I think the most likely issue is that while there just has to be other life of varying intelligences around the universe given the sheer number of galaxies and stars, the odds of intelligence popping up at the same time are somewhat astronomical.
Our planet’s been around for 4.5 billion years. Homo Sapiens have been around for about 200,000 years. We just started using radio for less than 150 years. There’s a not-negligible chance we may wipe out our own species with engineered disease or war in the next hundred years or so if we don’t get some backup humans off-planet. (Thanks, religious fanatics with modern weapons!) So that’s a mighty short window to broadcast to another civilization.
If you look at history as a 24-hour day, even if two species pop up a couple of seconds from each other, they’ll likely miss the window to communicate with each other.
The only way contact is likely is if intelligent species can survive in a technological era for many thousands of years. That’s going to require other species to be a lot more reasonable than ours is proven itself to be so far.DennyA, Quarter to Three Forums
