The Sound of Silence
For retired astrophysicist Daniel Whitmire, currently a mathematics professor at the University of Arkansas (UARK), humanity is typical. Not exactly in the sense that we're ordinary; we're typical in a statistical sense, following a concept in modern cosmology called the principle of mediocrity. This principle suggests that in the absence of evidence to the contrary, we should consider humanity to be a typical member of a certain reference class.
This was Whitmire's conclusion, in a study published in the International Journal of Astrobiology, when he revisited his thoughts on the Fermi Paradox — that we haven't encountered alien life, despite the high probability of it existing — and again asked if there's alien life out there. With all the billions of stars in billions of galaxies, chances are there's bound to be other intelligent life in the cosmos. So, where are they?
“I used to tell my students that by statistics, we have to be the dumbest guys in the galaxy," Whitmire said in a UARK press release. "After all, we have only been technological for about 100 years, while other civilizations could be more technologically advanced than us by millions or billions of years.”
But Whitmire changed his mind on this concept based on two observations: Firstly, that humanity was the first technologically advanced civilization that evolved on Earth, and we're currently in our early technological development. ("Technological," here, is to be understood as biological species that developed electronic devices and are capable of significantly changing the planet.)
On the surface, this may seem like an obvious observation. However, based on the Earth's habitable time span — from around 5 billion years ago, and for an estimated billion years in the future — it would have been possible for other technological civilizations to precede us on this planet. The thing is, there's no geologic record that shows someone else came before us. “We’d leave a heck of a fingerprint if we disappeared overnight,” Whitmire said.
Anybody Out There?
But what about life outside of the Earth? Following the same principle of mediocrity, technological civilizations that lasts millions of years or longer are atypical, Whitmire says. If one considers a bell curve of all supposedly extant technological civilizations in the universe, humanity would fall in the middle 95 percent.
If that is the case, the lack of communication from similar civilizations around us does not bode well. Whitmire explains the silence of the cosmos as a product of how typical technological civilizations work: They usually go extinct after attaining technological knowledge. This is the same explanation held by other scientists, and one even suggests that we should look for traces of alien technology instead of alien life.
The "Great Filter" hypothesis is another possible explanation. It suggests that before any life in the universe becomes technological or before technological life goes beyond the bounds of its own planet, it had to overcome some extremely difficult evolutionary threshold. Some even think that climate change is humanity's great filter.
For resident "Science Guy" Bill Nye, the Fermi Paradox should push humanity to explore further. The reason why we haven't found intelligent extraterrestrial life or even simple alien life is because we haven't been looking hard enough. There's still a big chance that they're somewhere out there.
Yet these theories assume that we're not a typical representative of life in the cosmos. “If we’re not typical then my initial observation would be correct,” Whitmire said. “We would be the dumbest guys in the galaxy by the numbers.”