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Using statistical models, scientists tried to answer questions about how long historical civilizations lasted and how long species lasted. The math shows that a file exists 10% chance that a civilization we can find is 10 times older than us.
Using statistical models, scientists tried to answer questions about how long historical civilizations lasted and how long species lasted. One of the first conclusions
According to a new statistical study, any intelligent civilization that Humanity can contact is likely twice the size of us and potentially much older.
The work, led by Columbia University’s Dr. David Kipping, is detailed in a new article in the International Journal of Astrobiology, which considers how humans could contact a billion-year-old civilization.
Understanding the importance of this question would require an estimate of the probability that a billion-year-old civilization exists. That’s not a particularly easy question to answer, as we have no direct evidence of billions of years of civilization.
However, the historical record provides two types of similar data sets, albeit on much smaller time scales: how long historical civilizations lasted and how long species lasted. The authors sought to find a statistical model that reasonably fit these two data sets, Universe Today reports.
Conveniently, both datasets adhere to a similar statistical model known as the exponential distribution. Exponential distributions are very common in statistics and, conveniently, they require only a single variable to determine the shape of the curve. In this model, the entire distribution is described by the half-life of a civilization. Historical data was still useful when looking for reasonable values of that parameter, the most suitable life span is about twice the current age of our civilization.
Dr. Kipping and his co-authors note that this exponential distribution, while a reasonable place to start extracting some details, is a simplification of what is likely to be a very complex calculation. Despite this simplification, the document can extract several ideas.
The average age of any potential extraterrestrial civilization is one such idea. The authors estimate that, on average, a civilization we detect will be roughly twice as old as ours. An interesting caveat here is that they do not directly establish the age of our civilization and point out that math works regardless of the age used. For example, if a person defines the age of our civilization as 12,000 years we have thrived, so civilizations are likely to continue to thrive in a detectable way for 24,000 years on average. However, this does not mean that civilization is destroyed at the end of that time period, it simply means that they are no longer doing what was used to define a “civilization”.
Another example shows how this might work. According to the author’s estimates, this is likely to be the case the lifespan of a civilization that emits radio waves into space is only 200 years, roughly double the lifespan of the 100 years we’ve already done. Around that time period, a civilization using radio would likely begin to use more advanced technologies that replace omnidirectional broadcast radio waves, such as lasers. So even though it has ceased to exist as a “radio station” civilization, its members are still alive and well using new, slightly less detectable technology.
Alternatively, we have also become more adept at seeing other potential characteristics of a technological civilization. Collectively, these characteristics are known as “technosignatures” and range from direct laser pulses to heat maps of exoplanets. Kipping points out that a new generation of telescopes will be able to detect some of these techno-signatures on nearby exoplanets, giving us insights into possible alien civilizations that we have never been able to observe before.
Another problem the paper addresses is the likelihood that a detected civilization is older or younger than us. This could have far-reaching implications for how, or even if, we decide to initiate first contact.
Exponential curves have a large part of the area under the curve (ie the total number of civilizations) at the bottom of the curve, with less and less in a farther extended “tail”. Using this exponential distribution curve, about 60% of civilizations are probably younger than us, while the 40% are probably older.
At first glance, this would imply that we are more likely to find a younger civilization than we are. However, this does not explain a phenomenon known as time distortion. Although there are more civilizations that have shorter lifetimes than ours, the fact that they have shorter lifetimes means that it is much less likely that we will end up existing at the same time as them.
This finding is the main conclusion of the article: that any civilization we detect is more likely to be older than us rather than younger. In fact, the math shows that a file exists 10% chance that a civilization we can find is more than 10 times older than us. If these civilizations follow the exponential technological growth curve that humanity has followed for centuries past, “the mind is bogged down on how far more advanced such a civilization could be,” notes Kipping.
He also noted that these statistical models have the most practical impact when considering civilizations of ambiguous technical capacity. If a civilization is considerably more advanced than us, such as one that can build a Dyson swarm (a star encased in a sphere to dominate its energy), there will be little doubt about what its technological capabilities are compared to ours. However, if we can detect a heat island on a nearby exoplanet, it could represent a civilization that is just past the stone age or that has already developed fully developed artificial intelligence.
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