At present, with the development of observation technology, the number of exoplanets discovered by humans exceeds 5,000, including many super terrestrial planets such as TOI-715b, but no trace of life has been found. It stands to reason that the observable universe has 2 trillion galaxies, 2000 trillion stars, and no matter what infinite monkey theorem and Drake's equation are, the universe should not be as empty as it is now.
Musk once said that if there were only human beings in the universe, it would be a terrible thing, just like a fish one day notices that it lives in pure water, which means that it is locked in a fish tank for people to see, and human beings are now surrounded by emptiness and dead silence, and the reason is that it may be interfered with by higher civilizations or even kept in captivity.
However, I personally think that there is another explanation, that is, although the base is large enough, theoretically there are other levels of civilization in other parts of the universe, but in addition to the high probability of staggering in time - human civilization is only a few thousand years, on the cosmic scale is just a moment, maybe there have been many civilizations in the universe, and even there have been many civilizations on the earth, but civilizations have eventually gone to destruction, leaving no trace with the passage of time, because the time span is too long, so that there is an insurmountable time difference between each civilization.
In addition, space will also be staggered - the universe is too big, the observable radius of the universe is 46.5 billion light years, from 1900, human beings have only used electromagnetic waves for more than 100 years, and the electromagnetic waves emitted by human civilization have only reached one third of the diameter of the Milky Way. Perhaps humanity had already turned to dust when aliens received electromagnetic waves emitted by human civilization.
I believe that there are other civilizations, but the possibility of meeting each other in the time period of the two civilizations is almost zero. On the earth, the East and the West can each develop different civilizations in different directions, and this is still the case for mankind itself, let alone the civilizations of different races. Besides, I don't think that the only way to transmit is electromagnetic waves, which humans can currently grasp and understand.
Also, in fact, the birth of human beings itself is a very low probability event, how low is this probability? If you have to explain it with theorems like the infinite monkey, it would be a bit of a sophistry. Don't just look at the number of stars in the universe and probability theory, first of all, the time factor and the propagation distance of light make it meaningful to have stars that are only a few hundred million light-years away from humans, and the light emitted by stars that are too far away is too early, and then there are no necessary conditions for the emergence of life.
Secondly, there are many stars in the universe, but the probability of life is not large, so it is important to analyze the size of the two, for example, the probability of naturally evolving a computer? I can't say that there isn't, but it's definitely close to zero, and it's almost impossible to happen in the universe. Cells are somehow more complex than computers.
Accidents in the universe will also occur frequently, such as meteorites or other disasters, making it difficult for extraterrestrial life to evolve into higher life, and it will continue to be extinct, and a few lower ones will survive and suffer disasters again. On Earth, the temperature, atmosphere, the influence of various microorganisms, etc., are slightly less than the current humans. Therefore, life may be all over the universe, but a civilization of this level like human beings may really win the only grand prize.
However, if this is really the case, if one day human beings can peek into the nature of the universe, human beings may also feel panic about the existence of loneliness, because human beings cannot communicate and share everything about the universe, and human beings have no way of knowing why they are conscious, what the significance of human existence to this empty universe, and there is no way to know where human civilization is going in the end.