Are We Alone?

Some of them very likely have planets, and therefore I can imagine civilizations immensely beyond the capabilities of our own. NASA just announced the discovery of 500 new planets; they're all orbiting other stars. Our place in the universe is relatively quiet. We have an average star orbited by eight planets, one of which contains us. For every grain of sand on Earth, there's 10,000 stars up in the sky, to be exact.

Sorta, there's between 10 to the 22 in 10 to the 24 total stars. Let's say that 5% of those stars are like our own Sun; that leaves 500 billion billion sun-like stars. All right, cool. So let's say that one in every five of those stars has a planet in the Goldilocks zone, a region around a star that can allow for liquid water and life as we know it to exist. That leaves 100 billion billion Earth-like planets out there.

Okay, good. Out of these planets, let's say that one percent of them actually have life show up. Then, every single grain of sand on Earth would then represent an Earth-like exoplanet with potential life. Using this math, there's about a hundred billion stars in the Milky Way, meaning that there's over 1 billion Earth-like planets in our galaxy alone. If 1% of those planets have life show up, then there's possibly between 100,000 and 1 million civilizations somewhere in our galaxy.

SETI, the search for extraterrestrial intelligence, has been searching for these signals for decades. But out of all of these possible civilizations, we've heard back from exactly zero. So where is everybody? The Fermi paradox addresses this exact question: if there's so many stars out there, if there's so many planets that are like Earth, why haven't we found them yet, or why haven't they found us?

Planets are actually really common in the universe. In just the past couple of years, our knowledge of habitable exoplanets—planets like Earth that exist outside of our solar system—have shot up drastically. We're now aware of around 3,800 exoplanets, some of which could possibly harbor life. The Trappist-1 system is thought to have seven habitable planets orbiting a star about the size of Jupiter. The worlds are rocky; they have water; Earth is just like them.

Okay, so if there's all these planets like Earth that could have life, why hasn't at least one other civilization, other than our own, been detected? Even though we continue to search for life every day, we've been acting like it already exists for decades. For example, when we first went to the Moon, the returning astronauts weren't able just to walk around and go to press conferences like they do today.

Instead, they were locked in quarantine for weeks. Why? Well, it was assumed that if there was life on the Moon—not developed life, but bacteria and microbes—then that could pose a serious threat to life back home and potentially wipe us off the face of the Earth. Seriously, it was a serious enough issue and concern that the practice was continued throughout the Apollo program up until Apollo 15 when we realized we were okay.

But that doesn't account for humans contaminating other moons or planets. There's quite literally thousands of pounds of junk just lying around on the Moon. Although it's unlikely, it is possible that there could be bacteria on those objects that may be able to live under those circumstances, and we may have provided the Moon its first life forms.

The reason why we send satellites into the atmospheres of planets to burn up after we're done with them is for this exact reason—to prevent those from spreading ourselves to places we shouldn't be. As bad as it sounds, every prediction we've ever made about the universe in the past has ended up being wrong in some way or another. There's been about a hundred billion people throughout the entirety of humanity's existence; almost all of them died without knowing what the planets actually were or what the universe is or was.

Ninety-nine percent of all species on Earth have died already. Are we going to be the next one? Hundreds of years ago, we believed in a geocentric theory and thought that everything in the universe revolved around us. We believed the Earth was flat, but today we obviously know these things are the furthest from the truth. So, based on our track record, it would be dumb to assume that we're the only life in the universe.

Frank Drake thought the same thing. He thought there's absolutely no way we're alone in the universe; there must be a way to calculate where everyone is, right? And from that simple question, we now have what is known as the Drake Equation. The Drake Equation breaks down all the necessary steps and requirements for a civilization to exist and thrive on a galactic level, allowing for us to detect them.

It breaks down the search step by step, and at the end, we're left with the number of civilizations out there waiting to be found. This is the Drake Equation in a single line: seven variables, when multiplied together, give us a way of measuring how many possible civilizations could exist in our galaxy at this very instant. It's an actual way of calculating what we did at the start of the video, and there's terms for each step.

It's a little daunting, but I'll break it down. N is the number of civilizations in our galaxy that we have a chance of talking to; this is what we're trying to figure out. R* is the average rate of star formation in our galaxy. Now, we don't know the exact number of stars that form every year, but we do know the amount of solar masses that form every year; it's about three.

So every year, about three average-sized stars form. Luckily, our Sun is a pretty average star, so it's a good way to view it. It could be one huge star or ten smaller stars; we don't know for sure, but this term in the equation is the one that we're the most certain of. Fp is the fraction of those stars that have planets; this number isn't certain, but some people have estimated that somewhere between 10 and 50 percent.

Now, super accurate. What is the term? Ne is the average number of planets that could potentially support life. So first we find the stars; second, we find the planets; third, we find the planets out of those that could support life. As I said at the start of the video, about 1 in every 5 stars has a planet in the habitable zone, so this is pretty certain as well.

Fl is where things start to get a little bit messy. Fl is the fraction of planets that actually develop life at some point. Our data on life is really, really small, and by really small, I mean us. We have one planet worth of information on life out of the billions of billions of planets out there in the sky. We're just going off the data that we have.

What if extraterrestrial life doesn't function even close to the way that we do? It's possible, and I think quite likely, that life beyond Earth doesn't always need water or oxygen or sunlight at all. They don't have to function the way humans do. There's trillions of planets in the universe with trillions of different living conditions, so it's only fair to assume that there's possibly trillions of circumstances that allow alien beings to survive.

So, Fl is hard to determine. Fi is the fraction of planets with life that can actually form civilizations like we have. Again, our data is limited to us and only us. Something I really think about a lot is if we live on such an average planet in an average galaxy around an average star, how did we get so lucky to be the only life to exist? If everything else around us is average, why did the anomaly known as life hop up here?

Or maybe life in general isn't an anomaly, but just intelligent life is. Life that is able to ask the kind of questions like, "Are we alone?" Out of all the species on Earth, as humans, we are the only ones who have developed language. Alien methods of communication might not even be imaginable by us; they might not even have language or gather information visually or through the senses that we have or even have any way of conveying things to species other than its own.

It's like humans trying to understand and speak whale. I don't know how to, and I don't know anyone else that does. The same logic may apply to extraterrestrial beings and how they communicate. How many other life forms on Earth actually have verbal means of communication other than us? When we discover ancient languages, we have ways to decipher them. We have ways to make connections to other languages.

We know how sentences are structured in various ways. With alien languages, there's nothing to refer to. We can refer to our own languages, sure, but cross-referencing entire civilizations on opposite ends of the galaxy with our own human language seems counterintuitive. Fc is the fraction of civilizations that develop technology that can be detected; we again are the only examples of this.

Let's say the Earth was created one year ago. Humans would then only be about 10 minutes old. The Industrial Revolution would have happened only two seconds ago. The majority of human history, we have had literally zero ways to even consider contacting alien life. It's a very, very recent thing.

We've been broadcasting radio waves into space for the past 100 years, but humanity has been around for as long as 1 million years. Out of our entire existence, only 0.00001% of that time have we even been able to conceivably contact aliens. Also, keep in mind radio waves are the only way that we've tried so far, and in 100 or 200 years, we may find another way of contacting extraterrestrial life that could work millions of times better than radio waves.

This could also be a reason why we haven't heard anything back. It would be like trying to talk to someone across the world via carrier pigeon while everyone else is using the internet. You would just look stupid. See, we expect all civilizations to be using the same kind of technology that we do. The only problem is we're either A) the first to get technology of our scale or B) we've fallen behind and everyone else ahead of us is only getting more and more advanced.

However, if they are able to detect our radio waves, they may have already found them. Every four computers now have primary control of critical vehicle functions. The last term in the Drake Equation is L; it tells us how long a civilization lasts. It represents how long we had to be found before it's too late. Extraterrestrial civilizations may send out signals for a long time until they stop or destroy themselves or find a better way to live—a life in a simulation perhaps.

The longer L is, the more advanced the civilization becomes. The Kardashev scale comes in handy here. I made an entire video on this topic; it's really bad, but I'll explain the important parts here. First, a civilization needs to find a way to take over its planet; this is called a type one civilization. We are on our way there; we're at about 0.72 at the moment.

A type two civilization is capable of harnessing the power of its entire host star. See, the further away you are from the star, the less energy you get from it. Earth only gets maybe one billionth of a percent of the sun's energy at any moment. Many structures have been proposed to somehow harness the sun's energy, but we won't be there for a very, very long time. The third stage for civilization is— you guessed it—a type three civilization.

This civilization has conquered the galaxy and has access to any and every planet. But from our knowledge, there isn't even one of those civilizations out there that are detectable, and that doesn't make sense. See, the universe is 13.8 billion years old; Earth has only been around for maybe a third of them. There's been at least five billion years prior to Earth coming into existence that could allow for civilizations to have risen and also fallen.

But yet we see nothing. If you could build a device, a huge ship that could travel at ten percent the speed of light, you could cross the galaxy in six hundred thousand years. I know it sounds like a long time, but in comparison to the Milky Way's at least 10 billion year old age, six hundred thousand years is literally nothing. All it takes is for one species to do this to cover the entire galaxy.

So if it's that easy, why haven't we seen it yet? Well, it might be a good thing because that would mean that the great filter is in front of us. There may be other life in the universe, but there are barriers that we all have to overcome. The great filter theory helps explain this very well. Imagine that there are 1 million civilizations in the Milky Way galaxy, but not all of them can get to the point that they take over the galaxy.

There are barriers in the way; these barriers are things that new life forms and civilizations must overcome. The first barrier might be multicellular life, and maybe that's an easy barrier to cross. Okay. Next barrier: the ability to have thoughts and a consciousness. Next, maybe we have to understand basic technology.

Okay, that's fine; we're good at that. Next, discover time travel? Okay, not so easy, or kind of stuck. See, there are things that prevent us from progressing, moving forward, and becoming a galactic civilization, but we don't know what those things are. There's hundreds of billions of planets in the Milky Way, but when we look for other life, there's nothing.

Where's it all at? Well, the great filter theory shows that there's certain steps that the species must get past in order to take over their planet, solar system, galaxy, and so on. Just like the Kardashev scale, there are just one or perhaps multiple of these filters that are extremely hard, or maybe impossible, to get past. The question is: have we already gotten past that barrier, or does it lie in front of us?

If it's behind us, then good; we've passed a nearly impossible step in building a civilization, and we may be one of, or even the first, advanced civilizations in the universe. If it's ahead of us, then we have our work cut out for us. For the majority of human history, the planet's fate was up to events that humans could control; for example, large asteroids that wiped the planet of its inhabitants.

But today—actually only in the past 80 years—we've developed technology capable of ending human civilization at a moment's notice. We're working on AGI that will then lead to super intelligent AI. These could be some of the barriers we must get past, and maybe where many civilizations fail. If we find an advanced civilization that has died in the process of advancing, then the great filter is in front of us, and this isn't good.

The great filter is a challenge that wipes out almost every species that encounters it. It's not just one that kills off 99% of a population—that would give them a chance to regrow and reconquer that barrier. This would kill 100% of every civilization that has ever existed and leave no chance for repairs. As with many other things that people believed to be stronger than them—things like super intelligent AI or aliens—many people tend to fear them.

Historically, whenever a stronger species or civilization, or for the future's sake, technology arose, it almost always resulted in the weaker party being wiped out. For example, humans and Neanderthals, or more recently, the discovery of North America. Perhaps this is only human nature, but based on what we know from the past, first contact with aliens might be the most dangerous thing humanity has ever faced.

A really important question arises here: if we do hear from or detect another civilization, should we let them know that we heard it? The futurist half of me says yes, of course, but the other half of me says maybe not. This could be exactly what alien civilizations are doing right now. It's possible that they have detected us already, but instead of responding, they're observing and patiently waiting.

Advanced alien species may just be observing us to see how we progress; consider us a science experiment, but on a potentially galactic scale. I touched on this in my AI video, but I'll bring it up again here: when you're building or observing something or someone who could be multiple times more powerful than you are, you need to be careful. You want to observe and keep a close eye on how it progresses.

Hey, this could help us colonize the galaxy and meet other life forms, but it could also cause the extinction of our species. What happens if super intelligent AI sees extraterrestrial life as a threat and makes attempts to take it out? It'll probably fail, and that is one of the worst scenarios for us. One of our own creations, perhaps our best creation, is the cause for the extinction of our species.

But with the case of AI that we're developing on our own planet, if it gets too powerful, we just shut it off, right? Take three civilizations, maybe doing the same thing with us. They may be observing us to see how other life in the universe becomes powerful, and if we eventually get to that tipping point, whatever it may be, they may decide to put an end to their experiment.

It sounds insane, but we do that here on Earth. There are parts of Earth that we couldn't inhabit; we don't just because it isn't convenient for us. Prime example: Antarctica. It's an entire continent that we don't colonize because it isn't convenient; it's frozen and just not super suitable for life. This could be how alien civilizations view Earth.

They may have found us, realized that we aren't special at all, and moved on. For all we know, we may have already been visited by aliens, just not recently. With all the time before Earth's formation that may have allowed civilizations to form, there's a chance that one or maybe multiple of those civilizations have stumbled upon Earth during its infancy when there was no life to be found.

Modern humans have only been around for maybe fifty thousand to a hundred thousand years. A hundred thousand years out of four-and-a-half billion is practically nothing in an entire galaxy. There's bound to be places that just aren't worth colonizing. Why waste time and resources on colonizing a planet that won't benefit you in any way? Aliens wouldn't come to Earth without a reason, whether it's good or bad.

Drake's equation is just that: an equation. The terms—mostly the last—are our educated guesses at best. That's all you can really do when trying to answer a question of this magnitude. There could be many, many more civilizations than we think, or maybe we're the only ones. If any of the values in Drake's equation end up being zero, that's it; we're alone.

There have been many calculations made with the Drake Equation, and it all comes down to how pessimistic or optimistic you are about the future. There have been calculations as high as a couple million civilizations in our galaxy, and there have been calculations that say we're alone, and at the moment, they both hold value. Enrico Fermi did ask one of the most important questions humans have ever asked, but at the same time, Fermi was also a pioneer in the creation of nuclear weapons.

The species that couldn't inhabit the entire galaxy is also the same species that stands capable of almost completely wiping itself out at a moment's notice. We search every day for signals from other civilizations. We look for techno signatures—signs of engineering, of things that just don't commonly appear in nature, like city lights from space. We search for those in other corners of the galaxy.

We study biosignatures in the atmospheres of exoplanets to find elements that may show that life could exist. We sent out radio waves hoping to find aliens. In 1974, Frank Drake himself sent out the Arecibo message to the M13 star cluster. It's a string of information describing humanity in hopes that someone or something would find it.

We send out satellites such as the Voyager crafts with specific instructions of who we are, what we are, and where we are. We're doing all we can to find alien life while also giving them all the information they need to find us. We want so badly not to be the only ones in the universe that we don't even consider the possible consequences of us not being alone.

Are we done, or are we just getting started? I guess the better question is: are we closer to the beginning or the end of human existence? There's only a finite amount of space on Earth for life, and there's only one place we can go. Either way, the clock is ticking down. Time is against us, and I don't want to be around to see what happens from that clock hitting zero. [Music]