DaHuuuuuudge on 27 April 2010
The big bang occured ~ 13.7 billion years ago.
Earth was formed ~ 4.57 billion years ago.
The first prokaryotes formed ~ 3.5 billion years ago.
Also, some people when hearing the term "ideal living conditions" seem to think that it means that earth was this temperature and oxygen levels were equil to those today, which is not true.
Early earth had
- Really high temperatures
- No oxygen, the only gasses were N2, CO2, H20, CO, and CH.
- Leathal (to humans) amounts of UV light.
Organisms are responsible to the oxygen on earth.
That being said, I believe that many planets are similar to what earth was, so I will have to say that most likely aliens exist.
