Although we can't currently be certain that these "earth like" planets discovered thus far are actually habitable at all. If they are and there are hundreds of advanced intelligent civilizations like ourselves, just in our own galaxy, it's one of those most heart breaking things that more than likely we will never hear from them. Since for most the light year distance will be much more than the alien civilization is likely to last before becoming extinct.
Even if one day we pick up an alien signal, chances are the civilization that it originated from has long been eradicated. Unless of course super advanced civilizations do exist and have mastered a life outside of their home planet.
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