Well we know they exist but what are they? They could be alien but as I have stated before they may be being operated by AI. We have barely scratched the surface involving AI, Think about what our technology on it will be a hundred years from now. OR, it could also be ours but UFO sighting have been around for hundreds of years. AI could withstand the long journey through space and could also withstand extremely high speeds close to the speed of light, or faster as some have opined. 25 years ago we had bag phones, now we have super computers in our pockets. Yes there is this quirky thing we call physics, but only as we know it. What did we know 150 years ago?
Angels are real. God does miracles, Angels use technology ... and there are good Angels and bad Angels. Angels exist physically in a different spacetime coordinate system, but we know from the Bible that they can come and go into our coordinate system. My bet is the UFOs are mostly bad Angels, and they are preparing The Great Lie to explain away the sudden departure of the Body of Christ Believers.