Where are all the aliens, and why haven't we heard from them?
The questions at the center of the Fermi Paradox are simple. In a new paper, a pair of researchers ask how long it will take to hear from another civilization.
Their answer was 400,000 years.
The species has only been around for a couple hundred thousand years and only discovered farming 12,000 years ago.
If we want to hear from alien civilizations, we need to keep this human experiment going for 400,000 years. According to new research, Communicating Extraterrestrial Intelligent Civilizations (CETIs) is a reality.
The paper is about the number of possible CETIs and the communication probability among them. The Department of Astronomy at Beijing Normal University has two authors. The paper was published in a journal.
As the only advanced intelligent civilization on the Earth, one of the most puzzling questions for humans is whether our existence is unique.
There have been many studies on extraterrestrial civilization.
It is difficult to study something we are not sure exists. That doesn't stop us.
Humans on Earth are the only data point we have for studying other civilizations. Many researchers have used rigorous scientific guidelines to tackle the question as a thought experiment. A study from 2020 concluded that there are at least 36CETIs in the Milky Way.
How long we might have to wait to hear from one of them is tied up.
We always wanted to know the answers to the questions. How manyCETIs exist in the universe? This is a difficult question. The authors write that they can only learn from a single point.
This is where the Drake Equation can be found. The Drake Equation tries to estimate how manyCETIs there may be based on our knowledge of the Milky Way.
Critics have explained the flaws of the Drake Equation. The number of civilizations it calculates isn't reliable because some of its variables are little more than conjecture. The Drake Equation is more of a thought experiment than a calculation. It gets us started when we start somewhere.
The authors of the new study got started too.
The Drake equation is the most popular method for determining the probability of life on a suitable planet.
You are not alone if you are skeptical about any of this. We don't know how many other civilizations there are. We are not knowledgeable enough. Studies like this are part of the ongoing conversation we have with ourselves. We can think about the context of our civilization with each one.
So how did they come up with 400,000 years?
The researchers are not the first to ask this question. Some of the previous scientific efforts to understand the incidence of other civilizations in the Milky Way are outlined in their paper. The 2020 study estimated that there are 36 CETIs in the Milky Way.
The number was derived from calculations involving star formation histories, metallicity distributions, and the likelihood of stars hosting Earth-like planets.
The subject of extraterrestrial intelligent and communicative civilizations will remain in the domain of hypothesis until a positive detection is made.
Scientists can still produce valuable models based on logical assumptions, that may at least produce plausible estimates of the occurrence rate of such civilizations.
Some of the same thinking is carried forward by this study. Two parameters are poorly understood. The first is about the number of planets that are suitable for life and the number of planets that evolve into aCETI. At the second stage of a host star's evolution would aCETI be born.
Each of these parameters was given a variable by the researchers. The stage of the host star's evolution required is (F), and the probability of life appearing and evolving into a CETI is (f c).
Song and Gao ran a series of Monte Carlo simulations using different values. They came up with two scenarios: optimistic and pessimistic.
The optimistic scenario used the values of 25 percent and 0.1 percent. A star needs to be at least 25 percent into its lifetime before it can be called aCETI. There is only a 0.1 percent chance of aCETI appearing on each planet.
It sounds like a lot, but it is not when spread throughout the galaxy at different times. We need to survive for another 2,000 years to achieve two-way communication. It almost sounds like it.
The optimistic scenario that makes the Universe seem friendly and inhabited by other welcoming civilizations is what makes it. Maybe some of them are already talking to each other, and we need to join in.
For the pessimistic scenario.
In the pessimistic scenario, F is 75 percent. The probability of any single planet hosting a CETI drops to a minuscule percentage when a star is much older. Where does this leave us?
The calculation produces only a small amount ofCETIs in the sky. We would need to survive another 400,000 years to have two-way communication with them. Star Trek starts in the 22nd century.
The Great Filter comes here. The Great Filter is the difference between life and advanced civilization.
The authors talk about that topic when they write.
"However, it has been proposed that the lifetime of civilizations is very likely self-limiting, due to many potential disruptions, such as population issues, nuclear annihilation, sudden climate change, rogue comets, ecological changes, etc. If the Doomsday argument is correct, for some pessimistic situations, humans may not receive any signals from other CETIs before extinction."
The values of c and F are full of unknowns according to the scientists in their paper. The paper and others that tackle the same question are more helpful than solid results.
We can't help but be compelled to explore it even though we don't know much about it. It is part of human nature.
The process of life evolving into a CETI and being able to send signals to space is highly unpredictable, and it is quite uncertain what proportion of planets can give birth to life.
Will humanity ever meet another civilization? It is almost certain that nobody alive today will ever have an answer to it.
We have to exist with other CETIs and communicate with them. It is1-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-6556 We will never know.
It is possible that humanity will survive a long time. Humans will flee to Mars or somewhere else if Earth is rendered uninhabitable. Would a Muskian outpost on a long-dead planet qualify as a CETI?
We like to think that other civilizations have been able to overcome problems. Will that be true? The descendants of a once-proud civilization that beamed with confidence until the Great Filter struck will be the first CETI.
Who knows? Our descendants are likely to be much different from modern humans in the future if we ever meet another technological species.
The Great Filter will stop us from finding an answer.
If humanity needs a goal, something to cling to that can keep hope alive.
The article was published by Universe Today. The original article is worth a read.
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