Where are all the aliens? One night 60 years ago, physicist Enrico Fermi looked up into the sky and asked himself the question: "Where is everyone?", Referring specifically to extraterrestrial life. In his opinion, the galaxy should literally be filled with all kinds of life, reminiscent of earthly and not so much. Today scientists only know that there are millions and even billions of planets in the Universe that can support life. Why, over the long history of everything, this life has not extended its hand (or tentacle) to people?
Maybe the universe is too big to be traversed with ease. Maybe aliens are deliberately ignoring us. Maybe any flourishing civilization is doomed to self-destruction (as we, for example, if we don't stop doing nonsense).
There may be something else, much stranger. Here are nine bizarre answers that scientists have tried to justify the Fermi paradox.
Aliens lurk in underground oceans
If humans want to interact with extraterrestrial life, we may need some icebreakers. Some believe that alien life is trapped in secret oceans buried deep within frozen planets.
Subsurface oceans of liquid water are found in several satellites in our solar system and may be quite common in the Milky Way. NASA physicist Alan Stern believes that underwater worlds like these could be ideal for the development of life, even if inhospitable conditions on the surface could harm any life. "Meteor falls and solar flares, supernovae nearby, an orbiting neighbor, a toxic atmosphere - none of this would prevent life underground," says Stern.
This is great for aliens, but it also implies that we can never find them with a telescope. Should we expect them to contact us? According to Stern, these creatures live so deeply that it is not known whether they know about the existence of the sky above.
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Aliens imprisoned in "super-lands"
No, super-earth is not the home of superheroes. In astronomy, this term denotes a type of planet with a mass 10 times that of the earth. Exploration of stars has resulted in heaps of such worlds that could have suitable conditions for the existence of liquid water. This means that alien life could evolve on super-earths throughout the universe.
Unfortunately, we are unlikely to meet with these aliens. A planet with a mass of 10 Earths will also have an escape velocity 2.4 times that of Earth, according to a study published in April; overcoming this pull could make rocket launch and space travel nearly impossible.
We're not looking there (because all aliens are robots)
Humans invented radio in the 1900s, but the first computer appeared in 1945, and today mass-produced devices are capable of billions of calculations per second. Full-blown artificial intelligence may be literally around the corner, and futurist Seth Shostak thinks it's enough to rethink our approach to finding intelligent aliens. Simply put, we need to look for cars, not little green men.
A truly advanced alien society could be inhabited entirely by superintelligent robots, Shostak argues, and this should affect our search for aliens. Instead of throwing all our energy into finding other habitable planets, we should look for places that are more attractive to machines - say, places with a lot of energy, such as the centers of galaxies. "We are looking for analogs of ourselves," says Shostak, "but I don't know what the majority of the intelligence in the universe will be."
We have already found aliens (but we don't understand it)
Thanks to popular culture, the word "alien" probably brings to you the image of a creepy humanoid with a large, shiny skull. That's fine for Hollywood, but sabotaging our search for alien life, as a group of psychologists in Spain wrote about earlier this year.
In a small study, scientists asked 137 people to look at images of other planets and find signs of alien buildings on them. Among all these images, a small man in a gorilla costume was hiding. Since the participants in the experiment were looking directly for alien life, only 30% of them noticed the "gorilla".
In reality, aliens are unlikely to be anything like monkeys. Maybe even with the help of light and sound waves it is not possible to see them. What conclusion can be drawn from this study? Our own imaginations and attitudes place limits on the search for extraterrestrial life. If we do not learn to push our boundaries of the comprehensible, we will not even see a gorilla under our noses.
People will kill all aliens (or have already killed)
The closer we get to aliens, the closer we are to their destruction. So says the theoretical physicist Alexander Berezin.
Here's his logic: any civilization capable of exploring its own solar system must be on the path of unlimited growth and expansion. As we know from Earth, this expansion is often costly for the small organisms that get in its way. Berezin says the divide and conquer principle is unlikely to disappear when we find aliens - if we spot them at all.
Aliens kicked off climate change (and died)
When the world's population burns resources faster than the planet supplies them, disaster is not far off. We know this very well from our relationship with the climate on Earth. Why can't an alien, energy-hungry community get into the same situation?
According to astrophysicist Adam Frank, this is not only possible, but also extremely likely. Earlier this year, Frank launched a series of mathematical models to test how a hypothetical alien civilization could have survived its rise and fall if it had sucked up all of the planet's resources. The bad news is that in three out of four scenarios, their society collapses and most of the population goes extinct. And only if the society notices the problem early and immediately switches to clean energy, civilization survives. This means that if aliens exist, chances are high that they will destroy themselves before we meet them.
“In all space and time, there are winners - who were able to see the future and prevent it - and losers who could not cope with the situation and lost civilization,” says Frank. "The question is, what category do we want to be in?"
The aliens were unable to evolve fast enough (and died)
Another excuse from the "aliens are already dead" category. The universe may be teeming with hospitable planets, but there is no guarantee that they will exist long enough for life to develop. Wet, rocky planets like Earth are highly unstable for life to begin, according to a 2016 Australian National University study; if alien life wants to live in such a world, it will have a very small window for development (only a few million years).
“Between the first heatstrokes, freezing, changing atmosphere and the growing greenhouse effect, maintaining life on a humid, rocky planet in a habitable zone can be like trying to ride a wild bull - most of life will fall,” the authors write. "Life in the universe may be rare, not because it is difficult for it to start, but because it is difficult for it to survive the first billion years."
Dark energy is tearing us apart
The universe is expanding. Slowly but surely, galaxies are scattering, distant stars are getting dimmer to us, all thanks to a mysterious, invisible substance that scientists call dark energy. They believe that in a couple of trillion years, dark energy will stretch the universe so much that even earthlings will not be able to see the light of galaxies outside our closest neighbors in space. This is creepy: if we don't explore the universe before, we may never explore it again.
"The stars will become not only unobservable, but also unreachable," says astrophysicist Dan Hooper. This means that we should hurry up if we want to find any aliens - and be one step ahead of dark energy, expanding the boundaries of the domain of our civilization.
Of course, it won't be easy. We may have to move the stars.
Plot Twist: We Are Aliens
You left the house and saw an alien. Your postman from another planet. Your neighbor too. Your parents and brothers and sisters are aliens, aliens and once again aliens.
At least, such conclusions can be drawn if we adhere to the theory of panspermia. In short, this hypothesis states that most of the life that we see on Earth today did not occur here, but was seeded here millions of years ago by meteors carrying bacteria from other worlds.
Proponents of this theory assumed that octopuses, tardigrades, and humans were sown from different parts of the galaxy - but, unfortunately, there is no real evidence to support this theory. Just one big counterargument: if bacteria carrying human DNA evolved on another planet nearby, why don't we see traces of humanity anywhere else besides Earth? Even if this hypothesis turns out to be plausible, it still does not answer Fermi's question: "Where is everyone?"
Ilya Khel