Scientists claim that humanity might not expect aliens to hear for 400,000 years

Scientists claim that humanity might not expect aliens to hear for 400,000 years ...

If there are so many galaxies, stars, and planets, where are all the aliens, and why haven''t we heard from them?

Those are the simple questions at the heart of the Fermi Paradox. A pair of scientists explain the next obvious question: how long will we have to endure to hear from another alien civilization?

How do they respond to their stories? 400,000 years.

A species that has only existed for a hundred thousand years and has only discovered agriculture 12,000 years ago has a long time.

If we want to hear from any other alien civilizations, 400,000 years is how long we''ll need to keep this human experiment going. That''s according to some new research into Communicating Extraterrestrial Intelligent Civilizations (CETIs).

The paper titled "The Number of Possible CETIs within Our Galaxy and the Communication Probability among These CETIs" is published in The Astrophysical Journal.

"As the only advanced intelligent civilization on the Earth, one of the most disturbing questions for humans is whether our existence is unique," says the authors.

"In the past few decades, there have been many studies on extraterrestrial civilization."

While it''s difficult to study something we''re even sure exists, there have certainly been instances of these events. But that isn''t the case.

It''s quite surprising that we only have one data point: humans on Earth. Yet many researchers have treated this issue as a thought experiment, using strict scientific guidelines. One study from 2020, for example, found that there are likely 36 CETIs in the Milky Way.

How many CETIs may exist is linked to how long we may have to wait to hear from one person.

"We have always wanted to know the answers to the following questions. First, how many CETIs exist in the Milky Way? This is a tricky question. We can only learn from one known data point (ourselves)," writes the authors.

The Drake Equation resides in this area. Based on our growing knowledge of the Milky Way, the Drake Equation tries to determine how many CETIs there may be in our galaxy.

The Drake Equation has its shortcomings, according to many critics. For example, some of its variables are little more than conjecture, and the number of civilizations it assesses isn''t reliable. However, the Drake Equation is more of a thought experiment than a real calculation. It requires us to start somewhere, and it gets us started.

A lot of work was done by the authors of this new study.

"Most research on this problem are based on the Drake equation," says the authors. "The obvious difficulty of this technique is that it is uncertain and unpredictable to estimate the likelihood that life might appear on a suitable planet and eventually develop into an advanced communicating civilization."

If you''re skeptical about any of these, you''re not alone. We can''t know scientifically how many other civilizations there are, or even if some exist. We''re not very well-versed enough. Studies like this are part of a constant conversation we have with ourselves about our situation. Each one one helps us think about our future.

So how did they finish with 400,000 years if we don''t even know how many CETIs there might be?

The pair of researchers aren''t the first to answer this question. Their paper outlines some of the previous scientific efforts to understand the incidence of other civilizations in the Milky Way. For example, they reference the study estimating that there are 36 CETIs in the Milky Way.

Calculations involving galactic star formation histories, metallicity distributions, and the possibility that stars will host Earth-like planets in their habitable zones matched that number.

"Che subject of extraterrestrial intelligent and communicative civilizations will remain in the domain of hypothesis until any positive detection is made," says the author.

They claim that scientists can still produce valuable models based on logical assumptions, which "may at least provide plausible estimations of the occurrence rate of such civilizations."

This review has a similar approach. Both of these are poorly understood. The first concerns how many terrestrial planets are habitable and how often life on these planets develops into a CETI. The second concerns at which stage of a host star''s evolution would a CETI be born.

In their calculations, the researchers provided one of these parameters a variable. The probability of life appearing and developing into a CETI is (fc), and the stage of the host star''s evolution is required (F).

Song and Gao created a series of Monte Carlo simulations using different values for these variables. They sat down at two scenarios: an optimistic outlook and a optimistic outlook.

The positive scenario used F = 25 percent andfc = 0.1 percent. So a star must be at least 25 percent into its lifetime before a CETI can emerge. For each terrestrial planet, there''s only a 0.1 percent chance of a CETI appearing.

Over 42,000 CETIs are created due to these optimistic variables, which sounds like a lot, but it isn''t when extended throughout the galaxy at different times. A third factor is that we''d need to last another 2,000 years in order to have two-way communication. That''s almost everything we need.

But that''s the optimistic scenario that makes the Universe seem like friends and inhabitable by other welcoming nations. Perhaps some of them are already talking to one another, and we need only to join in.

This is the moment in the pessimistic landscape.

F = 75 percent andfc = 0.001 percent in the pessimistic scenario. So a star can''t host a CETI until it''s much older, and the probability of any single terrestrial planet having a CETI drops to a tiny percentage. Where does this mean us?

In the Milky Way, this pessimistic calculation allows only about 111 CETIs. Even worse, we''d need to have another 400,000 years of two-way communication with them. (For perspective, Star Trek starts in the mid22nd century.)

Here''s where the Great Filter comes in. It''s what drives the matter from becoming life and then progressing towards becoming an advanced civilization.

When they write, the authors explain that topic:

"However, it has been proposed that the lifetime of civilizations is very likely self-limiting due to many potential limitations, such as population issues, nuclear annihilation, sudden climate change, rogue comets, ecological changes." If the Doomsday argument is correct, humans may not receive any signals from other CETIs before extinction.

The authors say that "the values offcand F are full of many unknowns." That''s the case in all of this type of work. This paper, and others that tackle the same issue, are more usefully seen as thought experiments than as solid results.

We can''t know any of this stuff without any certainty, but we cannot help but be obligated to investigate it. It''s part of human nature.

"It''s quite uncertain what proportion of terrestrial planets can lead to life," he says. Life''s transformation into a CETI and being able to detectable signals to space is extremely unpredictable.

Will humanity ever encounter another civilization? It''s one of our most compelling questions, and it''s almost certain that nobody today will ever have a clue.

First, there must be other CETIs, and then we must exist simultaneously with them and communicate somehow. It''s possible that another CETI had already detected life on Earth before they were destroyed by the Great Filter or by a natural catastrophe like a supernova explosion. We''ll never know.

Perhaps humanity will last a long time. Perhaps Earth will be rendered unhabitable, and humankind will flee to Mars or elsewhere. But would a Muskian outpost on a long-dead planet, populated by the bedraggled descendants of a ruined Earth, qualify as a CETI?

We like to imagine other civilizations having successfully conquered issues that we still struggle with. Will that be true? Or will the first CETI we discover be less than the descendants of a once-proud civilization that was triumphed in confidence until the Great Filter struck?

Who knows? If humanity ever does meet another technological species, it might be so far in the future that our descendants are almost unrecognizable from modern humans.

Perhaps we''ll never have a clue, and the Great Filter will halt us from finding one.

If humanity needs a goal, then it''s important to stick to that can keep hope alive. So, a dream of communicating with another CETI might do it.

This article was first published by Universe Today. Read the original article.

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