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Panspermia or The Great Filter May Answer Fermi’s Paradox

JupiterWe may never have an answer to the Fermi Paradox but possibilities are endless, hypotheses are abundant, and options are thought provoking. Last blog considered self-destruction as an answer to Enrico Fermi’s question: Where are they? They meaning extraterrestrial life forms.

Today we take a look at two popular explanations as to where they are. The Great Filter and Panspermia hypotheses warrant investigation and offer answers as to why we seem to be the only ones to exist in the vastness of space. (Probe Note: The difference between a hypothesis and a theory: a hypothesis is a best guess while a theory has been tested and has evidence to back up its claims.)

Seven New Planets

This information on the Trappist-1 system is presented on the NASA website.

All seven planets discovered in orbit around the red dwarf star TRAPPIST-1 could easily fit inside the orbit of Mercury, the innermost planet of our solar system. In fact, they would have room to spare. TRAPPIST-1 also is only a fraction of the size of our sun; it isn’t much larger than Jupiter. So the TRAPPIST-1 system’s proportions look more like Jupiter and its moons than those of our solar system. 
The seven planets of TRAPPIST-1 are all Earth-sized and terrestrial, according to research published in 2017 in the journal Nature. TRAPPIST-1 is an ultra-cool dwarf star in the constellation Aquarius, and its planets orbit very close to it. The system has been revealed through observations from NASA’s Spitzer Space Telescope and the ground-based TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) telescope, as well as other ground-based observatories. The system was named for the TRAPPIST telescope.

Hitchhiker’s Panspermia

In a recent National Geographic feature on the seven new Earth-like Planets, the reporter explores the possibility of Panspermia. Panspermia—seeds everywhere—suggests that primal life forms were dispersed throughout the universe on meteoroids, asteroids, comets, planetoids, or perhaps, spacecraft. The term can be traced backed to the 5th Century BC Greek Philosopher Anaxagoras.

“The seed of everything is in everything else.” 

The National Geographic article suggests the planets of Trappists-1 are so close to their stellar host that these seeds could hop from one planet to the next thus promoting life.  A tough journey scientists suggest but not impossible.

We are reminded of the tiny Tardigrades—aka little water bears. The tiny—less than a millimeter in size—creature receives the tag for being the most tenacious guy on the planet. Its evolutionary development has rendered it capable of elaborate dormancy strategies. They can shut down all but the essential biological processes when conditions are not conducive to supporting life, and they have survived space travel.

On September 14, 2007, on board an unmanned Russian Foton-M3, thousands of bears along with 40 other European Space Agency (ESA) experiments were successfully launched and spent 12 days in orbit. The experiments were exposed to microgravity and, in the case of the Tardigrades, to the harshness of open space. Two sets of Tardigrades were studied: one set was exposed to both space vacuum and solar radiation, and another set was exposed to space vacuum only.

Many of the water bears survived the trip and even managed to continue reproductive processes. Fewer survived exposure to UV radiation. BUT some did.

This gives us a possible explanation to life on our planet. Perhaps our hitchhiking seeds came from self-destroyed planets.

Directed Panspermia

There is another type of Panspermia. Deliberate distribution of the seeds of life is known as Directed Panspermia and poses that an Extraterrestrial Intelligence purposefully scattered these buds to generate life. English molecular biologist, biophysicist, and neuroscientist, Francis Crick, along with British chemist Leslie Orgel proposed this idea of Directed Panspermia.

The 2012 movie Prometheus gives a visually brilliant portrayal of Directed Panspermia on Earth as a humanoid alien’s DNA cascades into a waterfall. Here is a YouTube clip from the movie. The humanoid is called the sacrificial engineer.

So where are these engineers?  Are we them? But where are the ones who started the entire process?

Two conclusions can be drawn when considering the relevance of Directed Panspermia in our discussion. (1) They did the deed and then took off, never to return. (2) They will one day return to see how and if we advanced.


  • We’re meat. Perhaps the more we populate in numbers the more desirable we become. (ProbeNote: Humorous and thought provoking Nebular Award nominated short story by Terry Bissom depicts an alien race alarmed that we are meat.  It’s very short. Very funny. Can be read here.) It also explains why we may not have been contacted. Yet!


  • Something, maybe The Great Filter, happened and they are unable to return.

The Great Filter

The immensity and age of our galaxy indicate there ought to be evidence of extraterrestrial intelligences (ETIs) out there, unless you factor in something called The Great Filter that suggests there exists a barrier—a stumbling block—that prohibits advanced ETIs from continuing their evolution toward space exploration.

The etymology of the word “filter” is: c.1400, from M.L. filtrum “felt,” which was used to strain impurities from liquid. One might wonder what The Great Filter (TGF) of the universe considers impurities?

The notion of an almighty Great Filter was introduced in an online essay in 1996 by economist Robin Hanson. Starting with a planet, such as earth, and ending up with an evolved lasting life form, such as us, seems highly improbable when one examines Hanson’s list of nine evolutionary steps that must be climbed in order to ascend from the murky quagmire into the light of day, advance, and colonize into an observable world.

The nine ingredients needed for the To Serve Man recipe:

  • In a big bowl put: (Step 1)the right star system
  • Add a cup of:  (Step 2)reproductive molecules
  • Stir
  • Add in a cup of:  (Step 3) simple single cell life (prokaryotic-organisms whose cells lack a membrane-bound nucleus)
  • Stir and let rise.
  • Now you have: (Step 4) complex single-cell life (archaic and eukaryotic-eukaryotic organisms have cells that contain a membrane-bound nucleus)
  • Add to taste: (Step 5) sexual reproduction
  • Stir and bake several billion years.

Pause at any of the following steps, depending on the universe’s desired effect—the star system’s preferred doneness. In other words, does it want cookie dough or the whole enchilada?

  • (Step 6) multi-cell life
  • (Step 7) tool-using animals with big brains
  • (Step 8) where we are
  • colonization explosion (aka space travel to find other worlds to inhabit, aka interstellar colonization, aka STEP 9)

Hanson states this list of steps is not intended to be complete. He goes on to say: “The Great Silence implies that one or more of these steps are very improbable; there is a “Great Filter” along the path between simple dead stuff and explosive life. The vast vast majority of stuff that starts along this path never makes it. In fact, so far nothing among the billion trillion stars in our whole past universe has made it all the way along this path.”

To our knowledge, we appear to be the only ones to make it to step eight. If others were as lucky as we, our Milky Way would be populated with colonies. The Great Filter suggests that one of the steps above number eight, in the evolutionary recipe, is nearly impossible to permeate, because…so far…we humans exist in the Great Silence, a silence in which no one seems to be receiving or transmitting.

ETIs may have made it as far as we have, but never made it any farther—past the filter. This is bad news for us, but encourages us to ask hard questions like: Did their technology grow so rapidly, without precautionary measures, they obliterated themselves and erased any evidence of their existence?

My novella, Man’s Best, describes a civilization that might rise from such a scenario. A civilization that would learn from past mistakes, create a perfect world, and then hide from outsiders in an effort to protect their perfection. They didn’t send out any signals to alert the rest of the galaxy they’d found paradise.

The Final Frontier

Perhaps, it is the last step, Step 9, that is improbable. If so, is The Great Filter behind us? Hanson doesn’t seem to think so. Have we managed to filter through the improbable step or does it lie ahead of us?

Is the inevitability of self-destruction—whether it be outgrowing the earth’s resources or a natural or man-made catastrophe—the reason no one makes it to the final step? Where are they? Are we them?

Hanson suggests:

Rational optimism regarding our future, then, is only possible to the extent we can find prior evolutionary steps which are plausibly more improbable than they look. Conversely, without such findings we must consider the possibility that we have yet to pass through a substantial part of the Great Filter. If so, then our prospects are bleak, but knowing this fact may at least help us improve our chances.

For example, if our prospects are likely bleak we should search out and take especially seriously any plausible scenarios, such as nuclear war or ecological collapse, which might lead to our future inability to explode across the universe.


Twilight Zone
 The 1982 Twilight Zone episode entitled “To Serve Man,” written by Rod Sterling and based on the short story by Damon Knight, explores Earthlings’ fears about ETs.

In a 1982 Twilight Zone episode, Kanamits, an alien race, arrive on earth vowing the motive for their presence is to help mankind. After addressing the United Nations, the Kanamit speaker leaves behind a book.

Patty, a US government cryptographer, translates the title of the book and finds that it means, To Serve Man. Further study leads her to the discovery that the book is a cookbook.

In the style for which Sterling is famous, his commentary at the end of the episode puts mankind into the following perspective: from ruler of a planet to an ingredient in someone’s soup. 

Classic SyFy—do you remember the episode? Campbell’s, Extra Chunky, anyone?

The Probe’s Mission Statement

turtle-in-oceanThe Probe is a blog devoted to the exploration of the unexplainable, to finding the truth in occurrences that resemble science fiction, and to researching and reporting on topics that could be flung upon the wall of weird. New posts are featured as often as I can find WiFi, and as often as I have something I think you might find interesting.

Join me here for more close encounters of the alien kind, or ghost kind, or animal kind, or travel kind, and please share your own. Science Fiction or Fact? Doesn’t matter to me. I just like a story that gives me the chills, makes me laugh, makes me think, or makes me imagine. otter

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(BTW the animals pictures are my children’s animal totems. My daughter is Turtle. My son is Otter. My granddaughter is the Great Blue Heron. And Fox is my little grandson we lost in April but whose presence I feel every day.) fox

Clara Bush
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