Simply put, Fermi’s Paradox is, “Where is everyone?”
Fermi’s Paradox highlights the apparent contradiction between the sheer abundance of stars in the universe, the astonishing amount of time that has transpired, and the absence of any other intelligent life in the universe.
In reality, Fermi’s Paradox is Earth centric. Our ability to survey our own galaxy is extremely limited. At the moment, our efforts to look for extraterrestrial life are akin to someone standing on the shores of Africa looking for America. A lack of evidence isn’t evidence of lack, but rather demonstrates our efforts are in their infancy.
When it comes to Fermi’s Paradox, a number of potential solutions have been proposed, including The Great Filter, which suggests the emergence of life elsewhere in the universe may be common, but perhaps the emergence of an intelligent spacefaring species is astonishingly rare. The Great Filter proposes that there is something catastrophic that has hindered other species from making this leap. From our own experience, we can see the existential dangers of nuclear warfare, biological warfare, and even the possibility of artificial intelligence bringing our civilization to a grinding halt on the wrong side of the filter.
But there are a number of other possibilities, including The Great Suck.
If you haven’t heard of The Great Suck it’s probably because it’s a phrase I’ve just coined, along with The Great Gloom, to describe other plausible reasons we may not see intelligent interstellar species spreading out through our galaxy.
What is The Great Suck?
Gravity sucks. Literally. Gravity sucks far more than you probably realize.
Look at the Space Shuttle. To get into orbit it needed two massive solid fuel rockets and an enormous fuel tank.
Your car has a fuel tank, but at a guess, it’s probably not as disproportionately large as this one. Why?
The reason is because of the velocity required to reach orbit. Don’t be fooled. When you see astronauts floating around inside the International Space Station, it’s easy to think of them as sedate, just drifting there in space. Nothing could be further from the truth. They are literally falling AROUND the entire planet with the same acceleration you’d experience if the cable in your elevator gave way and you plummeted toward the basement. In the words of Douglas Adams “Flying,” or in our case getting into orbit, “…is throwing yourself at the ground and missing.”
In order for astronauts to stay in space without falling back to Earth they need to be moving so fast they fall OVER the horizon, constantly plummeting toward Earth but never reaching Earth because the curve of the planet falls away quicker than they do.
If you’ve ever thrown a baseball and watched it fall back to Earth, and then tried to throw it a little father and higher, you’ll know gravity really does suck.
To overcome Earth’s gravity, you need to be traveling at least 8 kilometers per second (or just over 5 miles per second). Picture somewhere 5 miles from where you live. Now picture yourself zipping past that point a second later—THAT’s what it takes to orbit Earth!
When you do the sums, being able to attain these kinds of crazy speeds is incredibly difficult. Whereas your car only needs to carry roughly 4% of its weight as fuel, rockets need to dedicate at least 85% of their weight to fuel (hence that massive fuel tank).
Rockets are astonishing. With 85% of their weight going to fuel, the entire rocket needs to be engineered exquisitely with the remaining 15%, and that remaining mass needs to be built with astonishing precision to ensure both performance and safety.
The external fuel tank on the Shuttle was designed to be structurally sound under 3Gs of force, while housing cryogenic fluid cooled to within 20 degrees of absolute zero, and under 60 pounds of pressure per square inch (that’s the same stress as applied to a submarine at 140ft beneath the ocean). And NASA’s scientists and engineers accomplished this with greater efficiency than you get in a flimsy can of soda!
Even with these incredible feats of engineering, the Space Shuttle was only able to deploy 1% of its total mass at launch into orbit.
Space travel seems easy. Star Trek does it all the time. In Star Wars they journey between planets in a few minutes. In reality, just getting into orbit is a herculean task. The largest, most powerful rocket ever successfully launched sent Armstrong, Aldrin and Collins to the Moon, but even then the Saturn V only delivered a payload of 4% into orbit. Rockets are BIG investments, with small physical returns (although the payoff for science is incalculable).
What does this have to do with Fermi’s Paradox? Quite a lot. You see, there are physical limits beyond which a chemical rocket could never reach orbit. Due to the constraints of Earth’s gravity, we can barely make it into orbit. If Earth was just 50% larger in diameter, we wouldn’t be able to get into orbit at all. If Earth was bigger, we physically couldn’t build a chemical rocket as the amount of fuel required would approach (and for larger planets even exceed) 100%.
Most people have heard of “Super Earths,” a class of planets larger than Earth, but smaller than the gas giants. If any of these held an intelligent extraterrestrial species, they would NEVER be able to leave their planet and explore space. Like us, they’re subject to the laws of physics, and The Great Suck would really suck.
Could they develop nuclear rockets or some other means of reaching orbit? Maybe, but the bigger the planet, the worse the problem becomes. At a certain point, it is physically impossible. For those civilizations, this is a serious problem—for them, space is something to be seen, not explored.
What would such a civilization think about the universe if they were forever trapped on the surface of their planet. Would conspiracy theorists win the argument of a flat super Earth? How astute would they be at managing their finite resources? Would they end up like the inhabitants of Easter Island, that destroyed themselves through exploitation?
Such a gravitationally-bound civilization would never get to see their equivalent of The Blue Marble. Communications satellites would be impossible. Their perception of reality would be skewed, perhaps be even more self-centered than our own pre-Copernican views.
Visual and radio astronomy would tell them a lot about the universe, but they wouldn’t be able to explore nearby planets. How would this affect their view of the broader universe? Would it be seen as a purely academic idea with little to no practicality?
Perhaps they’d like to reach out to other species via radio simply to seek escape from their gravity-bound prison. Certainly, their best option would be to have some other species (perhaps future humans), bring an asteroid into geosynchronous orbit and lower a cable to form a space elevator.
Can you imagine the clash of cultures at that meeting?
For us, looking out at them even just a few hundred light years away, there wouldn’t be much to see. We might detect their electromagnetic emissions, but they could be tens of thousands of years more advanced than us and yet under gravitational house arrest. Perhaps this is why we don’t see species spreading through the galaxy—a lot of them physically can’t.
The Great Gloom
Another interesting alternative to The Great Filter is The Great Gloom.
What would happen to an intelligent species that developed on a planet bound by thick cloud cover like those found on Venus?
From their perspective, the sky would always be overcast. Depending on how turbulent it was in the upper atmosphere, it might not be practical for them to breach the cloud tops and see the magnificence of space. For such an intelligence species, there would be a distinction between day and night, but no call from the stars, no intrigue or celestial mysteries to understand.
How would such a society perceive the universe? Perhaps they would develop radio astronomy and gain a glimpse of obscure, seemingly erratic signals reaching their tiny world. Would they muster the courage and curiosity to explore the universe?
At the moment, we have no way of knowing how wide-spread or limited life is elsewhere within the universe, but if super Earths dominate as rocky planets and are hospitable, there could be thousands of civilizations that are millions of years more advanced than our own that can’t reach their own moons!
Here on Earth, we live on an astonishing planet. We are a species on the cusp of interplanetary travel, and one day we will reach the stars. Other intelligent species may not have been so lucky, and perhaps that explains at least some of Fermi’s Paradox.
Peter Cawdron is a science enthusiast and science fiction writer. His latest novel, RETROGRADE, explores at the complexity of colonizing Mars and is available in hardback, paperback and electronic formats.