Have you heard of warp technology? Some places are starting to research it now, it will be interesting if it works. I'm sure shields will be developed to deal with this dust too. To say we'll never, ever get close to the speed of light is pretty naive I think. Almost certainly not within our...
I normally have this argument and use logistical challenges as my point, but they still could have harnessed some technology or loophole that we haven't discovered or even considered yet. I just think it's so overwhelmingly unlikely that they have visited us. And why the hell would they leave...