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The Fermi Paradox

Where is everybody?" was a question posed by physicist Enrico Fermi. The 'paradox' is that extraterrestrials should be here, yet there is no indisputable evidence to support that. Or is there? Those pesky UFOs just will not go away!

The Fermi Paradox (after physicist Enrico Fermi) briefly goes as follows. Extraterrestrial intelligences with advanced technology and interstellar spaceflight capability exist. Sub-light interstellar spaceflight violates no laws of physics. Adopting the mantra of quantum physics, ‘anything that’s not forbidden is compulsory’. The time it takes to explore every nook and cranny of our Milky Way Galaxy via sub-light interstellar spaceflight is a tiny fraction of the age of the Galaxy. There’s at least one universally valid reason to boldly go – species survival. No star, no solar system lives forever. We (Planet Earth) can’t hide from alien exploration and/or colonization. So, where is everybody? [By analogy, terrestrial life forms like bacteria, ants and cockroaches, birds, and of course humans, have explored and colonized Planet Earth in tiny fractions of the time that Earth itself has existed.] So again, where is everybody?

I can hear screams of ‘objection, objection’ now. It’s obviously too far and takes too long to get from there (wherever that is) to here. Well, life wasn’t meant to be easy! Seriously, if you think about it a while, methinks you protest too much!

Firstly, aliens could have a very long natural lifespan relative to us carbon-based terrestrial bipeds. There’s no natural law that confines intelligent life forms to an existence of just three score and ten.

Secondly, advanced extraterrestrials may have perfected various hibernation techniques. Put your spaceship on autopilot and sleep the long journey away.

Thirdly, there’s that way old sci-fi chestnut, the multi-generation interstellar spaceship. While I feel that’s an unlikely concept, especially for exploration, it might not be quite so far out if the objective is interstellar colonization.

Then there’s bioengineering, turning an organic body into something that’s more machine than flesh and blood, perhaps akin to Doctor Who’s Daleks. Given advances in artificial body parts for humans, albeit it hip replacements or dentures or even mundane tooth fillings, that’s certainly a valid possibility.

Fifthly, why stop there? Send 100% machines – artificial intelligences in the form of cybernetic ‘organisms’ or robots or androids or tiny nanotechnology machines. One obviously things of Data from ‘Star Trek: The Next Generation’, or something akin to the original ‘Battlestar Galactica’ Cylons. Think of the savings in not having to provide life support and other life essentials for biological organisms. We’ve made a start already down this path. There’s nothing different in principle between a Cylon and our Pioneer 10 & 11; our Voyager space probes. It’s just that a Cylon is a lot more sophisticated. The day will come when our Pioneers and Voyagers will morph into something approaching a Cylon, or any one of multi-dozens of similar ‘beings’ in the sci-fi literature. Since AI is nearly immortal (relative to flesh and blood), that takes care of travel time arguments, and the possible environments fit for relative easy exploration (colonization?) are expanded greatly.

Lastly, maybe, just maybe, a sort of warp drive, faster-than-light ship is possible. Aliens whose science is thousands of years more advanced than ours just might have gotten around Einstein’s speed limit. I wouldn’t want to wager any money on it, but I’d be less than open minded not to admit the possibility, however remote. Add to that, theoretical but allowable ‘gateways’ between distant points of our Universe, maybe even to other universes – wormholes and Black Holes. Maybe, just maybe, an advanced alien civilization has the ways and means to manipulate such objects and forces to facilitate easy travel in space (and time too maybe). An excellent hardcore science based sci-fi novel that doesn’t rely on pseudo techno-babble that illustrates this is Carl Sagan’s “Contact”.

So yet again, where is everybody?

Answers include (but aren’t really limited to) general concepts that suggest that…

They don’t exist; never have and never will. What’s wrong with that? Well, given the vastness (100,000 light-years across) and timelessness (over 12 billions of years minimum) of our Milky Way Galaxy’s entire expanse, the odds that we are the proverbial IT, the one and only, is extremely unlikely. It’s a massive violation of the Principle of Mediocrity or the Copernican Principle.

We’re the first kids on the block, not the new kids on the block. What’s wrong with that? Again, the odds that in all the vastness of our Milky Way Galaxy we should happen to be the first, is unlikely in the extreme. Our Solar System is but 4.5 billion years old; our Galaxy is way, way, way, way older than that.

They exist but don’t care to explore space, to seek out new life and new civilizations. They don’t want to boldly go or seek communications. They want to be left alone – isolationists. What’s wrong with that? That might be true for one, or several alien civilizations, but to extrapolate and suggest that that applies across the board to each and every extraterrestrial civilization is illogical.

They boldly go, but haven’t come our way yet. What’s wrong with that? Again, it doesn’t take that long to explore the entire Galaxy. It would be a fluke if we hadn’t of been noted and logged in some other civilization’s database.

They’re here, but leave us alone. What’s wrong with that? Again, that might be true for one, or several alien civilizations, but to extrapolate and suggest that that applies across the board again strikes me as illogical. There is such a thing called the Zoo Hypothesis to explain the Fermi Paradox. It’s both a Star Trek ‘Prime Directive’ concept combined with that of a zoo. Aliens (the zoo keepers) don’t interfere with us (though of course every now and then the zoo keepers have to interact with the animals (humans) in the zoo), don’t allow others to interfere with us, yet probably wouldn’t allow us to escape the cage (meaning probably the confines of our solar system – I mean we have been allowed to travel to the Moon).

They’re here and interact with us and our environment - UFOs anyone? What’s wrong with that? Absolutely nothing!

UFOs are a perfect answer to the Fermi Paradox!

Further readings: The Fermi Paradox

Hart, Michael H. & Zuckerman, Ben (Editors); Extraterrestrials: Where Are They?; Pergamon Press, N.Y.; 1982:

Hart, Michael H. & Zuckerman, Ben (Editors); Extraterrestrials: Where Are They? [2nd edition]; Cambridge University Press, Cambridge; 1995:

Verma, Surendra; Why Aren’t They Here? The Question of Life on Other Worlds; Icon Books, Cambridge; 2007:

Webb, Stephen; Where Is Everybody? Fifty Solutions to the Fermi Paradox and the Problem of Extraterrestrial Life; Copernicus Books, N.Y.; 2002:

johnprytz 7 Oct 26

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Even if there are a lot of extraterrestrial civilizations, they may be too difficult to contact, and we may be too difficult for them to contact.

  • Interstellar communication is too difficult
  • Interstellar is too difficult
  • We have not been searching long enough
  • We have not been searching for the right kind of evidence
  • We already have evidence of ET’s, but we don’t recognize it
  • We already have evidence of ET’s, but we are unwilling to recognize it

That last one is what many UFOlogists believe.

As to being unwilling to make contact, that has subcategories

  • They are not interested in making contact with other planets' civilizations
    • Considering it too unlikely (their version of the Fermi paradox)
    • Being inward directed (like us exchanging cat pictures)
    • Considering it too silly (Senator William Proxmire's argument)
    • Ideological objects (some Xian fundies believe that no ET's exist)
  • They are hiding from others
  • They know about us, but they are not willing to contact us
    • Incredulity at our nature: "They are made of meat!"
    • Considering us too nasty or backward to be worth contacting
    • The Zoo Hypothesis

Continuing with the Great Filter, there are a variety of natural disasters that can cause trouble on the way:

  • Asteroid impacts
  • Massive volcanism
  • Supernovae and gamma-ray bursts

Disasters that can cause more proximate causes of mass extinction like

  • Global warming
  • Global cooling
  • Blocking out incoming light
  • Letting in ultraviolet light

Technological civilizations can also suffer from a variety of self-inflicted calamities:

  • War
  • Environmental Problems
  • Resource Depletion
  • Disease
  • Social / Political / Economic Collapse
  • Technological Failure
  • Loss of Interest

I've seen oodles of proposed solutions to the Fermi Paradox. They fall into a few categories.

  1. ET's are rare or absent: "Great Filter" hypotheses, also, we may be the first
  2. ET's are too difficult for us to contact, and vice versa
  3. ET's know about us, but they choose not to contact us

If the history of our planet's biota is any indication, then the Great Filter is a series of filters. Here is a sketchy outline:

  • Earthlike planet
  • Emergence of a self-replicating molecular system
  • Emergence of methanogen-like metabolism: making all one's biological molecules while getting energy from inorganic-compound reactions, like CO2 + 4H2 -> CH4 + 2H2O
  • Emergence of oxygen-releasing photosynthesis
  • Emergence of multicellularity, especially animal-like multicellularity
  • Living on land
  • Human-scale intelligence, including human-scale language and large social groups
  • Technologies like agriculture and writing
  • Abstract science

I’ve been hoping we’d stumble across radio signals from alien civilizations my whole life but it’s not looking promising. My best guess is that civilizations have a limited life expectancy before they destroy themselves with war, disease, pollution, whatever. Civilized (more or less) humans have only been around a few thousand years, a blink of the eye in galactic terms, and we’ve only been sending and receiving radio signals a hundred years or so. So if technological societies only survive a few hundred years then it seems reasonable that they’re less likely to overlap long enough to establish communications with us.

Yeah, but it’s not looking great for us at the moment.


Here's a recent post from my group, but there are many articles & videos on this subject, positing Great Filters, vastness of the Universe, age of the Universe, etc...


Yeah, is beginning to look bleak. I suspect intelligience such as ours is an evolutionary dead end. And since we don't even know how likely it was for something like us to evolve, we might be the only one. SETI still has numerous promising avenues to explore though, so no need to give up hope yet.


Got a little personal fantasy in there at the end huh?

We have no evidence for anything, at all. But when you can't explain something for sure, the simplest answer is usually the best one.

Let's look at how we got here. To do that, we have to look at humanity's unique abilities.

1: Sweating. No other species that is built for a marathon sweats, they pant. Our ability to "walk" other animals to death is largely thanks to this. We cool ourselves as we exert, while panting only works from a standstill.

2: We can throw things. Seriously. We're the only animals that can chuck stuff really far. Other animals that can throw things can toss stuff at best.

Those are evolutionary factors. But how common are they? Even assuming complex life is fairly common in the universe, how often do complex organisms develop traits like these on top of tool use?

Those factors alone could be a great filter. Space travel isn't an evolutionary factor, that's a coincidence. We can travel in space because of our tool use and our bigger brains, which we only developed because our large gestation and maturation times and our meat-based diet (which we only acquired because of our super efficient hunting method, which we could only do because of our super efficient method of cooling ourselves) fed largely by monogamous parent couples who protected us.

Not to mention our discovery of fire, which helped certain parts of our bodies shrink (like our gut) to further preserve energy.

AND, not to mention, have you noticed something odd about humanity?

We're the only species of our genus still in existence. That's rare. I don't even know why that is, except maybe we all almost died at least once and the rest of them (neanderthals and such) did.

Look at all that. How many things had to happen for us to be able to put a man on the moon, and the time it took. It's fascinating. How often could events like that occur? How often does complex life get all that?

It's not just tool usage, other species on Earth do that, and they're not traveling to the moon any time soon.

Honestly. It looks like we're a rare species on a rare Earth. We probably have already passed the first great filter. Is there another? Several, before we reach interstellar travel?

It's no wonder there's no life coming to greet us. We very well could be among the first.

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