What are the advantages of robotic exploration of the solar system? What are the limitations? Is there any situation where human exploration is better?
What are Dyson spheres? What would be involved in building one? How much energy would it cost, and could we ever pay it back?
What’s the temperature of deep space? Can it get any colder than that? How do we even define temperature when there’s nothing around?
How do we know that the universe doesn’t rotate? Why would it matter if it did? What does all this have to do with time travel?
What are blue straggler stars? How were they first discovered? What do they tell us about star clusters and the evolution of stars?