Are We Being Visited By Aliens?

(Est. reading time: 8 minutes. With addendum, 11 min.)

There’s been a lot of publicity about the government’s release of files relating to UFOs (sorry: UAPs now; unexplained aerial phenomena). It has caused a resurgence in speculation, responsible and otherwise, about whether there are creatures from another planet wandering around our skies.

Q: Is the Earth being visited by creatures from another planet?

A: No.

Goodbye.

Okay, maybe I need to wrap a few more words around this. Let’s start by discussing something called “Occam’s Razor.”

Occam (William of Ockham) was a 14^th century Franciscan monk generally credited with the idea that, when you have more than one possible explanation for something, the one that requires you to make the fewest unprovable assumptions is the one you want to lean towards.

In other words: The simplest explanation is usually the correct one.

Here’s an example. You see paw prints in the grass in front of your house. One assumption is that an escapee from a lunatic asylum in Afghanistan traveled to your house carrying plaster models of the feet of small animals, pressed them into the grass and then flew back to Afghanistan.

Another is that a new species of subterranean bacteria evolved to inject toxins into grass in patterns mimicking animal prints in order to lure unsuspecting birds into crashing and dying so the bacteria could eat them.

Another is that a neighbor’s cat walked across your lawn when you weren’t looking.

Applying Occam’s Razor (the paring away of less likely assumptions) would lead you to conclude that it was neighbor’s cat what done it.

With me so far? Good. Now consider this scenario:

Some pilots photograph objects they’re unable to identify that seem to be traveling across the sky, performing unusual maneuvers that ordinary airplanes can’t do. What to make of this?

One possibility is that a government or well-funded enterprise is secretly experimenting with advanced drone aircraft.

Another is that an unusual confluence of clouds and sunlight is creating patterns that appear to swoop and zigzag depending on what angle they’re being observed from.

Another is that a group of creatures from a distant star system survived a million-year trip in a spaceship the size of the Astrodome in order to play grab-ass with a couple of F-18s but not otherwise announce themselves or make contact with humankind.

I don’t know about you, but I’m blown away at the number of people who will casually toss away the first two, entirely plausible possibilities and immediately jump to the conclusion that we’re being visited by extra-terrestrials.

Check out this image:

It’s part of some rock carvings made over 3,000 years ago in northern Italy. What do you think the image represents?

A lot of people got famous and made a lot of money writing books declaring this carving and others to be definitive proof that we were visited by ancient astronauts in spacesuits and helmets during the Iron Age.

Occam’s Razor would say the artist was drawing traditional headdresses and clothes.

One of my favorite such examples has to do with the hundreds of ancient artifacts that would have required the use of the wheel, which hadn’t been invented yet, and therefore had to have been made by alien visitors.

The only thing evidenced by all those artifacts is that the wheel was invented earlier than we thought, because that conclusion requires far fewer unprovable assumptions.

What’s wrong with the idea that we’ve been visited by aliens, or that they’re here now?

Surprisingly, it doesn’t have anything to do with whether there’s life elsewhere in the universe. That’s pretty much irrelevant, because even if there is life out there, it hasn’t come here.

The reason has to do with physics, timing and a little common sense.

The nearest planets thought to have the right conditions to support life outside our solar system lie in a star system called Tau Ceti. It’s 12 light years away, which translates to about 75 trillion miles. The odds of there being life on any of the planets in the star system that just happens to be closest to us are ridiculously small, but let’s ignore that for now and assume there is.

The fastest human-made object ever built was the Parker Solar Probe, launched in 2018 atop a Delta Heavy rocket. The rocket itself wasn’t all that fast off the pad, but using a series of gravitational “sling shot” assists from the Sun and Venus, the probe cranked itself up to a blistering 430,000 miles per hour. That’s New York to Tokyo in less than a minute.

Assuming that there is life on one of the planets in the Tau Ceti system, and assuming that the life forms there are highly advanced, and assuming they wanted to visit the Earth, and assuming that they managed to build a crewed spaceship that got up to the same speed as the Parker Solar Probe, to have gotten here by now they would have to have started the journey 18,000 years ago, during the last Ice Age. Even if they managed an unimaginable million miles per hour, the trip would still take about 9,000 years.

Ignoring what kind of propulsion and fuel that would take, how do you even keep the crew alive that long? Or, more correctly, a couple of hundred generations of crew because, unless you put the original guys in suspended animation (a science fiction concept with no basis in reality), they’re going to grow old and die so they better be procreating along the way.

And, what would even be the point of the trip if all they did when they get here is secretly flit around in our atmosphere? It doesn’t makes a lick of sense. (Then again, alien common sense might be very unlike our own.)

That’s assuming that there was anything alive in the Tau Ceti system at that time to attempt the journey. An advanced civilization, if it exists, is probably thousands or millions of light years away.

Which bring us to another, more subtle problem, and that has to do with timing. The Earth is about 4.4 billion years old. Humans have lived here for about 300,000 years, only settled into villages around 12,000 years ago, and only left our atmosphere 67 years ago. That’s a very small sliver of time over the total age of the Earth. For us to be visited by beings from another planet, that planet would have to have evolved over roughly the same time period so that its current residents would be in a position to visit us right now. A few thousand years sooner or later and it just wouldn’t work. Again, what are the odds of that much coincidence?

There’s also the matter of somebody out there even finding out we exist. We’ve only been transmitting radio and television signals for the last 130 years, so the only creatures capable of receiving a transmission as a clue to our existence would have to be within 130 light years of us. There are only a few thousand stars within that “radio bubble” and the odds of any of them containing planets with sentient beings are absurdly low.

But let’s say that there’s advanced life on a Tau Ceti planet and they caught wind of one of our transmissions a hundred years ago and got curious. Assuming it took 30 years for them to gear up for a trip, they’d have to travel at over 28 million miles per hour to have gotten here by now. That’s more than 4% the speed of light. To accelerate a 1000-ton spaceship to that speed would require energy equivalent to 10% of the entire Earth’s energy for an entire year, or 340 times the largest hydrogen bomb ever made.

By now, the science fiction fans among you are probably wondering why I’m sticking to “conventional” travel. Maybe you’re thinking, What about faster-than-light travel?

Forget it. There’s no such thing. The speed of light, about 300,000 kilometers per second, is the absolute speed limit of the universe. Nothing can go faster, and anything you’ve ever read saying otherwise is bunk. (I’ll explain why in another article, but 300,000 kilometers per second isn’t just a good idea; it’s the law.)

Okay, you’re thinking now, what about wormholes?

Wormholes. (Sigh) Alright. Imagine a piece of paper with a pencil mark near the top and another near the bottom. To travel from one to the other, you’d have to walk all the way across the sheet of paper.

But what if instead you bent the paper so the two pencil marks were very close, and then punched a hole through the paper to connect them? You’d save yourself a long trip.

That’s what a wormhole is, warping space itself to create a tunnel from one point to a distant other point. It’s how you bypass the speed limit of light and take a shortcut.

There’s just one problem: Wormholes don’t exist. If you read my article on Black Holes, you’d know that even two black holes colliding only manages to create a “ripple” less than the width of a proton. To create a disturbance big enough to give rise to a wormhole, you’d pretty much have to destroy a few million galaxies.

But why even travel as the first step? Let’s use some common sense here. If the Tau Ceti creatures wanted to make contact, wouldn’t it be easier, not to mention several thousand years quicker, to just shoot a signal down to us and see if we respond?

All of that aside, nobody out there is going to detect life on Earth anyway. Why would we think that somebody 12 light years away would be able to detect an episode of The Flintstones after it’s traveled through 72 trillion miles of interstellar space? TV and radio stations can’t even get a signal across the country without boosting it along the way.

To the listening universe, Earth is completely silent, just another nondescript chunk of rock orbiting a nondescript star, one among billions of such stars.

There would probably be nothing more exciting in the history of humanity than discovering that we’re not alone. Maybe one of these days we’ll detect a signal created by sentient beings quadrillions or quintillions of miles away.

(Physicist Enrico Fermi didn’t think so, by the way, and framed his famous Fermi Paradox very simply: “If the universe is teeming with life,” he asked, “where is everybody?”)

To be sure, we’re listening. A project called SETI (Search for Extraterrestrial Intelligence) has been aiming huge antennas at the cosmos for 65 years. So far, there’s been nothing.

(Okay, one thing. The explanation of why, sadly, it proved to be a false alarm is a little technical so I split it out in an Addendum below.)

It’s not at all unreasonable to believe that there are distant civilizations advanced enough to produce a signal strong enough to reach us. But a visit?

Not happening. As my friend Brian Dunning of Skeptoid.com put it to me, “Without exception, every video that has enough information to make identification possible shows a perfectly mundane object — almost always a plane or balloon — either floating with the wind or flying an ordinary course.”

So the next time you hear about something unusual occurring in the sky, assume it’s swamp gas, not aliens.

* * *

Addendum

The Wow! Signal

The following is not at all necessary for understanding what this article is about. But those of you who are curious about such things as the search for extra-terrestrial intelligence might find the story of the Wow! signal interesting.

On August 17, 1977, an astronomer named Jerry Ehman was looking over the printout of observations made by a large radio telescope at Ohio State University. Something caught his eye, and when he looked closer he was so floored he circled it in red ink and wrote “Wow!” next to it.

What shocked Ehman, as well as other astronomers he shared the data with, was that this signal looked exactly like what they’d speculated it would if it had been purposely sent by an alien civilization. (The “6EQUJ5” circled on the printout is not the signal. It’s just the strength of the signal written in shorthand code in order to save paper.)

The Ohio State radio telescope was immovable, relying on the rotation of the Earth to scan the sky. A fixed point in space would take exactly 72 seconds to pass across the telescope’s field of view. That’s exactly how long it took for the Wow! signal to trace out a perfect rise and fall in intensity, proving it came from a single source out in space and wasn’t the result of an equipment anomaly.

Furthermore, the frequency of the signal was 1420 mHz, which is the natural radio frequency of hydrogen. Hydrogen is the most abundant element in the universe, not surprising when you consider that it’s also the simplest, consisting of just one proton and one electron. The SETI people believed from the beginning of the project that if another civilization wanted to get someone’s attention, they’d use a 1420 mHz signal. It’s the most obvious way to shout “Hello!” into the void because any moderately advanced civilization would recognize it (and would probably be looking for it if they were looking at all).

One important thing to note about this frequency is that there’s a worldwide ban on using it, because of potential interference with astronomical observations. So we know it didn’t come from Earth, unless it was from some pranksters geeks.

The signal was also very narrow, without any of the other kinds of radiation normally accompanying emissions from well-studied astronomical phenomena. That sharpness led astronomers to believe that it was likely manufactured rather than natural.

At first, it was a very compelling, very tantalizing hint that we might have caught wind of an alien civilization. But there were a couple of problems.

The biggest was that the Wow! signal was a one-shot deal, and never recurred. The Ohio State telescope had two horns, the second of which scanned the same patch of sky only three minutes after the Wow! signal was received. That second horn found nothing. In subsequent years scientists aimed much more powerful instruments at that area, which was in the constellation Sagittarius very close to the center of the Milky Way galaxy, but nothing like Wow! was ever found there again.

If alien creatures were trying to send out a cosmic “Hello,” they wouldn’t just send one powerful blast a gazillion miles into space in the hope that some antenna somewhere would happened to be aimed at that exact spot at the exact moment of the signal’s arrival. They’d broadcast it continually for a very long time.

For that reason, Jerry Ehman himself had doubts. Those doubts eventually evolved into a deeper skepticism after an effort called the Arecibo Wow! Project was initiated to analyze years of archived radio telescope. To everyone’s surprise (and dismay), many other Wow!-type signals were found. They were weaker than the 1977 signal but had the same hydrogen-based, narrow-band profile.

Thus intrigued, scientists assumed there had to be a natural explanation, and eventually they found it: interstellar clouds of hydrogen gas. While the signals they emitted were faint, they could be highly amplified if something called a magnetar passed behind them. The magnetar would stimulate the hydrogen and turn the cloud into a maser, which is kind of like a laser but using microwaves rather than visible light.

The natural maser hypothesis perfectly explains the Wow! signal. The 1420 mHz frequency associated with hydrogen came directly from real hydrogen; the signal was intense because it was amplified by the magnetar; and it was brief and rare because it required a perfect alignment of magnetar, cloud and Earth that only lasted a matter of seconds.

Scientists, being scientists and not conspiracy theorists, went with the new evidence and gave up on the idea that Wow! meant we’d been contacted by ETs.

I dearly hope that’s not the end of it.

Postscript, June 22

CNN posted a news story this morning about something an F-15 pilot saw just before he was shot down over Iran in April. The whole story is here, but here are the takeaways: