I think the knowledge gap between humans and ants is less then humans/ alien species that traveled to earth. Hawking is right and we should avoid making contact with any alien species...Security through obscurity actually works well in this situation.
This is a pretty naive view of the universe. Humans have been civilized as we know it for what, 4000, 5000 years? In a little over 100 years we've gone from horse-and-buggy to detecting dark matter and building particle accelerators.
The universe operates on a time scale incredibly more significant than that, and so it's conceivable that there are intelligent beings that have been around for millions of years. Their technology and the form that they take would likely be so far beyond what we know that a similar gap in evolution would be entirely plausible.
