Basically my thoughts. The speed of light, while the fastest thing we know, is as slow as smell on the scale of the universe. Any race of beings able to get here, check us out, and leave, would need technology that would break physics as we understand it. Not to say it's impossible, but we've now firmly stepped into beliefs, rather than anything based on observable data. Also, the notion of a race being so advanced they can travel faster than light accidentally crashing on our planet is pretty silly to me.