Is light made of waves or particles? Is matter made of waves or particles? What does it mean for matter to “wave”, anyway? Why is this so hard to understand?
What’s so bad about Venus, besides everything? How did it get so bad? And are we next?
What is the “cosmic calendar”? What are some important scales in the universe? Why is it so hard to judge “importance” of events?
What are galaxy clusters made of, besides galaxies? How can we use them to understand dark matter? And how can we make pretend ones on a computer?
What is “information” in physics? Why do we think it’s preserved, and what happens to information when it falls into a black hole? Why is this a problem?