Re: Life on Mars
The Solar System is 4.5 billion years old. The universe is 13 bn yrs, the galaxy 12 bn yrs. It is possible to imagine that life arose elsewhere in the galaxy 8 bn yrs ago. Ejected rocks carrying bacteria could move around the galaxy at, say, 20 miles per second, or c/10,000. In 1 bn yrs they would then travel 100,000 light years, the diameter of the galaxy.
So life starting at one point in the galaxy could spread all over. It would not have time, however, to reach the Andromeda galaxy.
This is, of course, the old panspermia hypothesis. Maybe one day we shall be able to test it.
Biting the hand that feeds IT
