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'Mirage Earth' Exoplanets May Have Burned Away Chances For Life
vinces99 writes: Planets orbiting close to low-mass stars — easily the most common stars in the universe — are prime targets in the search for extraterrestrial life. But new research led by an astronomy graduate student at the University of Washington indicates some such planets may have long since lost their chance at hosting life because of intense heat during their formative years. Low-mass stars, also called M dwarfs, are smaller than the sun, and also much less luminous, so their habitable zone tends to be fairly close in. The habitable zone is that swath of space that is just right to allow liquid water on an orbiting planet's surface, thus giving life a chance. [Researchers found] through computer simulations that some planets close to low-mass stars likely had their water and atmospheres burned away when they were still forming because they were exposed to high temperatures from their parent stars.
Earth has been advertising itself for more like a half-billion years. An atmosphere with free oxygen is rare, at least we haven't found one yet out of the explanets we've discovered. To be sure, we haven't studied the atmosphere on very many, but at the very least we know how to do so, at least for some.
There has been some suggestion of merely chemical processes that can give rise to free oxygen in the atmosphere, but I don't know how likely (or un) those processes are, and whether they cause the levels the Earth has, especially with traces of methane present at the same time.
We know our atmosphere has been biosculpted, and that would be something others could have seen for half a billion years.
One must assume that any alien civilization capable of interstellar travel would know at least as much as we do about the relevant technologies. That would include something Keplar-like, only better. You don't want to take your first interstellar steps to a place with no relevant planets.
The living have better things to do than to continue hating the dead.
Actually, given that there's 100-400 billion stars in the galaxy, and 0.001^4 works out to one in a trillion, that gives you about a 10 to 40% chance of there being one intelligent species in the milky way. /semantic
But I agree, in general. The odds of earth being the only planet with life at all in the whole galaxy...are pretty astronomical, in my opinion.