The Common Europa Hypothesis

Hello, friends!  So Europa month ended a while ago, and I haven’t done much blogging since then.  Sorry about that.  I’ve been distracted by other writing projects.  But I now have some blog time in my schedule again, and I’m ready to blog about some new topics.  Except… I can’t help myself.  There’s one more thing I want to say about Europa.

I have this crazy idea.  I haven’t found much scientific literature to support me on this, but I still think this idea makes scientific sense.  I think that Europa—or rather, Europa-like worlds—may offer a solution to the Fermi Paradox.

For those of you who don’t know, in 1950, Italian physicist Enrico Fermi famously asked “Where is everybody?” in reference to extraterrestrial life.  Fermi argued that alien life should be all around us.  Almost everywhere we look in the cosmos, we should find alien beings waving back at us.  And yet, as of 1950, no real evidence of alien life had been found.  And as of today, in 2021, the situation remains much the same.

One possible answer to Fermi’s question came in the form of the rare Earth hypothesis.  Earth-like planets must be few and far between.  To be clear, when I say Earth-like planets in this context, I mean planets that meet the same Goldilocks parameters as Earth: not too hot, not too cold; not too big, not too small; not too wet, not too dry; et cetera, et cetera.  Planets that are so Goldilocks-perfect must be vanishingly rare in our universe.  Like, you could probably count on one hand how many Earth-like worlds exist in our whole galaxy.  So if life needs an Earth-like environment to survive, that may explain why alien life has been so frustratingly hard to find.

But then there’s Europa, the sixth moon of Jupiter.  Could there be life on Europa or on a Europa-like world?  And when I say a Europa-like world, I mean a world that looks like this:

A Europa-like world is a world with an ocean of liquid water covered up (and protected) by a thick shell of ice.  The mantle and core are hot, much like Earth’s, and hydrothermal vents on the ocean floor offer heat and nutrients to any potential life forms that might develop.

With respect to life on Europa herself, I’m 50/50.  There are good reasons to think Europa is habitable, and there are good reasons to think Europa falls just a little bit short of habitability.  But only a little bit.  Conditions on Europa are either just right for life or almost right.  So even if Europa misses the mark on habitability, another Europa-like world could easily hit it.

And here’s the important thing: while truly Earth-like worlds are rare, Europa-like worlds seem to be quite common.  There are at least two of them here in our own Solar System: Europa (obviously) and Enceladus, one of the moons of Saturn.  And there may be more.  In my research, Ganymede (moon of Jupiter), Dione (moon of Saturn), Titan (moon of Saturn), Ariel (moon of Uranus), and Triton (moon of Neptune) have all come up as places with certain suspiciously Europa-like qualities.  Even Pluto may have some liquid beneath her surface.

I’m choosing to call this idea the common Europa hypothesis, as a nod to the rare Earth hypothesis.  I think Europa-like worlds are common, both here in the Solar System and all across the cosmos.  Even if only 1% of these Europa-like worlds support life, that could still end up being an enormous amount of alien life out there.

Getting back to Enrico Fermi’s original question: “Where is everybody?”  Well, between the rare Earth and common Europa hypotheses, perhaps we have an answer.  Aside from us Earthlings and the lucky few who get to live on Earth-like planets, everybody is swimming around in Europa-like subsurface oceans, beneath thick layers of ice.


I suggest reading Exoplanets by Michael Summers and James Trefil.  Among other things, there’s plenty of discussion about all the surprising yet plausible places Europa-like worlds might exist.

The Fermi Paradox (Tomorrow News Network: A to Z)

Hello, friends!  For this year’s A to Z Challenge, I’m telling you more about the universe I’ve created for my upcoming Sci-Fi adventure series, Tomorrow News Network.  In today’s post, F is for:


Okay, bear with me.  This post is going to get weird.  Some of what I’m going to tell you is true.  The rest is totally made up Sci-Fi nonsense.


Historians disagree about the exact date, but sometime around 1950, nuclear physicist Enrico Fermi was having lunch with a few physicist colleagues.  The topic of conversation: extraterrestrial life.  It was during this conversation that Fermi famously quipped: “But where is everybody?”

Dr. Fermi then proceeded to lay out all the reasons why advanced alien civilizations should exist out there among the stars, and also all the reasons why we should have detected their presence by now.  And yet, despite our best efforts, we’ve found nothing.  So where is everybody?

This question is now known as the Fermi Paradox.  If you’re a scientist involved in SETI research, you will have to grapple with this issue at some point.  And if you’re a science fiction writer creating a sprawling Sci-Fi universe full of advanced alien civilizations, well… you should probably imagine up some sort of solution to the Fermi Paradox.

Mind you, it doesn’t have to be the most scientifically plausible solution.  But some of your readers will surely be wondering about this, so….


In time index 117-299, a Hykonian observation vessel crashed on Earth near a small Earthling village named Roswell.  The cause of the crash remains unknown.  The fate of the Hykonian crew remains unknown.  And what happened to the wreckage of the spacecraft itself?  Again, unknown.

Due to the suspicious circumstances surrounding the Roswell incident, the Galactic Inquisitor was forced to intervene.  The Hykonian Hegemony has demanded retribution; meanwhile, the local authorities on Earth continue to claim ignorance (something, something, weather balloons).  Until this matter is resolved, the Galactic Inquisitor has imposed an isolation ordinance over Earth.

All forms of interstellar communications are being jammed, and no spacecraft shall be permitted to enter of leave the Solar System.  Recent violations of this ordinance by NASA’s Voyager 1 and Voyager 2 space probes are currently under investigation.

Most Earthlings are left wondering, understandably, why they seem to be alone in the universe.  And so things shall remain until the Galactic Inquisitor’s ordinance is lifted.

Speaking of the Galactic Inquisitor, next time on Tomorrow News Network: A to Z, we’ll meet the timeless, near godlike being who maintains law and order in the galaxy.

Sciency Words A to Z: The Fermi Paradox

Welcome to a special A to Z Challenge edition of Sciency Words!  Sciency Words is an ongoing series here on Planet Pailly about the definitions and etymologies of science or science-related terms.  In today’s post, F is for:


The birth of the Fermi Paradox is, perhaps, one of the most poorly documented scientific events in recent history.  Nuclear physicist Enrico Fermi did not present his famous paradox at some scientific symposium or write it up for some academic journal. No, the whole thing started (apparently) with a comment Fermi made half-jokingly over lunch.

I normally draw all the illustrations on this blog, but I’m making an exception today.  In 1950, New York City was suffering an epidemic of disappearing garbage cans.  No one could figure out where the city’s garbage cans were going or who was taking them, so the New Yorker published this cartoon offering one possible explanation:

According to the historical narrative reconstructed in this report, that summer (or sometime thereabout) Fermi was visiting the Los Alamos National Laboratory in New Mexico.  He and a bunch of old friends from the Manhattan Project had seen that cartoon and were joking about extraterrestrial life over lunch.

As the conversation progressed, Fermi suddenly, almost out of the blue, said these fateful words: “But where is everybody?”  He then proceeded to lay out the fundamental problem that is now known as the Fermi Paradox.

In short, our galaxy is old—over ten billion years old by most estimations.  Earth is less than half that age, and our civilization—why, we’ve been around for barely a blink of an eye on the cosmic scale.  If civilizations like ours can pop up so suddenly, so abruptly, then over the last ten billion years advanced civilizations should have filled up the whole galaxy.  The aliens should be everywhere, and yet we can’t seem to find any evidence of their existence.

So where is everybody?

Many answers to that question have been proposed over the years.  Fermi and company are said to have run through most of them that day while they finished up their lunch.

  • Maybe Earth is part of a galactic nature preserve, or maybe intergalactic law forbids anyone from making contact with “primitive” cultures like our own.
  • Maybe Earth is out in the boondocks of the galaxy, far, far away from where all the aliens like to hang out.
  • Maybe interstellar travel is harder than we think, and so all the alien civilizations tend to keep to themselves and never leave their home planets or home solar systems.
  • Maybe intelligent life has an innate tendency to destroy itself.

That last one is a sobering thought, especially when you remember that these were the people who worked on the Manhattan Project!

Personally, I kind of like the notion that we’re part of a nature preserve.  I have no scientific justification for thinking that; I just find it comforting to suppose that maybe the aliens do know about us and think we’re worth preserving.  But what do you think the solution to the Fermi Paradox might be?  Let me know in the comments!

Next time on Sciency Words: A to Z, why is Earth “just right” for life?

Correction/Clarification: After reading some of the responses to this post, I think I may have been a little too flippant about the galactic nature preserve thing. I think that’s a cool idea, and I think it’s a fun thing to think about. But there is absolutely no scientific evidence to support that hypothesis at this point, and I do not actually take the idea seriously. I should have been clearer about that.