GTP parent
Great piece! However, I think there's something you literally got "upside-down": AFAIK it's our head that ages slower than our feet, due to the face that it is moving faster.
Actually no. Gravity is slightly weaker at your head than at your feet (because it’s farther from Earth’s center). According to general relativity, clocks tick faster in weaker gravity. The effect of your head being higher up outweighs the fact that it’s moving slightly faster due to Earth’s rotation.
If you’re standing up, your head experiences more time than your feet, by about 6.2 nanoseconds per year. So your brain is slightly older than your toes.