Question: “What if the Earth were made entirely of protons, and the Moon were made entirely of electrons?” (236).

The moon would have a huge amount of potential energy because its electrons would repel each other. General relativity shows that this much energy would warp space-time, subsuming the proton Earth and creating an electrically charged black hole as massive as the known universe.

Question: “If I pulled out my eyeball and aimed it so that it was looking into my other eyeball, what would I see (assuming the nerves and veins remain undamaged)?” (241).

You would see an eyeball, surrounded by double vision as the different views from each eye overlapped. There’s no need to remove an eyeball, however, since you can experience a similar effect by looking in angled mirrors.

Question: “If ALL of Japan’s islands disappear, would it affect Earth’s natural phenomena (plates, oceans, hurricanes, climate, and so on)?” (244).

The portion of Japan above sea level weighs approximately 440 trillion tons. If it disappeared, Earth’s center of mass and its axis of rotation would shift by a foot and a half toward Uruguay, on the opposite side of the world. The change in gravity would lower the sea level in East Asia by one to two feet and raise it around South America by the same amount.