Originally Posted by fdcg27
Surely we and our planet cannot be unique?
Whether we been visited or not is another question entirely.
This is my feeling on it.
If you look at the numbers, there's no way there aren't other Earths and other intelligent life. The galaxy, let alone the whole universe, is simply too large for other habitable planets not to have formed, and for there not to be other civilizations. I don't see how any thoughtful and reasonable person can not see it this way.
As far as whether we've been visited by extraterrestrial life from some of these other civilizations, I believe that we have. Again...just due to the numbers - in this case, the vastness of time. The galaxy is old. There are stars that are much older than the Sun, which have planets that are far older than Earth, and some of these planets are, no doubt, host to civilizations that have had the chance to surpass humankind's level of technological advancement beyond our wildest dreams... Most likely to the point of "cheating" the physical laws we're all slaves to...including the speed of light, and maybe even what we call time. I mean, just look at how far we've come in the last 100 years. We went from the Wright flyer in 1903, to men standing on the Moon, less than 66 years later! Now imagine a civilization that has a head-start on us of only a few thousand years. Think about where humanity was, say, 3000 years ago. We'd barely transitioned from the stone age into the iron age! Now think about someone from that era seeing a Boeing 747 fly over. Yeah. You start to get the idea of how relative progress between civilizations would look.
Now imagine a civilization that is hundreds of thousands of years, or even millions of years ahead of us. What they'd have...what they'd be capable of... It's enough to blow my mind.
To a civilization that advanced, it would be child's play to prevent us from knowing they were around. As far as the phenomena that have been observed, well, I don't know the answer to that.
Take a look at the Kardashev scale. Some of you are, no doubt, already familiar with it:
https://en.wikipedia.org/wiki/Kardashev_scale