many intelligent civilizations living in parallel to ours, since it’s a big universe, after all. But there is no substantial evidence they have visited Earth.

Simultaneously, I can’t explain some of the observed UAP phenomena. These two statements are not in contradiction—“I don’t know” and “that’s not a good hypothesis, therefore I don’t have to believe it” both speak to the spirit of scientific curiosity. This spirit moves us to explore the universe around us and let our imaginations run free … but to let the evidence ultimately decide what we should believe in.

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