Since about the middle of the 20th century, scientists began to call the anthropic principle the comparison of the features of our world with the possibility of life and reason existing in it. In a free and more understandable formulation, this principle affirms an amazing phenomenon, namely, that our world was created and exists solely in order for a person to appear and exist in it! In other words, all the properties of the Universe are adapted for the emergence of intelligent life, since we, observers, are present in it!
Why do we live in three-dimensional space?
Nature has chosen three-dimensional space (length, width and height) for our existence, although some physicists believe that in reality our space has 11 dimensions (!). But 8 of them are "folded", so we do not notice them. However, if the geometric parameters of the "rolled up" dimensions increase, then someday they will seriously affect the dynamics of our world. It should be added to this that such an important phenomenon of the evolving reality, as a stable motion, is possible only in three-dimensional space!
If our space had only two dimensions (length and width), or only one (length), then, as is obvious to everyone, the movement in such space would be so constrained that there could be no question of the emergence of life in it. If the number of dimensions in our space were more than three, then, for example, the planets could not be held near their stars - they would either fall on them, or fly away! A similar fate would befall the atoms with their nuclei and electrons.
Let's remind that today we know four types of basic natural forces: gravitational, electromagnetic and intranuclear - weak and strong.
So, it has been proven that even the slightest change in them will lead to a significant transformation of our Universe! Similar restrictions exist in the ratio of the masses of the electron and proton. Changing them would have unpredictable consequences.
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The factor of stability is time
Few people know that our space, strictly speaking, has not three dimensions, but four! And the fourth coordinate is … time!
Its most important difference from the other three coordinates is irreversibility, that is, for reasons unknown to us, time flows only in one direction - from the past to the future! And yet, without this coordinate, there would be no development and any evolution in the world.
According to modern scientific concepts, space, time and matter were all born simultaneously as a result of the so-called Big Bang. This idea has been developed quite well by scientists, although how everything happened at the micro level remains largely unclear.
In particular, it remains unclear why, as a result of the Big Bang, the amount of formed matter turned out to be slightly more than antimatter, although it seems that there should be equal amounts of them! “Someone” took care of this antisymmetry, because with an equal number of particles and antiparticles, they would all disappear (annihilate) and there would be nothing to create complex systems from.
Conditions for the existence of protein bodies
It is clear that intelligent life can exist only on a protein basis, and in a very narrow temperature range. Therefore, the orbits of the life-bearing planets should be chosen so that the average temperature on them does not go beyond these limits! It would be nice if this orbit was circular - otherwise the winters on these planets would be long and disastrous for all living things. A too hot summer would have killed the survivors! Moreover, our Earth is also tightly chained to its orbit - most living creatures on it could not survive even if its orbit was changed by only a tenth!
They say that the Moon with its ebb and flow is extremely necessary for the development of intelligent life on Earth. But it has been suggested that our planet once did not have the Moon. They say that "someone" brought her here! This fact is confirmed, in particular, by a very careful "installation" of the Moon in the earth's orbit: its diameter is 200 times smaller than the diameter of the Sun and it is located 200 times closer to us. As a result, during a total solar eclipse, the disc of the Moon exactly covers the disc of the Sun and we can see the night sky in broad daylight! “Someone” needed to show us this amazing picture!
The "suspicious" silence of space
Does it not symbolize the inevitability of the disastrous future of civilizations that have traveled the path of our planet? Let's try to assess the chances of finding one of them, as they say, in good health. To do this, consider our star system, the Galaxy, which is believed to contain about 100 billion stars.
Our Sun lit up 5 billion years ago, and during this time around it, on the planet Earth, intelligent life was born and has survived to this day. However, let's say that life around other stars arose much earlier - say, 10 billion years ago. Then, upon reaching the appropriate level of development and as the environment deteriorates, the then civilization decides to colonize the surrounding space for the settlement of its citizens. To this end, she will send in different directions three huge spaceships with a thousand settlers and the necessary supplies and equipment on each.
The path of a ship flying at a speed of 10 thousand kilometers per second (!) To the nearest star will take a hundred years! Let's give the settlers another 300 years to settle in a new place and wait for the moment when they send their ships to the next stars. With such "step" flights, the then civilization will populate the entire Galaxy in 20 million years! Moreover, this figure is clearly underestimated, since in fact it will take an unimaginably long time to find suitable planets. It is clear that the scenario outlined can be considered absolutely fabulous, since absolutely fantastic terms appear in it. And the longer the time frame, the more chances you have to face unpredictable events.
Universes can be different
The entire world that emerged after the Big Bang is many times larger than the part of it that we can see through telescopes. Therefore, today scientists admit the existence of universes with their own sets of fundamental parameters and laws, and we do not see them solely because of the gigantic cosmic distances.
As for the anthropic principle, it began to be widely discussed in the middle of the last century after the publication of the book by the American scientist W. Carter "The coincidence of large numbers and the anthropological principle in cosmology." The author explained this principle in the following way: "The universe should be such that observers could exist in it at some stage of evolution." Or: "Our observations must be limited to the conditions necessary for our existence as observers."
Gennady LISOV. "Secrets of the XX century" No. 51 2008