Astronomers have found the first Earth-sized planet located in the habitable zone of a star — the right distance away to host liquid water and possibly life. Story here. The system is only about 500 light years away.
This of course raises the issue of the Fermi paradox: if there is even a tiny chance of intelligent life arising on such a planet, and many of the stars around which we would expect to find such planets are billions of years older than the sun, then why hasn't some intelligent species already colonized our galaxy in such a way that we would have observed it?
To my mind, there are only a few premises one can plausibly deny that give rise to the paradox.
One is that there is any substantial chance at all of life arising at all on a planet with conditions more or less like ours. I admit that it is possible for this premise to be false, but I don't begin to see how that could be. Given the hundreds of billions of stars in our galaxy alone, let alone our local cluster, the needed probability here would be so tiny.
The second is that there is no substantial chance of life in general evolving into a life form that has the intelligence and other capacities required to create technology. This also strikes me as implausible.
The third is that given enough time, such a life form would eventually be capable of colonizing a nearby planet. This one seems very likely to be true, given that such a capacity does not even seem wildly out of reach for us.
The forth is that such life forms aren't extremely unlikely to _want_ to colonize nearby planets. Given that life forms tend to grow exponentially in number, and the fact that planets have finite resources and a finite capacity to absorb waste, this also seems like a tough one to deny.
The fifth is that some such life forms would colonize planets exponentially. That is, for example, each colonized planet would go on to colonize two more planets. Or even 1.1 more planets, on average. To make the paradox go away, one would have to deny that a single intelligent life form that had a large head start on us ever did this.
Sadly, it seems to me that the easiest premise to deny is this sixth one: intelligent life forms are never able to develop the technology, cooperative effort, etc. required to colonize a planet BEFORE they either use up all the resources, or capacity to absorb waste, of their home planet.
What do readers think? What resolves the Fermi paradox?
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