Why Haven't We Seen Aliens? Astrobiologists Explain Our Lack Of Encounters

With the probability that there are at least hundreds of habitable planets in our galaxy alone (never mind the fact that the universe is infinite, so that number is weak at best) alongside emerging evidence that plants like Mars likely once sustained life, you've probably wondered to yourself why we haven't seen aliens, or at least, why we don't know anything about them. Fortunately, science is here to offer us an explanation.

Astrobiologists at The Australian National University (ANU) have recently concluded that the universe is likely filled with habitable planets, but that they also probably went extinct very quickly. In research that was designed to understand how life develops on planets other than our own, scientists quickly discovered that any new life on another planet would die almost immediately due to the heating or cooling properties that are unlike those of Earth.

"The universe is probably filled with habitable planets, so many scientists think it should be teeming with aliens," said Dr. Aditya Chopra from the ANU Research School of Earth Sciences and lead author of the research, which was published in Astrobiology. "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."

Another theory that supports the idea is Gaian Bottleneck, or the idea that early extinction is inevitable. "One intriguing prediction of the Gaian Bottleneck model is that the vast majority of fossils in the universe will be from extinct microbial life, not from multicellular species such as dinosaurs or humanoids that take billions of years to evolve," said Associate Professor Lineweaver.

The research also argues that only about four billion years ago, Earth, Venus and Mars may have been habitable, however, Venus ultimately become too warm and Mars too cold. "Early microbial life on Venus and Mars, if there was any, failed to stabilize the rapidly changing environment," said co-author Associate Professor Charley Lineweaver. "Life on Earth probably played a leading role in stabilizing the planet's climate."

Dr. Chopra argued that the mystery as to why we haven't found signs of aliens has more to do with the "rapid emergence of biological regulation of feedback cycles on planetary surfaces" more than it does the likelihood of life or intelligence.

So there you have it: it's actually not a matter of whether or not extraterrestrial life exists (it does, it has, and it can), but whether or not the conditions are right for it to thrive and develop. It's a harsh universe out there. Perhaps we should remember that when this weekend's snow storm feels like the worst of things.

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