Do you believe in extraterrestrial life(aliens)?

[binary solo]

Out there, on their own planets, yes. Here on earth willingly secreted away in area 51, or Roswell New Mexico, no.

I imagine there are some pretty fundamental sociological principles that are necessary prerequisites to a species becoming technologically advanced. One of them being that over time the societies would tend towards greater cohesion and less violent conflict.

In our infinitesimally meager search of the galaxy so far how many planets have we found in the Goldilocks zone? I think it's about 2 or 3, but they have been gas giants so unlikely to support life as we might recognise it.

Essentially, all that's required for life to potentially develop (or maybe even be likely to develop) is liquid water, we think. As hydrogen and oxygen are pretty common throughout the universe water H2O is likely to be present on many planets. Life probably only needs an abundant liquid, so maybe life can develop in any liquid medium if there's a planet's load of the stuff. Who's to say that some sort of exotic life form couldn't form on a planet that has an abundance of liquid methane.

There's a theory that Jupiter's moon Europa might have liquid water under it's frozen crust. If there's plenty of liquid water under there then it's possible that simple life at least has developed.

Saturn's moon Titan has liquid methane lakes. And space scientists even talk about planets that exist in the "methane habitable zone" implying that liquid methane is a candidate substrate for life to develop. Titan also has water, but it's all ice given it's cold enough to support liquid methane in large quantities.

So my hypothesis is that any planet with large amounts of liquid anything (except maybe mercury) is more likely than not to evolve life.

Methane and Water are being found to be quite abundant substances