Where do parallel universes exist? Could we use wormholes to travel to them? What does time travel have to do with all this?
What is the Fermi Paradox? How rare is non-intelligent vs intelligent life? What are the challenges a species must overcome to colonize the galaxy? Where is everybody?
Are dark photons as sinister as they sound? What did the curvaton do in the early universe? And is everything really made of preons?