We Are Alone in the Universe: Improbable Chance or Human Blindness

We Are Alone in the Universe: The Thesis That Unsettles Science

Not a signal. Not a molecule. After decades of scanning with radio telescopes, the only thing confirmed is silence: Earth remains the only point in the universe where life is proven. Around that anomaly a controversy has built up, accumulating 517 days and 232 replies, with two incompatible accounts on the table. On one side, intelligence would be an unrepeatable accident. On the other, with hundreds of billions of stars in the Milky Way alone, the strange thing would be to be alone.

What Does the Thesis That No One Else Is Out There Claim?

The starting position holds that all the arguments used to explain the silence are flimsy. To the claim that civilizations are rare, it replies that on a single planet thousands of species and several hominid societies have emerged. To the claim that they destroy themselves, it replies that total extinction of the species would be required, something impossible to generalize. To the claim that we do not detect them, it replies that a civilization only a few thousand years ahead of ours should already have expanded across the galaxy using wormholes and technologies we cannot even imagine.

The thesis does not stop there. The claim that distances and time prevent it is, for this approach, a limit that is exclusively ours, typical of a recent civilization: moving through spacetime would be like riding a bicycle. The claim that they are already here without us noticing is dismissed with sarcasm: they would all have decided to observe us without intervening. And against the idea that advanced civilizations renounce expansion, a competition argument is launched: whoever hides knows that another will develop first and will end up finding them. The conclusion is only one. We are alone.

Why Is the Drake Equation in Question?

The classic formula that estimates the number of technological civilizations —the one that multiplies stars by fractions of habitable planets and probabilities of life— has carried decades of disrepute among those who maintain that it only served to install the idea of the extraterrestrial in the collective imagination, with NASA and Carl Sagan as mouthpieces for a self-serving narrative.

The statistical blow comes via the molecular route. The most repeated calculation suggests that an elementary functional protein assembling by chance in a single step has a probability on the order of 1 in 10^164, and that is without counting that the basic unit of the process is not the protein, but amino acids. The corollary: giving chance time does not resolve every impossibility. To this is added the Copernican principle, the idea that Earth does not occupy any privileged place. If the space telescope proves the opposite, the mystery grows instead of shrinking.

The Planets Outside the Solar System That Changed the Calculation

Until the 1990s, the existence of planets orbiting other stars was only a theory. Instrumental advances made it possible to spot the first ones and, since then, thousands have been confirmed. Today it is assumed that practically all stars have a planetary system around them. Red dwarfs have also been identified as the most common in the universe, with orbiting planets that could host life.

The counterweight to so much data comes from the very magnitude of the cosmos: visible matter —inert rocks, dust and gases— would represent barely 0,4% of the total, with the immensity of the void occupying the rest. Millions of species on a single planet and only one with intelligence, in a universe where the distance to the nearest star is already 4 light years.

Why Do Some Maintain That We Will Never Detect Anything?

The short answer is that our listening range is ridiculous. An ant from an anthill in the middle of La Sagra does not perceive that a few kilometers away there is a city like Madrid, even though the signals are obvious. Humanity has had the capacity to capture signals for only two hundred years, and the usual form of communication of an advanced species might not be radio or laser, but quantum communication, undetectable with our instruments.

Another line defends deliberate concealment: if an intelligence is colossal, perhaps the rational thing is to hide. And there is a more prosaic barrier. From Andromeda, at 2.500.000 light years, a telescope pointed at Earth would see it as it was 2.500.000 years ago, with no traces of civilization. For this school of thought, our island universe is the galaxy, and everything else are other worlds we will never reach: human signals have barely reached the doorstep.

The Great Filter and the Limits of the Model

The current that rejects the diagnosis of loneliness relies on the Fermi paradox and evolutionary filters. Abiogenesis, the passage from inert matter to life, has still not been replicated in the laboratory. And the transition from simple life to technological intelligence could require extremely unusual conditions. The Great Filter hypothesis adds that civilizations would limit themselves for sustainability or change their mode of existence, toward digital or non-expansive self-replicating forms.

The closing of this reading is direct. Not finding signals does not imply absence; it implies failures in the models and in detection capacity. And to affirm that we are alone would not be science, but anthropocentric bias. In parallel, another warning circulates: perhaps the error lies in searching for civilizations with our concept of civilization.

With 517 days behind it, the point remains exactly as stuck as the first time. There is a measurable silence, an equation that does not add up, and two ways of reading it that are not going to reconcile. Statistics say we should have company. The telescope says no.