BTW No quakes on Jupiter or the other gas giants.
Yes, we'd probably pick up a wormhole, but we might not detect a warp drive until after they'd arrived. It's hard to know what they might be using, since it's obviously going to have to be way beyond anything that we have now. I do believe that our first alien contact will be electromagnetic or, as you say, gravitational disturbance.
All of which suggests that a) Avi Loeb is an idiot who keeps seeing alien spacecraft where there aren't any and b) alien abductions aren't happening.
This does though not rule out alien visitors in the past who were mistaken for gods, as some believe. Could some of the biblical stories about people being "taken up" relate to a matter transfer or tractor beam? Would men in white space suits with jet packs be seen as angels? Was Ezekiel seeing a shuttlecraft? Were Joshua's trumpets actually sonic cannons? Did they teach the ancients how to build pyramids - up to a point?
I suspect we won't find out for sure in this lifetime, unless they make a return visit - which of course someone is supposed to have promised, and we're still waiting for
One exercise for when you're bored - on a train, flight or whatever - imagine you are abducted by an evil alien race. They want to learn the human reproductive process, and are forcing you to sleep with someone, or the planet gets destroyed. Mentally, you divide the species into 3 groups: those where you'd say Yes Please, those where it would be Okay If I Have To, and those whom you find so repulsive that you have to say Sorry Earth, Not Going To Happen.
Who is in your third group?
