The likelihood of alien life in the universe has decreased dramatically in the past hundred years. A hundred years ago, the possibility of moon men was considered to be realistic. Then we got obsessed about Martians until we landed probes there and found...just red sand and rocks. Oh, and NO canals. Then we figured SETI would detect intelligent life in the universe. So far...a big NOTHING.
If their are so many billions galaxies and of those
billion of stars stars each.(and many much older than us). We should have be n contacted by now.
Of course then thee is the Drake equation. Using the same phenomenal numbers…the odds we are alone are infinitesimally small. It’s just that through gazillion parsecs of space we haven’t been located yet.
And with the observation of other star systems we've found out how strange our own really is.
No hot Jupiter wiping out planets in the habitable zone.
No Super-Earth's with crushing gravity.
No planets at all within the orbit of Mercury.
The Earth itself with a large moon to stabilize wobbling and give a stable climate and a powerful magnetic field to hold it's atmosphere...
Of course SETI is only looking at the carrier wave WE use, which is actually a very small percentage of available carrier waves. We picked those to monitor because they’re easy. At least for our technology. Completely ignoring that somebody else might have invented something else and might find that section of the spectrum challenging. It’s a flawed project from the start.