Question #13b41

1 Answer
Jun 12, 2016

In the universe there are 100 billions of galaxies with 100 billions of stars each, so 10 000 billions of billions (or 10^22) stars.
We are discovering today that almost every star has a planetary system around with some planet in the habitable region.
The possibility of life on another planet, in my opinion, is extremely high.

A civilisation is another story. We do not know how long a civilisation stays. We are no longer monkeys since 1 million of years and we have some technology since few thousand of years.

On a cosmic time this number is nothing. Just to give you an idea: imagine that the Universe is just one year long. It means that the 1st of January we had the Big Bang. Then, the solar system appeared the 19th of August, The Earth is completely formed the 18th of May, and we arrive the 31st of December at 21:11:03.
Our story is a bit more of 2 hours in one year of Universe.
The probability that another civilisation exists at the same time of our, it is a bit less probable (still not impossible).

About this question there is a famous answer from Enrico Fermi: "ok, but where is everybody?".
If there are aliens, with a more advanced technology than our, capable to move faster than light, why we never met anyone?
There are three possibilities:

  • there is nobody;
  • the speed of light is a real limit;
  • the aliens do not want to interact with us.

Difficult to say which theory is correct. Probably we need to study more, two hours are not enough to give a good answer.