The Fermi Paradox: Where the Hell Are the Other Earths?

S

Everyone feels something when they're in a really good starry place a really good starry place on a really good starry night and they look up and see this:

S

Some people stick with the traditional, feeling struck by the epic beauty or blown away by the insane scale of the universe. Personally, I go for the old "existential meltdown followed by acting weird for the next half hour." But everyone feels something.

Physicist Enrico Fermi felt something too"Where is everybody?"

A really starry sky seems vastbut all we're looking at is our very local neighborhood. On the very best nights, we can see up to about 2,500 stars (roughly one hundred-millionth of the stars in our galaxy), and almost all of them are less than 1,000 light years away from us (or 1% of the diameter of the Milky Way). So what we're really looking at is this:

S

When confronted with the topic of stars and galaxies, a question that tantalizes most humans is, "Is there other intelligent life out there?" Let's put some numbers to it (if you don't like numbers, just read the bold)

As many stars as there are in our galaxy (100 400 billion), there are roughly an equal number of galaxies in the observable universeso for every star in the colossal Milky Way, there's a whole galaxy out there. All together, that comes out to the typically quoted range of between 10^22 and 10^24 total stars in the universe, which means that for every grain of sand on Earth, there are 10,000 stars out there.

The science world isn't in total agreement about what percentage of those stars are "sun-like" (similar to our sun in size, temperature, and luminosity)opinions typically range from 5% to 20%. Going with the most conservative side of that (5%), and the lower end for the number of total stars (10^22), gives us 500 quintillion, or 500 billion billion sun-like stars.

Read more:
The Fermi Paradox: Where the Hell Are the Other Earths?