At a lunch in 1950 Dr. Enrico Fermi posed the paradox which bears his name. He said that since the Universe in 13.8 billion years old and the solar system, aged 4.5 billion years then if we have not had alien visitation then maybe there are no advanced civilizations who might come to have a look at us. Fermi reasoned that during all this time surely the travel restrictions posed by the speed of light would have been solved, so where are they?
Photo courtesy of NASA & JPL, is an artists rendering of a world in the Trappist system.
This brings up several interesting questions. First though, I should mention that Fermi died in 1954, 39 years before the first exoplanet was discovered. As of today NASA has confirmed the discovery of 5,599 exoplanets.
The first question is how do we know we haven’t been visited? Fossil evidence suggests strongly that homo sapiens first appeared @300,000 years ago If aliens had visited us before this there is of course no record. The oldest book dates from 2,700 B.C., Cave paintings may provide an answer but understanding them is a diffficult task. That oldest book, the Sumerian poem, Gilgamesh does have a surviving version dating from 2,000 B.C. That book only exists as parts of numerous tablets and many translations have been printed but none seem to depict alien visitors.
For a summary of cave paintings in U.S. western states dating back around 9,000 years, there’s a link to an article from the National Endowment of the Humanities.
The oldest known cave paintings, found in Indonesia are over forty centuries old.
Here’s an example of some 10,00 year old paintings from Argentina, found on Wikipedia.
Cueva de las Manos, Perito Moreno, Argentina, Mesoamerica. The art in the cave is dated between 7,300 BC and 700 AD;[a] stenciled, mostly left hands are shown.
Thus, we are back where we started and lack any clear evidence of alien visitations in recorded history,
Our planet has been around for billions of years so aliens certainly have had chances to check us out.
And here’s an interesting theory - WE are the aliens, placed here by fellow aliens as an experiment. Or perhaps we were shipped her as punishment as was the case for white settlers of Australia, sent there when America no longer welcomed “undesirables” following our independence.
There are many scenarios on this line of thinking for to ponder as we move along to the matter of logistics.
Our sun and solar system are located far out on a spiral arm of the Milky Way galaxy, some 25,000 Light Years (LY) from galactic center, home to a voracious black hole.
Have a look, the gold, yellow and orange ring represent hot gases as they are sucked into the monster. Nothing, not even light can escape its clutches once the event horizon is crossed. Photo from the Institute of Advanced Study in New Jersey.
Our nearest stars, in the Proxima Centauri double str system, are 4.5 LYs away or @26 TRILLION miles from us, thus even if we could build a spacefaring vehicle and somehow get it moving at just 10% of light speed’s 186,000 miles per seond) it would take us 45 years travel. And we are a long, long, very long way from reaching that rate of movement. We’re not exactly in a crowded neighborhood either, in fact there are onlyafew stars eithin 10 LYs of us, http://members.fcac.org/~sol/solcom/stars/s10ly.htmhttp://members.fcac.org/~sol/solcom/stars/s10ly.htm
Soup up your spaceship to search in a 25 LY radius and there are 84 stars from which you can choose to visit.
https://en.wikipedia.org/wiki/List_of_star_systems_within_20–25_light-years
Let’s then ask this question: why would advanced civilizations decide to come say “howdy to us. ? Our Sun is an unremarkable star located way out on a spiral arm of the galaxy. Astronomers say that there are at least a hundred BILLION stars in our Milky Way galaxy, with estimates ranging up to 400 BILLION.
Why would we rank as a priority destination? I am assuming that as a traveler moves closer to galactic center, the stars are closer together. Well, they have had billions of years to explore so maybe there is a galactic census bureau which sends exploratory vessels to tally them but would they stop off and hang out or just check our solar system and move on to the next system? I am also assuming such vessels would contain non-biological intelligences so that they would not have to carry huge amounts of food, water and heating systems.
When astronomers consider which exoplanets would be a good target for Earthly expansion, they consider which exoplanets are within the “Habitable zone”, (aka The Goldilocks zone). The primary factors are the presence of surface water, temperature range, type of terrain, atmosphere, gravity and the condition of the parent star.
Naturally, such a zone is one defined for the human race. We have no way of knowing what the parameters of a habitable zone are for say, machine intelligences which have no need of water and would be able to function in a far wider temperature range than humans.
Back to Fermi, her are some answers, give me your picks in the comments section, please.
No Aliens have ever come, at least not yet. 2.
Aliens have come but we have no evidence of this..
Aliens are US.
Aliens have not come and probably never will.
None of the above, suggest your own ideas.
You may be wondering what music I list n ed to as I prepared this latest OF AMERICAN ORIGIN essay?
I pondered this question for a bit before dusting off my 1973 2-LP SPACE RITUAL LIVE FROM LIVERPOOL AND LONDON by U.K. space rock group, HAWKWIND and they were great companions as I mentally raced over the Milky Way!
Safe travels!
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