Why haven’t we found aliens yet?
S E E D E D C O N T E N T
One summer night, when I was a child, my mother and I were scouring the night sky for stars, meteors, and planets.
Suddenly, an object with a light that pulsed steadily from bright to dim caught my eye. It didn’t have the usual red blinkers of an aircraft and was going far too slowly to be a shooting star.
Obviously, it was aliens.
My excitement was short-lived as my mother explained it was a satellite catching the sun as it tumbled along its orbit. I went to bed disappointed: The X-files was on TV twice a week back then, and I very much wanted to believe.
Today that hope is still alive and well, in Hollywood films, the public imagination, and even among scientists. Scientists first began searching for alien signals shortly after the advent of radio technology around the turn of the 20th century, and teams of astronomers across the globe have been taking part in the formal Search for Extraterrestrial Intelligence (SETI) since the 1980s.
Yet the universe continues to appear devoid of life.
Now, a team of researchers at the University of Oxford brings a new perspective to this conundrum. In early June, Anders Sandberg, Eric Drexler, and Toby Ord of the Future of Humanity Institute (FHI) released a paper that may solve the Fermi paradox — the discrepancy between our expected existence of alien signals and the universe’s apparent lack of them — once and for all.
Using fresh statistical methods, the paper re-asks the question “Are we alone?” and draws some groundbreaking conclusions: We Earthlings are not only likely to be the sole intelligence in the Milky Way, but there is about a 50 percent chance we are alone in the entire observable universe.
While the findings are helpful for thinking about the likelihood of aliens, they may be even more important for reframing our approach to the risk of extinction that life on Earth may face in the near future.
Where is everybody?
In 1950, while working at Los Alamos National Laboratory, physicist Enrico Fermi famously exclaimed to his colleagues over lunch: “Where is everybody?”
He had been pondering the surprising lack of evidence of other life outside of our planet. In a universe that had been around for some 14 billion years, and in that time developed more than a billion trillion stars, Fermi reasoned there simply must be other intelligent civilizations out there. So where are they?
We still don’t know, and the Fermi paradox has only strengthened with time. Since the 1950s, humans have walked on the moon, sent a probe beyond our solar system, and even sent an electric sports car into orbit around the sun for fun. If we can go from rudimentary wooden tools to these feats of engineering in under a million years, surely there would have been ample opportunity in our 13.8 billion-year-old universe for other civilizations to have progressed to a similar level — and far beyond — already?
And then, surely there would be some lingering radio signals or visual clues of their expansion reaching our telescopes.
How scientists try to tackle the Fermi paradox, and why this paper is different
Space is a large place, and the task of accurately estimating the likelihood of little green men isn’t exactly easy.
In 1961, astronomer Frank Drake proposed a formula that multiplied seven “parameters” together to estimate N, the number of detectable civilizations we should expect within our galaxy at a given moment in time:
Ming Hsu
The Drake equation was only intended as a rough tool to stimulate scientific discussion around the probability of extraterrestrial life. However, in the absence of any reasonable alternatives, it has remained astronomers’ only method of calculating the probability of extraterrestrial intelligence. This is problematic because while some parameters, such as R* — the rate of new star formation per year — are relatively well-known, others remain hugely uncertain.
Take L, the average lifespan of a detectable civilization. If we look at the average length of the past civilizations here on Earth, it wouldn’t be unreasonable to assume a low value. If the Romans, Incas, or Egyptians are anything to go by, it seems hard to make it past a few hundred years. On the flip-side, you could argue that once a civilization becomes technologically advanced enough to achieve interstellar travel, it could conceivably last many billions of years.
This enormous uncertainty leaves the Drake equation ultimately vulnerable to the optimism or pessimism of whoever wields it. And this is reflected in previous scientific papers whose results give values of N ranging anywhere from 10 to many billions.
As astronomer and SETI co-founder Jill Tarter eloquently put it in an interview with National Geographic in 2000: “The Drake Equation is a wonderful way to organize our ignorance.”
Sincere attempts to overcome this vulnerability have previously been made via selecting a handful of conservative, medium, and bullish best estimates for each parameter value and then taking an average across them.
In their new paper, titled “Dissolving the Fermi Paradox,” the FHI researchers dispute this method by demonstrating how this technique typically produces a value of N far higher than it should, creating the illusion of a paradox.
This is because simply selecting a few point estimates and plugging them into the Drake Equation misrepresents the state of our knowledge. As an example, imagine three scientists who have differing opinions on the value of L:
If you take a normal, linear average of all the possible integer values from one to 1000, you would implicitly factor scientist C’s opinion 90 times more than scientist A’s because their range of belief is 90 times larger. If you use a logarithmic scale to represent the above so that each scientist’s range corresponds to one order of magnitude, all three opinions will be represented more equally.
Therefore, the researchers represented the full range of possible values on a logarithmic scale and ran millions of simulations to obtain more statistically reliable estimates for N. They then applied a technique known as a Bayesian update to those results. That means mathematically incorporating the information that we have not discovered extraterrestrial intelligence yet (because the absence of evidence of aliens is evidence itself!).
This two-stage process produced striking results: Based upon the current state of astrobiological knowledge, there’s a 53 to 99.6 percent chance we are the only civilization in this galaxy and a 39 to 85 percent chance we are the only one in the observable universe.
This implies that life as we know it is incomprehensibly rare, and if other intelligences exist, they are probably far beyond the cosmological horizon and therefore forever invisible to us.
But life can’t be that rare, can it?
To be clear, the paper’s authors do not appear to be making any definitive claim about whether or not aliens exist; simply, our current knowledge across the seven parameters suggests a high likelihood of us being alone. As new information becomes available, they would update that likelihood accordingly. For example, if we discover a second instance of abiogenesis — the process of rudimentary life emerging from non-living matter — on a comet or another planet, then this would narrow the uncertainty on the fl parameter significantly.
Nonetheless, their results have certainly caused a stir, especially after SpaceX CEO Elon Musk tweeted them:
Many reacted to the paper’s findings by calling it anthropocentric and narrow-minded, arguing that any conclusion suggesting we Earthlings are somehow special is simply human arrogance.
This is somewhat understandable because the idea that intelligent life is extremely rare in the universe feels completely counterintuitive. We exist, along with other intelligent life like dolphins and octopi, so we assume what we see must be extrapolatable beyond Earth.
But this alone is not proof that intelligent civilizations are therefore ubiquitous. Whether the true likelihood is as high as one in two, or as inconceivable as one in a trillion trillion trillion, the mere ability to consciously ask ourselves that question depends on the fact that life has already successfully originated.
This phenomenon is known as an observer selection effect — a bias that can occur when thinking about the likelihood of an event because an observer has to be there to observe the event in the first place. As we only have one data point (us), we have no reliable way to predict the true likelihood of intelligent life. The only conclusion we can confidently draw is that it can exist.
So if we are alone, is this good or bad news?
Regardless of which side you take, the idea that we might be alone in the universe raises serious scientific and philosophical questions. Is our rareness something to celebrate or be disappointed by? What would it mean for humans to be the only conscious entities in the universe?
This last question matters hugely. Not only are we depleting our environmental resources at an unsustainable pace, but for the first time in the history of mankind, we’ve reached the technological stage where we hold the entire future of our species in our own hands. Within a few years we built enough nuclear weapons to exterminate every human on earth many times over and made these weapons available to our leaders on a hair-trigger. Each decade has brought us novel technologies with ever-increasing potential for both immense good and immense destruction.
As we rang in the new year, the Bulletin of Atomic Scientists moved the Doomsday Clock to the closest it has ever been to midnight. Meanwhile, estimates from various specialists in existential risk suggest somewhere between a 5 to 19 percent chance of complete human extinction by the end of this century — an unacceptably large probability considering the stakes.
Not only does this dark gamble affect the 7 billion of us alive today; if you factor in the moral weight of the billion billions of future people who would also never get to live out their existences, it becomes clear that we urgently need to get our collective act together.
As Carl Sagan famously said in his 1990 Pale Blue Dot speech: “In all this vastness, there is no hint that help will come from elsewhere to save us from ourselves. The Earth is the only world known so far to harbor life. … the Earth is where we make our stand.”
He’s not wrong, especially in light of this paper’s findings. If humanity really is the only civilization that may ever exist in this universe, then we shoulder a responsibility on a truly astronomical scale.
Liv Boeree is a science communicator and TV host specializing in astrophysics, rationality, and poker.
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Drake's equation is fun because it will tell you whatever you want to hear....
With the apparent ease that microbial life on Earth established itself beginning with the stromatolites, and then survived several extinction events, I would say some kind of life is probably somewhat common in the Universe. Whether it would eventually evolve into humanoid form is pure speculation. We do know that liquid water existed on Mars, but life did not have time to get started there. I also believe that humans are but a brief stain upon the history of the planet and will eventually die off, after which Mother Earth will renew herself. Several millions of years from now, aliens will find some very strange fossils in the newer layers of rock, as plate tectonics continue to reshape the continents.
I often see some variation of this kind of undoubtedly true statement from climate science deniers as an excuse for not even trying to do anything to address global warming. Is that your angle?
I don't have any angle. Since you brought up climate change, my response is that lots is being done to mitigate climate change. What more should be realistically done? At what cost? Is climate change the sole fault of the US, and can all the world's nations come together to avert this coming catastrophe? I just don't see humankind surviving more than about 5000 years, and probably less than that. Overpopulation, running out of resources, disease, natural disasters are all in our future.
C'mon, guys... The subject here is aliens, and more specifically, why haven’t we met any.
Climate science is totally off-topic.
Thanks.
Doesn't climate/environmental stability figure into the Drake Equation's L variable? (length of time transmitting signals)
i didn't light that fire.
But to answer your question, there are probably no aliens here in the alpha quadrant that are capable of warp speed,
Borrowed dad's station wagon back when I was a kid. My lady and I were rudely interrupted by a huge, extremely bright light out in her father's cornfield. It came from directly above and made no sound. It disappeared as rapidly as it showed up. Kind of put a crimp in our lives from there on out. She became extremely paranoid and started carrying a gun. I bought a telescope.
Yikes!
I guess there are two categories: those who have seen "something", and those who have not. I have not.
I'm kinda envious...
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Space is vast, far more vast than most people can even comprehend. Humans have only been broadcasting, (TV, radio, etc..), with enough power to even make it to space for about 70 years. That means we have only reached out from our planet, 70 light years. In the galactic scheme of things, that's nothing. Also, there has to be someone, (something?), actually listening, they have to be able to respond, (which would take more time). So there is that.
The Drake Equation is a nifty little tool, but it was created to be used on a galactic level. I.E. the Milky Way, where we live. But if it is used properly, it does, for the most part, confirm that there could be literally thousands of intelligent civilizations in our own galaxy. How many galaxy's are there? Billions. There is no doubt in my mind that there are other civilizations with intelligent beings in the universe.
The biggest problem in finding alien life is literally the vastness of space. To get to our nearest star, (not Sol), with conventional technology would take us nearly 300,000 years.
The speed of light is extraordinarily fast, but on a cosmic scale, it's not very fast at all. Remember, it takes 8 minutes for light to get here from our own sun.
Maybe that's a good thing. We can't even get along with each other here on Earth.
I am pretty sure when humans die off, cats will take over as the next sentient species on Earth. Hide the catnip.
Are you so certain that they haven't taken over already? I feel like a slave to my cats
You speak truth, thee of the trout. I have three cats, I know the feeling. LOL
My male cat is around 15 years old and he is getting bitchier and bitchier. He's always talking to me and I just can't satisfy that cat
Ummm... Are you sure you aren't talking about Mr Giggles?
He's much older than 15...but he gets crankier every year, too
If we ever do receive an alien broadcast with a radio telescope it's likely that the broadcasters would already be extinct.
True. It's entirely possible. But then it's also possible that several thousands of advanced civilizations died off long before the Earth even existed. ~13 billion years is an insanely long time.
To quote the Hitchhikers Guide "Space is big, really big. You just won't believe how vastly, hugely mindbogglingly big it is"
A great example of the distances we are talking about are the Pillars of Creation, as seen here:
https://www.google.com/search?q=the+pillars+of+creation+destroyed&rlz=1C1CHBF_enUS799US799&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiy26-VyZLcAhW1HjQIHbkOD6IQ_AUICigB&biw=1707&bih=855#imgrc=ve7ZihXNkTbhnM:
They have already been destroyed by a supernova about 6,000 years ago, but we won't see it for another thousand years. They had been destroyed before we ever even laid eyes them. We are literally looking back thousands of years when we look at them, and yet that is not even 1/10th of the width of our single galaxy.
To get an idea of the vastness of space, (or in this case, our own solar system), this is what a journey would, "look like", for a photon of light traveling outward from our own sun.. I don't expect anyone to watch the whole thing, but after the first three planets, you'll get the idea...
That perfectly illustrates why we haven't found any aliens yet.
As far as looking for alien EM signals goes... I used to participate in the SETI@home thing, where they 'borrow' your computer's processing power in the hours of the day you aren't using it to process little packages of data recorded at Arecibo, looking for odd, possibly unnatural EM signals.
I remember a page describing their progress so far, and even after years and years of processing with their own equipment, and thousands and thousands of computers around the world to help through SETI@home, they had still only been able to scan a tiny number of frequencies from a tiny sliver of a tiny fraction of the sky. So the fact that SETI hasn't yet found EM signals that look artificial and were possibly created by an alien intelligence doesn't really mean much.
There's also the possibility that civilizations only use EM communications for a short time. It's possible that there are better ways of sending signals that we just haven't discovered and developed yet, but that may only be a few decades off for us (maybe something similar to quantum entanglement). If that's the case, then the window of time for EM detection could be small.
And lets not forget how weak our transmissions become over hundreds, thousands, and millions of light years. Our normal, everyday EM signature wouldn't exactly light us up like a Christmas tree to an observer who was very far away. We'd have to be intentionally sending out some kind of focused, high-powered beam to really stand out, but we'd only be able to send it to a tiny pin-prick in the sky, and likely only for a short time. The same would be true in reverse (with us as the observer).
Long story short... A civilization's EM communications phase may be fairly short lived, most signals would likely be too weak for us to notice anyway, and we've barely scratched the surface when it comes to scanning all of the possible frequencies from all points in the sky.
Gotta admit, I find it pretty depressing that our sorry asses (murderously violent, self-destructive, plagued with ignorance) might be as good as it gets in the entire observable universe. Damned dirty apes.
Here's hoping our "current state of astrobiological knowledge" has plenty of room for improvement, as in several orders of magnitude.
Then again, even here on Earth where we KNOW life is rich and abundant, only one out of the estimated 5 billion species that have existed across 4 billion years of time ever figured out how to make a radio.
One in 5 billion...
In 4 billion years...
Radios might be every bit as unlikely as their numbers suggest, even if our astrobiological knowledge did improve by several orders of magnitude.
That blows.
I still do, they have branched out to cancer research and other projects as well. They have changed the format and it's now run with BOINC. Same thing, different name is all.
Dear Friend Bob Nelson: This topic always sparks lively speculation.
Part of the riddle here is trying to imagine life evolving in ways we cannot imagine in conditions we do not yet know.
Super article.
Another winner!
E.
Given the vastness of both time and space, we are effectively alone. If anybody is out there, our signal may reach them 10 million years after they have died or 10 million years before they exist and that’s assuming that they have a means of receiving the signal we send. That’s compounded by the fact that an alien life form could be so different from us that we are unable to communicate with each other. Sending a radio signal to a dolphin or a caveman or a Roman outpost, for instance, would be pointless. Sending us a signal embedded in a medium we don’t detect would be equally pointless.
Well, one simple reason, the galaxy is fucking huge, and the universe is larger by orders of magnitude. Even light takes years to reach us from the nearest star, and the galaxy is nearly 100,000 light years across. An alien civilization could have easily risen and fallen well before we would even receive any sort of signal from them, and many probably have.
Yes. But that's also a reason why we should have had contact. There are some 250 billion stars in our Milky Way galaxy, and as you said, that's only one of our 100 billions of galaxies.
So even if life is rare, among the hundred billion times two hundred fifty billion stars... there should be... a lot.
That's the whole problem. The numbers just don't make sense.
There probably are a lot, but given the vast distances, the amount of time a signal of any kind even traveling at light speed takes to reach another star, and the fact that such a signal would have to be transmitted in a medium we could understand, it is not even slightly shocking that we haven't found any aliens. Hell an alien civilization could have been throwing TV shows our way for centuries, but it didn't matter because the Romans didn't have TVs. And now we have Tvs, but that doesn't matter because that civilization was wiped out 600 years ago and has stopped transmitting. We missed them and they didn't leave a voicemail.
Why Haven’t We Found Aliens Yet?
Maybe there isn't any.
Unlikely that we are the only sentient life in the universe.
The odds are significantly higher that we just haven't found them yet. Honestly, the chance that we are the only life in the galaxy, much less the universe, are incredibly small. When has anything only ever happened once?
Who's to say that other alien life forms aren't evolving just as slowly as we are?
But I'm kinda with 321Steve on this thing.....let's not advertise we're here.
They very well may be. And of course, they may already be extinct, or so advanced that we are a speck beneath their notice. All I am saying is I am positive other intelligent life exists in the galaxy, and the universe.
Agreed 100%. Honestly if I were an alien species and I discovered us, I would quarantine the planet. I wouldn't wipe us out, but given our nature I would forbid any travel here and prevent us from ever leaving this world. I would deem humanity as being too dangerous to be allowed off this rock. Regardless, I would rather not have someone find us first.
The day you were born. There is only one of each of us. We really could be the only planet that has life.
As far as we now know, we are. Look all ya want, I'll be surprised if you do find another especially one like this, or even close.
A lot of white, male, humans have been born. I am nothing special. I am me sure, but as far as what I am, it has happened tens of billions of times. I will try to be the best me that I can, but I am well aware that I am not significant.
And of course if you delve into the multiverse hypothesis, there are infinite versions of me. Many typing these very same words...
But however things end, however the universe goes about itself, I will have always been me. It cannot take that from me, or anyone. The universe can end, but I will have always existed, and I will have always been who I am.
Look all ya want, I'll be surprised if you do find another especially one like this, or even close.
I am not against looking I am against blatantly advertising our own existence and location.
And, If you are correct WHAT are we facing ? Also IF true, Better we know about it before it knows about us in my opinion.
So will I.
I agree.
I don't know, I only hope we have better weapons.
Agreed completely. Be the conquerors.
I don't want to be dinner
God damn, rereading that.... I should have that published.
LOL... Me too.
Unfortunately, any species that can transport itself here probably "out mans" us as well.
It was, I saw it on the internet.
lol
The very fact that they can get here en mass from another star automatically means we are outgunned. Again, I would prefer we do the invading lol. Spaniards or Natives folks, Spaniards or Natives.
What the fuck?! An alternate self has emerged...
Unfortunately, I can think of being worse things than just an alien’s dinner. At least being dinner is the end.
Long ago, unless today is the first day you've ever been on a computer. lol
Honestly, the inspiration came from the movie Dogma, though I wasn't thinking about it at the time. At least I am honest!
but what if they're lizard people like from V? I don't want to be eaten alive
Then I guess they dominate the earth eventually.
But if they got a great rack.... Just sayin...
oh...you....
"You certainly don't look like a lizard"
remember that line from the original V?
We are living in a computer simulation. That is why we can't find any life beyond earth. In this simulation only life on earth was created for the game.
Other simulations include life on other planets and galaxies along with life on earth.