Are we alone in the universe? The answer is almost certainly no. Given the vastness of the cosmos and the fact that its physical laws allowed life to emerge in at least one place—Earth—the existence of life elsewhere is guaranteed. But until now, despite looking for generations, we have not found it. In that time, however, we have learned enough to suggest that, while perhaps not alone, the interstellar gulf between us and our nearest neighbors effectively isolates us. That doesn’t mean we should stop looking, but we should manage our expectations and prepare for a long and lonely journey through space and time before we meet them, virtually or physically.
The possibility of alien life has been debated since ancient times. But rigorous searches have been available for less than a century, following an approach It was proposed for the first time in 1959 Physicists Giuseppe Cocconi and Philip Morrison demonstrated the feasibility of interstellar communications through radio telescopes. A year later, astronomer Frank Drake led the first Search for Extraterrestrial Intelligence (SETI) effort, Project Ozma, which used facilities at the National Radio Astronomy Observatory in Green Bank, W.Va., to search for such signals from suspected cosmic civilizations. In preparation for the project’s follow-up meeting, he developed his now famous “Drake equation”, a mathematical probability estimate for the number of communicable civilizations. NC, which may be in the Milky Way.
We are the products of progressive stages of evolution. With this in mind, the Drake equation can be formulated as:
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NC = astrophysical evolution × biological evolution × cultural evolution × technological evolution × life of a technological civilization
In this equation, each successive evolutionary phase arises from its predecessor. For us, this progression has taken almost the entire life of the Earth, about 4.5 billion years.
Attempts to “solve” the Drake equation have been hampered by insufficient knowledge of the probability of completing each evolutionary phase. However, modern observational advances now allow us to make much more reliable estimates of astrophysical evolution, especially by finding and studying what are considered “Earth-like” exoplanets in our galaxy, i.e. other rocky worlds in warm orbits around them. their stars Astronomers’ catalogs now boast more than 5,700 confirmed exoplanets, some of which reside in their star’s habitable zone, where starlight can heat liquid water on their surfaces. If we extrapolate these results to the entire Milky Way, the estimated number of Earth-like planets, NEit is about three billion. Knowing this empirical As a result, it is no longer necessary to include an estimate of the duration of a technological civilization in Drake’s equation, which can now be simplified:
Nc ≈ αNE
Here, the variable a (alpha) is the fraction of Earth-like planets that have reached the evolutionary thresholds associated with life, intelligence, and technology. Until alien life is discovered beyond Earth (or perhaps created in a laboratory), biological prerequisites a it will remain highly speculative, with considerations of earthly knowledge and technology even less constrained. For the sake of argument, let’s say there is a 100 chance of meeting each of these evolutionary thresholds. In that case:
a = 0.01 × 0.01 × 0.01 = 0.000001
That is, in this (probably optimistic) scenario, the chance that the evolution of an Earth-like planet would lead to a civilization capable of interstellar radio communication would be literally “one in a million”. If so, the number of communicative civilizations in the Milky Way today would be around 3,000. If their home worlds are evenly scattered among the hundreds of millions of stars in our galaxy, the average distance between them, Rs, It would be 3,000 light years. So contact by direct interstellar travel seems very unlikely. Even under ideal conditions, two-way communications via radio waves (or any other form of light) would take, on average, about 6,000 years, a timescale that can be challenging, to say the least, in terms of cultural longevity.
Therefore, as has been suggested many times in the recent past, interstellar communications between civilizations will necessarily be one-way, much like traditional radio or television broadcasts. The best example happened in our house just over 50 years agoWhen Frank Drake directed the transmission of a message to the globular cluster M13, 25,000 light-years away, through a powerful beam of radio waves 1,000 meters wide at the Arecibo Observatory in Puerto Rico. It was essentially a token effort—a tech demo that was only three minutes long—but it nonetheless marked a new evolutionary milestone for humanity.
Since then the chance of another planet emerging from the ravages of evolution is slim, suggesting that, of all the possible communicating civilizations in our galaxy, it may be the youngest and least advanced. Since it is technically easier than broadcasting radio waves, it makes more sense to be in the role of listener than transmitter. Less deliberate and targeted searches”technosignatures” from more advanced civilizations are possible. However a preliminary search 100,000+ galaxies yielded fewer than 100 targets for signs of hot debris from numerous extraterrestrial technologies exhibiting excessive infrared attractors (all of which can be explained without using pangalactic supercivilizations). This somewhat surprising conclusion, and the continued lackluster results of decades of radio SETI efforts, does not rule out the possibility that those efforts may eventually succeed, but it reinforces the fact that we are effectively on our own.
For now, our the best choice for finding life elsewhere and limiting value a will be on the lookout biosignatures in the atmosphere of a statistically significant exoplanet and, more precisely, by a deep search to live elsewhere within our solar system. These studies don’t take millennia. In fact, they can be completed during the human lifetime using existing technology. We are already in the process of launching fleets of robotic explorers search for life on marsalso in many cases Moons with oceans of giant planets. We are also planning advanced space telescopes, such as NASA’s Living World Observatory (could launch in the late 2030s or late 2040s) to spectrally probe dozens of potentially Earth-like worlds for signs of life.
With the odds looking so long, one might wonder why we even bother looking. Cocconi and Morrison had the answer to this from the very beginning, in their 1959 article “calculating the probability of success is difficult; but if we never seek, the chance of success is zero.’ Consider this: if only one they would get positive results from these searches, which would suggest that the universe is teeming with life. If all the results were negative, that would be the best empirical evidence yet that we are winners of a cosmic lottery, living in a highly prized planetary oasis in a vast galactic desert. If scientists could show that we could hit such a huge jackpot, would we care more about our world and each other so we don’t waste it? I like to think so.
This is an opinion and analysis article, and the views expressed by the author(s) are not necessarily their own. American scientific
