Alien Megastructures: Evidence of Advanced Civilizations or Human Creativity?

In just a few thousand years, humanity left the caves, created the Nokia Brick, built the pyramids, mastered electricity and reached space. If in such a short time of evolution we were able to do all this, imagine what an alien civilization, with millions, or even billions of years of technological advancement, would be able to achieve!

Some scientists imagine that their technology would be so advanced that they could build megastructures around their stars to capture all the energy they needed. While some scour the universe for such structures, which would be extraordinary evidence of the existence of intelligent life beyond Earth, others claim that these alien megastructures are simply unquestionable proof of human creativity.

The person who started this debate was Russian astrophysicist Nikolai Kardashev, who in 1964 proposed a scale to classify the technological level of a civilization based on the amount of energy it can harness. According to him, Type 1 civilizations would be able to utilize all the energy available on their home planet.

Now imagine if humanity had the ability to use all the energy available on Earth. Taking advantage of every waterfall, every square centimeter of sunlight, every atom of radioactive element, wind energy, tide energy… Anyway, if this seems unlikely to you, know that Type 1 is only the least developed on the Kardashev scale. And we humans haven't even reached that level yet.

The next level is that of Type 2 civilizations, which would be able to harness all the energy of their parent star, and Type 3 civilizations, which would be able to harness all the energy of an entire galaxy.

Well, Kardashev theorized that Type 3 civilizations probably don't exist, and Type 1 civilizations would be very difficult to detect. Type 2 civilizations, on the other hand, would need to build structures so large that they could be detected in order to capture all the energy from their star. The existence of such structures had already been proposed in the 1960s by the English physicist and mathematician Freeman Dyson, the so-called Dyson Spheres. But only recently has our technology allowed us to look for evidence that they actually exist.

Our telescopes do not yet have the capacity to directly observe a Dyson Sphere. Therefore, this search is carried out by analyzing anomalies in the light curves of stars or by identifying heat signatures that would indicate the presence of gigantic artificial objects. In 2015, for example, an article in The Astrophysical Journal raised the possibility that an alien megastructure was causing peculiar variations in the brightness of Tabby's Star. Today, this hypothesis is considered unlikely, but recently, two studies that analyzed the infrared emissions of almost 5 million stars found signs of possible Dyson spheres in 60 of them. But don't get too excited, the chances are very small.

That's because building a megastructure around a star is much more than a huge technological challenge. It would require such an absurd amount of raw material that it would be necessary to destroy several planets to achieve it. The energy used in this incredible feat of space engineering would be so great that aliens would need to steal cows from all over the galaxy just to pay the electricity bill.

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The odds are slim, yes, but in favor of the cosmic mega-contractors is the immensity of the Universe.

There's a passage in The Hitchhiker's Guide to the Galaxy that talks about how the vastness of the cosmos affects statistics. The universe is so unfathomably large, with such an infinite variety of stars and planets, that the most absurd world you can imagine is possible. Even a planet where talking mattresses live in swamps probably exists somewhere in the universe.

But fiction aside, when we look at the vastness of the Universe and the infinite probabilities it offers us, even the smallest possibility of the existence of a civilization with the technology and resources to build a Dyson sphere around its star has a high chance of being a reality somewhere in the Cosmos.

So far, we have not found any clear evidence of the existence of these alien megastructures. But the search continues! After all, finding just one of them would be unequivocal proof of the existence of technologically advanced alien life. Not finding them would be yet another demonstration of the incredible human creativity, capable of imagining civilizations at such an advanced stage that they could do something that seems truly impossible. Or maybe it just means that we haven't looked hard enough.