If you take that most of the stars are like our sun or smaller, most are binaries, that the estimated mass of our galaxy alone is in 300 billion solar masses range, and we only sampled the closests stars from us and we found over 200 planets and most of them around stars that no one expected planets around or closer then we expected them to be the stars. The chances there are planets the same size as earth is probably high well at least I think so.

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If it's just us, it seems like an awful waste of space.
Contact Carl Sagan