Our galaxy is huge. At over one hundred thousand light years in diameter, its seems to be huge, but when compared to other galaxies (like Andromeda, which is over 220,000 light years across) it seems small. And, well, the entire universe is over 93 billion light years across!
So, with all these planets, and potentially habitable planets, why have we found no other forms of life that aren’t native to Earth? Frank Drake (American astronomer and astrophysicist) formed an equation in 1961, titled “the Drake equation”, which would supposedly tell us how many inter-galactic civilizations there are; although there is a problem. The last 4 terms are estimates no one has solid numbers for, although Drake theorised that there should be 50 00 detectable civilisations in our universe.
11 years prior to formulation of this equation, Enrico Fermi -Italian physicist- often thought about whether or not we were alone in the universe, and it proceeded in him thinking about space empires (a civilisation that has permanently inhabited another planet). Fermi thought that it would only take 10 million years to inhabit every life sustaining planet, and considering the universe is 14 billion years old, 10 million is a flash!
And this gives rise to the Fermi Paradox. If everything could be inhabited, then why haven’t super intelligent aliens gone there yet?
Maybe aliens think we aren’t worth their time, or we’ve received signals, but we aren’t smart enough to find them. But since 1960, Drake and others have been emitting radio waves in hopes to find aliens. Or maybe civilisations don’t survive long enough to explore the galaxy; after all, it was the same Enrico Fermi who invented the atomic bomb.
Perhaps the conditions for life have only just become present, and the first life will be us...