Because the laws of physics are universal, extraterrestrials should have the same appearance as humans.

The public has been presented with a wide variety of representations of extraterrestrials thanks to world cinema. We have witnessed characters such as Leeloo from “The Fifth Element,” the humanoid from “Spielberg’s ET,” Neytiri from “Avatar,” and the humanoid lizard from “Signs.”

However, what exactly do aliens appear to be like? In this respect, the views put up by scientists are fairly realistic.

Researchers are of the opinion that the rules of the cosmos place a significant constraint on the amount of external variety that can exist. Charles Cockell, an astrophysicist who teaches at the University of Edinburgh and who is the author of the book “The Equations of Life: How Physics Shapes Evolution,” identifies three constraints that all forms of life, without exception, are required to adhere to.

“Physical laws are the same everywhere. For example, the force of gravity acts not only in the solar system, but also outside it.

The conditions for the existence of organic molecules are the same everywhere. On Earth and beyond, organic molecules break down at high temperatures and cease activity at low temperatures.

In every corner of the universe, life will use the same ingredients. Carbon is the optimal chemical element for the origin of life, and water is the ideal fluid for its transport.

What does this mean in practice? We know that there are three aggregate states of matter: solid, liquid and gaseous. And if the habitat of aliens is gas, then they must comply with the laws of aerodynamics.

In the same way as pterodactyls, sparrows, dragonflies and paper planes obeyed these rules. If our brothers in mind live in water, then they are subject to the laws of hydrodynamics and hydrostatics (the law of Archimedes in particular), therefore, the aliens must have an elongated streamlined body shape.

Those who live on a hard surface need limbs (paws, legs, arms) to reduce friction. Or, use the method of movement of snakes, which do well without limbs. Thus, structurally, the aliens will most likely be similar to the inhabitants of the Earth,

Will aliens have sense organs? It depends on the environment, says the president of the German Astrobiological Society, Dirk Schulze-Makuch of the Technical University of Berlin.

Who needs ears if there is no medium for transmitting sound waves? Light-sensitive organs on our planet have been developed by almost all living beings: vision takes on a variety of forms from the complex eye of a fly to the stereo vision of a person. But aliens may not need eyes if they live in places where light cannot penetrate.

In the case of contact with extraterrestrial intelligence, we will have to deal with predators – most scientists agree on this. And it’s not just that there are no examples of thinking plants and fungi on Earth.

It just makes no sense for a stationary organism to develop the rate of reactions and expend energy to maintain a high level of metabolism. Still, the mind is an expensive pleasure, for example, the human brain weighs 2% of the mass of the body, and consumes 25 percent of energy.

Not everyone can afford such a luxury. The brain pays off only if the living organism needs to look for food or save itself from the fate of becoming food.

Then why can’t aliens be descendants of herbivores? The fact is that plant foods provide less energy than other animal foods. It would be difficult for smart herbivores to develop their intelligence, because they would spend a lot of time on the process of eating low-calorie plant foods. From this point of view, carnivorous creatures have much more free time from eating.

And among the predators there is a clear hierarchy: if the lion must be smarter than the antelope, then the wolf must be smarter than the lion, because he hunts in a pack and the wolf needs to learn to cooperate with the members of the team.

So, most likely, the aliens with whom we will have to deal (unless, of course, we are alone in the Universe) are in the past a pack of predators. That is why many scientists are wary of attempts to establish contacts with extraterrestrial intelligence.

However, it is unlikely that guests from the space will be our mirror image. A brain in a big head, a nose above the mouth – all this tuning, fashionable in the solar system, is likely to be irrelevant in other parts of the universe.

Even on Earth, some innovators go the other way. For example, in octopuses, neurons are distributed throughout the body, including tentacles, and only a small part of the brain is in the head, recalls Dr. Dirk Schulze-Makuch.

Birds, in an effort to reduce their flight mass, have acquired a very useful thing: their packing of neurons in the brain is much denser than that of humans. By the way, this is why we underestimate their intelligence, relying on such a seemingly reliable indicator as the ratio of head to body weight.

Meanwhile, the New Caledonian crows are able not only to use tools, but also to create them themselves. And in terms of intelligence they are not inferior to primates.

Finally, aliens can be not just a creation of nature, but a kind of symbiosis with high technology.

“People have already built into their bodies such technical devices as contact lenses, pacemakers and all kinds of prostheses,” explains Dirk Schulze-Makuch.

“Aliens are quite capable of going further in turning themselves into cyborgs.For example, they can load the brain into an electronic-mechanical shell and circumvent the limitations imposed by nature on the lifespan of organic bodies.

“And if you asked me what the aliens would look like, I would say that the most advanced of them will be fully mechanized.”