Where Are All the Aliens? The Fermi Paradox

20 Jun , 2013 by Video

Consider this. The Universe is enormous.

There are as many as four-hundred billion stars in our galaxy: the Milky Way. And there are more than one-hundred-and-seventy billion galaxies in the observable Universe. Most of those stars have planets, and many of those planets have got to contain useful minerals and fall within their star’s habitable zone where liquid water is present.

The conditions for life are probably everywhere.

But where are all the aliens?

And think about this.

The Universe has been around for 13.8 billion years. Human beings originated 200,000 years ago, so we’ve only been around for 0.01% of the age of the Universe. An intelligent species could arise on any one of those countless worlds, and broadcast their existence to the entire galaxy.

Once a species developed interstellar travel, they could completely colonize our galaxy within a few tens of millions of years; just a heartbeat in the age of the Universe.

So where are they?

As far as we know, Earth is the only place in the Universe where life has arisen, let alone developed an intelligent civilization.

This baffling contradiction is known as the Fermi Paradox, first described in 1950 by the physicist Enrico Fermi.

Scientists have been trying to resolve this mystery for decades, listening for radio signals from other worlds. We’ve only sampled a fraction of the radio spectrum, and so far, we haven’t detected anything that could be a signal from an intelligent species.

How can we explain this?

Maybe we really are the only planet in the entire Universe to develop life. Maybe we’re the first civilization to reach this level of advancement in the entire galaxy. But with so many worlds out there, that really seems unlikely.

Artist impression of an asteroid impact on early Earth (credit: NASA)

Artist impression of an asteroid impact on early Earth (credit: NASA)

Maybe civilizations destroy themselves when they reach a certain point. Nuclear weapons, global warming, killer epidemics, and overpopulation could all end humanity. Asteroids could strike the planet and wipe us out. But would this happen to every single civilization? one-hundred-percent of them? Even if ninety-nine-percent of civilizations destroy themselves, we’d still have a couple that made it through and fully colonized the galaxy.

Maybe they’re just too far away, and our signals can’t reach each other. But then, self-replicating probes could traverse those distances and leave a local artifact in every single star system.

Maybe we can’t understand their signals or recognize their artifacts. Maybe, but if aliens constructed a series of artifacts on Earth, I think we’d notice them. The aliens would have experience creating obvious structures.

Maybe they’re just too alien and we just can’t understand them. Maybe we’re too insignificant, and they don’t think we’re even worth talking to. We don’t need to talk to them to know they exist. If they flew through our Solar System, ignoring us, we’d still know they’re around.

Maybe they’re not talking to us on purpose, and we’re really in some kind of galactic zoo. Or aliens have a Prime Directive, and they’re not allowed to talk to us. Again, all the aliens? Not a single one has gotten through and snuck us some evidence?

Milky Way. Image credit: NASA

Milky Way. Image credit: NASA


There are many other potential solutions to the Fermi Paradox, but I personally find them all insufficient. The Universe is big, and old, and if extraterrestrial life is anything like us, it wants to multiply and spread out.

Perhaps the most unsettling thought is that something happens to 100% of intelligent civilizations that prevents them from exploring and settling the galaxy. Maybe something good, like the discovery of a transportation system to another Universe. Or maybe something bad, like a destructive technology that has destroyed every single civilization before us.

How do you feel about the Fermi Paradox? How do you resolve the contradictions? Whatever the solution, it’s really fun to think about.

We’ve recorded a couple of episodes of Astronomy Cast about the Drake Equation and the Fermi Paradox, and we did a sequel episode called, Solutions to the Fermi Paradox.


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Astro Wagon
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Astro Wagon
June 20, 2013 5:07 PM

Fermi Complex

Nexus
Member
June 20, 2013 10:14 PM

My gut feeling is that life is ubiquitous, but technological civilizations are comparatively rare.

William928
Member
William928
June 20, 2013 10:26 PM

Well said. Any civilization sufficiently technologically advanced to conduct interstellar travel would likely require several hundreds of millions of years of evolution. The odds of finding intelligent ET life in my lifetime are unfortunately extremely long.

TonyTrenton
Member
TonyTrenton
June 21, 2013 2:24 PM
There are words in the English language that I find totally misused and that need clarification. 1; ‘Intelligence’ : The I.Q. or ‘Intelligence Quotient’ is a measure of the ability to learn relative to time. Having a high I.Q. doesn’t make you smart. I have met many ‘intelligent’ idiots in my 69 years. How you use it determines that. 2; ‘Believe’ A much maligned term that we as fallible humans should not use with such abandon. If you are a sincere person. You cannot say ” I believe this” , Then the next day when more information changes your opinion say ” I believe that ” The term ‘believe ‘ is an absolute term.’ We must by default… Read more »
William928
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William928
June 21, 2013 10:25 PM

How did I misuse intelligent? Should I have said technologically advanced?

William Nicholls
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William Nicholls
June 20, 2013 11:51 PM

I’m pretty sure we’ll find that life is ubiquitous – or at least very common within my lifetime. Technological species are unlikely enough that they should be rare. The universe is vast, so there are likely many technological species even with tiny odds of them overlapping with our ability to detect them, but we’ve just barely started looking and listening for them. The idea that a species like ours is destined to expand through the galaxy is naive and laughably premature.

duncan@r-p-m.eu
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[email protected]
June 21, 2013 2:42 AM
Humans are a colonistic species. Never ending expansion if history thought us anything about our own kind. We are at the birth of colonizing the moon and mars, making our first baby steps out of our own planet and its gravitational pull. Its stubborn to assume we will end there. The moment we figure out to get to alpha centauri we will go there, even if we cant figure out to go faster than the speed of light. and if earths most intelligent and advanced species has are like that, its quite safe to assume this can be the case for other planets with life forms.doesn’t mean we shouldn’t look for anything else, but we should focus on… Read more »
William Nicholls
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William Nicholls
June 21, 2013 3:23 PM

To see us as at the “birth” of colonizing the Moon and Mars is quite optimistic. And what could possibly motivate civilizations to make more than a tiny human presence on worlds so hostile, difficult and expensive to inhabit? Destroying the very “spaceship” that this species evolved on? I suppose that if this species can’t adapt its behaviors then it will have to spread out to consume new resources – if that’s technologically possible before ecosystems and civilizations collapse.

duncan@r-p-m.eu
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[email protected]
June 21, 2013 8:17 PM

It is optimistic. The plans and technology to do it is available. Its just a matter of money. And I meant it more of that we have starting to go into space, have a manned space station. The next steps will of course be the moon and mars smile
If it was known that Earth would collapse in a few years. We’d by on the moon by monday.(figuratively speaking)

Global View
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Global View
June 20, 2013 7:50 PM

Perhaps intelligent alien life is here on Earth at this very moment. Perhaps the aliens are here recording our daily lives, the highlights of which they then beam back to their home planet for showing on their weekly “The Universe’s Most Stupid Animals” show smile

cschur
Member
June 20, 2013 10:27 PM

I agree – bacterial life certainly must be very common. But complex cells that can congregate into multi cellular animals must be very uncommon, since it took nearly 3 billion years on our planet of just plain bacterial to finally make a multicellular package!

Ettalb
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Ettalb
June 20, 2013 10:28 PM

I’ll stick with intelligent and planned design of all creation. (For the record, i dont believe the earth is 6000 yrs old)

Kevin
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Kevin
June 21, 2013 12:13 PM

I grant that it can’t be ruled out as silly superstition just because of the lack of proof. I wonder if “God” is life’s own creation – the way my individual brain cells don’t realize they are making up a living person, but do anyway. Each consciousness on earth making up a small neuron of the whole.

Jason
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Jason
June 20, 2013 10:35 PM

The difference between us and chimps is less that 1% and that 1% is
enough to see massive differences. If the aliens are 1% more than us
could we even understand what they are? Would they see us as chimps… or chumps?

Icculus760
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Icculus760
June 21, 2013 8:54 PM

This sounds like something Neil DeGrasse Tyson said. Oh wait, he did. That being said, it’s an interesting perspective to ponder.

Jason
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Jason
June 24, 2013 6:23 PM

He did and that’s where I snagged it from.

Ole Jørgen Nordhagen
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Ole Jørgen Nordhagen
June 20, 2013 11:28 PM

Great video. Thanks! Guess they are all just too shy – like teenage girls, giggling around us without us noticing. Happens to me all the time… smile

James Johnson
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James Johnson
June 20, 2013 7:35 PM

Only God Knows!!

caveman664
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caveman664
June 21, 2013 12:46 AM

It could just be that the laws of physics will never let us, or any intelligent species, leave their solar system and do any practical exploration. Perhaps we should just get used to the fact that for all intents and purposes, we are alone in the Universe.

duncan@r-p-m.eu
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[email protected]
June 21, 2013 2:56 AM

We are still able to cruise hundreds of light years. Giant spaceships are very possible in the future. And so is bringing that spaceship towards the speed of light will some day be a possibility(how close is still a ? Though)and we are able to keep humans alive in an isolated environment.
if there is life with a few 100light years it will be reachable. Wether this will be very useful is also a question razz
and i cant imagine we are even close to figuring out everything there is in the universe while this is already based on current technologies.

Joknjokn
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Joknjokn
June 21, 2013 12:48 AM
Just a brainstorm: Imagine all these different parameters intelligent life consists of that we know, and multiply that with whatever. Feelings like aggression, love, curiosity, boredom. Lifeforms relative size to surroundings and the possibility to sensor different things. I guess you need certain light sensors in order to become aware of the sky/universe. You need some bodyparts that can handle things, doing experiments and so on. You need to be social. Many, many more parameters. If lifeforms miss some of those, or if earthlike life has some kind of abnormal extreme in some of those parameters, which made us more intelligent/aware – then that could be a coincidence only happening to 1/100, 1/1000, or maybe even 1/100000 lifeforms.… Read more »
Planemo
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Planemo
June 21, 2013 5:08 PM
Damn well said. There’s way more to it than what you typed. I liked it . And Sensors? Oh yes, and then some with special optics are needed. We cannot see, nor are we aware of the many, many, many possibilities of there being real dimensions. Space-time is freaky! REAL FREAKY! It is uncomprehensible to the human mind and eyes. There must be dimensions but proving it is the hardest thing to do. Some scientists are so closed minded its so pathetic. They say there is NO this and no that. It just cannot be. Their ‘egos’ are disrespectful to science! Remember all scientists saying the sun was the ONLY source to maintain life as we knew it.… Read more »
Tex
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Tex
June 20, 2013 7:58 PM

Or. . . . .maybe they really “are” more advanced than us and developed an infinite and renewable energy source, decided it was better to love and care about each other, rather than hate and kill each other and developed a culture not dependent on “money.” This being said, maybe they just want to leave all the other warlike, ignorant planets (like us) alone, and they are content with their own culture and identities.

Tex
Member
Tex
June 20, 2013 8:07 PM

Or. . . . .maybe they really “are” more advanced than us and developed an infinite and renewable energy source, decided it was better to love and care about each other, rather than hate and kill each other and developed a culture not dependent on “money.” This being said, maybe they just want to leave all the other warlike, ignorant planets (like us) alone, and they are content with their own culture and identities.

Tex
Member
Tex
June 20, 2013 8:37 PM

Or. . . . .maybe they really “are” more advanced than us and developed an infinite and renewable energy source, decided it was better to love and care about each other, rather than hate and kill each other and developed a culture not dependent on “money.” This being said, maybe they just want to leave all the other warlike, ignorant planets (like us) alone, and they are content with their own culture and identities.

TJ
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TJ
June 21, 2013 2:05 AM
I just think technological life is probably rare enough to be at least 1000 light years apart from each other. I mean, we haven’t been listening to radio waves for THAT long. Our transmissions would need to get to other civilizations before they would hear us and reply. Really advanced civilizations are even rarer and therefore are probably much farther away. We seem to be in a void right now where the signs of civilization haven’t reached us, but we have transmitted outward for 150 (light) years so far. My gut feeling is there are many wave fronts of transmissions from various civilizations racing towards us. The first one could arrive tomorrow, or in 10,000 years from now.… Read more »
TJ
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TJ
June 21, 2013 2:07 AM

lol. I meant “undisturbed” not “undies turned”. Gotta love autocorrect….

TonyTrenton
Member
TonyTrenton
June 22, 2013 1:06 PM

There are a number of statistical analysis that estimate that there are + – 10 K space fairing civilizations out there in our galaxy alone

PrometheusOnTheLoose
Member
June 21, 2013 2:38 AM

The answer may be simpler than you would think; we have not been around long enough for any other civilization to intercept our signals, so they are not even aware that we exist. I’d bet that that goes for a lot of the civilizations out there. I have no doubt that there are some out there, but the vast distances prevent interception of many signals that are probably going out now. If a way could be found to break the distance barrier, we would see signals all over I would bet . . . . but that is not likely to happen anytime soon, if at all.

bfmorris
Member
bfmorris
June 21, 2013 3:16 AM
Fun to speculate. I personally suspect our own solar system is contaminated by wherever it’s life began, rather than life springing up independently, anywhere conditions allow for survival. Not so fun is realization our faith in odds-based expectations say more about us, not the universe. They could easily be meaningless. When we realize we don’t even have sight of life’s origin nor do we understand what it is, that’s not so fun either. Is it any more or less realistic to say there has gotta be more Fraser Cains out there because there are so many stars and galaxies. Seems there must be many Fraser Cains out there that look exactly the same, identical genetics, identical fingerprints, each… Read more »
universetoday
Member
June 21, 2013 3:56 AM

I personally find the Panspermia theory pretty compelling. In fact, there could be a trail of biological material streaming behind the Solar System, so maybe star systems pollute each other with life.

Coacervate
Guest
Coacervate
June 21, 2013 10:56 AM

Right. If you consider the charge density on Earthly spores, they are almost certainly conveyed along lines of mag force at the poles up into space. this would be easily tested by simple culture experiments by ISS. Very low risk, very high potential return experiment.

rholcomb
Member
rholcomb
June 21, 2013 1:36 PM

I personally find the Pamspermia theory pretty irritating. It begs the question: if life didn’t start here, where did it start? And how? Why put it off to some nebulous somewhere else?

Ken
Guest
Ken
June 22, 2013 1:54 AM

Because it gives you more time. Although the evolution of life on this planet from simple to complex forms is pretty well understood, how the simple versions originated in the first place is a harder problem. Perhaps key parts of the process need much larger timeframes than are available if you try to limit the whole process to one planetary lifetime.

Lawrence B. Crowell
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Lawrence B. Crowell
June 21, 2013 3:30 AM
I think the number of technologically advanced intelligent life forms is small, or they have a low density = # ETI per galaxy as measured either on the Hubble frame or the past light cone of any observer. I also suspect that intelligent life runs into a problem of fabricating a synthetic world that is too complex for their mental abilities or social structures to manage. I suspect we humans are running into this sort of problem now. Global warming is mentioned as a possible extinction route, and with our world we are still besotted with retro-minds that deny science from evolution to climate. Of course the US of A is unique in its cultural trend for amplifying… Read more »
mick
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mick
June 21, 2013 11:55 AM

That makes me think of that syngularity theory. Maybe it’s true. Maybe it’s good. It may be bad also…

Lawrence B. Crowell
Member
Lawrence B. Crowell
June 21, 2013 1:25 PM

I think it is possible the brain may become the primary mode on the internet. Computer and communications technology I think is already becoming more integrated into us. It is noteworthy how much time people spend on smart phones and i-gadgets these days. The Google glasses and other devices are integrating this closer to our senses. Already experiments with ECG and direct neural interfacing have been performed.

This will push humanity into the direction of virtual reality instead of some future reality in space. We may also become somewhat BORG-like in time. This direction is inward in a sense, rather than outwards such as with becoming a space faring species.

LC

mick
Member
mick
June 21, 2013 2:30 PM

I find both directions (inward and outward) to be appealing.
Humans are dual as universe is. We may explore both directions.
I hope so. This may be the key to progress, graviting around an equilibrium in order to avoid imploding inward or exploding outward…

Douglas Orr
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Douglas Orr
June 21, 2013 3:38 AM

Assume that Earth is about an average age planet and that the rate of evolution on Earth is about average. Exclude those planets were life is less evolved than on Earth. Of those that are at least as evolved, about 99.98% would be at least 1 million years more evolved than humans. We would be apes by comparison. Worse yet, nearly 90% would be at least 1 billion years more evolved than humans. We would be little more than bacteria by comparison!

uptotrix
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uptotrix
June 21, 2013 4:08 AM

There are no super advanced civilizations in this universe. Firstly because – intelligent life always looks to get ahead by any means possible, this means life always searches for life, there cannot be any other way. This also means there are no hostile aliens as well, because if a civilization has existed for millions of years it would know the value of life. And lastly, there are no bug eyed creepy aliens- intelligence cannot make you look ugly.

k3narthur
Member
k3narthur
June 21, 2013 6:54 AM

What about this argument? It would suggest that that life has taken most of the age of the Universe to develop to its current state of complexity; hence that advanced civilisations are only now emerging … http://phys.org/news/2013-04-law-life-began-earth.html

universetoday
Member
June 21, 2013 12:15 PM

I think that’s a totally legit answer to the problem, but it seems unlikely. Are we really first? Or, firstish?

mick
Member
mick
June 21, 2013 12:54 PM

The argument does not states that we are first. But that we are all (earthling and others) first.
It’s close to my previsous comment. It may happen that T=”time from ARN to technological beings” has a very small mean deviance.
Or not. You cannot guess when your sample size is one.

Ken
Guest
Ken
June 21, 2013 6:18 PM

I agree – the theory still allows plenty of room for much older civilisations than ours to exist out there, hence many of the issues you raise are still there.

Ken
Guest
Ken
June 21, 2013 6:30 PM

I suppose this theory would also tend to constrain the maximum age of any existing civilisation – although by how much? But you wouldn’t have to cope with the idea of civilisations that are billions of years old, for example.

TonyTrenton
Member
TonyTrenton
June 22, 2013 1:25 PM

As it appears that we and our Universe are ‘ average ‘.

Definitely firstish

Ancient Brit
Guest
June 21, 2013 7:29 AM
A number of things occur to me. One is that the lack of communication may be a deliberate policy (as others have observed, cf the Prime Directive). It would seem sensible in the light of our own history here on Earth (the decimation and even destruction of more primitive peoples). Another is that since dark matter and dark energy (assuming they do exist) constitute the greater part of the Universe, maybe there’s more fruitful ground to explore there (for dark aliens? ) Yet another is that apparently superluminal communication and even travel may be possible using technologies we have yet to develop (by exploiting as yet undiscovered dimensions outside space-time). Under that circumstance we’d be so off the… Read more »
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