[Nateman]

While I’m not going to say there is no other intelligent life out there I am of the opinion it’s going to be very rare even among planets that have life. The reason comes down to one element : oxygen. The only element more electronegative is fluorine and with one rare exception it’s never found in its elemental state. So how did Earth end up with an atmosphere filled with this highly reactive element oxygen? Plants obviously pump out copious amounts of oxygen. So much so that it simply overwhelmed the Earth. After combining with nearly ever thing it touched it saturated the air to the point things became stable. (With the exception of fires every now and then).

Now why do plants pump out oxygen? It requires quite a bit of energy to bust up the water molecule to liberate oxygen yet after doing so the plant just throws this juicy bit of chemical energy away. Normally nature tries to minimize energy usage but in this case it was so wasteful nature succeeded in saturating an entire planet with the stuff! It must have required some extreme bit of luck to lock plants into such a wasteful expenditure of energy.

Oxygen reactions are so energetic they not only make fire possible it gives animals enough energy to move around. It’s this ability to move around and explore things that makes intelligent life a possibility. Plants are not known for their intelligence.

So far over 4000 exoplanets have been discovered . On one confirmed planet that had elemental oxygen , it was on a world so hot and close to its star the abundance of high energy was busting up molecules with oxygen.

I suspect it’s going to take looking at a lot more world’s before we ever find one with oxygen on it like Earth has.Perhaps mankind will someday find a world with elemental fluorine in its atmosphere, but I’m pretty sure I’m not going to be around to see that either.

[jmacusa]

Nitrogen and methane can support life. Honestly no one can prove there is life on other worlds nor can they prove there isn’t. But consider this, to think that the same conditions that made life possible here couldn’t exist under the same or similar circumstances is foolish. Any serious student of astrophysics and science would be laughed out of any laboratory or observatory.