[OPINIONS] Extraterrestial life?

[PutraenusAlivius]

Do you guys believe in ET? I do.

There are millions of galaxies in the Universe, and there's a probability that 1 in 200 or so star systems have planets.
If we use Earth criteria which includes:

• Existence of H20
  
• Existence of O2 and C02
  
• Hydrocarbons
  
• Right temperature
  
• Similar to Earth pressure
  
• A viable atmosphere and magnetosphere
  
• In the hospitable part of a star
  

We would probably got 10 - 20 billion hospitable planets or so. But we used EARTH based systems. I mean do extraterrestial life follow Earth? I don't think so.
If we used that concept then the criteria should be:

• Hydrocarbons
  
• Right temperature
  
• A viable atmosphere and magnetosphere
  
• In the hospitable part of a star
  

By using that instead, then hospitable planets get to be 90 - 190 billion right? But what about intelligent life?
Since that is different, we have to use the same Earth criteria.
And out of approx. 90 - 190 billion hospitable life, approx. 10 - 20 billion may have intelligent life.

But, this is just my opinion. Please share yours here and probably you can discuss something.