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One night about 60 years ago , physicist Enrico Fermi looked up into the sky and asked , " Where is everybody ? "
He was talking about unknown .
Scientists have discovered thousands of planets beyond our solar system. So where are all the aliens?
Today , scientist know that there are jillion , perhaps one thousand million of planets in the universe that could sustain life . So , in the tenacious story of everything , why has n’t any of this spirit made it far enough into space to shake hired hand ( or claws … or tentacle ) with humans ? It could be that the universe is just too enceinte to get across .
It could be that the stranger are deliberately ignoring us . It could even be that every grow civilization is irrevocably doomed to put down itself ( something to look forward to , fellow Earthlings ) .
Or , it could be something much , much weirder . Like what , you ask ? Here are 12 strange reply that scientists have proposed for theFermi paradox .
Related:‘It ’s hard not to trust he saw something ' : Historian Greg Eghigian on how UFOs took over the world
We’re looking in the wrong universe
Maybe we have n’t found aliens because our creation is n’t particularly conducive to animation . Maybe Earth is an anomaly — a lucky blue dot adrift in a Brobdingnagian ocean of darkness and idle worlds . Maybe we ’d have good fortune bet for life in the next existence over .
That last estimate is thepremise of a 2024 studythat assumes our cosmos is just one potential population within an endless " multiverse " of realities , each one slightly dissimilar from the rest . To test whether our universe has the optimum weather for life story to come forth , the researchers compared genius formation rate here to star formation rates in a server of hypothetical , parallel universes with different concentration of matter and energy .
The main factor the team considered was a macrocosm ’s density of non-white vitality — a mysterious power that drives the constant , speed up expansion of the cosmos . A population with too muchdark energywould expand too apace , scattering lead - forming stuff and stunting the growth of large - scale structures like galaxy clusters . But in a universe with too little dismal energy , sombreness might become overwhelming , causing large structures to collapse before habitable major planet had the chance to form .
The team ’s example revealed that the optimum density of dark energy within a universe of discourse would enable up to 27 % of average matter to turn into stars . But in our population , only an judge 23 % of matter turns into stars — meaning there are few stars here than there could be and , as a result , fewer places for alien life to emerge . Better chance in the next creation !
Aliens don’t live on planets
Every foreign coinage needs a inhabitable satellite to live on , right ? Surprisingly , a 2024 study argue that may not always be the case .
In apaperaccepted for publishing in the journal Astrobiology , investigator proposed a scenario in which an alien colonycould survive by floating freely in space , no planet need . It may sound wild , but it ’s not without real - populace precedent ; humans , for example , can go for C of days without a planet while residing on theInternational Space Station(albeit with never-ending livery of crucial resources from their planet ) , andhardy tardigradescan subsist the vacuum of space .
A theoretical planet - gratuitous alien colony would have to overpower many challenge , include a want of resource , exposure to cosmic irradiation and the vacuity of blank space , and access to enough sunshine . With this in mind , the researchers paint the characterization of a species that could subsist these trials : a free - floating settlement of being measuring up to 330 feet ( 100 meters ) across , encase in a sparse , arduous , transparent scale that could exert a livable temperature and pressure through the nursery event .
encounter such a species is a long shot , but it ’s not impossible . A loose - floating exotic settlement could also explicate why no intelligent aliens are answering our calls : They do n’t have a land line to use .
The aliens are hiding in underground oceans
If homo hope to discourse with ET , we ’ll postulate to have a few icebreakers ready to hand . No , severely — alien living isprobably trap in secret oceansburied deep inside frigid planet .
Subsurface oceans of fluent water system slosh beneath multiple moons in oursolar systemand may be common throughout theMilky Way , astronomers say . NASAphysicist Alan Stern call up hugger-mugger water human beings like these could put up a arrant stagecoach for germinate spirit , even if inhospitable surface experimental condition plague those works . " Impacts and solar flares , and nearby supernovae , and what compass you ’re in , and whether you have a magnetosphere , and whether there ’s a toxicant ambiance — none of those things weigh " for life that ’s hole-and-corner , Stern told Space.com .
That ’s great for the aliens , but it also think we ’ll never be able to detect them just by glance at their major planet with a telescope . Can we expect them to touch us ? Heck , Stern said — these critter live so mysterious , we ca n’t even expect them to make love that there ’s a sky over their head . as luck would have it , NASA ’s Europa Clipper spacecraftis on the direction to one such synodic month to look for grounds of life up - close . The Clipper will make it at Jupiter ’s quick-frozen Sun Myung Moon Europa in 2030 .
The aliens are imprisoned on “super-Earths”
No , " top-notch - earthly concern " is not Captain Planet ’s dorky cousin . In uranology , the condition refers to a type of major planet with a mass up to 10 times bully than Earth ’s . genius survey have turned up oodles of these worlds that could have the right condition for fluent water supply . This think alien life could conceivably be acquire on super - Earths all over the universe .
Unfortunately , we ’ll in all likelihood never gather these extraterrestrial being . harmonise toa study published in 2018 , a planet with 10 times Earth ’s sight would also have an escape velocity 2.4 times greater than Earth ’s — and overcoming that pull could make skyrocket launch and space travel near unsufferable .
" On more - massive major planet , spaceflight would be exponentially more expensive , " study author Michael Hippke , a research worker affiliated with the Sonneberg Observatory in Germany , previously differentiate Live Science . " Instead , [ those aliens ] would be to some extent hold on their home planet . "
We’re looking in the wrong places (because all aliens are robots)
Humans invented the radiocommunication around 1900 , built the first computer in 1945 and are now in the business of mass - develop handheld devices capable of making billions of calculations per moment . Full - blown artificial intelligence activity may be right around the corner , and futurist Seth Shostak said that ’s reason enough to reframe our lookup for intelligent aliens . but put , we should be looking for machines , not little green men .
" Any [ alien ] society that formulate radiocommunication , so we can hear them , within a few centuries , they ’ve make up their heir , " Shostak say at the Dent : Space group discussion in San Francisco in 2016 . " And I cerebrate that ’s important , because the successor are machines . "
A truly advanced foreign fellowship may be completely populate by super - reasoning robots , Shostak suppose , and that should inform our search for aliens . Instead of concentrate all our resources on finding other inhabitable planets , perhaps we should also seem to places that would be more attractive to machine — say , places with lots of energy , like the center of galaxies . " We ’re looking for analogues of ourselves , " Shostak say , " but I do n’t know that that ’s the bulk of the intelligence in the universe . "
We’ve already found aliens (but are too distracted to realize it)
Thanks to pop refinement , the word " exotic " probably makes you visualize a spooky humanoid with a big , bald-pated head . That ’s hunky-dory for Hollywood — but these preconceived images of E.T.could countermine our search for exotic sprightliness , a team of psychologists from Spain write in the beginning this year .
In a small survey , the researchers asked 137 people to calculate at pictures of other planets and scan the images for signs of exotic structures . blot out among several of these range was a tiny humankind in a gorilla lawsuit . As the participants hound for what they think alien spirit to depend like , only about 30 % observe the gorilla Isle of Man .
In reality , aliens in all probability wo n’t calculate anything like emulator ; they may not even be perceptible by clean and sound waves , the researchers wrote . So , what does this study show us ? fundamentally , our own imagination and aid span restrain our search for extraterrestrialsy . If we do n’t learn to broaden our skeletal frame of reference , we could miss the gorilla staring us in the face .
Humans will kill all the aliens (or already have)
The nearer we get to finding aliens , the closer we get to destroying them . That ’s one probable contingency , anyway , order theoretic physicist Alexander Berezin .
Here ’s his thought process : Any civilization adequate to of exploring beyond its own solar organization must be on a path of unrestricted increase and expansion . And as we know on Earth , that elaboration often come at the expense of smaller , in - the - way being . Berezin said this me - first brain probably would n’t terminate when foreign sprightliness is finally encountered — assuming we even notice it .
" What if the first living that hand interstellar - travel capability needfully eradicates all rival to fire its own expanding upon ? " Berezin write in a paper posted in 2018 to the preprint journal arXiv.org . " I am not suggesting that a highly develop civilization would consciously wipe out other life - shape . Most probably , they simply wo n’t notice , the same agency a expression work party demolishes an formicary to build existent demesne because they lack inducement to protect it . " ( Whether human beings are the ants or the bulldozers in this scenario remains to be watch . )
The aliens triggered climate change (and died)
When a population fire through resource quicker than its satellite can furnish them , catastrophe loom . We know this well enough fromthe on-going climate - change crisishere on Earth . So , is n’t it potential that an advance , push - guzzle alien lodge might hunt into the same issues ?
According to astrophysicist Adam Frank , it ’s not only potential but highly potential . Earlier this year , Frank ran a series of mathematical models to simulatehow a hypothetic exotic culture might spring up and fallas it more and more convert its planet ’s resource into energy . The sorry news is that in three out of four scenarios , the society fall apart and most of the universe go bad . Only when the society get the problem early and immediately flip to sustainable energy did the refinement cope to pull round . That means that , if aliens do exist , the betting odds are pretty mellow they ’ll destroy themselves before we ever gather them .
" Across cosmic space and time , you ’re going to have winners — who finagle to see what was going on and figure out a path through it — and losers , who just could n’t get their bit together , and their civilization hang by the wayside , " Frank say . " The question is , which category do we desire to be in ? "
Aliens used clean energy, but still triggered climate change (and died)
A sufficiently advanced exotic mintage will inescapably fire up up its satellite as its society and its energy needs uprise . This could trigger runaway climate change , as humans are doing on Earth , and may destine those noncitizen to an former defunctness . But what if the tight - growing alien society made an other switch to eco - friendly , renewable vigor ? Could that spare them , allowing the aliens to grow , thrive and inflate throughout the cosmea without consequence ?
Sorry , but no , according to ableak theoretical studypublished to the preprint databasearXivin September 2024 . The survey find that an exponentially growing alien metal money using 100 % renewable vim would still heat up their planet with wastefulness heat , which is inevitably produced from any energy expenditure harmonize to the second law of thermodynamics . This waste heat would continue to work up up as long as the high society ’s energy requirement grew , eventually triggering disastrous mood change within 1,000 old age of that bon ton ’s industrial revolution .
If true , this mean that an push - guzzling foreign race would probably never survive long enough to venture deep into the cosmos and set up shop on nearby planet . It ’s not only a pitiful expectation for aliens but an pressing wake - up call for Earth .
The aliens couldn’t evolve fast enough (and died)
register another excuse under " the outlander are dead already " category . The universe may be teeming with hospitable planet , but there ’s no warrantee they ’ll stay that path long enough for life to evolve . concord to a2016 sketch from Australia National University , wet , rocky planets like Earth very unstable when they start their careers ; if any foreign liveliness hopes to evolve and flourish on such a world , it has a very limited windowpane ( a few hundred million years ) to get the ball rolling .
" Between the former estrus pulses , freezing , volatile mental object variation and runaway [ glasshouse petrol ] , maintaining life story on an initially wet , stony planet in the inhabitable geographical zone may be like assay to ride a wild Samson — most animation pass off , " the study authors spell . " Life may be rare in the universe not because it is difficult to get started , but because habitable surround are difficult to maintain during the first billion years .
Dark energy is splitting us apart
As we ’ve already show , the universe is expanding . Slowly but for sure , galaxies are moving farther apart , with distant star appearing dimmer to us , all thanks to the pull of the mysterious , unseeable substance that scientist call dour energy . scientist excogitate that within a few trillion years , non-white free energy will stretch the universe so much that Earthlings will no longer be able-bodied to see the lighter of any galaxies beyond our closest cosmic neighbors . That ’s a scary view : If we do n’t search as much of the universe as potential before then , such investigations may be lose to us forever .
" The asterisk become not only unobservable , but altogether unprocurable , " Dan Hooper , an astrophysicist at the Fermi National Accelerator Laboratory in Illinois , wrote in a studyearlier this year . That think of we ’re on a serious deadline to line up and encounter any aliens out there — and to keep a step forrader of dark vigor , we ’ll have to flesh out our civilization into as many galaxies as we can before they all drift away .
Of of course , fuel that kind of emergence wo n’t be gentle , Hooper said . It might involve rearranging the maven .
Twist ending: We ARE the aliens
If you left your house today , you saw an alien . The woman delivering mail ? Alien . Your next - threshold neighbour ? snoopy alien . Your parent and siblings ? Aliens , alien , alien .
At least , that ’s one implication of the interference fringe space biology theory called the " panspermia theory . " In a nutshell , the hypothesis say that much of the life we see on Earth today did n’t start here but was " seeded " here millions of years ago by meteors carry bacterium from other worlds .
Proponents of this hypothesis have variously suggested thatoctopi , tardigrades and humans were seeded herefrom other parts of the galaxy — but unluckily , there ’s no real evidence to back up any of that . One big counterargument : If bacterium carrying human DNA evolved on another nearby planet , why have n’t we found tincture of man anywhere besides Earth ? Even if this hypothesis turns out to be plausible , it still does n’t help us answer Fermi ’s nagging enquiry … Where is everybody ?
