Question: Are There Such Things as Aliens?

Mark Kennedy answered on 16 Nov 2016:

Probably – but we don’t know for certain.

We have never detected alien life of any kind (intelligent, or even just single cells). But here’s my reason for believing that there are aliens out there:

We think there are about 100,000,000,000 galaxies in the Universe. Each Galaxy has about 400,000,000,000 stars in them, and about 1/4 of those stars have planets.

Meaning there are maybe 10,000,000,000,000,000,000,000 planets in the Universe. The chances that there is just life on Earth, on just one of those planets, is tiny. So I think other planets probably have life.

Now, it might not be life like you and I know it. It might not be intelligent (it might just be a planet of little bugs). But that would still count as alien life.

PS: The idea that life should exist in the Universe, and yet we don’t see intelligent life, is called the Fermi Paradox (https://en.wikipedia.org/wiki/Fermi_paradox).

PPS: There might be alien life in our solar system. We’re looking at the oceans on the moons of Europa (which orbits Jupiter https://en.wikipedia.org/wiki/Europa_(moon)) and Enceladus (which orbits Saturn https://en.wikipedia.org/wiki/Enceladus)