The Milky Way (our galaxy) contains hundreds of billions of stars, and beyond it there are also hundreds of billions of other galaxies, each with its own set of stars, planets and other celestial bodies, leading us to accept the existence of planets very similar to Earth, with liquid water and potentially habitable atmospheres.
By Gonzalo Cáceres – journalist
The existence of intelligent life outside our world is one of the great enigmas that stimulate our experience as thinking and innovative beings. Consequently, the answer comes by its own weight, because logic dictates that it is difficult to accept that there is no one else in the neighborhood.
SIGNS
With the help of powerful space telescopes, probes, missions and other instruments, humanity has been able to begin the study of a tiny part of the universe in radio wavelengths, revealing phenomena such as pulsars, quasars and the cosmic microwave background, among others.
On August 15, 1977, the most important incident in the field took place. On that day, a SETI (Search for Extraterrestrial Intelligence) project at the Big Ear radio telescope at Ohio State University, under the command of astronomer Jerry Ehman, received a signal that lasted approximately 72 seconds. It was significantly more intense than normal background noise and appeared to be of origin outside the solar system.
This signal was centered around a frequency of 1420 MHz (a natural resonance of hydrogen, the most abundant element in the universe) and was so unusual that Ehman wrote “Wow!” in the margin of the printed data record. Despite many attempts to listen to it again, it was never detected again, leading to a flurry of speculation and debate about its origin.
Another important event came on October 19, 2017, when astronomer Robert Weryk with the Pan-STARRS1 telescope (Hawaii) spotted the first confirmed interstellar object to visit our solar system. They named it ‘Oumuamua’ (‘messenger from afar arriving first’ in Hawaiian).
According to calculations, ‘Oumuamua’ probably came from the direction of the Lyra constellation and passed close to the Sun. Due to its unique and mysterious characteristics (elongated, cigar-like shape, with dimensions of about 800 meters long and 80 meters wide) it raised speculations about its possible natural or artificial origin.
TOO MANY CHANCES
Why accept the existence of another form of intelligent life?
The various active research projects in astronomy and astrobiology have identified some 4,000 exoplanets, of which hundreds would have ecosystems that are conducive to life, to cite some of the most promising: TOI-700 d, LHS 1140 b and/or some exoplanets located in the (4) TRAPPIST-1 system.
But let’s look at something more concrete. Located about 1,400 light-years away in the constellation Cygnus, a serious candidate for hosting life is, for example, the exoplanet Kepler-452b. It is located within the habitable zone of a star very similar to the Sun, so similar to our world in size, orbit and composition that it received the nickname “Earth 2.0.”
Kepler-452b is speculated to have liquid water on its surface, raising the odds that it might at least harbor some form of plant or animal life. There are hundreds, and possibly billions, of other worlds like Kepler-452b waiting to reveal their secrets. How soon could we reach one of these planets? With current energy sources and transportation and propulsion technology, most likely never.
Assuming that among these billions of habitable worlds is one with intelligent life, a civilization as advanced or more advanced than our own, or with the technology to master deep space travel, why have they not contacted us? It must be understood that our current technology may not be sensitive enough to detect faint extraterrestrial signals, or we could be looking in the wrong part of the electromagnetic spectrum.
Thus, convinced of the existence of intelligent life somewhere in the cosmos, the scientific community leaned towards a series of theories that try to give logic to our ‘loneliness’:
BIG FILTER
The Great Filter theory posits that there is some kind of obstacle that prevents civilizations from advancing from simple stages (such as single-celled life) to complex life forms technologically capable of colonizing space. This filter could be related to catastrophic events, mass extinctions, or problems inherent to civilizations, such as self-destruction through weapons and/or climate change. Sound familiar?
ODORATION
But there is a line of theorists who suggest that complex, intelligent life could be extremely rare (not unique) in the universe. This could be due to specific conditions that favor the development of life, such as the long-term stability of a planetary environment or the existence of liquid water, among others.
It should also be noted that extraterrestrial life forms may be different in biological and cultural terms, and therefore their forms of communication could be radically different from ours.
DISTANCE AND TIME
The Milky Way, our galaxy, is estimated to have a diameter of approximately 100,000 light years (the distance light travels in one year in a vacuum, approximately 300,000 kilometers per second) which is equivalent to approximately 9.461 trillion kilometers.
The nearest star to our Sun, Proxima Centauri, is about 4.24 light years away and the center of the Milky Way is about 26,000 light years from our solar system, too far away.
Although alien life may exist, the distances between stars are so great that the time required for light and signals to travel between star systems may be prohibitive. This makes direct contact as well as the detection of weak radio or light signals difficult. In other words, the universe would be so ridiculously vast that it would hinder any form of contact.
STAGES
If they exist, extraterrestrial civilizations may not have reached a technological level advanced enough to be detected or to communicate effectively across interstellar space. Or they could be at a very different stage of development than ours, focused on other things rather than contact.
CONTACT US FOR WHAT?
On a philosophical level, extraterrestrial civilizations could choose not to reveal themselves and/or communicate with other less developed, or much more advanced, civilizations for various reasons, or to avoid interfering in their evolution.
We are not talking about an “ethical” issue here, but rather we can ask the question of whether they really consider us “advanced” or, at least, primitive and impulsive and a real danger to their own safety and existence.
THE LAST?
Planet Earth was formed approximately 4.5 billion years ago, and the first life forms emerged at 3.8 billion years. The first known link in the human evolutionary chain appeared between 6 and 7 million years ago, and modern man appeared “only” 200,000 years ago. Sumer, the first recorded human civilization, dates back about 6,000 years, and space exploration began just under 70 years ago. In other words, in terms of the cosmos, we are very green.
A much-discussed theory, one might even say depressing, states that perhaps humanity arrived late. That is, we would be the last, the last form of intelligent life.
DANGERS
We have gone from depression to fear, because there are also those who speculate that we would be much safer alone and in silence. The Dark Forest theory, although much debated, assumes that the universe would be like a huge, dense jungle, with an entire food chain.
And humanity would not be the strongest link in this chain, no. Rather, it would be protected by its still obsolete technology, which prevents it from standing out and consequently being exposed to the potential hostile beings lurking among the stars.
We must keep in mind that these theories are not mutually exclusive and that the answer to the great enigma may be a combination of multiple factors. Continued research in areas such as astrobiology, the search for exoplanets and the exploration of interstellar space will likely yield results in the future.
