It would be very tough to win an arguement that aliens (if they exist) can't visit us, when it's impossible to articulate what type of form they may have, what sort of substances they are made of, what requirements they may have for existing, (they may have different nutritional needs then us. They may not breath oxygen as we do. They may not breath at all.) What kind of technology they have available.
For example, what if a thousand of them can condense themselves to fit into a space of one cubic meter? but their ship is ten times the size of the International Space Station, and they have an antimatter annialition propulsion technology?
The G forces is a minor problem, even for us at our level of knowledge.
G forces only occur during acceleration. Once the desired speed is achieved, they can coast for years, or even decades without slowing down significantly.
The arguement that aliens
can't come here is a loser.
But now if you were to argue the point that aliens
haven't come here, then there is no way you can lose.
Because the opponent has to prove absolutley that aliens have been here, and/or are here now. Which is quite impossible short of having a newsclip of their ship landing on the front lawn of the White House, and shaking hands, paws, tenticles or whatever with the President.
