Are we alone in this universe? According to the logic of statistics, there may be other than us, which is the possibility that Fermi's paradox is trying to help us think about.
Given the plethora of stars that potentially host Earth-like planets, providing them with life-supporting conditions such as liquid water and a temperate atmosphere, alien civilizations may have already sprung up, flourished, and spread among the stars.
For these aliens, intergalactic travel can be a very easy task, like getting from home to the nearest restaurant.
If so, does this not mean that we do not need to search for them in worlds far from us, and instead; how are they going to try to contact us?
No doubt it's a frightening and exciting idea at the same time, but how will aliens communicate with humanity? A leaked secret document from the US National Security Administration reveals what some of the world's leading scientists assume about how it will allow aliens to contact the human race.
The aliens must be alive and constantly trying to communicate with us:
With the increasing development of human-created technology thanks to the advancement of experimental sciences, we have come to know new ways that intelligent aliens can penetrate the depths of the deep universe and communicate with us.
The growing consensus among scientists is that contact with alien civilizations may be inevitable, a feature of human evolution, societies and civilization—that is, it will happen, albeit unintentionally, quite naturally, like our spontaneous discovery of radioactivity, or our first steps on the moon.
"It's no longer just a fantasy, but a natural event in human history that may happen in the lives of many of us," reads the study, which has been declassified on the NSA's website.
Here we must recall what radio astronomer Sir Bernard Lovell once said: "There must be planets with the right chemistry, dimensions, and temperature to support organic evolution in our galaxy."
NASA research indicates that our galaxy has at least about 100 billion stars, and the maximum estimate is close to 400 billion.
As a reminder, aliens must meet some basic requirements in order to contact us. First, to try to communicate constantly, and not to give up on this idea. There is also a possibility that they have tried this for thousands of years and are waiting for our response. Finally, they must be alive or at least alive at the time the message was sent.