For as long as any of us have been around, scientists have been pulled by the gravity of their responsibilities to answer one fundamental riddle of existence: “Is there anybody out there?” As many have stated over the years, it seems like the answer should be a fun one. But you know what’s really strange? The more we uncover about the universe and its treasures, the more we appear to be living by ourselves. In this article, you’ll understand why I am drawn so much to this strange question of being by ourselves.
There’s a model called the Fermi Paradox. It was named after the scientist Enrico Fermi. It’s about the apparent contradiction between the very high probability that there could be lots of intelligent life in the universe and the fact that we have not yet seen, heard, or otherwise detected any of it. Why the paradox? Well, you know how it is when you have to pour two jugs of water and you just pour one, and the other one doesn’t get any water? There’s actually quite a lot of chance for things to go wrong on a great-phrase principle. That’s why the jugs are a good analogy for the Fermi Paradox.
Astronomer Frank Drake formulated the Drake Equation. It gives us an idea of the number of active and communicative ET civilizations that we might be able to detect today. When astronomers use this equation in a best-case-scenario manner and plug in the numbers, they often discover that Earth may be their one and only data point.
In addition, scientific models like the Rare Earth theory imply that a planet with conditions just right for life to exist and develop over billions of years must be a one-in-a-billion kind of world. It seems that nearly everything must be perfect for a star’s planetary system to produce a world like our own. And, if worlds just like ours are super rare, then it’s safe to say that Earth is pretty special, too.
The Great Filter hypothesis suggests that there might be many very difficult obstacles on the path of an evolving civilization, and that these hurdles might be too much for any life-form to overcome, to essentially ensure that extraterrestrial civilizations are very rare, that if Earth’s pre-human, biological life forms were to exist on other worlds, then these life forms should, by all accounts, have already transformed into space-faring, interplanetary or even interstellar crossovers that we assume account for very old “aliens” or “alien civilizations.”
When we look at all these scientific models together, we’re faced with a disturbing conclusion: the universe might not have as much life in it as we thought. Potential habitable worlds might be quite common, but the basic building blocks for life, such as water, and the even more specific kinds of conditions necessary for the emergence of intelligent, highly advanced civilizations, are fundamental features of our own world that might be difficult to replicate elsewhere.
On the flip side of this “terrestrial exclusivity” argument, however, is our potentially limited human imagination. That’s because the existence of Earth and our conspicuous (and as yet largely inexplicable) intelligence doesn’t seem to be a feature that’s all that likely to be unique to our home world.
Certainly, these models are not conclusive evidence of the cosmic loneliness of our species. Instead, they are just theoretical frames built from what we now know of astrophysics, biology, and blanketed laws of cosmology—one could just as well buy into some other less lonely model. They churn not only with what is probable but also with what is possible, and thus they envelop the stuff of fervid imagination. Yet by their nature, these models are testable, and they have not been found to violate any known laws.
As we press on to encompass the whole of the cosmos and find those signs of life beyond Earth, the models that scientists construct in their increasingly powerful supercomputers are becoming humbling yardsticks. The current crop of models takes in a vast array of data, including the weird world of quantum mechanics, and then attempts to reproduce just how the universe of stars, galaxies, and the great expanses of the cosmic web must have formed and evolved over nearly 14 billion years. The results are, of course, somewhat figurative, but they nonetheless speak volumes.