Aside from the more or less philosophical questions covered recently (click here to learn more), the problem of humans meeting at least one advanced extraterrestrial civilization gets more complicated every time you start digging deeper into the problem. And this, the culmination, is not because there are no civilizations of this type. Or that they will be very far from us. If we even take into account the Drake equation, then their number must be in the billions. And this is only in the Milky Way.

no The chances are slim, since all such hypothetical life forms are probably trapped on their worlds. The fact is that we, humans, are fantastically lucky to find ourselves at a point in the galaxy and on a planet where absolutely all conditions are created not only for the appearance of intelligent life, but also for its spread beyond the borders of the earth. I will explain right away.

Oxygen trap

At the end of last year, two researchers (Amedeo Balbi from the University of Rome, respectively, Adam Frank from the University of Rochester, USA) published an extremely interesting idea in the journal Nature, which for some reason escaped the attention of many. Namely, that oxygen is necessary for the metabolism of terrestrial multicellular life. Thus, we are fully justified when we believe that its presence in the atmosphere of other planets can lead to a complex biosphere in which intelligent life forms will also appear.

So far so good. However, there is one factor that is often overlooked. Oxygen concentration. Too high a concentration of oxygen, say 35%, would make it impossible for forests to form. We are bypassing the fact that too high a concentration of oxygen in the atmosphere can lead to severe glaciation, in which life forms will not have many options for development. But if there were forests, burning would be facilitated by a large amount of oxygen. In short, the fires would destroy the vegetation.

A low oxygen concentration (for example, below 18.5%) will make combustion extremely difficult. And without fire, it is hard to believe that significant scientific progress can be achieved. Just consider the role of fire in the evolution of our species, from Australopithecus onwards. Weapons, tools capable of changing the environment, cooked food, bigger brains, metalworking, civilization, industrial revolution, space flight, etc. Without fire, none of this would be possible.

If we do an exercise in imagination and try to visualize an intelligent species in a world where the oxygen concentration was, say, 1-5%, these people would have no idea what fire is. And they would be forever trapped in the stone age stage, the most progress they could make.

With this in mind, all we can do is congratulate ourselves for the chance to live in a world with 21% oxygen concentration (which is exactly what it is now). Ah, the optimal model that provides combustion, abundant vegetation growth and does not send us to Earth versions of the ice globe, is the one where we are talking about an oxygen concentration of 20-21%. As it turned out, from this point of view, we live in an ideal world. But the chances of finding a world similar to ours are extremely small.

Gravity and its problems

From reading Isaac Newton, we know that two bodies with masses M1 and M2 attract each other with a force directly proportional to the product of the masses of the bodies and inversely proportional to the square of the distance between them in the direction of a straight line. connection of the centers of gravity of two bodies. If you prefer the simpler version, any body tossed up falls, fatally, down.

Based on this idea, we have to consider that going into outer space involves technology that will allow you to overcome the gravity of the planet you are about to leave. Theoretically, on Earth, the speed required to reach the planet’s orbit is about 11.2 kilometers per second (40,270 kilometers per hour).

Basically, this calculation refers to ballistic objects without a power plant. Our space rockets have a propulsion system, which means they only need 28,100 kilometers per hour to reach Earth’s orbit. It takes almost 25,031 kilometers per hour to completely exit the Earth’s gravitational field. This, I repeat, under the conditions that exist here. And yet we need massive amounts of fuel and advanced technology to make such moves.

But the population living on the super-earth will face much different problems. For example, a huge gravitational force. And if we are guided by the calculations of the Spanish astronomer Elio Quiroga, a professor at the University of Atlantico Medio, Las Palmas, Spain, there is no known material, no fossil fuel, that would allow the creation of a vehicle capable of leaving the gravitational field. the force of a planet with a mass, say, ten times that of Earth.

They just couldn’t handle the pressure. Obviously, we imagine that everywhere in the Milky Way there are the same metals we know and the same combinations of chemical elements. In short, an advanced civilization on such a planet would be trapped there with no real possibility of leaving the mother planet.

On the other hand, if you’re thinking about planets with much less mass than Earth, that doesn’t mean spaceflight will be much easier. Rather, it means that the planet in question is not very capable of maintaining its own atmosphere. And in such a schedule it makes no sense to talk about the appearance of life. At least as we know it.

Going back to spaceflight on a super-Earth-type planet, let’s say that somehow a civilization invents technology that allows it to reach space. The problem is that they have to come back. And on a planet with ten times the mass of Earth, as in the scenario proposed by the Spanish professor, re-entry and habitation would be extremely difficult, for the same reasons that it would be difficult to get out.

In addition, the density of the atmosphere, which does not create a huge frictional force, should be taken into account. In summary, the possibility of a civilization emerging from such a world is almost zero.

Aquarium effect

Professor Elio Quiroga also brings another set of serious difficulties into the equation that will prevent presumed intelligent life forms from leaving their world. In fact, the Spanish astronomer claims that many of them don’t even know that space exists.

A clear example is communications. Quiroga begins with a scenario in which advanced life originated and evolved in an oceanic environment. In such a world, he says, sound travels through a fluid medium much more easily than in an Earth-like atmosphere. He can do it even for hundreds of kilometers. As a result, such a civilization would not need means of communication. And without such technology, it is hard to believe that these people could have unleashed the technology of interplanetary travel.

In addition, one more aspect must be taken into account. The ability to see stars. A planet completely and permanently covered by clouds would not allow us to see the stars. The same applies to a double or even triple star system where there will be constant light. Relatively the same would be the case with water worlds, especially those covered by ice caps. Without seeing the stars, would you ever wonder what lies beyond your world?

Apparently this is what Professor Quiroga says too, it’s just an exercise in imagination. But what is certain is that they demonstrate that the known Drake equation is much more complicated than it appears at first glance, that it also requires other unknowns. And with each such factor, the number of possible civilizations with which we could communicate is drastically reduced.

On the other hand, we can only congratulate ourselves, once again, that we live on a planet where all the conditions are met to allow us to appear, even the possibility of reaching other worlds.