do astronauts think there's life on other planets?
It's complicated.
The reason alien life seems likely is the same reason it's so hard to find. The universe is big. So freaking big.
"We've basically proven that every star has planets," said Canadian astronaut Chris Hadfield, who has spent 4,000 hours in space. "Then you start doing the math."
The math isn't easy. How many stars are in the universe? Well, that depends on the size of the universe. We're able to observe the cosmic microwave background (CMB), radiation formed around 400,000 years after the Big Bang. It tells us the observable universe goes back around 14 billion years. But there could be something beyond the CMB, or even other universes contained in a massive "multiverse."
Within the constraints of the observable universe, there could be 1,000,000,000,000,000,000,000,000 (or septillion) stars, according to astronomer David Kornreich. (He conceded to Space.com that the number could be a gross underestimate.)
If every one of those stars has at least one planet, then, well, it seems inconceivable that life wouldn't exist elsewhere.
Still, no evidence yet. The theme is clear: Life on Earth is miraculous. Out of a nearly infinite combination of possibilities, the conditions were right for single-celled organisms to rise from inorganic material, which evolved sheltered by Earth's magnetic field and ozone, with a bounty of oxygen and water to support them.
IMAGE: NATIONAL GEOGRAPHIC/NUTOPIA
"You look at all these systems … and it’s amazing all the things that have to come together to make this grand reality happen," Aronofsky said.
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