[allendale]

You either believe UFOs are mechanical entities from civilizations hundreds of light years away or you believe Einstein’s theory of relativity. You can’t believe both. Now that is not to say that advanced alien civilizations don’t exist or do not know we exist. Humans have been transmitting logical radio transmissions for over 120 years first in analog and the digitally. It is not unreasonable to assume an alien civilization say fifty light years away has heard them and learned much about us, our planet and its atmosphere. Now it would be a physical impossibility for a mechanical device carrying biological entities to actually visit but an advanced civilization could send radio waves that use our atmosphere as a video screen. This would account for sightings of rapidly moving images that leave no physical trace. Who knows? Perhaps there are a string of alien civilizations linked by long distance radio transmissions. Perhaps one day soon our computers may receive a truly wondrous transmission.

[RoosterRedux]

Some people are speculating that they're from Earth...moving in and out of a parallel dimension. Which is why these little gray aliens can walk through walls when entering bedrooms to abduct people.

The more that comes out about this stuff, the more it sounds "paranormal" and not so sci-fi. More like Amityville Horror than Close Encounters of the Third Kind.

[cgbg]

“You either believe UFOs are mechanical entities from civilizations hundreds of light years away or you believe Einstein’s theory of relativity. You can’t believe both.”

Yikes.

All you need are natural or artificial or combined wormholes/portals and all the “impossible” travel gets trivial in a hurry.

[Openurmind]

“Now it would be a physical impossibility for a mechanical device carrying biological entities to actually visit.”

By who’s level of technology? Not at all impossible for theirs. They can fold space and time.

https://youtu.be/p2hk8Qp8dd0

[curious7]

See Miguel Alqubierre. Has a theory of a way around GR limit.

[Hot Tabasco]

You either believe UFOs are mechanical entities from civilizations hundreds of light years away or you believe Einstein’s theory of relativity. You can’t believe both

Why is it necessary to believe in either one if we are experiencing visitations from a civilization perhaps a thousand years more advanced than us that has already overcome Einstein's theory and mechanical entities?

You're basing your assumption on what we know of today's limited knowledge of propulsion and even quantum physics.

Can you tell me with certainty what science and astro physics will discover and develop within the next 100 or 200 years?

Of course you can't......