Are we alone in the universe? Many people who argue that alien life must exist say that it is impossible that Earth could be the only planet capable of sustaining life. They state that it seems only logical that if there is life on one planet that there would be life elsewhere. Skeptics fire back that if there was other life, it seems improbable that we would see no signs of it anywhere.
This debate is so common that it even has a name–the Fermi paradox. The paradox is quite simply that we seem sure that there must be alien life, but that we have never been able to find any existing life anywhere. Now, astrobiologists from Australian National University believe they know why this is the case–all of the alien civilizations are already dead.
In a new paper published in Astrobiology, the Australian National University researchers lay out a theory that holds that life on other planets likely developed quickly and then died out just as quickly. The scientists believe that other planets have conditions that are too unstable to support life over a long period of time.
The Australian National University paper posits that alien life may once have dwelt on Earth’s nearest neighbors Venus and Mars; however, about 1 billion years after the three planets formed, conditions on the neighboring planets turned oppressive. Temperatures became beyond sweltering on Venus, whilst Mars became frigidly cold. This is often referred to as the Gaian bottleneck, an extinction event that presumably affected the entire universe at once and left very few survivors.
The scientists responsible for the Australian National University paper believe that at that point all three planets had primitive life, but that the life forms on Mars and Venus were unable to adapt to the severe climactic changes. They actually credit the early lifeforms on Earth for giving off gases and creating conditions that helps to prevent our planet from going through the apocalyptic sort of changes that Venus and Mars did.
So if all of the alien civilizations have been wiped out does that mean that mankind is safe from total annihilation?
In a recent interview, Stephen Hawking said no.
The renowned theoretical physicist and cosmologist believes that mankind could become extinct, but not by an alien threat. He believes that ultimately, humans will destroy themselves.
During the interview, Stephen Hawking recounted a number of potential threats to the future of mankind. He said that human-caused global warming, nuclear war and genetically engineered microorganisms all had the potential to cause extinction events on Earth. Hawking said that the risks to humans will only increase as our technology continues to evolve. Quite simply, he believes that the more humans learn to do, the more ways we open ourselves up to a potential cataclysmic events.
On the other hand, Hawking feels that the extinction of mankind by natural causes is low. He believes that by the time a major astronomical natural disaster befalls the Earth, humans will already have set up colonies away from the Earth’s surface.