Molecular machines are nano-scale assemblers that construct themselves and their surroundings into ever more complex structures. They're widely misunderstood, so let's separate the science fact from science fiction.
CERN is pimping some images of its newly renovated Large Hadron Collider today. It's an exciting upgrade for particle physics, but it also reminds me of the very first time CERN pimped some images on the web.
If it really came down to it, and you did have to defend yourself against an interstellar attacker, would a traditional gun actually be able to do the trick? Let's gaze at the idea, and crunch some numbers to find out.