Over the past few years, a new pseudoscientific thought line has emerged as a result of the growth of social media networks: flat-earth theory.
It is a movement in which its followers show a clear lack of understanding of physical and astronomical concepts and discredit, without basis, the knowledge that humanity has been building and verifying over 2 millennia.
The real and serious problem with all of this is not the flat-earth theory itself, but the philosophy behind it.

The 21st century is undoubtedly the era in which not only are the fastest changes taking place in various fields of human knowledge, but also, and particularly, in social behavior. Just to give an example, social networks have had a colossal impact on our lives. There are considerable paradoxes. While on our mobile devices we have the most accessible information in all of human history, misinformation pervades everyday life.

Today, taking into account that information is the most precious asset we have, there is one element that is scarce and plays a fundamental role in all of this: having the ability to filter it, analyze it, and give it value. We are faced with a substantial, and very dangerous, oxymoron.

In the 1950s and 1960s of the last century, there was a current of opinion in which an unfounded emptiness on our planet Earth was manifested. Its faithful followers claimed that we lived on a "hollow" Earth.

Another clear and famous example of unfounded opinion was the UFO issue. In a world where cell phones did not yet exist, tens of thousands of photographs appeared in magazines and newspapers every day with the alleged ships of beings from other worlds. What a paradox that today these "proofs" have disappeared, literally counting with billions of cameras at all times and places on the planet.

Lately, for a few years now, a new line of pseudo-scientific thinking has emerged along with the growth of social networks: flat Earthism. It should be said that it is one of the clearest and concrete examples of this nefast "post-truth era" in which we are immersed.

This is a movement in which its followers and faithful believers, without any foundation, ignore the knowledge that humanity has been building and cross-checking for 2 millennia. Furthermore; they not only ignore this (the checking of information among peers, institutions, nations, work groups), but paradoxically, they exercise their right to opinion from the most absolute ignorance of physics, mathematics, astronomy, to mention a few areas of human knowledge.

I want to be very clear on one concept. From no point of view am I trying to restrict freedom of expression. Who am I to do so? It would be a gross error on my part to take such a position. But it is no less true to emphasize the importance of giving opinions the necessary weight, not based on the people who express them, but particularly on the foundations on which they are based.

The Earth is round

The building of human knowledge is based on premises which must be respected in order to reach a good port. In the case of physical and natural sciences, it is clear that observation is one of them with the corresponding peer review. It only takes one test that contradicts a theory, for that theory to cease to be valid. And thus, our understanding, for example, of the planet we live on and its place in the cosmos, has increased over time.

It was not with Christopher Columbus that we learned of the sphericity of the Earth, but much earlier. For starters, it was the same navigator who, knowing the true shape of the Earth, imagined reaching the east by departing from the kingdom of Spain and sailing west. More than 2 millennia ago, Eratosthenes, an extraordinary astronomer and mathematician, became aware of something very curious. As the director of the Alexandria Library, he found in a papyrus that every June 21st at noon, the Sun's rays fell vertically on the city of Siena, causing any vertical stake not to produce a shadow.

Eratosthenes realized that at the same moment, in Alexandria, this situation did not occur, but any obelisk would produce a respective shadow. He not only concluded that the way this phenomenon could occur was through a curved surface, but also, with only knowing the distance between both cities, paper, pen and extraordinary ingenuity, he determined with a simple mathematical calculation the size of the Earth.

Two millennia after that singular event, another of the convincing proofs of the sphericity of the Earth was obtained from the first image of our planet captured from space as a result of the launch of the V2 rocket on October 24, 1946.

Adherents to flat-earth theory show a clear lack of understanding of basic physical and astronomical concepts. This is not a problem in itself, but the audacity with which they openly debate issues such as the reasons for solar and lunar eclipses, how we measure distances to other objects in the universe, or why ocean water is attached to the Earth's crust and does not "fall" (in that case, I wonder where it would go). A mere investigation into their understanding of Antarctica is enough to give us an idea of what we're dealing with.

We could offer hundreds of arguments to show how literally unbelievable it would be to live on a "Flat Earth." On a flat earth, the moon could not be observed at the same time by people in both hemispheres of the earth. Circumnavigation of the seas and air routes would not be possible as they are today, with the first example having been done for millennia. The daily observation of the sun and the moon would not correspond to what we observe on a daily basis.

Of course, flat-earthers have the courage to answer each of these phenomena, and if they cannot offer an answer, they give themselves the possibility of continuing their research to obtain the necessary answers. And here is one of the big disadvantages they face: obviously, without an appropriate physical-mathematical model, when trying to answer a phenomenon, they thereby invalidate another existing one. In other words, if a model allows me to answer why such an observation occurs, that model contradicts a second phenomenon.

If you think that these gross contradictions discredit the flat-earth position, let me tell you that it is the exact opposite. In the impoverished era of post-truth, "anything goes." Even some of their most fervent followers have found a significant source of income.

The True Danger of Terraplanism

I believe it's time to clearly state what the true and serious problem is in all of this. It's not flat earthism, but the philosophy behind it. Here, the enemy is post-truth. It's not a coincidence that a high percentage of its followers fervently believe that the arrival of man on the moon is a fraud, that vaccines are not important, and even that drinking chlorine dioxide is healthy. Public opinion leaders have shown this with total disregard for medicine and public health.

Towards the end of 2019, an opinion from a well-known Argentine actor caught my attention. Without any foundation, I was concerned about his unfounded expression of his belief in a flat earth. It made me think that such a way of constructing an argument, an idea, could easily be extrapolated to the non-importance of vaccines, one of society's main instruments - along with sewage systems - for eradicating global pandemics.

That's why in December of that year (2019) I embarked on the idea of making a series of videos for YouTube to unmask these fervent believers, knowing full well that I could never achieve it against the prevailing philosophy of post-truth on the other side of the counter.

The paradox of this story is that in the first chapter of the series, the true danger of all of this was realized, mentioning as an example the anti-vaccine movements. Who could have known that 3 months after that publication we would be facing the greatest pandemic in modern history, showing once again how human knowledge was able to respond to millions of deaths in the world.

The strength of human knowledge lies in its construction step by step, from solid steps on which we can rely to continue advancing. Let us have the capacity of discernment. It's what will save us as a species. Because ultimately, it's the human mind that distinguishes us from the rest of the existence in this wonderful and unfathomable cosmos.

Diego Bagú, astronomer from the Faculty of Astronomical and Geophysical Sciences of the National University of La Plata