This is a great thread, I've learned much :thumbup: I've been interested in UFOs since the early 50's, when I was a kid
A few random thoughts, in no particular order:
Regarding the stone work at the Great Pyramids and Machu Pichu (spelling?): I think it had to be done by aliens. How were the stones so perfectly cut and how did they get there? There was a PBS special, challenging a couple of building contractors to make a small pyramid. They couldn't.
Another PBS special featured a man in Canada who cast a few 30-ton concrete columns. Using homemade levers and wheels and ramps and dirt-digging, he showed how he singlehandedly moved them, by himself, and placed them upright into an arch, a la Stonehenge.
Others have exclaimed that the ancient Egyptians oriented the pyramids to geographical true North and South, how could they do that since they knew nothing about the North and South poles? Any boy scout knows. The Egyptians were Sun worshippers, they oriented their square pyramids to East (the rising of the Sun) and West (the setting of the Sun). The other corners just fell into place, North and South, not that that was of any concern to them.
Much is made of the infinite number of stars, planets, and galaxies in the vast universe and that surely it is probable that other species like ours exist. Possible, but not necessarily probable. Probability is based on past experience, not future speculation. It is just as probable and possible, that we are the only ones of our type and alone in the universe. Given the thrust of our technology, we may become the aliens exploring the universe, and the seed population for future cultures. It will take a long time...we could be at the very birth of a vast exploration...if we don't destroy ourselves first.
I was intrigued by the recent comment by the physicist Stephen Hawking that it may not be in our best interests to try to contact alien species. They may be bent on colonization and exploitation, if not exploration for food supplies.
Some of these ideas are contradictory, but we know so little about what is happening.