By Jim O’Neal
I was discussing with friends the famous Fermi paradox, which raises the question: Why haven’t we detected signs of alien life, despite high estimates of probability – such as observations by the Kepler telescope of planets in the “habitable zone” around a Sun-like star and calculations of hundreds of billions of Earth-like planets in our galaxy that might support life?
Now, astrobiologists from Australian National University (ANU) Research School of Earth Sciences say they have the best answer: Because life on other planets would likely be brief and would become extinct quickly from runaway heating or cooling.
“The universe is probably filled with habitable planets, so many scientists think it should be teeming with aliens,” said Aditya Chopra, lead author of a paper published in Astrobiology. In fact, “early life is fragile, so we believe it rarely evolves quickly enough to survive. Most early planetary environments are unstable. To produce a habitable planet, life forms need to regulate greenhouse gases such as water and carbon dioxide to keep surface temperatures stable.”
For example, about 4 billion years ago, Earth, Venus and Mars may have all been habitable. However, a billion years after formation, Venus turned into a hothouse and Mars froze into an icebox. Early microbial life on Venus and Mars, if there was any, failed to stabilize the rapidly changing environment, while life on Earth played a leading role in stabilizing the planet’s climate.
The authors name this near-universal early extinction the “Gaian Bottleneck,” which also leads to the prediction that the vast majority of fossils in the universe (found in future meteorites, for example) will be from extinct microbial life, not from multicellular species such as dinosaurs or humanoids that take billions of years to evolve.
So far, that is the case.
The aliens are silent because they’re dead.
Intelligent Collector blogger JIM O’NEAL is an avid collector and history buff. He is President and CEO of Frito-Lay International [retired] and earlier served as Chairman and CEO of PepsiCo Restaurants International [KFC Pizza Hut and Taco Bell].