There's a UFO in My Garage

What would Carl Sagan say about the public frenzy over Unidentified Anomalous Phenomena (UAPs)?

In light of the July 26, 2023 Congressional hearings over UFOs and UAPs, and in honor of the late astronomer Carl Sagan—who legitimized and popularized the search for extraterrestrial intelligence more than anyone before or since—here is a thought experiment based on the one he presented in his magisterial 1996 book The Demon Haunted World: Science as a Candle in the Dark, which I call Sagan’s Dragon (that begins “A fire-breathing dragon lives in my garage”).

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“There’s a UFO in my garage. Would you like to see it?”

Sure you would. Who wouldn’t? UFOs are more popular today than any time in history, and now even politicians, military personnel, intelligence officers, media members, and the general public are demanding that the government disclose what it knows about aliens visiting our planet, buzzing our air space, snooping around military bases and naval assets, surveilling our nuclear weapons sites, and even committing violent acts against our citizens.

You’d like to believe in aliens. In the vastness of the cosmos jammed with hundreds of billions of galaxies, each of which has hundreds of billions of stars, around which almost all have planets, it seems highly improbable that we are the only intelligence around. But you don’t want to just believe. You want to know, as in knowledge, as in justified true belief. In science, justification comes from evidence.

“Yes, I most certainly would love to see your UFO!” you enthuse.

I eagerly oblige by taking you to my garage and opening the door. You look inside and see boxes of junk, empty cans and bottles, discarded tools and auto parts, a bicycle and assorted other nicknacks, but no UFO. “Where’s the alien spaceship?” you ask.

“Oh, uh, well, this spaceship has a cloaking device that renders it invisible,” I reply.

An “invisible UFO?” you query skeptically. Perhaps there’s a way to get around the spaceship’s stealthiness, you suggest, “by sprinkling flour on the floor of the garage so we could see the outline of the craft.”

“That won’t work,” I demur, “because this invisible UFO hovers a couple of feet above the ground.”

“Seriously? How does it do that?”

“My understanding is that it uses an anti-gravity propulsion system, and when it’s parked it is on idle and so it floats.”

“Um, interesting,” you acknowledge, then ask “what if we take a can of spray paint and spray all around the garage so we could at least see the body of the spaceship?”

“That won’t work, either” I explain, “because the energy from the cloaking device pushes all matter and energy—even light—out and around the spaceship, as if it were not even there, like those galactic-size lenses in space that bend the light from behind them. Maybe that’s where the aliens learned how to cloak their ships.”

“But,” you press on, your intrepid desire to test my claim leading you to think of other methods, “how about we get one of those portable thermometers everyone has been using during the pandemic and measure the temperature at different places in the garage to detect the heat from the UFO? Surely any cloaking technology and anti-gravity propulsion system would have to give off some heat energy, no?”

“Sorry,” I reply, “but I’m told that this spaceship operates at extremely low temperatures—remember, it traveled all the way to Earth from a distant planet through the coldness of space—so what little heat it gives off would be immeasurable by human-made thermometers.”

“Let me get this straight,” you groan in exasperation. “This UFO of yours is invisible, levitates, and gives off no heat whatsoever. Why should I believe you, then?”

“Because,” I rejoin confidently. “I have three eyewitnesses who saw the UFO with their own eyes.”

“Oh yeah?” you sputter with a raised eyebrow. “Who are these eyewitnesses and why should I believe them?”

“Well, one of them is a pilot. Another one is an astronaut. And the third one is a General.”

“So what?” you ask. “They’re humans and their senses and perceptual systems work the same as mine, and I know that I can easily misperceive things or be fooled by illusions.”

“Their credentials are impeccable,” I boast, filling in for you their military ranks, educational achievements, career awards, and endorsements from notable figures in government and the private sector, adding that even a former rock star vouches for their credibility.

“Fine,” you snort. “Can I talk to these eyewitnesses?”

“Sorry, no,” I explain. “They are afraid to come forward because of the possible consequences of sharing what they know.”

“Consequences?”

“Yes. One of them signed a Non-Disclosure Agreement, and as you know you can get into big legal trouble if you violate an NDA.”

“What about the others?” you reasonably ask.

“They can’t go on the record either because they’re afraid that whistleblower laws won’t adequately protect them, and because the information they have about the alien spaceship is classified they’re afraid of going to prison for disclosing government secrets.”

“Why would the government want to keep the discovery of extraterrestrial intelligence spacecraft a secret? Wouldn’t that be the greatest discovery in human history, one to be shared with all humanity? Wouldn’t NASA, the Department of Defense, DARPA, and the Pentagon all be able to go to congress with this big news and ask for larger budgets to study the aliens?”

“I’m told it is because we have a multi-decade UAP crash retrieval and reverse-engineering program and we don’t want the Russians and the Chinese to get their hands on this technology. It’s like another arms' race.”

“I get that,” you counter. “But why are these UFOs only landing or crashing in America? Aren’t other governments recovering downed spaceships?”

“Some are, yes,” I explain cautiously, concerned that this conversation might be monitored. “But one of my sources tells me that we have treaties with other nations about how to handle UAPs. He said: ‘The non-human intelligence phenomenon is real. We are not alone. Retrievals of this kind are not limited to the United States. This is a global phenomenon’.”

“Doesn’t the U in UAP, as in UFO, just mean these things are ‘unidentified’?” you continue inquisitively.

“Technically, yes,” I clarify. “But my sources tell me that from what they’ve seen these things are definitely off-world.”

“Off-world? How would they know for sure unless they knew everything that is on-world? Give me an example.”

“Okay, one of the pilots of an F-18 fighter jet said he saw something that looked like, in his words, ‘dark grey or black cubes…inside of a clear sphere, where the apex or tips of the cubes were touching the inside of that sphere.’ That sounds off-world to me.”

“Actually,” you retort, “that sounds like a balloon. In fact, I was reading this book on UFOs, written by a journalist who believes we’re being visited, who admits that 90-95 percent of all sightings can be explained by, in her list, ‘weather balloons, flares, sky lanterns, planes flying in formation, secret military aircraft, birds reflecting the sun, planes reflecting the sun, blimps, helicopters, the planets Venus or Mars, meteors or meteorites, space junk, satellites, swamp gas, spinning eddies, sun-dogs, ball lightning, ice crystals, reflected light off clouds, lights on the ground or lights reflected on a cockpit window, temperature inversions, hole-punch clouds,’ and the list goes on! Isn’t it far more likely that the remaining unexplained phenomena are some of these and not extraterrestrials?”

“I don’t know,” I begrudgingly retort. “Another one of my sources assures me that ‘We are not talking about prosaic origins or identities. The material includes intact and partially intact vehicles’.”

“Again,” you press on skeptically, “how does your source know all possible vehicles, intact or otherwise, to be able to conclude that they are not prosaic?”

“Look,” I note in frustration, “all I know is that the people I’ve talked to, who have gold-standard credentials, assure me that we are being visited by aliens.”

“Wait,” you say with a start, “when you say ‘aliens’ do you mean actual alien beings, as in bodies recovered with these spaceships?”

“Indeed,” I confirm. “One of my sources says that these spaceships are piloted by biologics.”

“Biologics?”

“Yeah, you know, non-human.”

“If aliens are able to traverse the vast distances of interstellar space and manage to find the one planet in our solar system with intelligent life, why do they keep crashing?” you wonder credulously. “And why do they always seem to crash in remote places and never in populated areas where a lot of people could examine the debris and describe the incident?”

“Look, these are all good questions,” I acknowledge. “But I only know what I’m told. I haven’t seen anything myself.”

“Are there photographs and videos of these things?” you reasonably wonder.

“Why sure, they’re all over the Internet.”

“Why are they all blurry and grainy? These pilots say that they see these things all the time buzzing our airspace. With hundreds of millions of smart phones with high-definition high-resolution cameras, why are there no clear photographs and videos?”

“Beats me,” I shrug. “Maybe they also have cloaking devices or stealth technology that blurs the images.”

“Could they be a threat to our civilization or to humanity itself?” you reasonably wonder.

“Not only could they be a threat,” I continue, “one of my sources says that he and his wife have witnessed violence against humans by aliens.”

“What? Violence? Seriously? Did he call 911? Did he alert the local police?”

“Not that I know of, but he says he’s scared,” I continue. “He told me he’s afraid of what the government might do to him if he talks. He called it ‘administrative terrorism’ and added ‘I have knowledge of active and planned reprisal activity against myself and other colleagues’.”

“Don’t whistleblower laws protect people like these eyewitnesses?” you ask.

“Uh, well, yeah, I think so, but maybe not. I don’t know. It’s complicated.”

“Let me ask you something,” you ponder in contemplative overview of what is or is not in the garage here. “What is the difference between an invisible levitating heatless un-detectable UFO purportedly witnessed by people who cannot or will not provide any evidence whatsoever of their existence…and no alien spaceship at all?”

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The answer to my imaginary interlocutor’s question is none!

There is no difference, and that’s the point. Here is how Carl Sagan put it with regard to his imaginary dragon:

Now, what's the difference between an invisible, incorporeal, floating dragon who spits heatless fire and no dragon at all? If there's no way to disprove my contention, no conceivable experiment that would count against it, what does it mean to say that my dragon exists? Your inability to invalidate my hypothesis is not at all the same thing as proving it true. Claims that cannot be tested, assertions immune to disproof are veridically worthless, whatever value they may have in inspiring us or in exciting our sense of wonder.

Be skeptical of anyone who claims to believe in something that cannot, even in principle, be confirmed or disconfirmed. When someone tells you a fantastic story or proclaims some (literally) unbelievable claim, try asking “What would it take to falsify your claim?” or “How could we test that claim?” or “Do you have any evidence for your claim?”

If they don’t have a good answer—or no answer at all—then it is reasonable to withhold your provisional assent. And if they have no evidence whatsoever, you can invoke what I call Hitchens’ Dictum, named after the late journalist and writer Christopher Hitchens:

“What can be asserted without evidence can also be dismissed without evidence.”

In this case we may be talking about Negative Truths, or truths for which the absence of evidence is evidence of absence. That is, when the nonexistence of something is the truth. For example, as editor of Skeptic magazine I am often asked if I “believe” in something, like aliens or Big Foot. My response is usually along these lines: “show me the body and I’ll believe, otherwise I’ll remain skeptical.”

In science, a negative truth is called the null hypothesis—that is, the nonexistence of something is the truth about it, until proven otherwise (“reject the null hypothesis” in the research jargon). At this point, some ask “can you prove Big Foot doesn’t exist?” or “can you prove aliens don’t exist?” The answer to these questions is no, but the burden of proof is not on the skeptic of the claim; the burden of proof is on the claimant. For all I know, aliens are zipping around our airspace or Big Foot is stomping around the hinterlands of the Himalayas even as I write these words. But I’m not the one making the claim, so it’s not up to me to disprove it.

A final point: as I’ve said many times, I think it highly likely that there are extraterrestrial intelligences somewhere in the cosmos, but I also think it highly unlikely that they have come to Earth. As I calculated in this Quillette article (using the Drake Equation), there are probably only a handful of ETIs in each galaxy, therefore “if there were only a few intelligent and communicating civilizations the probability of them making contact with one another is astronomically low.” Why?

Just how vast and empty is space? If our star were the size of an orange and it were in Los Angeles, the nearest star would be an orange in Chicago 2,000 miles away. In about four billion years, the Andromeda galaxy will collide with our own, but the stars are so far apart from one another that it is conceivable there will be no stellar collisions. A final example: the speed of our most distant spacecraft, Voyager I, is 38,578 miles per hour. If it were heading to the Alpha Centauri star system, the closest to our sun at 4.3 light years away (which it isn’t), it would take Voyager 74,912 years to get to there.

If there are ETIs in our galaxy, the chances of them finding Earth and visiting us even once is staggeringly low, let alone buzzing our airspace on a daily basis. Thus, the UAP = ETI hypothesis is extremely unlikely to be true.

Nevertheless, like any good scientist or Bayesian reasoner, I have an open mind on the matter. Here is how I described it in the above article:

To put it a slightly different way in this context, an extraordinary claim—for example, that UFOs = ETIs—has a low Bayesian prior because of the poor quality of the evidence for it, and thus the credence for the hypothesis that UAPs = ETIs remains low unless better evidence emerges. Until then, we should have a lower credence in the claim of being visited by ETIs.

The same Bayesian reasoning applies to UAPs as Russian or Chinese assets. Given what we know about the evolution of technological innovation—that it is gradual, recombinant, contagious, collaborative, and cumulative—no nation or corporate entity can have built drones or aircraft with such extraordinary physics and aerodynamics without us knowing about it. So, again, lacking extraordinary evidence in the form of an actual captured object, our credence that these UAPs represent extraordinary terrestrial craft remains low.

If the evidence improves I will adjust my priors and increase my credence that we have made contact with aliens. So let’s once and for all get to the bottom of these UFOs and UAPs, stop with the secrecy, cover-up, and classificatory obfuscation, and reveal for all to see what, exactly, is going on. Otherwise, my garage remains empty.

Michael Shermer is the Publisher of Skeptic magazine, Executive Director of the Skeptics Society, and the host of The Michael Shermer Show. His many books include Why People Believe Weird Things, The Science of Good and Evil, The Believing Brain, The Moral Arc, and Heavens on Earth. His new book is Conspiracy: Why the Rational Believe the Irrational.