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Where Are All the Aliens? The Fermi Paradox

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.

Enrico FermiThis 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.

About 

Fraser Cain is the publisher of Universe Today. He's also the co-host of Astronomy Cast with Dr. Pamela Gay.

Comments on this entry are closed.

  • Lynn Chetwynd June 22, 2013, 12:28 AM

    I too think that life is ubiquitous, even “intelligent” life. However, if Einstein is correct and nothing can travel faster than the speed of light, and; if wherever we look, we are seeing into the past, I would think that interstellar communication in any real sense of the term is highly improbable. Any alien signals within our own galaxy would take perhaps hundreds of light years to reach us.

  • Tony Trenton June 22, 2013, 12:44 PM

    Yes ! we are too primitive to be acceptable into the Federation of Planets.

    Better to keep us isolated

  • Tony Trenton June 22, 2013, 1:16 PM

    One of the characteristics of abductions is their ability to remotely incapacitate us with a beam of something we perceive as a light.

    They are very familiar with our physiology !!

  • Jack June 22, 2013, 1:50 PM

    Our problem is that all we do is search for our own limitations in outer space. We need to overcome our anthropomorphised perspective on the universe.

  • campbell s w June 22, 2013, 2:30 PM

    Patience.On the timescale of the Universe we’ve only been looking for milliseconds.

  • Dav_Daddy June 22, 2013, 4:16 PM

    You may have hit the nail on the head there. Most of our problems are related to energy. If there is a species that develops a technology where energy is no longer an issue?

    Based off of humanity they’d either make leaps and bounds in art & science, or use it to kill each other. That would also explain why we haven’t found any ET’s yet, the ones that do make it would go to lengths to conceal themselves till we are past the tipping point.

  • kaplanfx June 23, 2013, 12:28 AM

    “Life needs a wide variety of elements and compounds to exist, be it life-as-we-know-it, OR OTHERWISE.”

    Wow you really snuck that “or otherwise” in there. Since we have exactly 0 samples of non “life-as-we-know-it”, I don’t think you or I could speculate on what the requirements for life are.

  • Guest June 23, 2013, 5:56 AM

    I would have to disagree with the implication that there’s no evidence for ET’s. In fact there is lot’s of types of evidence for the existence of ET’s both past and present.

    In the present there are groups like:

    – ‘The Disclosure Project’, formed by Dr Steven Greer.

    “We have over 500 government, military, and intelligence community witnesses testifying to their direct, personal, first hand experience with UFOs, ETs, ET technology, and the cover-up that keeps this information secret.”

    This includes Edgar Mitchell, 6th man on the moon.

    – ‘The Citizens Hearing on Disclosure’

    “From April 29, 2013 to May 3, 2013 researchers, activists, political leaders, and military/agency witnesses representing ten countries gave testimony in Washington, DC to six former members of the United States Congress on the evidence for an extraterrestrial presence engaging the human race. ”

    Plus many other isolated cases of ET contact, and countless UFO sightings around the world.

    In our recorded history there are cultures, many that developed completely independently of one another saying similar kinds of things.

    – How many of the pyramids around the world were built is still a great mystery. The egyptians, who were very keen on documenting themselves, don’t once mention how they built them, but speak about the ‘Sun Gods’ coming down from to sky, showing them how to build them. The Mayans also mention beings that helped them construct their pyramids.

    – The Hopi indians said that their ancestors were brought there by ‘giant flying tortoise shells’, which sounds similar to many of the ‘disk’ shaped UFO’s that are being sighted.

    – Hinduism tells us of their deities and half deities, who came in their ‘Vimana’, meaning ‘flying machines’, (which have been depicted with drawings), passing down their advanced knowledge and advising humanity. In the scriptures they describe the Earth as a sphere, where the sun never sets. They make references to gravity, atoms, and much more. These writings are over 5,000 years old!

    – The bible speaks of the ‘nephilim’, the giant gods that mated with our women and bore half-gods. Sounds pretty flesh and blood to me!

    Another small thing to note are the meteors that we discover containing fossilised bacteria. If we have evidence of life, quite literally ‘falling out of the sky’, I think it’s safe to assume that we live in a universe abundant with life, where life is the rule not the exception.

    There’s a lot more I could go into, it’s a fascinating subject and well worth investigation!

  • Nicolai Martin June 23, 2013, 10:59 AM

    I would have to disagree with the idea that there’s no evidence for ET’s. In fact there is lot’s of types of evidence for the existence of ET’s both past and present.

    In the present there are groups like:

    – ‘The Disclosure Project’, formed by Dr Steven Greer.

    “We have over 500 government, military, and intelligence community witnesses testifying to their direct, personal, first hand experience with UFOs, ETs, ET technology, and the cover-up that keeps this information secret.”

    This includes Edgar Mitchell, 6th man on the moon.

    – ‘The Citizens Hearing on Disclosure’

    “From April 29, 2013 to May 3, 2013 researchers, activists, political leaders, and military/agency witnesses representing ten countries gave testimony in Washington, DC to six former members of the United States Congress on the evidence for an extraterrestrial presence engaging the human race. ”

    Plus many other isolated cases of ET contact, and countless UFO sightings around the world.

    In our recorded history there are cultures, many that developed completely independently of one another saying similar kinds of things.

    – How many of the pyramids around the world were built is still a great mystery. The egyptians, who were very keen on documenting themselves, don’t once mention how they built them, but speak about the ‘Sun Gods’ coming down from to sky, showing them how to build them. The Mayans also mention beings that helped them construct their pyramids.

    – The Hopi indians said that their ancestors were brought there by ‘giant flying tortoise shells’, which sounds similar to many of the ‘disk’ shaped UFO’s that are being sighted nowadays.

    – Hinduism tells us of their deities and half deities, who came in their ‘Vimana’, meaning ‘flying machines’, (which have been depicted with drawings), passing down their advanced knowledge and advising humanity. In the scriptures they describe the Earth as a sphere, where the sun never sets. They make references to gravity, atoms, and much more. These writings are over 5,000 years old!

    – The bible speaks of the ‘nephilim’, the giant gods that mated with our women and bore their children; half-gods. Sounds pretty flesh and blood to me!

    Another small thing to note are the meteors that we discover containing fossilised bacteria. If we have evidence of life, quite literally ‘falling out of the sky’, I think it’s safe to assume that we live in a universe abundant with life, where life is the rule, not the exception.

    There’s a lot more I could go into, it’s a fascinating subject and well worth investigation!

  • Nicolai Martin June 23, 2013, 11:05 AM

    I would have to disagree with the idea that there’s no evidence for ET’s. In fact there is lot’s of types of evidence for the existence of ET’s both past and present.

    In the present there are groups like:

    – ‘The Disclosure Project’, formed by Dr Steven Greer.

    “We have over 500 government, military, and intelligence community witnesses testifying to their direct, personal, first hand experience with UFOs, ETs, ET technology, and the cover-up that keeps this information secret.”

    This includes Edgar Mitchell, 6th man on the moon.

    – ‘The Citizens Hearing on Disclosure’

    “From April 29, 2013 to May 3, 2013 researchers, activists, political leaders, and military/agency witnesses representing ten countries gave testimony in Washington, DC to six former members of the United States Congress on the evidence for an extraterrestrial presence engaging the human race. ”

    Plus many other isolated cases of ET contact, and countless UFO sightings around the world.

    In our recorded history there are cultures, many that developed completely independently of one another saying similar kinds of things.

    – How many of the pyramids around the world were built is still a great mystery. The egyptians, who were very keen on documenting themselves, don’t once mention how they built them, but speak about the ‘Sun Gods’ coming down from to sky, showing them how to build them. The Mayans also mention beings that helped them construct their pyramids.

    – The Hopi indians said that their ancestors were brought there by ‘giant flying tortoise shells’, which sounds similar to many of the ‘disk’ shaped UFO’s that are being sighted.

    – Hinduism tells us of their deities and half deities, who came in their ‘Vimana’, meaning ‘flying machines’, (which have been depicted with drawings), passing down their advanced knowledge and advising humanity. In the scriptures they describe the Earth as a sphere, where the sun never sets. They make references to gravity, atoms, and much more. These writings are over 5,000 years old!

    – The bible speaks of the ‘nephilim’, the giant gods that mated with our women and bore half-gods. Sounds pretty flesh and blood to me!

    Another small thing to note are the meteors that we discover containing fossilised bacteria. If we have evidence of life, quite literally ‘falling out of the sky’, I think it’s safe to assume that we live in a universe abundant with life, where life is the rule, not the exception.

    There’s a lot more I could go into, it’s a fascinating subject and well worth investigation!

  • Buck Wheat June 23, 2013, 8:29 PM

    The Fermi Paradox is total non-sense, Man as we currently are now has not been around 200000 years, I believe a whole lot less. Yes the solar system is old, our planet is old, but we were designed by a intelligent being that I refer to as God. Is God an alien from another world, he vary well may be, but he created us in his own image, keep that in mind. As for finding intelligent life out there with our current technology, I’m not holding out to much hope on that. If a species can skip over the Universe, worm holes, bend time & space than there technology is far far beyond ours. God said he was going to return, hopefully it will not be a end of days situation, but I do believe he or they will return.

  • Really20 June 24, 2013, 4:46 AM

    In my view, advanced extraterrestrials ARE gods. So yes, God knows.

  • Aqua4U June 24, 2013, 4:32 PM

    I like what you wrote and add that I feel we have been summarily dismissed as irrelevant due to our seeming inability to appreciate life in general. It may be that the true test of time for an evolving race is to transcend species related survival imperatives. Would that we were able to sacrifice our species dominant indulgences then we might be considered highly enough evolved to be contacted… but not beforehand. Am I overstating the obvious?

  • DarkGnat June 24, 2013, 5:42 PM

    They are here already, but they are not interested in us.

    They are looking for some guy they call “Kal-El.”

  • Christopher Barrett June 25, 2013, 2:45 PM

    I am sure that the universe is teeming with life. However, I believe that there are problems in making contact with aliens, such as:
    1. Distances too far, and we as humans have only really started to explore space in the last 50 years or so. This means that it will take MANY MANY years for a signal to reach another planet.
    2. Life forms could be very diverse, and thus communicating with them would be impossible.
    3. Our technology is simply not advanced enough.
    4. As suggested by the author, aliens may be trying to avoid us. This would not be surprising, given our destructive nature.

  • Francisco Casasola Cruzado June 30, 2013, 7:18 AM

    All these comments are very good is many of them could be merged for example:

    Sure there life in the universe, some more overdue, others to our level and more advanced technologically and culturally. The ones we are interested in right now are those who are more advanced by muñtiples reasons, although I recognize that people fear if they are hostile.

    But if it is the case and are there in space or on Earth would you think if you have an interest in exchanging information, in short in helping us advance scientifically and technologically, is so crucial help in fields like medicine given the many diseases that plague humanity such as cancer, AIDS etc etc.

    Well the big question is if they do they want to contact us?, Or how can we send them a signal that they recognize as intelligent and contact is made? ……. having made this question is one that concerns me, if as many say “they are here among us”, and know of our problems and therefore I wonder ….. why not help us? Do not you care if we kill in stupid and endless wars?, What we die of diseases that we are not yet able to cure?, In order that this final question concerns me very strange if not …….

    (excuse the bad English translation, Please thank you)

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