15-30 Billion Earths: "Where is Everybody?"

Avatar do usuário Henry Cunha 9960 2 17 177
That's the estimate of how many habitable earths there might be in our Milky Way galaxy alone, according to data from the Kepler space mission. There's an interesting visual overview of the research at http://exoplanets.newscientistapps.com/.

Which leaves us with the conundrum of why we've never heard from any sentient beings from anywhere else in the galaxy. If they exist and know we are here, are they just ignoring us? Or is it a case of a time mismatch between civilizations at different stages of technological progress? Or are we (and they) simply not tuned to a common radio frequency? Will we ever know? I hope so.

The same question led Enrico Fermi to ask the famous question "Where is everybody?", the so-called Fermi Paradox. More (much more, with many hypotheses) on that at http://en.wikipedia.org/wiki/Fermi_paradox. I particularly like the "too far apart" hypothesis.

Food for thought, anyway.
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Avatar do usuário Marcio Osorio de Fa 1030 18
How many habitable earths do all the galaxies have, if I may ask?
Avatar do usuário OEstudantedeIngles 5450 2 16 106
Márcio, there exist 50 sextillion habitable planets. that's the number astronomers estimate for all the universe..

Avatar do usuário Daniel Reis 875 1 13

Vale a pena lembrar que quando fazemos ou vimos estimativas do genêro, estamos falando do universo observável, pois o real tamanho do universo, se é que existe um e se é que podemos expressar esse tamanho ou número, está além do nosso compreendimento.
Procurem por '' A lei de hubble - the hubble law'', é bastante interessante.

Avatar do usuário Marcio_Farias 12350 1 22 206
We can always find a planet we can go to in times of trouble, can't we?